A Snapshot on the Genomic Epidemiology of Turkey Reovirus Infections, Hungary

SIMPLE SUMMARY: A genomic epidemiological study was conducted to describe the genetic diversity within turkey reoviruses circulating in Hungary. Phylogenetic analyses confirmed that turkey reoviruses comprise a well determined genetic clade; however, evidence shows occasional genetic interaction between turkey reoviruses and reoviruses of other avian species. A better understanding of the source and the route of reovirus infections in the field requires extended sampling of strains from additional geographic areas and from different phases of turkey production. ABSTRACT: Reovirus infections in turkeys are associated with arthritis and lameness. Viral genome sequence data are scarce, which makes an accurate description of the viral evolution and epidemiology difficult. In this study, we isolated and characterized turkey reoviruses from Hungary. The isolates were identified in 2016; these isolates were compared with earlier Hungarian turkey reovirus strains and turkey reoviruses isolated in the 2010s in the United States. Gene-wise sequence and phylogenetic analyses identified the cell-receptor binding protein and the main neutralization antigen, σC, to be the most conserved. The most genetically diverse gene was another surface antigen coding gene, μB. This gene was shown to undergo frequent reassortment among chicken and turkey origin reoviruses. Additional reassortment events were found primarily within members of the homologous turkey reovirus clade. Our data showed evidence for low variability among strains isolated from independent outbreaks, a finding that suggests a common source of turkey reoviruses in Hungarian turkey flocks. Given that commercial vaccines are not available, identification of the source of these founder virus strains would permit a more efficient prevention of disease outbreaks before young birds are settled to fattening facilities.