Recombinant Porcine Interferon Alpha Enhances Immune Responses to Killed Porcine Reproductive and Respiratory Syndrome Virus Vaccine in Pigs

In this study, the immunoadjuvant effects of recombinant porcine interferon alpha (rPoIFN alpha) on the killed virus vaccine (KV) of porcine reproductive and respiratory syndrome virus (PRRSV) in pigs were investigated. The experimental pigs were divided into six groups, including normal control group, rPoIFN alpha control group, PRRSV KV control group, KV+40,000 U rPoIFN alpha immunization group, KV+400,000 U rPoIFN alpha immunization group, and KV+4,000,000 U rPoIFN alpha immunization group. The experimental pigs were boosted immunized on the 28th day after the initial immunization, and the heparinized blood and serum samples were collected at different time points of these two immunizations to detect and evaluate the immune responses of pigs after immunization by ELISA assay, neutralization assay, flow cytometry, and so on. The results showed that the proportion of the levels of PRRSV-specific antibodies, neutralizing antibodies, stimulation index, IL-4, IFN-gamma, and lymphocytes within the groups immunized with KV+rPoIFN alpha were significantly higher than that group immunized with KV alone. The humoral and cellular immune responses in pigs were markedly enhanced by rPoIFN alpha after the coadministration with KV vaccine. Therefore, we tentatively think that rPoIFN alpha is a potential immune promoter with prospects for future applications in the pig industry.