Abstract:

Vaccine efficacy and immune response to Mycoplasma hyopneumoniae challenge in pigs vaccinated against porcine reproductive and respiratory syndrome virus and M hyopneumoniae

Tamara B. Boettcher, DVM, MS; Brad J. Thacker, DVM, PhD; Patrick G. Halbur, DVM, PhD; W. Ray Waters, DVM, PhD; Robert Nutsch, DVM, MS, MBA; Eileen L. Thacker, DVM, PhD

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Objective: To investigate the efficacy and level of immune response induced by a Mycoplasma hyopneumoniae (MH) bacterin in pigs previously vaccinated with a modified live virus (MLV) porcine reproductive and respiratory syndrome (PRRS) vaccine and subsequently challenged with MH.

Methods: Pigs were vaccinated once with MLV PRRS vaccine (Day 0), twice with MH vaccine (Days 8 and 22), or both, and challenged with MH on Day 36. Necropsies were performed on Days 35 and 61-63. Efficacy of MH vaccine was determined by reduction in the percentage of lung affected by mycoplasmal pneumonia. Serum antibodies to PRRS virus (PRRSV) and MH, antibodies to MH in bronchoalveolar lavage fluid (BAL), and production of MH-specific interferon-gamma- (IFN-[gamma]-) secreting cells in tissues and peripheral blood were measured on Days 0 and 14 and at necropsy. Immunological assays included ELISAs for PRRSV and MH antibodies and an enzyme-linked immunospot assay for MH-specific IFN-[gamma]-secreting cells.

Results: Mycoplasma vaccine efficacy was not decreased by prior administration of PRRS vaccine. Serum MH antibody levels in pigs receiving both vaccines and challenged were numerically but not signifi-cantly higher than those in pigs receiving only MH vaccine and challenged. Pigs receiving both vaccines had significantly lower PRRSV sample:positive (S:P) ratios, but remained ELISA-positive (S:P>0.4). Levels of MH-specific IgG and IgA in BAL were significantly higher in both groups vaccinated for MH and challenged.

Implications: Administration of an MLV PRRS vaccine to MH-free pigs prior to vaccination with MH vaccine did not interfere with vaccine efficacy or immune responses to MH infection.

Keywords: Mycoplasma hyopneumoniae, PRRSV, porcine reproductive and respiratory syndrome virus, vaccine, antibodies

Cite as: Boettcher TB, Thacker BJ, Halbur PG, et al. Vaccine efficacy and immune response to Mycoplasma hyopneumoniae challenge in pigs vaccinated against porcine reproductive and respiratory syndrome virus and M hyopneumoniae. J Swine Health Prod 2002;10(6):259-264.

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