Are extensive T cell epitope polymorphisms in the Plasmodium falciparum circumsporozoite antigen, a leading sporozoite vaccine candidate, selected by immune pressure?
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.
Kumkhaek
Chutima
C
Department of Microbiology and Immunology, Mahidol University, Bangkok, Thailand.
Phra-Ek
Kooruethai
K
Rénia
Laurent
L
Singhasivanon
Pratap
P
Looareesuwan
Sornchai
S
Hirunpetcharat
Chakrit
C
White
Nicholas J
NJ
Brockman
Alan
A
Grüner
Anne Charlotte
AC
Lebrun
Nicolas
N
Alloueche
Ali
A
Nosten
François
F
Khusmith
Srisin
S
Snounou
Georges
G
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
D018984:Epitopes, T-Lymphocyte; D015800:Protozoan Proteins; D016052:Protozoan Vaccines; C041595:circumsporozoite protein, Protozoan