Response of the porcine immune system to Mycoplasma hyopneumoniae vaccination
Abstract
Studies were conducted with an inactivated commercial Mycoplasma hyopneumoniae bacterin to determine its efficacy, its immunosuppressive potential, and the nature of the immune response it elicits. Efficacy of administering the bacterin to pigs by intramuscular injection and by aerosol was evaluated by vaccinating one group of pigs intramuscularly (IM) with the bacterin, a second group of pigs by aerosol (AERO) with the bacterin, and a third (control) group of pigs by aerosol with phosphate buffered saline solution (PBSS). Two weeks after vaccination, no M. hyopneumoniae-specific antibody responses were detected in either serum or pulmonary fluid of any vaccinated pig. Two weeks after vaccination, pigs were challenge infected with virulent Mycoplasma hyopneumoniae. The AERO and PBSS groups developed typical mycoplasmal pneumonia. The IM group had substantially reduced (p $<$ 0.05) pneumonia. By four weeks after challenge infection, specific antibody was present in the serum and pulmonary fluid of all pigs, but was higher (p $<$ 0.05) in the IM group. To determine whether the bacterin interferes with humoral immunity to pseudorabies vaccine, a group of pigs (BACT) was vaccinated intramuscularly with M. hyopneumoniae bacterin and pseudorabies vaccine at the same time. A control group was vaccinated with PBSS and pseudorabies vaccine. The M. hyopneumoniae bacterin did not suppress (p = 0.43) the pseudorabies antibody response of the BACT group. To determine whether the bacterin suppresses porcine lymphocytes and macrophages, a group of pigs (BACT) was vaccinated intramuscularly with the bacterin, and a control group was vaccinated with PBSS. After vaccination, lymphocytes were collected, counted, and tested for lymphoblastogenic response to PHA, ConA, and PWM, and T cell growth factor production. The BACT group was not lymphopenic, and their lymphocyte functions were not significantly lower (P $>$ 0.10) than those of the PBSS group. Alveolar macrophages were collected from all pigs and tested for bactericidal activity, and TNFa production. Bactericidal activity was not different (p = 0.27) between the groups. Endotoxin-stimulated TNFa production was higher (p = 0.0014) in the BACT group. The bacterin was substantially protective, lacked noticeable side effects, and was not demonstrably immunosuppressive. Aerosol administration was ineffective, and no relationship was demonstrated between specific pulmonary antibody and protective immunity.
Degree
Ph.D.
Advisors
Alstine, Purdue University.
Subject Area
Veterinary services
Off-Campus Purdue Users:
To access this dissertation, please log in to our
proxy server.