Field PRRS

Comparison of virus detection, productivity, and economic performance between lots of growing pigs vaccinated with two doses or one dose of PRRS MLV vaccine, under field conditions

2022-05-22T13:21:00.006-07:00

. 2022 May 13;204:105669.

doi: 10.1016/j.prevetmed.2022.105669.Online ahead of print.

Comparison of virus detection, productivity, and economic performance between lots of growing pigs vaccinated with two doses or one dose of PRRS MLV vaccine, under field conditions

Cesar A A Moura 1, Reid Philips 2, Gustavo S Silva 1, Derald J Holtkamp 1, Daniel C L Linhares 3

Affiliations

1Veterinary Diagnostic and Production Animal Medicine Department, College of Veterinary Medicine, Iowa State University, Ames, IA, USA.
2Boehringer Ingelheim Animal Health USA Inc., Duluth, GA, USA.
3Veterinary Diagnostic and Production Animal Medicine Department, College of Veterinary Medicine, Iowa State University, Ames, IA, USA. Electronic address: linhares@iastate.edu.

PMID: 35594607
DOI: 10.1016/j.prevetmed.2022.105669

Abstract

Porcine reproductive and respiratory syndrome virus (PRRSV) causes a significant economic impact on swine production. It has been demonstrated that PRRS modified-live virus (MLV) vaccination of pigs, with one full dose, significantly reduces clinical consequences of wild-type PRRSV infection compared to non-vaccinates. However, there is limited information about the effect that two doses of PRRSV MLV vaccine have on the performance of growing pigs, compared to vaccination with a single dose. This study was conducted with the objectives to compare (a) the wild-type PRRSV detection in oral fluids over time, (b) key closeout productivity indicators, and (c) economic performance between lots of growing pigs vaccinated with two doses of Ingelvac PRRS® MLV vaccine and lots vaccinated with a single dose of the same vaccine. This randomized field trial included 15 lots of growing pigs from PRRSV positive-unstable sow farms and 66 lots from PRRSV positive-stable sow farms, according to the American association of swine veterinarians' terminology. All pig lots received the first vaccination either around processing or weaning age. Lots allocated in the two doses group received the second vaccination three to four weeks after the first vaccination. The pig lots were monitored for PRRSV detection over time. Six oral fluids samples were collected in three weeks intervals and were tested for wild-type PRRSV-2 RNA by RT-qPCR and open reading frame 5 (ORF)- 5 sequencing. Regression models were used to compare wild-type PRRSV detection dynamics on oral fluids samples and to compare key closeout performance indicators between one dose group and two doses group. Additionally, a benefit-cost ratio analysis compared economic performance between one dose group and two doses group. The proportion of wild-type PRRSV detection on oral fluids samples and the log counts of viral RNA per ml of oral fluids from the two doses group was lower than the one dose group on lots originated from PRRSV positive-stable sow farms, with a risk ratio of 1.24 and a rate ratio of 1.17, respectively. The two doses group had a significantly lower mortality rate than the one dose group, with a rate ratio of 1.21. The effect size increased on lots originated from PRRSV positive-unstable sow farms, and on lots with higher frequency and diversity of wild-type PRRSV detection during the growth phase. No differences in growth performance were detected between two doses group and one dose group. The second MLV vaccination dose had a benefit-cost ratio of 1.83. For lots originated from PRRSV positive-unstable farms, the benefit-cost ratio was 4.45, and for lots originated from PRRSV positive-stable farms, the benefit-cost ratio was 0.45. Under study conditions, vaccinating growing pig lots with two doses of PRRS MLV vaccine was a useful strategy to immunize growing pigs against PRRSV, lowering the wild-type PRRSV detection, lowering mortality rate, and increasing profitability, compared to lots of growing pigs that received a single dose of the same vaccine.

Keywords: Field epidemiology; Growing pigs; PRRSV; Two MLV doses; Vaccination.

Safety of PRRSV-2 MLV vaccines administrated via the intramuscular or intradermal route and evaluation of transmission upon needle-free and needle delivery

2021-12-03T07:10:00.005-08:00

Sci Rep.

2021 Nov 29;11(1):23107. doi: 10.1038/s41598-021-02444-3.

Safety of PRRSV-2 MLV vaccines administrated via the intramuscular or intradermal route and evaluation of PRRSV transmission upon needle-free and needle delivery

Adthakorn Madapong 1, Kepalee Saeng-Chuto 1, Angkana Tantituvanont 2, Dachrit Nilubol 3

Affiliations

PMID: 34845289
PMCID: PMC8629989
DOI: 10.1038/s41598-021-02444-3

Free PMC article

Abstract

Two distinct experiments (Exp) were conducted to evaluate the shedding and efficacy of 2 modified live porcine reproductive and respiratory syndrome virus (PRRSV) type 2 vaccines (MLV) when administered intramuscularly (IM) or intradermally (ID) (Exp A), and the potential of PRRSV transmission using a needle-free device (Exp B). One-hundred fifty-four, 3-week-old castrated-male, pigs were procured from a PRRSV-free herd. In Exp A, 112 pigs were randomly allocated into 4 groups of 21 pigs including IM/Ingelvac MLV (G1), IM/Prime Pac (G2), ID/Prime Pac (G3), and non-vaccination (G4). Twenty-eight remaining pigs were served as non-vaccination, age-matched sentinel pigs. G1 was IM vaccinated once with Ingelvac PRRS MLV (Ing) (Boehringer Ingelheim, Germany). G2 and G3 were IM and ID vaccinated once with a different MLV, Prime Pac PRRS (PP) (MSD Animal Health, The Netherlands), respectively. Following vaccination, an antibody response, IFN-γ-SC, and IL-10 secretion in supernatants of stimulated PBMC were monitored. Sera, tonsils, nasal swabs, bronchoalveolar lavage, urines, and feces were collected from 3 vaccinated pigs each week to 42 days post-vaccination (DPV) and assayed for the presence of PRRSV using virus isolation and qPCR. Age-matched sentinel pigs were used to evaluate the transmission of vaccine viruses and were introduced into vaccinated groups from 0 to 42 DPV. Seroconversion was monitored. In Exp B, 42 pigs were randomly allocated into 5 groups of 3 pigs each including IM/High (T1), ID/High (T2), IM/Low (T3), ID/Low (T4), and NoChal. Twenty-seven remaining pigs were left as non-challenge, age-matched sentinel pigs. The T1 and T2, and T3 and T4 groups were intranasally challenged at approximately 26 days of age with HP-PRRSV-2 at high (106) and low (103 TCID50/ml) doses, respectively. At 7 days post-challenge, at the time of the highest viremia levels of HP-PRRSV-2, T1 and T2, and T3 and T4 groups were IM and ID injected with Diluvac Forte using needles and a need-less device (IDAL 3G, MSD Animal Health, The Netherlands), respectively. Same needles or needle-less devices were used to inject the same volume of Diluvac Forte into sentinel pigs. Seroconversion of sentinels was evaluated. The results demonstrated that PP vaccinated groups (G2 and G3), regardless of the route of vaccination, had ELISA response significantly lower than G1 at 7 and 14 DPV. PP-vaccinated groups (G2 and G3) had significantly higher IFN-γ-SC and lower IL-10 secretion compared to the Ing-vaccinated group (G1). The two different MLV when administered intramuscularly demonstrated the difference in virus distribution and shedding patterns. PP-vaccinated pigs had significantly shortened viremia than the Ing-vaccinated pigs. However, ID-vaccinated pigs had lower virus distribution in organs and body fluids without virus shedding to sentinel pigs. In Exp B, regardless of the challenge dose, sentinel pigs intradermally injected with the same needle-less device used to inject challenged pigs displayed no seroconversion. In contrast, sentinel pigs intramuscularly injected with the same needle used to inject challenged pigs displayed seroconversion. The results demonstrated the transmission of PRRSV by using a needle, but not by using a needle-less device. In conclusion, our results demonstrated that ID vaccination might represent an alternative to improve vaccine efficacy and safety, and may be able to reduce the shedding of vaccine viruses and reduce the iatrogenic transfer of pathogens between animals with shared needles.

PRRS Surveillance in breeding herds and nurseries using tongue tips

2021-11-29T06:31:00.007-08:00

Vet Sci

. 2021 Nov 2;8(11):259.

doi: 10.3390/vetsci8110259.

Porcine Reproductive and Respiratory Syndrome Surveillance in breeding Herds and Nurseries Using Tongue Tips from Dead Animals

Jordi Baliellas 1, Elena Novell 1, Vicens Enric-Tarancón 1, Carles Vilalta 2, Lorenzo Fraile 3 4

Affiliations

1Grup de Sanejament Porcí, 25192 Lleida, Spain.
2Upnorth Analytics, Arbeca, 25140 Lleida, Spain.
3Agrotecnio Center, 25198 Lleida, Spain.
4Departament de Ciència Animal, ETSEA, University de Lleida, 25198 Lleida, Spain.

PMID: 34822632
PMCID: PMC8625958
DOI: 10.3390/vetsci8110259

Free PMC article

Abstract

The detection capacity of Porcine Reproductive and Respiratory Syndrome virus (PRRSV) in tongues from dead animals in breeding herds (stillborns and piglets dying during the lactating period) and nursery farms (naturally dead animals) for PRRSV surveillance was evaluated. The samples were selected if pairs of serum and tongues were available from 2018 to 2020. Serum (pools of five) and exudate from tongues (one bag) were analyzed by PRRSV RT-PCR. The agreement between the serum sample procedure versus tongues exudate was assessed using a concordance test (Kappa statistic) at batch level. A total of 32 submissions, corresponding to 14 farms, had PRRSV diagnostic information for serum and tongues exudate. The overall agreement of batch classification as positive or negative, based on RT-PCR PRRSV results, between serum and tongue exudate of the 32 pairs was 76.9%. Cohen's Kappa was 0.55. The main discrepancy came from the presence of positive samples in tongues exudate and not in serum, suggesting that tongue exudate to monitor PRRSV seems to be more sensitive than serum. These results suggest that this sample procedure could be also used for PRRSV surveillance and monitoring.

Keywords: PRRSV; monitoring; swine; tongues exudate.

Next Generation of Voluntary PRRS Virus Regional Control Programs

2021-11-23T06:17:00.002-08:00

Front Vet Sci

. 2021 Nov 5;8:769312.

doi: 10.3389/fvets.2021.769312. eCollection 2021.

Next Generation of Voluntary PRRS Virus Regional Control Programs

Edison S Magalhães 1, Jeffrey J Zimmerman 1, Derald J Holtkamp 1, Dyneah M Classen 2, Douglas D Groth 2, Lauren Glowzenski 3, Reid Philips 4, Gustavo S Silva 1, Daniel C L Linhares 1

Affiliations

1Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA, United States.
2Carthage Veterinary Service, Ltd., Carthage, IL, United States.
3TriOak Foods Inc., Oakville, IA, United States.
4Boehringer Ingelheim Animal Health USA Inc., Atlanta, GA, United States.

PMID: 34805344
PMCID: PMC8602550
DOI: 10.3389/fvets.2021.769312

Abstract

Porcine reproductive and respiratory syndrome virus (PRRSV) became pandemic in the 1980's and today remains one of the most significant pathogens of the global swine industry. At the herd level, control of PRRSV is complicated by its extreme genetic diversity and its ability to persist in pigs, despite an active immune response. Ultimately, PRRSV control or elimination requires the coordination and active cooperation of producers and veterinarians at the regional level. Early voluntary PRRSV regional control programs focused on routine diagnostic testing and voluntary data-sharing regarding the PRRSV status of participants' herds, but no pre-defined action plans or decision trees were developed to secure project successes (or recover from failures). Given that control of PRRSV is paramount to producer profitability, we propose a coordinated approach for detecting, controlling, and ultimately eliminating wild-type PRRSV from herds participating in regional projects. Fundamental to project success is real-time, multi-platform communication of all data, information, and events that concern the regional project and project participants. New to this approach is the concept of agreed-upon action plans to be implemented by project participants in response to specific events or situations. The simultaneous and coordinated implementation of these strategies allows for early detection of wild-type PRRSV virus introductions and rapid intervention based on agreed-upon response plans. An example is given of a project in progress in the Midwest USA.

Keywords: PRRS (porcine reproductive and respiratory syndrome virus); elimination; monitoring; regional; swine.

Whole-herd risk factors associated with wean-to-finish mortality (in the US)

2021-11-22T06:43:00.005-08:00

Prev Vet Med

. 2021 Nov 18;198:105545.

doi: 10.1016/j.prevetmed.2021.105545.Online ahead of print.

Whole-herd risk factors associated with wean-to-finish mortality under the conditions of a Midwestern USA swine production system

Affiliations

PMID: 34801793
DOI: 10.1016/j.prevetmed.2021.105545

Abstract

Swine wean-to-finish (W2F) mortality is a multifactorial, dynamic process and a key performance indicator of commercial swine production. Although swine producers typically capture the relevant data, analysis of W2F mortality risk factors is often hindered by the fact that, even if data is available, they are typically in different formats, non-uniform, and dispersed among multiple unconnected databases. In this study, an automated framework was created to link multiple data streams to specific cohorts of market animals, including sow farm productivity parameters, sow farm and growing pig health factors, facilities, management factors, and closeout data from a Midwestern USA production system. The final dataset (master-table) contained breeding-to-market data for 1,316 cohorts of pigs marketed between July 2018 and June 2019. Following integration into a master-table, continuous explanatory variables were categorized into quartiles averages, and the W2F mortality was log-transformed, reporting geometric mean mortality of 8.69 % for the study population. Further, univariate analyses were performed to identify individual variables associated with W2F mortality (p < 0.10) for further inclusion in a multivariable model, where model selection was applied. The final multivariable model consisted of 13 risk factors and accounted for 68.2 % (R2) of the variability of the W2F mortality, demonstrating that sow farm health and performance are closely linked to downstream W2F mortality. Higher sow farm productivity was associated with lower subsequent W2F mortality and, conversely, lower sow farm productivity with higher W2F mortality e.g., groups weaned in the highest quartiles for pre-weaning mortality and abortion rate had 13.5 %, and 12.5 %, respectively, which was statistically lower than the lowest quartiles for the same variables (10.5 %, and 10.6 %). Moreover, better sow farm health status was also associated with lower subsequent W2F mortality. A significant difference was detected in W2F mortality between epidemic versus negative groups for porcine reproductive and respiratory syndrome virus (15.4 % vs 8.7 %), and Mycoplasma hyopneumoniae epidemic versus negative groups (13.7 % vs 9.9 %). Overall, this study demonstrated the application of a whole-herd analysis by aggregating information of the pre-weaning phase with the post-weaning phase (breeding-to-market) to identify and measure the major risk factors of W2F mortality.

Keywords: Mortality; Risk factors; Swine; Wean-to-finish; Whole-herd.

Emergence of a New Lineage 1C Variant of PRRSV-2 in the United States

2021-11-05T06:18:00.008-07:00

2021 Oct 18;8:752938. doi: 10.3389/fvets.2021.752938. eCollection 2021.

Emergence of a New Lineage 1C Variant of Porcine Reproductive and Respiratory Syndrome Virus 2 in the United States

Mariana Kikuti¹, Igor A D Paploski¹, Nakarin Pamornchainavakul¹, Catalina Picasso-Risso¹, Mark Schwartz^{1

2}, Paul Yeske³, Brad Leuwerke³, Laura Bruner³, Deborah Murray⁴, Brian D Roggow⁵, Pete Thomas⁶, Lori Feldmann⁷, Matt Allerson⁸, Melissa Hensch⁹, Tyler Bauman⁹, Brent Sexton⁹, Albert Rovira¹, Kimberly VanderWaal¹, Cesar A Corzo¹

Abstract

We report an ongoing regional outbreak of an emerging porcine reproductive and respiratory syndrome virus (PRRSV2) variant within Lineage 1C affecting 154 breeding and grow-finishing sites in the Midwestern U.S. Transmission seemed to have occurred in two waves, with the first peak of weekly cases occurring between October and December 2020 and the second starting in April 2021. Most of cases occurred within a 120 km radius. Both orf5 and whole genome sequencing results suggest that this represents the emergence of a new variant within Lineage 1C distinct from what has been previously circulating. A case-control study was conducted with 50 cases (sites affected with the newly emerged variant) and 58 controls (sites affected with other PRRSV variants) between October and December 2020. Sites that had a market vehicle that was not exclusive to the production system had 0.04 times the odds of being a case than a control. A spatial cluster (81.42 km radius) with 1.68 times higher the number of cases than controls was found. The average finishing mortality within the first 4 weeks after detection was higher amongst cases (4.50%) than controls (0.01%). The transmission of a highly similar virus between different farms carrying on trough spring rises concerns for the next high transmission season of PRRS.

Keywords: disease outbreak; epidemics; epidemiology; porcine reproductive and respiratory disease virus; swine diseases.

Copyright © 2021 Kikuti, Paploski, Pamornchainavakul, Picasso-Risso, Schwartz, Yeske, Leuwerke, Bruner, Murray, Roggow, Thomas, Feldmann, Allerson, Hensch, Bauman, Sexton, Rovira, VanderWaal and Corzo.

Efficacy of a Modified-Live PRRSV-1 Vaccine Administered to 1-Day-Old Piglets

2021-10-26T05:38:00.004-07:00

Pathogens

. 2021 Oct 18;10(10):1342.

doi: 10.3390/pathogens10101342.

Efficacy of a Modified Live Virus Vaccine against Porcine Reproductive and Respiratory Syndrome Virus 1 (PRRSV-1) Administered to 1-Day-Old Piglets in Front of Heterologous PRRSV-1 Challenge

Affiliations

PMID: 34684293
PMCID: PMC8537468
DOI: 10.3390/pathogens10101342

Free PMC article

Abstract

PRRSV is one of the most important viruses in the global swine industry and is often controlled by the use of modified live virus (MLV) vaccines. This study assessed the impact of a PRRSV-1 MLV vaccine applied to 1-day-old piglets challenged on day 28 of life with a PRRSV-1 field isolate (AUT15-33). Twenty-one piglets were vaccinated within 24 h of birth (T02), whereas 20 piglets were left unvaccinated (T01). Necropsy was performed two weeks post-challenge. Comparing the two groups, T02 piglets showed significantly higher (p = 0.017) average daily weight gain. In addition, significantly lower (p < 0.0001) PRRSV RNA loads were measured in serum of T02 piglets at all investigated time points. All T01 piglets were viremic and shed virus in nasal swabs, whereas only 71.4% and 38.1% of the T02 group were viremic or shed virus, respectively. Piglets from T02 had significantly higher numbers (p < 0.0001) of IFN-γ producing lymphocytes compared to T01. At necropsy, differences in gross and histologic lung lesions were statistically significant (p = 0.012 and p < 0.0001, respectively) between the two groups. Hence, this MLV vaccine administered to 1-day-old piglets was able to protect piglets against PRRSV infection at weaning.

Keywords: 1-day-old pigs; AUT15-33; IFN-γ; MLV; PRRSV; cellular immune response; shedding; vaccination; viremia.

Conflict of interest statement

M.C., G.T., M.B. and L.P.T. are employees from the sponsor company. They were involved in the design of the study, in sample collection, analyses of data and in the decision to publish the results as indicated in the Author Contributions

Disinfection and conditions associated with thermo-assisted drying and decontamination inconsistently produce negative PRRSV rRT-PCR results on metal surfaces

2021-10-03T12:54:00.003-07:00

Vet Microbiol

. 2021 Sep 20;262:109240.

doi: 10.1016/j.vetmic.2021.109240. Online ahead of print.

Disinfection and conditions associated with thermo-assisted drying and decontamination inconsistently produce negative PRRSV rRT-PCR results on metal surfaces

Rita Anne Neat 1, Zhang Jianqiang 2, Hai Hoang 3, Lauren McKeen 4, Christine L Mowrer 5, Derald J Holtkamp 6

Affiliations

1Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, 1800 Christensen Drive, Ames, IA, 50011, United States. Electronic address: ritaneat@iastate.edu.
2Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, 1800 Christensen Drive, Ames, IA, 50011, United States. Electronic address: jqzhang@iastate.edu.
3Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, 1800 Christensen Drive, Ames, IA, 50011, United States. Electronic address: hai.hoangthanh@hcmuaf.edu.vn.
4Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, 1800 Christensen Drive, Ames, IA, 50011, United States. Electronic address: lamckeen@iastate.edu.
5Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, 1800 Christensen Drive, Ames, IA, 50011, United States. Electronic address: clmowrer@iastate.edu.
6Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, 1800 Christensen Drive, Ames, IA, 50011, United States. Electronic address: holtkamp@iastate.edu.

PMID: 34600200
DOI: 10.1016/j.vetmic.2021.109240

Abstract

Because contaminated livestock trailers are a significant risk for transmitting viruses between herds, various methods of washing, disinfecting, and thermo-assisted drying and decontamination (TADD) have been evaluated for their effectiveness in inactivating porcine reproductive and respiratory syndrome virus (PRRSV) on contaminated surfaces. Information on when to expect negative qRT-PCR results after adequate trailer sanitation is lacking. The objective of this study was to evaluate whether there are conditions associated with washing-disinfectant-TADD procedures that will consistently produce a negative qRT-PCR result for the purpose of monitoring compliance with trailer sanitation and decontamination protocols for PRRSV on metal surfaces. 144 diamond plate aluminum coupons were spiked with PRRSV or phosphate-buffered saline (PBS) and treated with a designated disinfectant protocol. Disinfectants evaluated included multiple accelerated® hydrogen peroxide (AHP) disinfectants and a quaternary ammonium and glutaraldehyde combination disinfectant. Disinfectant was applied for 5 or 60 minutes of contact time at either 20 °C or -10 °C in a matrix of feces or PBS. All coupons were heated until the surface temperature of the coupon reached 71 °C and then held for 10 minutes to simulate TADD under field conditions. Post-treatment swabs for all treatment groups, except negative control groups, were positive by PRRSV qRT-PCR. Under the conditions evaluated in this study, consistently negative qRT-PCR results after treatments were not found. Therefore, for the purpose of monitoring compliance with trailer sanitation and decontamination protocols for PRRSV, alternatives to qRT-PCR should be explored.

Keywords: PCR; PRRSV; Swine; biosecurity.

Description of changes of key performance indicators and PRRSV shedding over time in a naïve breeding herd following a PRRS MLV exposure

2021-09-24T06:29:00.003-07:00

Transbound Emerg Dis

. 2021 Sep 23.

doi: 10.1111/tbed.14327. Online ahead of print.

Description of changes of key performance indicators and PRRSV shedding over time in a naïve breeding herd following a PRRS MLV exposure

Giovani Trevisan 1, Clayton Johnson 2, Neil Benjamin 2, Laura Bradner 1, Daniel C L Linhares 1

Affiliations

PMID: 34553831
DOI: 10.1111/tbed.14327

Abstract

Porcine reproductive and respiratory syndrome (PRRS) is an important economic swine disease. The usage of PRRS modified live vaccines (MLV) is the predominant breeding herd immunologic solution used in the United States to minimize the economic losses associated with wild-type PRRS infection. Most of the current information on the effects of contemporary PRRS MLV vaccination on breeding herd performance under field conditions comes from herds with previous PRRSV exposure. Hence, there is little information on key performance indicators (KPI) changes after the exposure to a PRRS MLV in PRRSV-naïve breeding herds. The main objective of this longitudinal observational study was to describe selected KPI changes in a naïve breeding herd after PRRS MLV exposure. The secondary objective was to describe the pattern of detection of PRRSV RNA by RT-qPCR in processing fluid samples. There were transient increases for mummies during weeks 4-23 (+0.86%); increased pre-weaning mortality on weeks 3-5 (+3.76%); decrease in live born on weeks 4-5 (-0.46) leading to a decreased pig weaned/litter on weeks 5-10 (-0.69), and increased repeated services on weeks 3-23 (+5.53%). Transient changes observed after PRRS MLV exposures did not moved total pigs weaned to outside the control intervals. Starting on week 83 and for 53 consecutive weeks, there was no PRRSV detection in processing fluids, even though two whole-herd MLV exposures occurred within that period. This article is protected by copyright. All rights reserved.

Keywords: KPI; PRRSV MLV vaccine; naïve breeding herd; swine.

Probability of PRRS virus detection in pooled processing fluid samples

2021-08-20T07:18:00.002-07:00

Vet Microbiol

. 2021 Aug 12;261:109190.

doi: 10.1016/j.vetmic.2021.109190.Online ahead of print.

Probability of PRRS virus detection in pooled processing fluid samples

Affiliations

1Veterinary Diagnostic and Production Animal Medicine Department, College of Veterinary Medicine, Iowa State University, Lloyd Veterinary Medical Center, 1809 S Riverside Dr., Ames, IA 50011-3619, United States; PIC North America, 100 Bluegrass Commons Blvd #2200, Hendersonville, TN 37075, United States.
2Veterinary Diagnostic and Production Animal Medicine Department, College of Veterinary Medicine, Iowa State University, Lloyd Veterinary Medical Center, 1809 S Riverside Dr., Ames, IA 50011-3619, United States.
3Veterinary Diagnostic and Production Animal Medicine Department, College of Veterinary Medicine, Iowa State University, Lloyd Veterinary Medical Center, 1809 S Riverside Dr., Ames, IA 50011-3619, United States; Pipestone Veterinary Services, 1300 US-75, Pipestone, MN 56164, United States.
4Department of Statistics, College of Liberal Arts and Sciences, Iowa State University, Ames, IA 50011, United States.
5Zoetis, Parsippany, NJ, United States.
6Veterinary Diagnostic and Production Animal Medicine Department, College of Veterinary Medicine, Iowa State University, Lloyd Veterinary Medical Center, 1809 S Riverside Dr., Ames, IA 50011-3619, United States. Electronic address: linhares@iastate.edu.

PMID: 34411996
DOI: 10.1016/j.vetmic.2021.109190

Abstract

There has been a tremendous increase in recent years of population-based diagnostic monitoring and surveillance strategies in swine populations. One example is the use of processing fluids (PF) to screen breeding herds for porcine reproductive and respiratory syndrome virus (PRRSV) activity. An important question from practitioners using such methods is on how intensively can the sample be pooled. More specifically, processing fluids of how many litters can be pooled into a single sample for diagnostic testing to preserve a high probability of PRRSV RNA detection at low prevalence situations? The objective of this study was to model the effect of pooling PF samples on the probability of PRRSV RNA detection. For this study, a PRRSV-positive PF field sample with a RT-rtPCR quantification cycle (Cq) value of 28 was selected to represent a litter of 11 pigs with a single viremic piglet. PF samples from a PRRSV-naïve herd were used to perform 6 replications of 8 two-fold serial dilutions of the PRRSV-positive sample, thus modeling the pooling effect (dilution). Each two-fold dilution represented an increase in the number of PRRS-negative pigs in the sample by a factor of 2. Samples were tested for PRRSV RNA by RT-rtPCR and the data was analyzed using linear and probit regression models. There was an average increment of 1.37 points in Ct for each two-fold dilution. The estimated probability of testing positive on RT-rtPCR was 43 %, 80 %, and 95 % when there was a single PRRSv-positive piglet among 784, 492, and 323 PRRSv-negative piglets contributing to the sample respectively. Results from this study support the practice of collecting and aggregating PF samples from multiple litters for PRRSV RNA testing.

Keywords: Monitoring; PRRS virus; Pooling; Processing fluids; Surveillance; Swine.

Factors associated with PRRS outbreaks in US breeding herds

2021-05-10T12:17:00.006-07:00

Prev Vet Med

. 2020 Oct;183:105128.

doi: 10.1016/j.prevetmed.2020.105128. Epub 2020 Sep 1.

Spatial relative risk and factors associated with porcine reproductive and respiratory syndrome outbreaks in United States breeding herds

Juan M Sanhueza 1, Mark A Stevenson 2, Carles Vilalta 3, Mariana Kikuti 4, Cesar A Corzo 4

Affiliations

PMID: 32937200
DOI: 10.1016/j.prevetmed.2020.105128

Abstract

Details of incident cases of porcine reproductive and respiratory syndrome (PRRS) in United States breeding herds were obtained from the Morrison's Swine Health Monitoring Project. Herds were classified as cases if they reported an outbreak in a given season of the year and non-cases if they reported it in a season other than the case season or if they did not report a PRRS outbreak in any season. The geographic distribution of cases and non-cases was compared in each season of the year. The density of farms that had a PRRS outbreak during summer was higher in Southern Minnesota and Northwest-central Iowa compared to the density of the underlying population of non-case farms. This does not mean that PRRS outbreaks are more frequent during summer in absolute terms, but that there was a geographical clustering of herds breaking during summer in this area. Similar findings were observed in autumn. In addition, the density of farms reporting spring outbreaks was higher in the Southeast of the United States compared to that of the underlying population of non-case farms. A similar geographical clustering of PRRS outbreaks was observed during winter in the Southeast of the United States. Multivariable analyses, adjusting for the effect of known confounders, showed that the incidence rate of PRRS was significantly lower during winter and autumn during the porcine epidemic diarrhea (PED) epidemic years (2013-2014), compared to PRRS incidence rates observed during the winter and autumn of PED pre-epidemic years (2009-2012). After 2014, an increase in the incidence rate of PRRS was observed during winter and spring but not during autumn or summer. Pig dense areas were associated with a higher incidence rate throughout the year. However, this association tended to be stronger during the summer. Additionally, herds with ≥2500 sows had an increased incidence rate during all seasons except spring compared to those with <2500 sows. PRRS incidence was lower in year-round air-filtered herds compared to non-filtered herds throughout the year. We showed that not only the spatial risk of PRRS varies regionally according to the season of the year, but also that the effect of swine density, herd size and air filtering on PRRS incidence may also vary according to the season of the year. Further studies should investigate regional and seasonal drivers of disease. Breeding herds should maintain high biosecurity standards throughout the year.

Keywords: Factors; Incidence; PRRS; Risk; Sow; Spatial.

Longitudinal piglet sampling in commercial sow farms highlights the challenge of PRRSV detection

2021-04-14T09:44:00.001-07:00

Porcine Health Manag

. 2021 Apr 12;7(1):31.

doi: 10.1186/s40813-021-00210-5.

Longitudinal piglet sampling in commercial sow farms highlights the challenge of PRRSV detection

Marcelo Nunes de Almeida 1, Cesar A Corzo 2, Jeffrey J Zimmerman 3, Daniel Correia Lima Linhares 3

Affiliations

1Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, 1811 Veterinary Medicine Annex, 1856 Christensen Dr. Ames, Ames, Iowa, 50011, USA. malmeida@iastate.ed.
2Veterinary Population Medicine Department, College of Veterinary Medicine, University of Minnesota, St. Paul, MN, USA.
3Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, 1811 Veterinary Medicine Annex, 1856 Christensen Dr. Ames, Ames, Iowa, 50011, USA.

PMID: 33845917
DOI: 10.1186/s40813-021-00210-5

Free article

Abstract

Background: Processing fluids (PF) and family oral fluids (FOF) are population-based surveillance samples collected from 2- to 5-day-old piglets and due-to-wean piglets, respectively. Although they are described for the surveillance of PRRSV in sows and piglet populations at processing and weaning, there is limited information on their use in commercial herds. This observational study described PRRSV RNA detection over time in PF, FOF, and piglet serum collected from farrowing groups in commercial breeding farms with the objective of achieving robust, practical, and effective PRRSV surveillance protocols. Weekly PF (an aggregate sample of all litters processed in a week from each room), and FOF (a convenience sample attempted from at least 20 individual litters in at least one farrowing room each week) samples were collected from six PRRSV-endemic commercial breeding herds for up to 38 weeks. A total of 561 PF room samples, 2400 individual litter FOF samples, and 600 serum samples (120 pools of 5 samples) were collected during the study period and tested for PRRSV RNA. Data were evaluated for patterns of PRRSV RNA detection by specimen within farms over time.

Results: In particular, the detection of PRRSV was commonly sporadic over time within farms (weeks of PRRSV RNA negative results followed by one or more weeks of positive results); was often non-uniform within farms (negative and positive farrowing rooms at a given point in time); and PF and FOF testing results agreement was 75 and 80% at week and room level, respectively, demonstrating that both sampling methods could complement each other. Non-uniformity in PRRSV detection in rooms sampled within the same week and detection after ≥11 consecutive weeks of PRRSV negative PF and FOF results underline the challenge of consistently detecting the virus.

Conclusions: These results suggest that monitoring protocols for breeding herds attempting PRRSV control or elimination can use both PF and FOF to improve PRRSV detection in suckling pig populations.

Keywords: Family oral fluids; PRRSV; Processing fluids; Serum; Surveillance; Swine.

PCR assay for specific detection of PRRSGard vaccine-like virus

2021-03-26T04:01:00.001-07:00

Transbound Emerg Dis

. 2021 Mar 24.

doi: 10.1111/tbed.14084. Online ahead of print.

Development and validation of a reverse transcription real-time PCR assay for specific detection of PRRSGard vaccine-like virus

Gaurav Rawal 1, Wannarat Yim-Im 1, Fabian Chamba 2, Chad Smith 2, Jeff Okones 2, Charles Francisco 2, Jianqiang Zhang 1

Affiliations

PMID: 33763963
DOI:10.1111/tbed.14084

Abstract

Increasing use of modified live virus (MLV) vaccines presents challenges to interpret positive results of porcine reproductive and respiratory syndrome virus (PRRSV) screening PCR that can detect both wild-type and vaccine strains. Instead, vaccine-specific PCR provides a convenient tool to detect vaccine-like virus from a sample. Here we report the development and validation of a real-time RT-PCR specific for PRRSGard® , a newly available commercial PRRSV-2 MLV vaccine. Analytical specificity, sensitivity, and diagnostic performance of PRRSGard PCR were evaluated and compared to a commercial PRRSV screening PCR (reference PCR). PRRSGard and reference PCRs did not cross-react with any of the 27 non-PRRSV swine pathogens. PRRSGard PCR did not cross-react with other PRRSV-2 vaccine viruses and 31 laboratory and field PRRSV-2 isolates representing various genetic lineages of PRRSV-2. PRRSGard and reference PCRs consistently detected up to 10-6 and 10-5 dilutions of PRRSGard vaccine virus, respectively. Based on testing serial dilutions of in vitro transcribed RNA, the 95% limit of detection of PRRSGard PCR was 16 genomic copies/reaction with CT cut-off value of 36 and 7 genomic copies/reaction with CT cut-off value of 37. Diagnostic performance of PRRSGard PCR was evaluated using 846 clinical samples (684 serum and 162 oral fluid samples). Compared to the reference screening PCR, diagnostic sensitivity, specificity, and agreement of PRRSGard PCR were 95.34%, 98.85%, and 97.52% with cut-off CT value of 36 and 98.14%, 96.56%, and 97.16% with cut-off CT value of 37. In addition, PRRSGard PCR was able to detect PRRSGard vaccine virus in a sample even with the co-presence of another PRRSV strain. In summary, in contrast to a reference screening PCR that detects both vaccine and field PRRSV strains, PRRSGard PCR provides a convenient tool to specifically detect PRRSGard vaccine-like virus and to inform PRRSV vaccination protocols.

Keywords: PRRSGard; PRRSV; Porcine reproductive and respiratory syndrome virus; Reverse transcription real-time PCR; Vaccine-like; reference screening PCR.

Commercial PRRS Modified-Live Virus Vaccines

2021-03-08T12:00:00.007-08:00

Review

. 2021 Feb 22;9(2):185.

doi: 10.3390/vaccines9020185.

Commercial PRRS Modified-Live Virus Vaccines

Chanhee Chae 1

Affiliations

PMID: 33671826
PMCID: PMC7926738
DOI: 10.3390/vaccines9020185

Free PMC article

Abstract

Porcine reproductive and respiratory syndrome (PRRS) virus (PRRSV) presents one of the challenging viral pathogens in the global pork industry. PRRS is characterized by two distinct clinical presentations; reproductive failure in breeding animals (gilts, sows, and boars), and respiratory disease in growing pigs. PRRSV is further divided into two species: PRRSV-1 (formerly known as the European genotype 1) and PRRSV-2 (formerly known as the North American genotype 2). A PRRSV-2 modified-live virus (MLV) vaccine was first introduced in North America in 1994, and, six years later, a PRRSV-1 MLV vaccine was also introduced in Europe. Since then, MLV vaccination is the principal strategy used to control PRRSV infection. Despite the fact that MLV vaccines have shown some efficacy, they were problematic as the efficacy of vaccine was often unpredictable and depended highly on the field virus. This paper focused on the efficacy of commercially available MLV vaccines at a global level based on respiratory disease in growing pigs, and maternal and paternal reproductive failure in breeding animals.

Keywords: modified-live virus vaccine; porcine reproductive; respiratory syndrome virus.

Conflict of interest statement

The authors declare no conflict of interest.

The impact of PRRSV genotypes, established on the basis of ORF-5 sequences, on three production parameters in Ontario sow farms

2021-03-08T12:00:00.003-08:00

Prev Vet Med

. 2021 Feb 23;189:105312.

doi: 10.1016/j.prevetmed.2021.105312.Online ahead of print.

The impact of porcine reproductive and respiratory syndrome virus (PRRSV) genotypes, established on the basis of ORF-5 nucleotide sequences, on three production parameters in Ontario sow farms

Dylan John Melmer 1, Terri L O'Sullivan 2, Amy Greer 2, Lori Moser 3, Davor Ojkic 4, Robert Friendship 2, Dinko Novosel 5, Zvonimir Poljak 2

Affiliations

PMID: 33676324
DOI: 10.1016/j.prevetmed.2021.105312

Abstract

The porcine reproductive and respiratory syndrome virus (PRRSV) is an enveloped RNA virus, with high mutation rates and genetic variability; which is evident by the large number of discrete strains that co-circulate in swine populations. Veterinary practitioners frequently identify certain discrete PRRSV strains as having a higher clinical impact on production. However, with exception of a few strains, production impact is not well characterized for the majority of PRRSV variants. Predictive analytics, coupled with routine diagnostic sequencing of PRRSV, provide opportunities to study the clinical impact of discrete PRRSV strains on production. Thus, the primary objective of this research was to evaluate clinical impact of discrete PRRSV clades observed in Ontario sow farms. PRRS viruses were classified into discrete clades using Bayesian analysis of the nucleotide sequences of the ORF-5 region of the genome. Production data were gathered through veterinary clinics from herds participating in the ongoing PRRSV surveillance system. Data about pre-weaning mortality, sow mortality, and abortion rates were measured up to 8 weeks post initial PRRSV outbreak. Through conventional regression analysis, results support that clinical impact of the viruses varied among clades over time for abortion rate (p = 0.05) and pre-weaning mortality (p < 0.01). Using predictive modelling approaches based on grouped K-fold cross-validation, it was identified that PRRSV clade designations and other measured factors showed low predictive performance for abortion (R2 = 0.07), pre-weaning mortality (R2 = 0.09), and sow mortality (R2 = 0.04). Clade designation consistently showed moderate importance for abortion and pre-weaning mortality, with clade 2 viruses being identified, on average, as having higher impact. These results demonstrate that the prediction of clinical impact, through production parameters, based on phylogenetic classification of PRRS viruses is possible. However, very high impact outbreaks were difficult to predict across production parameters. More surveillance-derived data are required to continue to improve predictive performance of the models.

Keywords: BEAST; Bayesian; Ontario; PRRSV; Phylogenetics; Porcine reproductive and respiratory syndrome; Predictive modeling; Random forest; Swine.

Effect of PRRSV stability on productive parameters in breeding herds of a swine large integrated group in Spain

2021-02-28T08:51:00.004-08:00

Porcine Health Manag

. 2021 Feb 26;7(1):21.

doi: 10.1186/s40813-021-00203-4.

Effect of PRRSV stability on productive parameters in breeding herds of a swine large integrated group in Spain

D Torrents 1 2, J Miranda 3, P C Gauger 4, A Ramirez 4, Dcl Linhares 4

Affiliations

PMID: 33637120
DOI: 10.1186/s40813-021-00203-4

Free article

Abstract

Background: In breeding herds, porcine reproductive and respiratory syndrome (PRRS) clinically manifests as increased abortions, number of stillbirths, and pre-weaning mortality, and as a direct consequence, results in a decrease of the number of piglets weaned per sow per year. Breeding farm classification according the PRRS virus (PRRSV) status (unstable or stable) is a key control strategy for this disease. The aim of this study was to evaluate the production improvement related to achieving a PRRSV stable status in breeding herds in Spain. For this purpose, epidemiological and productivity data were collected from a systematic PRRSV monitoring program in 35 breeding herds from a large integrated swine group in Spain. A comparative statistical analysis was conducted using four key production indicators (KPI) between different PRRSV status and a generalized linear mixed model: weekly abortions/1000 sows (ABTHS), born-alive rate (BAR), pre-weaning mortality rate (PWMR), and number of weaned piglets per 1000 sows (WPTHS).

Results: From the 35 monitored farms during a total period of 58 weeks, we collected 49 to 58 weeks of production data and PRRSV classification status for each study farm. This represented a total of 1997 (741 unstable and 1256 stable) weekly data collected that was eligible for the KPI comparative study. PRRSV stability was associated with significant improvement in BAR (+ 1.10 %, p < 0.001), PWMR (-0.88 %, p < 0.002) and WPTHS (+ 24.52, p < 0.0001).

Conclusions: These results demonstrate for the first time the improved production due to achieving PRRSV stability in breeding herds under field conditions in a European country. Increased number of born-alive piglets and a reduction of piglet pre-weaning mortality represents an increase of 1.28 weaned piglets per sow per year if PRRSV stability was achieved and maintained for one-year period in a breeding farm.

Keywords: Farm classification; Monitoring; Production parameters; Sows; Weaned piglets.

Antibody responses to PRRSv, IAV, and M. hyopneumoniae from weaning to the end of the finisher stage in fourteen groups of pigs in Ontario

2021-02-19T13:58:00.005-08:00

BMC Vet Res

. 2021 Feb 17;17(1):82.

doi: 10.1186/s12917-021-02756-6.

Antibody responses to porcine reproductive and respiratory syndrome virus, influenza A virus, and Mycoplasma hyopneumoniae from weaning to the end of the finisher stage in fourteen groups of pigs in Ontario, Canada

Elana Raaphorst 1, Abdolvahab Farzan 2 3, Robert M Friendship 4, Brandon N Lillie 1

Affiliations

PMID: 33596907
DOI: 10.1186/s12917-021-02756-6

Abstract

Background: Respiratory diseases are among the most important factors affecting swine farm productivity in Canada. The objectives of this study were to investigate antibody responses to porcine reproductive and respiratory syndrome virus (PRRSV), influenza A virus (IAV), and Mycoplasma hyopneumoniae (M. hyopneumoniae) from weaning to the end of the finisher stage on a subset of commercial swine farms in Ontario, Canada, and to examine the association between nursery diet and antibody responses.

Results: Overall, older pigs were more likely to test seropositive for PRRSV and less likely to test seropositive for M. hyopneumoniae (p < 0.001). Pigs were more likely to test seropositive for IAV at weaning and the end of the grower and finisher stages compared to the end of nursery (p < 0.001). Pigs that were seropositive for IAV were more likely to test seropositive for both PRRSV and M. hyopneumoniae (p < 0.001). Two, 9, and 4 groups that had more than 20% of pigs seropositive to PRRSV, IAV, and M. hyopneumoniae, respectively, from the end of nursery to the end of finisher were classified as seropositive. Pigs fed a plant-based (low complexity) diet during nursery were more likely to be seropositive for PRRSV (p < 0.001) but there were no significant differences in seropositivity to IAV or M. hyopneumoniae due to nursery diet complexity.

Conclusions: This study provides information regarding changes in serum antibody in pigs across different stages of production and highlights periods of vulnerability. Additionally, these findings may encourage further research into the effects of nursery diet complexity on disease susceptibility and immune response.

Keywords: Antibody response; ELISA; Influenza A virus; Mycoplasma hyopneumoniae; Nursery diet; Porcine reproductive and respiratory syndrome; swine.

Association of wild-type PRRSV detection patterns with mortality of MLV-vaccinated growing pig groups

2021-02-08T06:07:00.001-08:00

Prev Vet Med

. 2021 Jan 27;189:105270.

doi: 10.1016/j.prevetmed.2021.105270.Online ahead of print.

Association of wild-type PRRSV detection patterns with mortality of MLV-vaccinated growing pig groups

Cesar A A Moura 1, Reid Philips 2, Gustavo S Silva 1, Alejandro Ramirez 1, Phillip C Gauger 1, Derald J Holtkamp 1, Daniel C L Linhares 3

Affiliations

PMID: 33550121
DOI: 10.1016/j.prevetmed.2021.105270

Abstract

PRRS is a viral disease characterized by increasing reproduction losses in breeding herds and worsening performance of growing pigs, which leads to a considerable economic impact. A better understanding of the differences in the infection patterns of the virus in growing pig batches would help to develop cost-effective surveillance methods and disease control and elimination programs. Therefore, field studies documenting growing pig productivity according to the patterns of wild-type-PRRSV (wt-PRRSV) detection in the field are needed. This study was conducted with the objectives to (1) characterize patterns of wt-PRRSV-1 and wt-PRRSV-2 RNA detection over time in modified-live virus (MLV)-vaccinated batches of growing pigs raised in pig-dense regions of the USA; (2) compare wean-to-finish mortality among batches of growing pigs characterized with the different patterns of wt-PRRSV-1 and wt-PRRSV-2 detection; and (3) compare wean-to-finish mortality among batches of growing pigs characterized with the different patterns of wt-PRRSV-2 detection and vaccinated with two different doses of PRRS MLV vaccine. Eighty-one batches of growing pigs were originated from PRRSV positive-stable and unstable sow farms and vaccinated with two different doses of PRRS MLV vaccine. All batches were monitored for wt-PRRSV by testing six oral fluids every three weeks from weaning to marketing. Diagnostics were conducted to detect wt-PRRSV-1 and wt-PRRSV-2 by RT-qPCR testing and ORF-5 region sequencing. K-means clustering analysis was applied to identify batches sharing similar patterns of wt-PRRSV detection over time. Regression analyses were used to compare mortality among batches of growing pigs characterized with different patterns of wt-PRRSV detection over time. Thirty-eight percent of batches were detected with wt-PRRSV-1 during the growth phase, with three different patterns of detection. Detection of wt-PRRSV-1 was not associated with significant increase on mortality. Ninety-one percent of batches were detected with wt-PRRSV-2 during the growth phase, with four different patterns of detection. Batches originated from PRRSV positive-unstable farms had highest mortality rate (p < 0.0001) and were characterized as Unstable wt-PRRSV-2 detection pattern. Batches characterized with Early wt-PRRSV-2 detection pattern had higher mortality than batches characterized by Mid, Late and No wt-PRRSV-2 detection during the growth phase (p < 0.0001). Batches with Mid wt-PRRSV-2 detection had higher mortality than batches characterized with Late wt-PRRSV-2 detection (p < 0.0124). Mortality rate of batches characterized with Unstable and Early wt-PRRSV-2 detection patterns was lower when pigs were vaccinated with two doses of PRRS MLV vaccine, compared to batches that received only one dose. Results presented in this study suggested that early wt-PRRSV exposure on pig populations was associated with higher wean-to-finish mortality. Additionally, results suggested that vaccination with two PRRS MLV doses was associated with lower mortality rate, when growing pig populations had early wt-PRRSV exposure.

Keywords: Field epidemiology; Growing pigs; Mortality; PRRSV; Swine.

Survival of PRRSV and PEDV in compost formed from preprocessed carcasses

2020-10-12T06:27:00.006-07:00

Transbound Emerg Dis

Survival of swine pathogens in compost formed from preprocessed carcasses

Brent Pepin 1, Todd Williams 1, Dale Polson 2, Phillip Gauger 3, Scott Dee 1

doi: 10.1111/tbed.13876.

Abstract

An introduction of a Foreign Animal Disease (FAD) like African Swine Fever Virus (ASF) would be financially devastating. For example, ASF, a highly contagious pathogen with high mortality rates, is a World Health Organization reportable disease that has recently been spreading across Asia and Europe. Control of ASF would likely require mass euthanasia of infected and exposed animals similar to the United Kingdom's elimination of Foot and Mouth Disease (FMD). Subsequent disposal of infectious carcasses must adequately eliminate the virus and prevent further transmission of the disease. Although composting swine carcasses is widely used throughout the industry, limited data is available describing pathogen survival or elimination during this process. While current methods have evaluated the composting of swine carcasses under temperature-controlled settings, they have not considered the effects of adverse weather conditions (e.g., cold winter conditions) where composting is routinely performed. This study utilized preprocessing (grinding) of swine carcasses prior to composting, which decreases the amount of required carbon material and land space. The ability of composting to reduce the level of viral nucleic acid during cold weather conditions and the risk of environmental contamination that may occur during preprocessing was evaluated. In this study, pigs challenged with Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) and Porcine Epidemic Diarrhea Virus (PEDV), common domestic diseases, before euthanasia provided infectious carcasses containing pathogen surrogates. Composting of preprocessed carcasses achieved adequate temperatures necessary to eliminate FAD and common swine pathogens during cold weather conditions (monitored by compost temperature over time, virus diagnostic testing, and swine bioassay for PRRSV and PEDV). Under the conditions of this study, composting preprocessed carcasses presents minimal risk to air and groundwater contamination. In conclusion, composting preprocessed euthanized swine under adverse weather conditions is a safe and feasible option for mass disposal of infected carcasses.

Keywords: Compost; Grinding; PEDV; PRRSV; Pathogen; Pre-processing.

Spatial relative risk and factors associated with PRRS outbreaks in US breeding herds

2020-09-17T06:48:00.000-07:00

Prev Vet Med

. 2020 Sep 1;183:105128.

doi: 10.1016/j.prevetmed.2020.105128. Online ahead of print.

Spatial relative risk and factors associated with porcine reproductive and respiratory syndrome outbreaks in United States breeding herds

Juan M Sanhueza 1, Mark A Stevenson 2, Carles Vilalta 3, Mariana Kikuti 4, Cesar A Corzo 4

PMID: 32937200
DOI: 10.1016/j.prevetmed.2020.105128

Abstract

Keywords: Factors; Incidence; PRRS; Risk; Sow; Spatial.

Feasibility of oral fluid collection from pre-weaning piglets

2020-08-03T06:55:00.005-07:00

. 2020 Feb 13;9:100099.

doi: 10.1016/j.vas.2020.100099. eCollection 2020 Jun.

Feasibility of pooled oral fluid collection from pre-weaning piglets using cotton ropes

Gwenaël Boulbria 1, Valérie Normand 1, Mily Leblanc-Maridor 2, Catherine Belloc 2, Pauline Berton 1, Franck Bouchet 1, Arnaud Lebret 1

Affiliations

1Porc.Spective Swine Vet Practice, ZA de Gohélève, 56920 Noyal-Pontivy, France.
2BIOEPAR, INRA, Oniris, Université Bretagne Loire, 44307 Nantes, France.

PMID: 32734109
PMCID: PMC7386738
DOI: 10.1016/j.vas.2020.100099

Free PMC article

Abstract

Collection of pooled oral fluid (OF) by allowing pigs to chew on a cotton rope is an alternative to blood sampling. However, little is known about the applicability of this method to suckling piglets. The objectives of the present study were to describe the spontaneous interaction of suckling piglets with a rope and to investigate the influence of a rope pre-exposure on the success rate of sampling. We studied the interaction dynamics of 21 and 28 days-old suckling piglets with a cotton rope presented for 30 min. Ropes were manually wrung out inside plastic bags to release the oral fluid. A total of 49 litters were included. Percentages of success of pooled OF collection for 28-day-old, 21-day-old and 21-day-old pre-exposed litters were 82%, 62% and 100%, respectively. The mean volume collected did not differ between groups. Without pre-exposure, 84.7% and 95% of piglets interacted spontaneously with the rope at 21 and 28 days of age, respectively. The latency between rope presentation and interaction was highly variable between piglets within litters: from < 10 s to 30 min. Among piglets having interacted with the rope, the interaction lasted for at least 60 s for 90% and 91.4% of 21 and 28-day-old piglets, respectively. Pooled OF collection is achievable prior to weaning in piglets of at least 21 days of age. Pooled OF sampling is representative at litter level if collection is successful. In order to improve the success rate of collection, pre-exposing the piglets with a rope one day prior to sampling is effective.

Keywords: Diagnostic; Disease surveillance; Oral fluid; Pig; Suckling piglets.

Use of a Demonstration Project to Evaluate Viral Survival in Feed: Proof of Concept

2020-06-15T09:12:00.002-07:00

. 2020 Jun 14.

doi: 10.1111/tbed.13682. Online ahead of print.

Use of a Demonstration Project to Evaluate Viral Survival in Feed: Proof of Concept

Scott Dee 1, Apoorva Shah 2, Roger Cochrane 1, Travis Clement 3, Aaron Singrey 3, Roy Edler 1, Gordon Spronk 1, Megan Niederwerder 4, Eric Nelson 3

PMID: 32536022

DOI: 10.1111/tbed.13682

Abstract

In 2014, the hypothesis that feed ingredients could serve as vehicles for the transport and transmission of viral pathogens was proposed and evaluated by multiple investigators under laboratory conditions. In an attempt to validate these data, we used a demonstration project to test whether three significant viruses of swine could survive in feed ingredients under real-world shipping conditions. Samples of soybean meal (organic and conventional), lysine, choline, and vitamin A were spiked with a mixture of PRRSV 174, PEDV, and SVA and transported for 21 days in the trailer of a commercial transport vehicle, encompassing 14 states and 9741 km. Samples were tested for viral genome and viability at the end of the transit period. Regarding viability, PRRSV, PEDV and SVA were all detected as infectious in bioassays following inoculation with both soy products. In addition, viable PRRSV and SVA were detected by bioassay pigs inoculated with samples of vitamin A and infectious SVA was detected in pigs inoculated with samples of lysine and choline. These results provide further evidence that select viral pathogens of pigs can survive in certain feed ingredients during commercial transit.

Keywords: animal feed; demonstration project; proof of concept; swine viral diseases.

Studies on Heterologous Protection Between Japanese PRRSV-1 and PRRSV-2

2020-05-26T06:18:00.004-07:00

. 2020 May 22.

doi: 10.1292/jvms.20-0122. Online ahead of print.

Studies on Heterologous Protection Between Japanese Type 1 and Type 2 Porcine Reproductive and Respiratory Syndrome Virus Isolates

Hiroshi Iseki 1, Kenji Kawashima 1, Michihiro Takagi 1, Tomoyuki Shibahara 2 3, Masaji Mase 1 4

Affiliations

1Division of Viral Disease and Epidemiology, National Institute of Animal Health, National Agriculture and Food Research Organization.
2Division of Pathology and Pathophysiology, National Institute of Animal Health, National Agriculture and Food Research Organization.
3Department of Veterinary Science, Graduate School of Life and Environmental Sciences, Osaka Prefecture University.
4United Graduate School of Veterinary Sciences, Gifu University.

PMID: 32448816
DOI: 10.1292/jvms.20-0122

Abstract

The objective of the present study was to evaluate the cross-protective immunity between type 1 and type 2 porcine reproductive and respiratory syndrome virus (PRRSV) isolates in growing pigs. Japanese type 1 PRRSV, first isolated from a pig with respiratory disorders in a farm in 2009, exhibits unique genetic characteristics. The pathogenicity of a Japanese standard strain of type 2 PRRSV, EDRD1, in pigs immunized by the type 1 PRRSV isolate, Jpn EU 4-37 was determined by evaluating clinical signs, viremia, antibody response, and pathological lesions. Similarly, we evaluated the pathogenicity of Jpn EU 4-37 in pigs immunized by EDRD1 and compared the cross-protective immunity between these isolates. The EDRD1 challenge after Jpn EU 4-37 inoculation reduced viral clearance and shedding in pigs, compared to those treated with the EDRD1 single infection. On the other hand, the pathogenicity of Jpn EU 4-37 after EDRD1 infection did not differ significantly compared to non-immunized pigs treated with Jpn EU 4-37. Therefore, exposure to Jpn EU 4-37 could not induce enough immunity to reduce the viremia against subsequent infection by type 2 PRRSV. However, the immunity induced by Jpn EU 4-37 infection may play a role in reducing viremia caused by type 2 PRRSV. Moreover, the immunity induced by the EDRD1 and other genetically related viruses, which are broadly distributed in Japan, may not contribute to cross-protection against Jpn EU 4-37 as an emerging virus.

Keywords: immunity; pig; porcine reproductive and respiratory syndrome virus.

Practical Aspects of PRRSV Detection in Processing Fluids

2020-05-21T06:49:00.000-07:00

. 2020 May 4;180:105021. doi: 10.1016/j.prevetmed.2020.105021.Online ahead of print. Practical Aspects of PRRSV RNA Detection in Processing Fluids Collected in Commercial Swine Farms
Will A López 1, Jeffrey J Zimmerman 2, Phillip C Gauger 2, Karen M Harmon 2, Laura Bradner 2, Min Zhang 3, Luis Giménez-Lirola 2, Alejandro Ramirez 2, Jean Paul Cano 1, Daniel C L Linhares 4

Veterinary Diagnostic and Production Animal Medicine Department, College of Veterinary Medicine, Iowa State University, Lloyd Veterinary Medical Center, 1809 S Riverside Dr., Ames, IA 50011-3619, United States; PIC North America, 100 Bluegrass Commons Blvd #2200, Hendersonville, TN 37075, United States.

Veterinary Diagnostic and Production Animal Medicine Department, College of Veterinary Medicine, Iowa State University, Lloyd Veterinary Medical Center, 1809 S Riverside Dr., Ames, IA 50011-3619, United States.

Department of Statistics, College of Liberal Arts and Sciences, Iowa State University, Ames, Iowa 50011, United States.

Veterinary Diagnostic and Production Animal Medicine Department, College of Veterinary Medicine, Iowa State University, Lloyd Veterinary Medical Center, 1809 S Riverside Dr., Ames, IA 50011-3619, United States. Electronic address: linhares@iastate.edu.

PMID: 32428814
DOI: 10.1016/j.prevetmed.2020.105021

Abstract

Processing fluid samples are easily collected under field conditions and provide the means to test more piglets more frequently in a practical way, thereby improving PRRSV surveillance. However, a deeper understanding of the diagnostic characteristics of this newly described sample type is still required. Therefore, the objective of this field-based study was to determine the relationship between viremic piglets and the detection of PRRSV RNA in processing fluid samples. In two PRRSV-positive breeding herds, processing fluids (n = 77) and individual piglet serum samples (n = 834) were collected from 77 litters in three sampling events and tested for PRRSV RNA. Among the 77 litters in the study, 55 litters (71.4%) contained no viremic piglets and processing fluids tested negative for PRRSV RNA. Among the 22 (28.6%) litters with ≥1 viremic piglets, 10 litters contained a single viremic piglet and 5 of the 10 processing fluids from this group tested positive for PRRSV RNA. Based on a fitted mixed effects logistic regression model, the probability of detecting PRRSV RNA in processing fluids was highly dependent on the number of viremic piglets contributing to the sample. When the within-litter prevalence was ≥39%, the probability of detecting PRRSV RNA in processing fluids was ≥95%. By extension, the results suggest that pooling processing fluids from several litters increases the probability of PRRSV RNA detection because of the greater likelihood of including multiple litters each with ≥1 viremic piglets. In contemporary breeding herds that use processing fluid samples for PRRSV surveillance, the diagnostic costs associated with testing 100% of the processing-age piglet population can be estimated at €0.077 ($0.086 USD) per pig weaned. In contrast, to achieve an equivalent testing coverage with the use of individual piglet serum samples, the diagnostic costs associated would be €4.48 ($5.00 USD) per pig weaned. Processing fluid represents a practical, reliable and efficient method to surveil breeding herds for PRRSV because it allows for continuous surveillance at a low cost.

Keywords: Monitoring; PRRS virus; Processing fluids; Surveillance; Swine.

Understanding and interpreting PRRSV diagnostics in the context of “disease transition stages”

2020-04-30T13:50:00.000-07:00

https://doi.org/10.1016/j.rvsc.2020.04.023

Highlights

•: PRRSV infection is characterized by changes in its tissue distribution over time.
•: Therefore, the rate of PRRSV detection varies over time by specimen-assay selection.
•: The choice of specimen-assay must be tailored to specific PRRSV testing objectives.

Abstract

Herein we review broad issues that affect test performance for agents that produce persistent infections. Using PRRSV as an example, the relationship between “disease transition stages” and “diagnostic transition stages” is discussed using meta-analyses of diagnostic data (n = 4307 results) from the refereed literature to highlight the key issues. Although diagnostic technology will continue to improve, it may be concluded from the analysis that there can be no single best diagnostic approach; rather, the choice of specimen and test must be tailored to the specific testing objective. In most cases, meeting the testing objective(s) will require the use of more than one assay and/or specimen type.