The fibrinogen-like domain of FREP1 protein is a broad-spectrum malaria transmission-blocking vaccine antigen.

FREP1 in mosquito midguts facilitates parasite transmission. The fibrinogen-like (FBG) domain of FREP1 is highly conserved (>90% identical) among species from different continents, suggesting that anti-FBG antibodies may block malaria transmission to all anopheline mosquitoes. Using standard membrane-feeding assays, anti-FREP1 polyclonal antibodies significantly blocked transmission of and to and , respectively.