Strategy to improve swine influenza virus (SIV) vaccination

Abstract

The objective of this study was to assess the effect of concurrent infection with porcine reproductive and respiratory syndrome virus (PRRSV) on the efficacy of an inactivated swine influenza virus (SIV) vaccine. Eight groups of pigs were used in the study. One group was infected with a virulent PRRSV isolate between the two SIV vaccines or at the time of SIV challenge. Control groups included SIV vaccination without PRRSV and pigs infected with SIV and/or PRRSV. Pigs infected with PRRSV during vaccination showed increased levels of macroscopic and microscopic lesions compared to pigs vaccinated against and challenged with only SIV. The presence of PRRSV decreased SIV vaccine efficacy as measured by increased clinical disease and levels of SIV shedding at the acute phase of infection. No alterations in systemic and local antibody response to either SIV vaccination or challenge were observed. These findings demonstrate the impact that PRRSV infection has on SIV vaccine efficacy is important for disease control.