Detection of avian reoviruses causing tenosynovitis in breeder flocks in Iran by reverse transcription-polymerase chain reaction [RT-PCR] and restriction enzyme fragment length polymorphism [RFLP]

Avian reoviruses [ARVs] are members of the Orthoreovirus genus; one of the 12 genera of the Reoviridae family. The ARVs are the cause of some important diseases in poultry such as reovirus-induced arthritis, tenosynovitis, chronic respiratory disease, and mal-absorption syndrome. In this study, the presence of ARVs in the Iranian breeder flocks was investigated through reverse transcriptionpolymerase chain reaction [RT-PCR] and restriction enzyme fragment length polymorphism [RFLP]. A total of 800 fecal swab samples were initially collected from breeder flocks [older than 45 weeks of age]. They were then sent to the laboratory in containers with PBS, and after that they were pooled and finally to 120 samples were obtained. The total RNA extracted from the pooled fecal samples were used to amplify the selected parts of the S1 [1023 bp] and S4 [437 bp] genes from the ARV field isolates using RT-PCR. The positive RT-PCR amplified products were further analyzed by RFLP using five restriction enzymes. Based on the findings, 5 samples were positive with the S1 primer and 6 samples were with the S4 one. The patterns observed after the digestion of PCR products revealed that the isolates of this study were identical to both the S1133 vaccine and standard strains. The findings suggested that the RT-PCR/RFLP analysis might be considered as a simple and rapid approach for the differentiation of ARV isolates. This study was the first molecular detection of the ARVs presence in the Iranian breeder flocks using the RTPCR amplification of the S1 and S4 genes and RFLP analysis

Susceptibility of cell lines to avian viruses

The susceptibility of the five cell lines - IB-RS-2, RK-13, Vero, BHK-21, CER - to reovirus S1133 and infectious bursal disease virus (IBDV vaccine GBV-8 strain) was studied to better define satisfactory and sensitive cell culture systems. Cultures were compared for presence of CPE, virus titers and detection of viral RNA were detected in CER and BHK-21 cells after retrovirus inoculation and in RK-13 cell line after IBDV inoculation and with high virus titers. Virus replication by production of low virus titers occurred in IB-RS-2 and Vero cells with reovirus and in BHK-21 cell line with IBDV