title: Are extensive T cell epitope polymorphisms in the Plasmodium falciparum circumsporozoite antigen, a leading sporozoite vaccine candidate, selected by immune pressure?
abstract: Protective cellular immune responses depend on MHC presentation of pathogen-derived Ag fragments. MHC diversity renders this process sensitive to point mutations coding for altered amino acid sequence of the short target Ag-derived peptides epitopes. Thus, in a given host, a pathogen with an altered epitope sequence will be more likely to escape detection and elimination by the immune system. At a population level, selection by immune pressure will increase the likelihood of polymorphism in important pathogen antigenic epitopes. This mechanism of immune evasion is found in viruses and other pathogens. The detection of polymorphic hot spots in an Ag is often taken as a strong indication of its role in protective immunity. We provide evidence that polymorphisms in the T cell epitopes of a malaria vaccine candidate are unlikely to have been selected by immune pressure in the human host.
authors.affiliation: Department of Microbiology and Immunology, Mahidol University, Bangkok, Thailand.
authors.forename: Chutima
authors.initials: C
authors.lastname: Kumkhaek
authors.forename: Kooruethai
authors.initials: K
authors.lastname: Phra-Ek
authors.forename: Laurent
authors.initials: L
authors.lastname: Rénia
authors.forename: Pratap
authors.initials: P
authors.lastname: Singhasivanon
authors.forename: Sornchai
authors.initials: S
authors.lastname: Looareesuwan
authors.forename: Chakrit
authors.initials: C
authors.lastname: Hirunpetcharat
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: White
authors.forename: Alan
authors.initials: A
authors.lastname: Brockman
authors.forename: Anne Charlotte
authors.initials: AC
authors.lastname: Grüner
authors.forename: Nicolas
authors.initials: N
authors.lastname: Lebrun
authors.forename: Ali
authors.initials: A
authors.lastname: Alloueche
authors.forename: François
authors.initials: F
authors.lastname: Nosten
authors.forename: Srisin
authors.initials: S
authors.lastname: Khusmith
authors.forename: Georges
authors.initials: G
authors.lastname: Snounou
mesh_terms: D000818:Animals; D004252:DNA Mutational Analysis; D018984:Epitopes, T-Lymphocyte / Q000235:genetics*; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D010963:Plasmodium falciparum / Q000235:genetics* / Q000276:immunology; D011110:Polymorphism, Genetic / Q000276:immunology*; D015800:Protozoan Proteins / Q000235:genetics* / Q000276:immunology; D016052:Protozoan Vaccines; D012641:Selection, Genetic
chemical_list: D018984:Epitopes, T-Lymphocyte; D015800:Protozoan Proteins; D016052:Protozoan Vaccines; C041595:circumsporozoite protein, Protozoan