WHAT:
Researchers have identified a substance, or antigen, that generates antibodies that can hinder the ability of malaria parasites to multiply, which may protect against severe malaria infection. The antigen, known as PfSEA-1, was associated with reduced parasite levels among children and adults in malaria-endemic areas. Mice exposed to PfSEA-1 in an investigational vaccine also experienced lower malaria parasite levels. The discovery of PfSEA-1 could be a critical addition to the limited pool of antigens currently used in candidate malaria vaccines. The findings, which appear in the May 23 issue of Science, result from a collaboration of scientists from the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, and NIAID grantees.
An estimated 627,000 people die from malaria each year according to the World Health Organization, with most deaths from the mosquito-borne parasitic disease occurring among young children living in sub-Saharan Africa. People who live in areas where malaria is common frequently develop protective immune system responses that can limit malaria parasite levels in the blood and prevent the high fever and illness associated with malaria infection. Using plasma samples from 2-year-old Tanzanian children who were either resistant or susceptible to malaria infection, researchers performed gene-screening experiments and a series of laboratory tests that identified PfSEA-1. Multiple tests confirmed that antibodies to PfSEA-1 halted malaria infection at the point when the parasite leaves one red blood cell to invade a new one. This stage offers a unique target for future malaria vaccines as previous vaccine candidates have tried to block the stage when parasites enter red blood cells, according to the authors.