Plasmodium falciparum: immune pressure in Saimiri sciureus monkeys can select for a parasite population inducing a protective immunity that is not controlled by antibody.
Protective immunity against a Plasmodium falciparum blood infection can be passively transferred by antibodies in humans and in the primate experimental malaria model Saimiri sciureus. We report here the emergence of a novel virulent parasite population after such passive transfer of hyperimmune serum in splenectomized monkeys. These FUP-2 parasites have been partially genotyped and phenotyped. Although no genotypic variation was detected for four polymorphic loci compared to the original FUP-1 parasite population, FUP-2-infected erythrocytes exhibit little or no detectable surface determinants, including those reacting with antibodies raised against FUP-1 surface antigens. In addition, FUP-2-infected erythrocytes exhibit no rosetting or autoagglutination. Interestingly, although Saimiri monkeys control efficiently FUP-2 parasites after repetitive infections, this protection cannot be passively transferred to naive recipients. Our results suggest that antibody-mediated and antibody-independent T-cell-mediated protective responses may cooperate in controlling P. falciparum infection in splenectomized Saimiri monkeys.
Laboratoire d'Immunologie Parasitaire, Institut Pasteur de Guyane, Cayenne Cédex, BP 6010, 97306, France.
M E
ME
Morales-Betoulle
Y O
YO
de la Salmonière
J
J
Zwetyenga
C
C
Le Scanf
H
H
Jouin
J C
JC
Michel
D000818:Animals; D000917:Antibody Formation; D000953:Antigens, Protozoan / Q000276:immunology; D000954:Antigens, Surface / Q000276:immunology; D004912:Erythrocytes / Q000276:immunology / Q000469:parasitology; D006386:Hemagglutination Tests; D006801:Humans; D007116:Immunization, Passive; D016778:Malaria, Falciparum / Q000097:blood / Q000276:immunology* / Q000517:prevention & control; D008297:Male; D010587:Phagocytosis; D010963:Plasmodium falciparum / Q000276:immunology* / Q000472:pathogenicity*; D012397:Rosette Formation; D012453:Saimiri; D013156:Splenectomy; D014774:Virulence
D000953:Antigens, Protozoan; D000954:Antigens, Surface