Inhibition of in vitro growth of Plasmodium falciparum field isolates mediated by human antibodies to Pf155/RESA and Pf332

The capacity of antibodies to interfere with Plasmodium falciparum growth in in vitro cultures is considered to reflect some of their potential protective effects in vivo. Almost all previous analyses of antibody mediated inhibition of parasite growth in vitro were performed with different laboratory strains of P. falciparum. This study was performed to investigate if the long-term culturing of parasites has any effect an their susceptibility to such growth inhibition. The growth inhibitory effects of human antibodies to the vaccine candidate antigens Pf155/RESA and Pf332 on fresh field isolates from children in Burkina Faso were analysed and compared with their effect on an established laboratory strain of the parasite. Although there was variation in the inhibition titres between different isolates tested against one antibody preparation, the differences in inhibition capacity for the three different antibodies were highly significant. No correlation was found between serum levels of anti-Pf155/RESA or -Pf332 antibodies and sensitivity of the corresponding parasite isolates to antibody mediated growth inhibition.