The present invention relates to novel strains of avian reovirus isolated from severe cases of Runting Stunting Syndrome in young broiler chickens in southeast United States. The invention is directed to avian reoviruses that impair digestion in poultry, diagnostic assays using nucleotide- or amino acid-specific components of such viruses, and to vaccines that protect chickens from disease caused by such viruses. Nucleotide sequences for the S1 gene, encoding the sigma C minor outer capsid protein, were amplified, and the nucleotide and predicted amino acid sequences were compared with sequences from other recently isolated reovirus field isolates and vaccine strains. Antigenic and molecular characterization of the newly isolated reoviruses revealed a lack of homogeneity with current U.S. isolates, with less than 60% percent amino acid similarity across the sigma C protein. Sequence comparisons with previously reported malabsorption isolates from Europe and Asia revealed a higher amino acid similarity, approaching 80%.
