EFFECT OF ATTENUATED ERYSIPELOTHRIX-RHUSIOPATHIAE VACCINE IN PIGS INFECTED WITH PORCINE REPRODUCTIVE RESPIRATORY SYNDROME VIRUS

Twenty 2nd specific pathogen-free pigs were divided into 4 groups: Gro up A were infected with porcine reproductive and respiratory syndrome (PRRS) virus at 6 weeks of age and treated with available swine erysip elas and swine fever combined vaccine (vaccinated) at 7 weeks of age; Group B were vaccinated at 7 weeks of age and infected with PRRS virus at 8 weeks of age; Group C were vaccinated at 7 weeks of age: Group D were neither vaccinated nor infected with PRRS virus. All pigs were c hallenged to Erysipelothrix rhusiopathiae C42 strain at 10 weeks of ag e. No clinical signs appeared after vaccination of group A and B pigs, thus confirming that the safety of the vaccine was not influenced by infection with PRRS virus. None of the pigs in Groups A and C develope d erysipelas after challenge exposure to E. rhusiopathiae. In contrast , fever and/or urticaria appeared transiently in all pigs of Group B a fter challenge exposure. At the time of challenge exposure to E. rhusi opathiae, the PRRS virus titer was high in sera of Group B, but was lo w in those from Group A. However, vaccination of pigs with attenuated E. rhusiopathiae was effective in dual infection with PRRS virus and E . rhusiopathiae, because the clinical signs were milder and the E. rhu siopathiae strain was less recovered from these pigs compared to pigs of group D.