Advances in the immunosuppression of porcine reproductive and respiratory syndrome virus.

Porcine reproductive and respiratory syndrome (PRRS) is a highly infectious disease caused by the PRRS virus (PRRSV), its impact is second only to that of African swine fever (ASFV). Since the discovery of this disease, comprehensive studies have been conducted on its genome structure, protein function, pathogenicity, transmission route, and epidemiology as well as vaccines, prevention, and control. Despite the availability of numerous vaccines, complete immune protection in pigs is lacking. This limitation may be attributed to immune evasion, immunosuppression, or inherent characteristics of pigs. From the view of immunosuppression, the antigen escape, delayed neutralization antibody production, T cell immunity, antibody dependence enhancement, dendritic cell function inhibition, regulatory T cell induction and thymic destruction of PRRSV were discussed in this review to better understand PRRSV pathogenesis and inform vaccine development.