That focus on the parasites' complex life cycle is helping researchers understand when different genes switch on and off as the pathogens metamorphose through seven different life stages. In turn, that molecular-level data may benefit biomedical scientists who are identifying new targets for vaccines that would impede the parasite during stages when it is particularly vulnerable to intervention.

"We hope this project will help vaccine researchers find the best targets against malaria," says scientist Neil Hall, the first author of the paper that appears in the January 7th issue of Science. "The study's findings will help scientists identify parasite genes that are interacting with the host as well as new gene targets for vaccines that aim to prevent parasite transmission in the mosquito."

The study highlights the genes in four malarial species that evolve rapidly because of "selective pressures" in the stages of their life cycles in their mosquito vectors and in their mammalian hosts. Malaria parasites undergo three stages in their mosquito vectors, three stages in their vertebrate hosts and a sexual development stage during which the parasite is transmitted between vector and host.

The Science paper represents the culmination of four years of cooperative work by scientists at several research institutes, including: the Wellcome Trust Sanger Institute in the U.K., where the sequencing and genome annotation was performed on two species of rodent malaria (Plasmodium chabaudi and P. berghei); the University of Leiden in the Netherlands and Imperial College in England, where scientists carried out gene expression studies; and The Institute for Genomic Resea
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10-Jan-2005