Human T cell clones define S1 subunit as the most immunogenic moiety of pertussis toxin and determine its epitope map.

Abstract

Human T lymphocyte clones specific for pertussis toxin (PT) were used to analyze the fine specificity of the response to PT, the basic component of new acellular vaccines against whooping cough. The majority (83%) of the clones specific for PT recognized S1, the subunit that in animal models has been shown to be highly immunogenic. To map T cell epitopes on S1, 18 S1-specific clones were tested for recognition of recombinant fragments representing NH2-terminal and COOH-terminal deletions of S1 and two recombinant S1 subunits containing amino acid substitutions. This approach led to the identification of three regions of the protein as the sequences containing T cell antigenic sites: 1-42, 181-211, and 212-235. Synthetic peptides were eventually used for a finer localization of the T cell epitopes. Two peptides, one of 13 residues (27-39) at the NH2 terminus and one of 24 residues (171-194) at the COOH terminus, stimulated proliferation of three and four clones, respectively. Both peptides are recognized in association with HLA DR1 molecules. These results stress the role of S1 in the immune response to PT and provide data useful for the development of a recombinant or synthetic antipertussis vaccine containing T cell epitopes from S1.

RecombinantMycobacterium bovisBCG Expressing Pertussis Toxin Subunit S1 Induces Protection against an Intracerebral Challenge with LiveBordetella pertussisin Mice

“…A recombinant Salmonella enterica serovar Typhimurium aroA strain expressing the five subunits of PT failed to protect mice from a virulent challenge, probably due to incomplete processing of the subunits (8). Of the five subunits composing the PT holotoxin, S1 has been characterized as the most immunogenic moiety (10), and passive immunization with an anti-S1PT monoclonal antibody protected mice against a virulent challenge (39). The S1 subunit has been expressed in fusion or unfused and has been purified from recombinant E. coli or Bacillus subtilis, maintaining its activity and immunochemical properties (3,23,30,37).…”

Bordetella pertussis Proteins Dominating the Major Histocompatibility Complex Class II-Presented Epitope Repertoire in Human Monocyte-Derived Dendritic Cells

“…2) and some encode known T cell epitopes (29,35,50,51). In fact, preceding B. pertussis harvesting, in-culture gene expression values for groES, PPP, ASS, and PAL were comparably high (groES and PAL) or even lower (PPP and ASS) than those for FHA, P.69 Prn, PtxS1, or Fim2 (52) (B. van der Waterbeemd, personal communication).…”

“…Unfortunately, information on the fine-specificity and breadth of human B. pertussis-specific CD4 ϩ T cell responses is largely absent, not in the least because of the difficulty of propagating B. pertussis-specific CD4 ϩ T cells in vitro (R. M. Stenger, M. Poelen, and C. A. C. M. van Els, unpublished data). The few human B. pertussis-specific CD4 ϩ T cell epitopes that have been elucidated were all sought only on the basis of known virulence factors (29,(35)(36)(37). We were interested in gaining nonbiased insight into the natural repertoire of B. pertussis-specific major histocompatibility complex (MHC) class II-presented epitopes, available for T cell recognition at the cell surface of human professional antigen-presenting cells after processing of the whole bacterial proteome.…”

Mucosal Immunization with a Genetically Engineered Pertussis Toxin S1 Fragment-Cholera Toxin Subunit B Chimeric Protein

“…Among the virulence factors produced by B. pertussis, pertussis toxin (PT) is one of most important (18) and is the prominent component of all acellular pertussis vaccines, which are given parenterally. The A-protomer (S1 subunit) of PT is immunodominant (4). Antibodies against the S1 subunit have been shown to neutralize the toxin in vitro and protect mice from B. pertussis infection in aerosol and intracerebral challenges (7,16,17).…”