Current studies related to the development of transmission-blocking malaria vaccines: a review

Transmission-blocking malaria vaccines are expected to induce an immune response which, acting in the mosquito, will prevent its infection. It is generally considered that antigametocyte antibody is one factor in this effect, but there is also evidence that phagocytes and lymphocytes may contribute to blocking mosquito infection. Transmission-blocking immunity develops naturally. Antibody capable of interfering with infection of mosquitoes was shown to persist for 4 months after parasitaemia disappeared. Titres of antibody to a 230 kDa protein in developing Plasmodium falciparum oocysts correlated with the transmission-blocking capacity of serum. Monoclonal antibodies have been raised which are capable of blocking infection of mosquitoes by P. falciparum. Some of these interfere with fertilization. The antibodies react with protein expressed in freshly emerged gametes. It should be emphasized that despite progress in laboratory studies of transmission-blocking immunity, there remains a great need for specific epidemiological studies to determine the role of transmission-blocking immunity in endemic areas.