Immunological properties of recombinant proteins of the transmission blocking vaccine candidate, Pfs48/45, of the human malaria parasite <i>Plasmodium falciparum</i> produced in <i>Escherichia coli</i>

Abstract

A precondition for the development of a transmission blocking vaccine based on the sexual stage-specific surface antigen Pfs48/45 of Plasmodium falciparum is its heterologous synthesis in a native state. Here we describe the production of recombinant Pfs48/45 in Escherichia coli. Two recombinant proteins, of which one is a glutathione-S-transferase fusion protein, were produced. Enzyme-linked immunosorbent assays showed that at least a subfraction of the recombinant proteins had a conformation capable of binding transmission blocking monoclonal antibodies. However, despite the fact that both proteins were very immunogenic, they did not induce transmission blocking immunity in mice or rabbits. Immunological studies with congenic mouse strains demonstrated that immune responses could be boosted with gametocyte extracts and were not restricted to a particular class II major histocompatibility complex haplotype.