Avian reoviruses (ARVs) are considered as an important cause of several diseases in poultry, particularly arthritis and tenosynovitis. Tenosynovitis and arthritis, which are among the causes of chronic lameness in breeder flocks, can result in reduced egg production and culling of breeder hens. In this study, the molecular characteristics of ARVs in some broiler breeder flocks were investigated in Iran. After RNA extraction of the field samples, reverse transcription-polymerase chain reaction (RT-PCR) was performed to amplify two regions of ARVs for S1 and S4 genes. The positive samples were further analyzed by five restriction enzymes in restriction fragment length polymorphism (RFLP) for determining the strains. The phylogenetic analysis of S1 and S4 genes from the isolates indicated divergence into five and four major lineages, respectively. The sequence analysis of S1 and S4 genes of ARVs revealed that most of the positive samples were closely related to tenosynovitis-inducing ARVs (with less than 2% nucleotide divergence). Also, these samples were most homologous to S1133 strain, with 99.90% nucleotide and amino acid affinity.
