Repeating Amino Acids Point to Important Structural Motifs in NS3 and NS5 Proteins of Flaviviruses

10 June, 2026

Background and Objective: Many studies point to conserved motifs in various proteins of the Orthoflavivirus genus. This study aimed to uniformly designate conserved motifs in two nonstructural proteins based on the “amino acid repeat” model and point out the connection, on the one hand, with their role in the functions of proteins and their role in the ecological strategy of the virus. Materials and Methods: It was supposed in the study, that some of the repeating amino acids in the protein sequence of the viruses remain conservative within a genus or a group and point to meaningful segments of the protein. The repeating amino acids were detected in all proteins of flavivirus, in the genomes of more than 70 virus types. The location of the repeats in the tertiary structure was analyzed. The position of conservative repeats in groups of viruses was associated, according to its vectors. Results: It was observed that NS3 and NS5 proteins have conservative repeats in different regions of the proteins. The genus-specific repeats QQ352-353 and KK461-462 of the interdomain region of the NS5 protein may be involved in blocking innate immunity through the STAT2 system. Also, group-specific repeats of a previously unexplored interface from the back side of EE438-439 helicase, RR450-451 and DDDD481-484, may be responsible for the difference in virus reproduction in ticks and mosquitoes. Conclusion: A method of amino acid repeats proves its effectiveness. Conservation of repeat within a genus may be important for virus survival. On the other hand, conservation of repeat within a group may have implications for viral propagation in a particular vector or host.

Comparative Study on Virus Inoculation Routes in Embryonated Chicken Eggs for Duck Plague Vaccine Production

10 June, 2026

Background and Objective: Duck Plague, caused by duck plague virus (DPV), leads to severe outbreaks in ducks, impacting poultry industries. Embryonated chicken eggs (ECEs) are widely used for DPV cultivation, but the optimal inoculation route remains unclear. This study evaluated the chorioallantoic membrane (CAM) and allantoic cavity (AC) inoculation routes in ECEs to optimize DP vaccine production by assessing harvested fluid yield and viral concentration from April to June, 2024. Materials and Methods: Ten days old ECEs were divided into six groups: E1, E2, E3, E4, E5 and E6. Each group had two categories: The CAM and the AC route of inoculation. Chicken fertile eggs were collected from the Government Central Poultry Farm, Mirpur and the Government Poultry Farm, Savar. The DPV, produced by the livestock research institute (LRI) at Mohakhali, had a titer of 10^3.5 chicken embryo lethal doses 50 (ELD₅₀) per 0.1 mL used for inoculation. The virus concentration in harvested fluid was measured by titration. The mean virus concentration and harvested fluid amount from CAM and AC inoculation routes were analyzed using a paired t-test and chi-square test in SPSS (Excel Window 16), with significance set at p<0.05. Results: The mean volume of harvested fluid for the CAM and AC routes of inoculation was 129.17 mL and 199.17 mL, respectively (p<0.05). The virus concentration of harvested fluid for the CAM route category in six groups, E1, E2, E3, E4, E5 and E6 was 10^5.83, 10^5.69, 10^5.65, 10^5.62, 10^5.87 and 10^5.42, respectively. On the other hand, the virus concentration of harvested fluid for the AC route category in six groups, E1, E2, E3, E4, E5 and E6 was 10^4.71, 10^5.17, 10^4.51, 10^4.54, 10^4.55 and 10^4.69, respectively. The mean virus concentration of harvested fluid in the CAM and AC route was 10^5.68 and 10^4.69, respectively (p<0.05). Conclusion: The CAM route of inoculation revealed a bit lower amount of fluid but had 10 times higher virus concentration than that of the AC route of inoculation, which could be beneficial for DP vaccine production.

International Journal of Virology - Current Issue

Repeating Amino Acids Point to Important Structural Motifs in NS3 and NS5 Proteins of Flaviviruses

Comparative Study on Virus Inoculation Routes in Embryonated Chicken Eggs for Duck Plague Vaccine Production