Cellular immune responses of pigs induced by vaccination with either a whole cell sonicate or pepsin-digested Brachyspira (Serpulina) hyodysenteriae bacterin

Brachyspira (Serpulina) hyodysenteriae infection of pigs (swine dysentery) causes a mucohemorrhagic diarrhea resulting in significant economic losses for producers. A commercial vaccine consisting of a proteinase-digested bac terin has shown efficacy in the reduction of disease due to B. hyodysenteri ae, Vaccines consisting of whole cell bacterins, however, generally fail to protect pigs from disease. In the present study, cellular immune responses induced by a proteinase-digested bacterin were compared to responses induc ed by a whole cell sonicate antigen preparation. In addition, usage of eith er squalene or Freund's incomplete adjuvants in combination with each antig en preparation was also compared. Both antigen preparations induced signifi cant cellular immune responses as measured by in vitro (IFN-gamma productio n and T cell proliferation) and in vivo methods (DTH responses). No signifi cant differences were detected in proliferative, interferon-gamma (IFN-gamm a), or delayed type hypersensitivity (DTH) responses by pigs receiving eith er adjuvant or antigen preparation. T cells (CD3(+)) but not B cells from v accinated animals proliferated in response to in vitro stimulation with B, hyodysenteriae antigen. CD8(+) (single positive and CD4/CD8 double positive ) and gamma delta(+) T cells were particularly responsive. In addition, hig h percentages of both CD8 single positive and CD4/CD8 double positive cells were detected in antigen-stimulated cultures. These findings demonstrate t he unique sensitivity of porcine CD8(+) T cells to priming for recall respo nse by vaccination with a proteinase-digested B. hyodysenteriae bacterin. ( C) 1999 Elsevier Science Ltd. All rights reserved.