Plasmodium falciparum: administration of anti-sporozoite antibodies during sporogony results in production of sporozoites which are not neutralized by human anti-circumsporozoite protein vaccine sera.

Five days after receiving a Plasmodium falciparum NF54 infectious blood meal, Anopheles stephensi mosquitoes were fed rat anti-P, falciparum sporozoite or rabbit anti-R32tet32 antibodies. Sporozoites isolated from salivary glands were tested by the inhibition of sporozoite invasion (ISI) assay using monoclonal antibody (Mab) 2A10 to P. falciparum circumsporozoite protein or sera from human volunteers immunized with P. falciparum R32tet32 or (NANP)3-TT vaccines. Whereas sporozoites from control mosquitoes were neutralized by Mab 2A10 and vaccine sera, only the Mab and not the vaccine sera neutralized sporozoites from immune-fed mosquitoes. The implications of these results in vaccine design and the impact on transmission are discussed.