Concurrent vaccination of boars with type 1 and type 2 porcine reproductive and respiratory syndrome virus (PRRSV) reduces seminal shedding of type 1 and type 2 PRRSV.

The objective of the present study was to determine the effect of concurrent vaccination of boars with type 1 and type 2 porcine reproductive and respiratory syndrome virus (PRRSV) on seminal shedding of both genotypes. The boars tolerated well concurrent administration of 2 commercial PRRSV vaccines, and no adverse reactions were observed. No interference in the humoral immune response (measured as the level of anti-PRRSV antibodies) or the cell-mediated immune response (measured as the level of PRRSV-specific interferon-γ-secreting cells) was observed after concurrent administration compared with single administration of the same vaccines. Concurrent vaccination significantly reduced the load of type 1 and type 2 PRRSV in blood and semen after singular (type 1 or type 2) and dual (type 1 and type 2) PRRSV challenge, and it did not significantly affect the efficacy of each vaccine. The results demonstrate that concurrent vaccination of boars with type 1 and type 2 PRRSV reduces shedding of both genotypes in semen.