Genetic characterization of newly emerging avian reovirus variants in chickens with viral arthritis/tenosynovitis in Israel

In recent years, new avian reovirus (ARV) variants caused a variety of symptoms in chickens worldwide, the most important of which was Viral arthritis/tenosynovitis which caused substantial economic losses and has become a concern to the worldwide chicken industry. In this study, we characterized emerging ARV variants in Israel and analyzed their genetic relationship with reference strains. One hundred thirty-four ARV variants were isolated from tendons and synovial fluids of commercial broiler chickens with signs of arthritis/tenosynovitis. Phylogenetic analysis of the partial segment of the sigma C (sigma C) gene confirmed that these field isolates from Israel could be clustered into all six known clusters. The majority of ARV isolates in Israel belonged to the genotypic cluster 5 (GC5). The strains in this study had a low sequence identity when compared to the commercial vaccine (strain S1133). The findings of this study demonstrated the genetic diversity of ARV strains in Israel from 2015 to 2022. It is reasonable to conclude from the preliminary results of this investigation that Israel has not been subject to selection pressure or the emergence of new ARV variants since the introduction of the live vaccine (ISR-7585). Due to the ongoing emergence of ARV variants, a robust epidemiological monitoring program supported by molecular biology techniques is required to track ARV strains in Israeli poultry flocks.

Automated summary

In recent years, new variants of avian reovirus (ARV) have caused a variety of symptoms in chickens worldwide, including viral arthritis/tenosynovitis. This study analyzed emerging ARV variants in Israel and found significant genetic diversity. Most ARV isolates in Israel belonged to genotypic cluster 5 (GC5). The study suggests that Israel has not experienced the emergence of new ARV variants since the introduction of the live vaccine (ISR-7585), but ongoing monitoring is needed due to the continuous emergence of ARV variants.