Effect of monoclonal antibodies on the entry and development of Plasmodium vivax sporozoite in cultured cells.

We have observed the effect of monoclonal antibodies against sporozoites (2F2,NV3,2E10) and blood stages (4B2,8E3) of P. vivax on entry and subsequent development of P. vivax sporozoites in HepG2--A16 cells in vitro. The results demonstrated that inhibitory effects of monoclonal antibodies on the attachment and entry were found to be related to the antibody concentration. At 25 micrograms/ml, the percentages of inhibition of sporozoite invasion were 100% (2F2), 76%(NVS3) and 10.5% (2E10). Even if the invasion was not totally inhibited, the presence of abnormal exoerythrocytic schizonts suggested that continued effect of antibodies after sporozoite penetration still existed. No significant effects of 4B2 (4.5%) and 8E3 (3.4%) were recorded as compared with normal mouse serum. These findings indicate that inhibition of sporozoite invasion assay may be useful for determining the protective effect of anti-sporozoite antibodies in vitro.