Genetic control of immune responses in mice to synthetic peptides of a Streptococcus mutans surface protein antigen.
The immune responses to a cell surface protein antigen (PAc) of Streptococcus mutans and a peptide corresponding to residues 301 to 319 of the protein antigen [PAc(301-319)] in various strains of mice were studied, with attention being given to the haplotype of major histocompatibility complex (MHC) class II genes. Subcutaneous immunization of mice carrying the MHC class II I-Ad gene [BALB/c, B10.D2, B10.GD, and (B10.D2 x B10.G)F1 mice] with the peptide induced strong serum immunoglobulin G (IgG) responses to recombinant PAc (rPAc) and the peptide. Subcutaneous immunization of mice carrying the haplotype k or b of the H-2 I-A gene (C3H/HeN, C57BL/6, B10.BR, B10.A, or B10 mice) with the peptide induced intermediate serum IgG responses to rPAc and the peptide, and subcutaneous immunization of mice carrying the haplotype s or q of the H-2 I-A gene (DBA/1, B10.S, or B10.G mice) induced weak serum IgG responses to rPAc and the peptide compared with the responses of mice carrying the I-Ad gene. PAc(301-319) strongly induced PAc(301-319)-specific T-cell proliferation in B10.D2 mice but not in B10.G mice. The T-cell proliferation in B10.D2 mice was inhibited by treatment of antigen-presenting cells with anti-I-Ad monoclonal antibody but not with anti-I-Ab monoclonal antibody. These results indicate that the immune responses to the peptide in mice are genetically restricted or dominated by the MHC class II gene (I-Ad). To map antigenic epitopes in PAc(301-319) and PAc in mice bearing different H-2 haplotypes, 10 overlapping decapeptides covering PAc(301-319) and 153 decapeptides covering the entire mature PAc were synthesized. Of 10 decapeptides covering PAc(301-319), 6, 7, 1, and 1 decapeptides showed strong reactions with anti-PAc(301-319) sera from B10.D2 (H-2d), B10.GD (H-2g2), B10.BR (H-2k), and B10.A (H-2a) mice, respectively. None of these overlapping decapeptides reacted with anti-PAc(301-319) sera from B10.S (H-2s) and B10.G (H-2q) mice. Epitope-scanning analyses of the mature PAc molecule showed that antigenic epitopes scattered throughout the molecule and that antigenic epitope patterns differed in mice with different H-2 haplotypes. In addition, there was little overlap of immunogenic peptides among the mice with different haplotypes.
Department of Dental Research, National Institute of Health, Tokyo, Japan.
I
I
Takahashi
K
K
Matsushita
T
T
Nisizawa
N
N
Okahashi
M W
MW
Russell
Y
Y
Suzuki
E
E
Munekata
T
T
Koga
D000595:Amino Acid Sequence; D000818:Animals; D000907:Antibodies, Bacterial / Q000032:analysis; D000942:Antigens, Bacterial / Q000276:immunology*; D000954:Antigens, Surface / Q000276:immunology; D000939:Epitopes / Q000032:analysis; D007074:Immunoglobulin G / Q000032:analysis; D051379:Mice; D008815:Mice, Inbred Strains; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000276:immunology*; D011994:Recombinant Proteins / Q000276:immunology; D013045:Species Specificity; D013295:Streptococcus mutans / Q000276:immunology*
D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D000954:Antigens, Surface; D000939:Epitopes; D007074:Immunoglobulin G; D010446:Peptide Fragments; D011994:Recombinant Proteins