Immunogenicity of synthetic peptides derived from the sequences of a Streptococcus mutans cell surface antigen in nonhuman primates.
The immunogenicity and antigenicity of synthetic peptides (SP) derived from the sequences of a cell surface Ag of Streptococcus mutans were investigated in macaque monkeys. Immunization with the free peptides of 11, 17, and 21 residues failed to elicit serum antibodies or T cell responses. However, immunization with the SP17 and SP21 linked to tetanus toxoid (TT) as a carrier elicited serum antibodies and proliferative responses of lymphocytes, not only to the SP but also to the native streptococcal Ag. In vivo recall of SP-TT immunized monkeys with suboptimal doses of the native streptococcal Ag resulted in a significant increase in antibodies, both to the SP and the streptococcal Ag, confirming that the SP shares antigenic epitopes with the native Ag. B and T cell epitopes were then determined and a B cell epitope was found in residues 8-13, whereas an overlapping T cell epitope was located in residues 7-15. The T cell epitope has an amino-terminal leucine and carboxy-terminal glycine and alanine added to residues 8-13 of the B cell epitope. In spite of the B and T cell epitopes being expressed in SP17 (residues 1-15), the monomer failed to induce serum antibodies without a carrier. However, immunization with a dimer of SP17 elicited both serum antibodies and proliferative responses of lymphocytes without a carrier. The results suggest that the monomeric SP17 is not immunogenic and needs to be dimerised in order to elicit antibodies and T cell responses, both to the SP and to the streptococcal Ag.
Lehner
T
T
Department of Immunology, United Medical School of Guy's Hospital, London, UK.
Walker
P
P
Bergmeier
L A
LA
Haron
J A
JA
D000595:Amino Acid Sequence; D000818:Animals; D000942:Antigens, Bacterial / Q000008:administration & dosage / Q000138:chemical synthesis / Q000276:immunology*; D000954:Antigens, Surface / Q000008:administration & dosage / Q000276:immunology*; D001402:B-Lymphocytes / Q000032:analysis; D002352:Carrier Proteins / Q000276:immunology; D000939:Epitopes / Q000032:analysis; D007074:Immunoglobulin G / Q000096:biosynthesis; D007963:Leukocytes, Mononuclear / Q000378:metabolism; D008252:Macaca fascicularis; D008253:Macaca mulatta; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010455:Peptides / Q000008:administration & dosage / Q000138:chemical synthesis / Q000276:immunology*; D011487:Protein Conformation; D013295:Streptococcus mutans / Q000276:immunology*; D013601:T-Lymphocytes / Q000032:analysis; D013936:Thymidine / Q000378:metabolism
D000942:Antigens, Bacterial; D000954:Antigens, Surface; D002352:Carrier Proteins; D000939:Epitopes; D007074:Immunoglobulin G; D010455:Peptides; D013936:Thymidine