Lack of protection of mice against Staphylococcus aureus despite a significant immune response to immunization with a DNA vaccine encoding collagen-binding protein.
Collagen-binding protein (CNA) is the major Staphylococcus aureus adhesin responsible for high affinity binding to collagen and is assumed to be a major virulence factor in infection and disease. Mutants lacking the cna gene are less virulent than the parent strain in models of septic arthritis, osteomyelitis, keratinitis, and endocarditis. In order to investigate the immunological and protective properties of a CNA-based DNA vaccine, a eukaryotic expression vector pCNA was constructed which expressed the collagen-binding domain of this adhesin in transfected cells. Three groups of 11 Balb/c mice received three injection of either pCNA, the empty expression vector (pCI) or PBS. Those injected with pCNA showed hi titre (64000) antibody and evidence of a cell-mediated immune response (CMI). The anti-CNA antibodies recognized the intact bacteria and prevented binding to collagen in vitro. However, the vaccination did not protect against bacterial challenge using the intra-peritoneal route of infection. Moreover, S. aureus that had been treated with sera from vaccinated mice caused a more severe infection than bacteria treated with sera from non-vaccinated mice. In summary, DNA vaccination against CNA produced a strong antibody and cellular response in mice but failed to protect from i.p. infection by S. aureus.
Therrien
Roseline
R
Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada J1K 2R1.
Lacasse
Pierre
P
Grondin
Gilles
G
Talbot
Brian G
BG
D018829:Adhesins, Bacterial / Q000276:immunology*; D000818:Animals; D000907:Antibodies, Bacterial / Q000096:biosynthesis / Q000494:pharmacology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D019556:COS Cells; D049109:Cell Proliferation; D002522:Chlorocebus aethiops; D015169:Colony Count, Microbial; D005057:Eukaryotic Cells; D007074:Immunoglobulin G / Q000276:immunology; D051379:Mice; D010538:Peritonitis / Q000276:immunology / Q000382:microbiology; D010957:Plasmids / Q000235:genetics; D011994:Recombinant Proteins / Q000276:immunology; D013203:Staphylococcal Infections / Q000276:immunology* / Q000382:microbiology / Q000517:prevention & control*; D013209:Staphylococcal Vaccines / Q000276:immunology*; D013211:Staphylococcus aureus / Q000276:immunology*; D019444:Vaccines, DNA / Q000276:immunology
D018829:Adhesins, Bacterial; D000907:Antibodies, Bacterial; D007074:Immunoglobulin G; D011994:Recombinant Proteins; D013209:Staphylococcal Vaccines; D019444:Vaccines, DNA; C048165:adhesin, Staphylococcus aureus