Safety and Efficacy of a Recombinant DNA Plasmodium Falciparum Sporozoite Vaccine

摘要

A recombinant DNA Plasmodium falciparum sporozoite vaccine produced in Escherichia coli (FSV-1) was tested in doses of 10 micrograms to 800 micrograms protein in fifteen volunteers. No serious adverse reactions occurred. Antibodies that reacted with P falciparum sporozoite antigens by enzyme-linked immunoassay developed in twelve of the volunteers. The highest antibody titres induced were similar to those resulting from lifelong natural exposure to sporozoite-infected mosquitoes. Post-immunization serum samples from a majority of volunteers mediated the circumsporozoite (CS) precipitation reaction and inhibited sporozoite invasion of hepatoma cells in vitro. Six immunized volunteers receiving a fourth dose of FSV-1 and two non-immunized controls were challenged by bites of mosquitoes infected from cultured P falciparum gametocytes. Parasitaemia did not develop in the volunteer with the highest titre of CS antibodies, and parasitaemia was delayed in two other immunized volunteers. This study confirms that human beings can be protected by CS protein subunit vaccines and provides a framework for the further development and testing of more immunogenic sporozoite vaccines. Keywords: Vaccines, Reprints. (KT)