Inhibitory effects of transfer factor against avian reovirus infection in chicks

Avian reovirus (ARV) infection causes viral arthritis, growth retardation, and immunosuppression in chickens. Current immunoprophylaxis, which relies mainly on vaccination, offers limited protection. This study evaluated the efficacy of transfer factor (TF) against ARV infection. One-day-old specific-pathogen-free (SPF) chicks were randomly divided into 4 groups (n = 35 each): a prophylaxis group (TF administered at 3 to 5 days of age), a treatment group (TF administered at 9 to 11 days of age), an infected group, and a blank control group. All chicks except the blank controls were infected with ARV at 7 days of age. At 7-day intervals post-infection, body weight and immune organ indices (organ weight/body weight) were measured, pathological changes in the footpads and tarsal joints were observed, and ARV loads in tendons and cloacal swabs were determined by quantitative real-time PCR. The results showed that the infected group consistently had the lowest body weight throughout the study period, accompanied by significant enlargement of the liver, spleen, and thymus, atrophy of the bursa of Fabricius, and swelling and hemorrhage in the footpads and tarsal joints. In contrast, both TF-treated groups exhibited significantly attenuated body weight loss and markedly reduced damage to immune organs. Furthermore, ARV loads in tendons were lower in both TF groups than in the infected group. At 14 days post-infection, viral shedding in cloacal swabs was significantly higher in the infected group than in either TF-treated group. These findings indicate that TF, whether administered prophylactically or therapeutically, effectively suppresses ARV replication in target organs and alleviates associated pathological damage, suggesting that TF could serve as a viable adjunctive strategy for the clinical control and prevention of ARV infections.