Identification of T- and B-cell epitopes in synthetic peptides derived from a Streptococcus mutans protein and characterization of their antigenicity and immunogenicity.
Natural immunity to synthetic peptides (SP) derived from the sequences of a 3800 Mr Streptococcus mutans antigen was found in human subjects. Significant serum IgG antibodies were detected both to the native streptococcal antigen and to the SP17, containing essentially residues 1-15. A series of short peptides with deletions at the amino- and carboxy-termini were then tested to identify the B-cell epitopes. Residues 8-13 and 1-6 bound significant serum IgG antibodies but only the former consistently inhibited human antibodies, suggesting that residues 8-13 constitute a major B-cell epitope. The human CD4 subset of T-cells was then examined and this showed a significant uptake of [3H]-thymidine when stimulated with both the native streptococcal antigen and the SP17. The series of short peptides was then used to stimulate CD4 cells, in order to determine the T-cell epitope. The synthetic peptide with residues 6-15 was the shortest peptide that stimulated significant [3H]-thymidine uptake and this peptide was designated as a T-cell epitope. The immunogenicity and antigenicity of SP17 was also investigated in macaques. Immunization of monkeys with the free SP17 failed to elicit serum antibodies or T-cell responses. However, immunization with SP17 linked to tetanus toxoid as a carrier elicited serum antibodies and proliferative responses of lymphocytes, not only to the synthetic peptide but also to the native streptococcal antigen. As in the human studies a B-cell epitope was found in residues 8-13, whereas an overlapping T-cell epitope was located in residues 7-15.(ABSTRACT TRUNCATED AT 250 WORDS)
Lehner
T
T
Department of Immunology, United Medical School, Guy's Hospital, London, England.
Walker
P
P
Smerdon
R
R
Childerstone
A
A
Bergmeier
L A
LA
Haron
J
J
D000276:Adjuvants, Immunologic; D000595:Amino Acid Sequence; D000818:Animals; D000907:Antibodies, Bacterial / Q000096:biosynthesis / Q000302:isolation & purification; D000942:Antigens, Bacterial / Q000502:physiology*; D001402:B-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D001426:Bacterial Proteins / Q000276:immunology* / Q000302:isolation & purification; D000939:Epitopes / Q000302:isolation & purification*; D006801:Humans; D007114:Immunization; D007074:Immunoglobulin G / Q000302:isolation & purification; D008213:Lymphocyte Activation; D008252:Macaca fascicularis; D008253:Macaca mulatta; D008969:Molecular Sequence Data; D010455:Peptides / Q000138:chemical synthesis / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D013936:Thymidine / Q000493:pharmacokinetics
D000276:Adjuvants, Immunologic; D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D000939:Epitopes; D007074:Immunoglobulin G; D010455:Peptides; D013936:Thymidine