Plasmodium berghei sporozoites acquire virulence and immunogenicity during mosquito hemocoel transit.

YUKO SATO; GEORGINA N. MONTAGNA; KAI MATUSCHEWSKI

INFECTION AND IMMUNITY

AMER SOC MICROBIOLOGY

Lugar: Washington; Año: 2013

0019-9567

Malaria is a vector-borne disease caused by the single-cell eukaryote Plasmodium. The infectious parasite forms are sporozoites,which originate from midgut-associated oocysts, where they eventually egress and reach the mosquito hemocoel. Sporozoitesactively colonize the salivary glands in order to be transmitted to the mammalian host. Whether residence in the salivary glandsprovides distinct and vital cues for the development of infectivity remains unsolved. In this study, we systematically comparedthe infectivity of Plasmodium berghei sporozoites isolated from the mosquito hemocoel and salivary glands. Hemocoel sporozoitesdisplay a lower proportion of gliding motility but develop into liver stages when added to cultured hepatoma cells or afterintravenous injection into mice. Mice infected by hemocoel sporozoites had blood infections similar to those induced by sporozoitesliberated from salivary glands. These infected mice display indistinguishable systemic inflammatory cytokine responsesand develop experimental cerebral malaria. When used as metabolically active, live attenuated vaccine, hemocoel sporozoiteselicit substantial protection against sporozoite challenge infections. Collectively, these findings show that salivary gland colonizationdoes not influence parasite virulence in the mammalian host when sporozoites are administered intravenously. This conclusionhas important implications for in vitro sporozoite production and manufacturing of whole-sporozoite vaccines.