title: Mycoplasma pneumoniae reinfection and vaccination: protective oral vaccination and harmful immunoreactivity after re-infection and parenteral immunization.
abstract: Animal model studies of Mycoplasma pneumoniae infection after live respiratory challenge were conducted to investigate the issues of challenge-rechallenge associated accentuated pathology, postparenteral vaccination associated accentuated pathology, and oral vaccination. Live M. pneumoniae inocula were grown in hamster serum-based medium in order to reduce the potential for the serum growth component to participate in the hyperaccentuated histopathological response as seen with challenge-rechallenge experiments which have used horse serum-based growth media. Despite the use of homologous animal serum, an early hyperaccentuated response occurred (day 3 score 13.3 vs day 10 score 7.7; P = 0.02) which included perivascular infiltrates, and histopathological scores for early (day 3) and late (day 10) disease were similar (P > 0.10) between experiments of challenge-rechallenge when either homologous or heterologous sera were used in inoculum growth media. Parenteral vaccination with heat-killed bacteria also led to an early hyperaccentuated histopathological response after live respiratory challenge (scores on day 3: vaccinated 18.3, unvaccinated 6.2; P < 0.01) and this response was not significantly diminished when inocula were cleaned of growth medium components. An early accentuated response did not follow oral vaccination with heat-killed bacteria (score on day 3: vaccinated 5.7) and the late reaction was significantly less after challenge (scores on day 10: vaccinated 10.3, unvaccinated 14.6; P = 0.011). Studies of parenteral vaccination should include analyses for early disease after live challenge. Oral vaccination offers a promising route for stimulating protective immunity while minimizing undesirable recall immune events.
authors.affiliation: Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, Canada.
authors.forename: N
authors.initials: N
authors.lastname: Cimolai
authors.forename: A C
authors.initials: AC
authors.lastname: Cheong
authors.forename: B J
authors.initials: BJ
authors.lastname: Morrison
authors.forename: G P
authors.initials: GP
authors.lastname: Taylor
mesh_terms: D000284:Administration, Oral; D000818:Animals; D000907:Antibodies, Bacterial / Q000032:analysis*; D001428:Bacterial Vaccines / Q000008:administration & dosage* / Q000009:adverse effects / Q000276:immunology*; D006224:Cricetinae; D006736:Horses; D007074:Immunoglobulin G / Q000032:analysis; D007274:Injections, Intraperitoneal; D008168:Lung / Q000382:microbiology / Q000473:pathology*; D009177:Mycoplasma pneumoniae / Q000276:immunology*; D011019:Pneumonia, Mycoplasma / Q000209:etiology / Q000517:prevention & control*; D014611:Vaccination; D015164:Vaccines, Inactivated / Q000008:administration & dosage
chemical_list: D000907:Antibodies, Bacterial; D001428:Bacterial Vaccines; D007074:Immunoglobulin G; D015164:Vaccines, Inactivated