title: Contribution of adjuvant to adaptive immune responses in mice against Actinobacillus pleuropneumoniae.
abstract: The authors have previously demonstrated that adjuvant-mediated differences in early cellular responses to antigens significantly affect subsequent adaptive immune responses. To investigate further the contribution of adjuvant to adaptive immune responses, outer-membrane proteins (OMP) purified from the respiratory pathogen Actinobacillus pleuropneumoniae, given either alone (antigen group) or complexed with SAMA4 (vaccine group), were injected intradermally into groups of mice. Controls were given PBS. Inclusion of adjuvant did not significantly alter the kinetics of antibody responses against OMP in serum or respiratory tract washings (RTW) over 21 weeks. Re-exposure to OMP at 21 weeks also induced identical recall responses in both immunized groups. However, differences between the responses of the vaccine and antigen groups were apparent when sera and RTW were reacted against OMP and OMP-derived polysaccharide antigens (ODPA). Serum and RTW reactivity against protein antigens was stronger in the vaccine group than in the antigen group. Serum and RTW from the vaccine group also reacted against a greater number of proteins than did the antigen group. Although serum reactivity against ODPA was equivalent for both groups, RTW from the vaccine group reacted only faintly against ODPA compared with the antigen group. The results suggested that shifting of antibody reactivity away from polysaccharide antigens toward protein antigens was an adjuvant-mediated effect. The rapid death of controls following intranasal inoculation confirmed that protection was ultimately dependent on the presence of specific antibodies in the serum and respiratory tract. However, since both groups responded equally to intranasal infection with A. pleuropneumoniae, as seen by the rapid clearance of bacteria from the lungs, the biological significance of any differences between the groups was unclear. Knowledge of the effects of adjuvants may provide a rational basis for adjuvant selection and the ability to manipulate immunological outcomes more precisely.
authors.affiliation: NSW Agriculture, Elizabeth Macarthur Agricultural Institute, PMB 8, Camden, NSW 2570, Australia1.
authors.forename: Fernando
authors.initials: F
authors.lastname: San Gil
authors.affiliation: NSW Agriculture, Elizabeth Macarthur Agricultural Institute, PMB 8, Camden, NSW 2570, Australia1.
authors.forename: Bernadette
authors.initials: B
authors.lastname: Turner
authors.affiliation: Department of Biological Sciences, University of Wollongong, Wollongong, NSW 2522, Australia2.
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Walker
authors.affiliation: NSW Agriculture, Elizabeth Macarthur Agricultural Institute, PMB 8, Camden, NSW 2570, Australia1.
authors.forename: Steven P
authors.initials: SP
authors.lastname: Djordjevic
authors.affiliation: NSW Agriculture, Elizabeth Macarthur Agricultural Institute, PMB 8, Camden, NSW 2570, Australia1.
authors.forename: James C
authors.initials: JC
authors.lastname: Chin
mesh_terms: D000189:Actinobacillus Infections / Q000276:immunology* / Q000517:prevention & control; D016977:Actinobacillus pleuropneumoniae / Q000276:immunology*; D000276:Adjuvants, Immunologic; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D000942:Antigens, Bacterial / Q000008:administration & dosage / Q000276:immunology; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000276:immunology*; D001428:Bacterial Vaccines / Q000008:administration & dosage / Q000276:immunology*; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005260:Female; D007110:Immunity, Active; D018928:Immunity, Mucosal; D015151:Immunoblotting; D008168:Lung / Q000382:microbiology; D051379:Mice; D008807:Mice, Inbred BALB C; D011135:Polysaccharides, Bacterial / Q000276:immunology
chemical_list: D000276:Adjuvants, Immunologic; D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001428:Bacterial Vaccines; D011135:Polysaccharides, Bacterial