Impact of PRRS vaccination timing in pigs with different maternal immunity levels

摘要

Most studies that evaluated the vire-mia and serological response following vaccination were done using naive pigs.1 These pigs usually become viremic and seropositive at about two and 10 to 14 days post vaccination, respectively. Field experiments conducted in Quebec suggest that maternal immunity can delay by weeks and even months the time when pigs vaccinated for PRRS become viremic and seroconvert to the vaccine (Cardinal, unpublished data; Desrosiers R, personal communication, 2012). This was found to be the case in situations where pigs were vaccinated at 3-4 weeks of age or younger. The main objective of this study was to further investigate this issue and determine if vaccination of older pigs would induce an earlier viremia and seroconversion.