Utilizing a killed PRRSV vaccine in combination with M. hyopneumoniae and PCV2 vaccines; impact on weight gain in vaccinated animals

摘要

Porcine reproductive and respiratory syndrome virus (PRRSV) and Mycoplasma hyopneumoniae are two of the most commonly isolated pathogens of the porcine respiratory disease complex. In pig flows where both of these pathogens are present infection withM hyopneumoniae often predisposes pigs to infection with PRRSV.1 In an in vitro model, increased levels of inflammatory cytokines are induced by coinfection, which may continuously draw more macrophages to the site of infection in the lung and prolong the infection.2 If this translates to the field, pneumonia induced by coinfection may result in a longer duration of PRRSV induced pneumonia than is observed when the infection is potentiated by the virus by itself. PRRSV strains currently circulat-ingin the field possess a high level of genetic heterogeneity such that commercial vaccines are often unable to provide protection against heterologous strains of virus.3 Recently, a new strain of PRRSV exhibiting a 1-7-4 RFLP pattern has been increasing in prevalence within the United States.4 Preliminary reports from the field have described a lack of protection obtained with commercial vaccines against this virulent new strain. When M. hyopneumoniae is present on a farm, the outcome of infection with this virus may be worsened. New vaccination strategies are needed that can combat the combined pathologies associated with these two pathogens, particularly after weaning when pigs become most susceptible to infection. In the wotk presented here we performed afield study in which we tested four different vaccination strategies to determine whether they would be able to enhance weight gain from weaning to 12 weeks of age. The results demonstrate a significant weight advantage for animals that received an M. hyopneumoniae vaccination.