Recombinant human antibodies specific for the Pfs48/45 protein of the malaria parasite Plasmodium falciparum

We report the first construction of two combinatorial human phage display l ibraries derived from malaria-immune patients. Specific single-chain Fv fra gments (scFv) against Pfs48/45, a gamete surface protein of the sexual stag es of Plasmodium falciparum, were selected and analyzed extensively. The se lected scFv reacted with the surface of extracellular sexual forms of the p arasite and showed Pfs48/45 reactivity on immunoblot. The scFv inhibit bind ing of human malaria sera to native Pfs48/45 from gametocytes. Moreover, th e scFv bind to target epitopes of Pfs48/45 exposed in natural infections. S equence analysis of eight scFv clones specific for epitope III of Pfs48/45 revealed that these clones could be divided into one V-H family-derived ger m-line gene (V(H)1) and two V-L family segments (V(L)2 and VKI).