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M F Good

Publications and source records attributed to M F Good.

152 records · Page 9Linked to original sources
PubMedDate not supplied

Recognition of dominant T cell-stimulating epitopes from the circumsporozoite protein of Plasmodium falciparum and relationship to malaria morbidity in Gambian children.

Cellular immune responses to the Plasmodium falciparum circumsporozoite (CS) protein were measured by proliferation and interferon-gamma production in a cohort of children aged 3 to 8 years, living in The Gambia. Anti-CS antibody titres, malariometric indices and sickle cell status were also determined. Malaria morbidity in the ensuing malaria transmission season was monitored by weekly health questionnaire, axillary temperature measurements and examination of blood films. Exposure to malaria was inferred from entomological data collected during the transmission season. Immunological and parasitological measurements were repeated at the end of the rainy season. Immunological findings were compared between children who experienced clinical malaria or asymptomatic infection and children who had no evidence of infection. No association was found between cellular immune responses to the CS protein at the beginning of the transmission season and subsequent susceptibility to infection except among children with high titres of antibody to (NANP)40. Seropositive children who did not become infected had a higher mean proliferative response to the Th3R epitope than seropositive children who did become infected. High titres of anti-(NANP)40 antibodies alone were not protective. Responses to the Th2R epitope were significantly higher at the end of the rainy season than at the beginning in children who experienced an asymptomatic infection. Responses to variant sequences of the 2 epitopes were highly correlated at an individual level but there was no correlation between proliferative and interferon responses to a particular epitope.

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Memory B cell responses and malaria.

Malaria is a serious cause of morbidity and mortality in millions of individuals each year. People living in endemic areas build up partial immunity only after repeated attacks of malaria over several years. At this meeting we discussed current knowledge about long-term protection and the challenges we face in the development of an effective malaria vaccine.

Animals↗
PubMedDate not supplied

Peptide immunization can elicit malaria protein-specific memory helper but not proliferative T cells.

We have studied the proliferative and helper T cell responses in mice to a malaria sporozoite vaccine candidate currently undergoing human trials. Following immunization of B10 (I-Ab) mice with the purified recombinant baculovirus-expressed Plasmodium falciparum circumsporozoite protein, draining lymph node cells were challenged in vitro with a series of overlapping synthetic peptides which span the construct. Surprisingly, only a single peptide from the protein was immunodominant in that it could reproducibly elicit a significant proliferative response from the immunized lymph node cells. This epitope, (NANP)n, is also the repetitive immunodominant B cell epitope of the protein. However, immunization of mice with synthetic peptides revealed at least 3 cryptic proliferative epitopes--epitopes not revealed by protein immunization--two of which represent conserved regions of the protein. While cryptic peptide-immunization did not elicit protein-specific proliferative T cells, it did reveal protein-specific helper T cells, as shown by an in vivo assay. Identification of "cryptic" epitopes not only for malaria but for other infectious diseases may aid vaccine design, especially in situations where subunit vaccines are sought.

Amino Acid Sequence↗
PubMedDate not supplied

Assessment of human cytotoxic T cell activity using synthetic peptides: potential for field application.

The use of synthetic peptides to delineate epitopes recognized by major histocompatability complex-restricted cytotoxic T lymphocytes has been well documented. In the present study, we report a method for the generation and assay of peptide-specific cytotoxic T lymphocytes adapted for the field situation where quantities of blood are often limited. From a single bleed of the donor and using minimal quantities of peptide (less than 5 micrograms/ml), up to 100 potential epitopes could be screened within a short time frame. Subsequent cloning of positive cultures for further analysis of defined epitopes is permissible. The system is readily adaptable to a wide range of viral, parasitic or bacterial infections.

Amino Acid Sequence↗
PubMedDate not supplied

Mapping a conserved conformational epitope from the M protein of group A streptococci.

The carboxyl terminus of the M protein of group A streptococci (GAS) is highly conserved and contains epitopes that have been shown to induce opsonic antibodies and protection against GAS infection. This region of the protein can also stimulate T cells, which can react in vitro with heart antigens. Since different segments of the carboxyl terminus may be involved in immunity to GAS and in the pathogenesis of autoimmune disease (rheumatic heart disease), it is important to precisely define critical epitopes. However, the M protein is known to be a coiled coil, and a critical immunodominant antibody-binding epitope within this region (peptide 145, a 20-mer with the sequence LRRDLDASREAKK-QVEKALE) is shown here to be conformational. Thus, small synthetic overlapping peptides of 8-12 amino acids in length that span peptide 145 (p145) were unable to capture antibodies present in p145-immune mouse sera or in endemic human sera, even though antibodies raised to these small peptides coupled to diphtheria toxoid could bind the smaller peptides and, in some cases, p145. A series of mutated peptides in which every residue of p145 was sequentially altered also failed to identify critical residues for antibody binding. We thus devised a strategy to produce chimeric peptides in which small peptides copying the M protein sequence were displayed within a larger 28-mer peptide derived from the sequence of the GCN4 leucine zipper DNA binding protein of yeast. A 12-amino-acid window of the p145 sequence was inserted into the GCN4 peptide in such a way as to preserve any potential helical structure. The window was moved along one residue at a time to give a series of peptides representing p145. Circular dichroism demonstrated that these larger chimeric peptides and p145, but not a shorter 12-mer peptide, displayed alpha-helical potential in 50% trifluoroethanol. Certain chimeric peptides efficiently captured antibodies specific for p145 and thus enabled us to map the minimal antibody-binding sequence. RRDLDASREAKK, referred to as J(1)2. The chimeric peptide containing this sequence, referred to as J2, was able to inhibit opsonization of GAS by human antisera containing anti-peptide 145 antibodies. The T-cell response from p145-immunized responder B10.BR mice to J2 and J(I)2 was much lower than the response to p145 and mapped to a different peptide.

Animals↗
PubMedDate not supplied

Synthetic peptides from P. falciparum sexual stage 25-kDa protein induce antibodies that react with the native protein: the role of IL-2 and conformational structure on immunogenicity of Pfs25.

To identify B-cell epitopes of the Plasmodium falciparum 25-kDa ookinete protein, Pfs25, 41 overlapping synthetic peptides spanning the entire length of the protein were used individually to immunize CAF1 (F1 hybrid of BALB/c female and A/J male) mice. Antipeptide sera were tested for reactivity to live intact zygote/early ookinete (post-fertilization stage) by immunofluorescence, and by Western blot analysis under nonreducing and reducing conditions, immunoprecipitation of 35S-cysteine-labeled antigen, and ELISA using a vaccinia recombinant Pfs25 antigen. Fourteen B-cell epitopes were identified. These peptides were immunogenic only when administered with high-dose recombinant interleukin-2. Antibodies to 11 peptides recognized only the native conformational structure, one peptide induced antibodies that recognized both reduced and native protein, and two other peptides, after primary immunization, made antibodies to denatured Pfs25, but after boosting the antibodies reacted to both denatured and native Pfs25. Anti-sera to peptides in the first (peptide 7) and fourth (peptide 34) epidermal growth factor-like domains of Pfs25 reacted most strongly with zygotes/ookinetes by immunofluorescence assay. The antibodies elicited by immunization with peptide 34 suppressed infectivity of the parasite to mosquitoes. We further observed that the secondary structure of Pfs25 may be important for immunogenicity because monoclonal antibodies (MAbs) 1C7 and 1D2, both transmission-blocking MAbs, protected enzyme cleavage sites in Pfs25 from proteolysis, suggesting that discontinuous segments of Pfs25 may come together to form immunogenic epitopic sites. Thus, definition of B- and T-cell epitopes may be required to construct a Pfs25 vaccine for optimum immunogenicity.

Amino Acid Sequence↗