Mice Developed to Secrete a Malaria Vaccine

A study has demonstrated that an experimental malaria vaccine secreted by mice and injected into monkeys was able to protect four of five animals from a lethal dose of malaria. Conducted by researchers at the US National Institute of Allergy and Infectious Diseases (NIAID) and Genzyme Transgenics Corp. (Framingham, MA, USA), the study was published in the December 18, 2001, online issue of the Proceedings of the National Academy of Sciences (www.pnas.org).

The researchers produced two transgenic mouse strains. Each carried a form of the gene for a surface protein from the deadliest malaria parasite, Plasmodium falciparum. The transgenes were designed to be switched on by cells that line the mammary glands, so that the resulting proteins would be secreted into the animals' milk. Both mouse strains produced large quantities of the desired vaccine, which was then used to vaccinate monkeys against malaria. Only one of the five immunized animals contracted malaria, while six out of seven unvaccinated animals had to be treated for virulent malaria.

The high yield of the protein and its ability to stimulate protective immunity in mice offers promising evidence that the same technique could also be used in goats or cows, say the researchers. Preliminary experiments suggest that the procedure works well in larger animals, a possibility that offers a far more practical option for large-scale production.

"A vaccine must not only be effective, it must be cheap to manufacture if it is to be used in those countries hit hardest by malaria,” said Anthony Stowers, Ph.D., lead author and a malaria researcher at NIAID. "Using transgenic animals to achieve both ends is an exciting possibility. If it works, a herd of several goats could conceivably produce enough vaccine for all of Africa.”




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