ChAd63 Pfs25-IMX313

ChAd63 Pfs25-IMX313 is an investigational malaria transmission-blocking vaccine candidate. It uses a replication-deficient chimpanzee adenovirus serotype 63 (ChAd63) vector to deliver genetic material encoding a fusion protein of the Plasmodium falciparum sexual-stage antigen Pfs25 and the oligomerization domain IMX313. The IMX313 component, derived from complement inhibitor C4b-binding protein, enhances immunogenicity by promoting heptamer formation with the fused antigen, thereby improving antibody responses. The vaccine aims to induce immune responses that target the sexual stages of the malaria parasite within mosquitoes, preventing onward transmission rather than directly protecting vaccinated individuals from infection. Clinical studies have shown that ChAd63 Pfs25-IMX313 is safe and immunogenic in healthy adults but has demonstrated only weak transmission-reducing activity in most volunteers[1][2][4].