Plasmodium yoelii merozoite antigen protects mice against parasitemia.

2003 JAN 8 - (NewsRx.com & NewsRx.net) -- by Maria G. Essig, MS, ELS, senior medical writer - A vaccine containing a recombinant form of the surface protein of the merozoite stage of the malaria parasite protected mice against malaria infection, according to a report in Infection and Immunity.

"One of the difficulties in developing an effective malaria vaccine is the antigenic change of the parasite during the life cycle," explained Yuko Kawabata and colleagues at Nagasaki University. "It is desirable that vaccine-induced protective immunity be effective at different stages of parasite development. Merozoite surface protein 1 (MSP1) is a candidate vaccine antigen against blood-stage malaria, but it is also expressed in the exoerythrocytic forms. It was not known, however, whether the anti-MSP1 immune response is effective against the liver-stage malaria parasite."

The investigators fused MSP1 to heat-shock cognate protein 70 (hsc70) and used the combination as a vaccine against a challenge of Plasmodium yoelii sporozoites in C57BL/6 mice (Merozoite surface protein 1-specific immune response is protective against exoerythrocytic forms of Plasmodium yoelii, Infect Immun, 2002;70(11):6075-6082).

Malaria infection was delayed or prevented in vaccinated mice. Real-time reverse transcription-PCR analysis of the infected livers revealed that the levels of parasite-specific rRNA were decreased in mice that received the fusion product but not in mice that received only hsc70, indicating that the vaccine was effective against the exoerythrocytic form of P. ...