WILD ISOLATES OF PLASMODIUM-FALCIPARUM MALARIA SHOW DECREASED SENSITIVITY TO IN-VITRO INHIBITION OF PARASITE GROWTH MEDIATED BY AUTOLOGOUS HOST ANTIBODIES
Bw. Flyg et al., WILD ISOLATES OF PLASMODIUM-FALCIPARUM MALARIA SHOW DECREASED SENSITIVITY TO IN-VITRO INHIBITION OF PARASITE GROWTH MEDIATED BY AUTOLOGOUS HOST ANTIBODIES, Clinical and experimental immunology, 107(2), 1997, pp. 321-327
Antigenic diversity in field populations of Plasmodium falciparum para
sites may delay the acquisition of protective immunity to malaria, the
development of which may thus require repeated exposure to infection
over a prolonged period of time. In this study we show that P. falcipa
rum parasites may vary in their sensitivity to antibody-mediated invas
ion/growth inhibition in vitro. Wild isolates of P. falciparum from ch
ildren living in an endemic area of Burkina Faso were tested for their
sensitivity to the growth inhibitory effects of antibodies originatin
g from the same (autologous) and from other donors (heterologous). A s
ignificantly lower invasion inhibition activity was obtained when the
isolates and antibodies were tested in autologous compared with hetero
logous combinations. The lower sensitivity to growth inhibition by aut
ologous antibodies may be due to immune pressure in vivo, selecting fr
om a heterogeneous parasite population those with a low expression of:
he antigens recognized by the host's antibodies. Alternatively, the pa
rasites cultured from each child might represent expanding parasite po
pulations, mainly constituting strains not earlier seen by the immune
system of that specific host. The results reinforce the concern about
Plasmodium antigenic diversity as a major obstacle towards the develop
ment of an effective malaria vaccine.