Vaccine to prevent spread of malaria
Scientists in the US have developed a malaria vaccine that, while not protecting against an outbreak, does stop the malaria parasite from reproducing in the mosquito. This could stop malaria epidemics.
Previously, vaccination against the tropical disease was considered difficult because the malaria pathogen Plasmodium eludes the human immune system in the blood. The researchers led by Rachel Schneerson from the National Institute of Child He alth and Human Development in Bethesda therefore chose a different path: they created a vaccine that only takes effect in the mosquito gut, where the malaria parasites reproduce sexually.
The protein Pfs25 (Plasmodium falciparum surface protein 25), which is only found on the cell surface of the fertilized stage, the ookinete, served as the basis for the vaccine. However, because the protein alone is not enough to boost the immune system, the researchers coupled Pfs25 with other proteins, such as Pseudomonas aeruginosa exotoxin A and ovalbumin, to which the immune system is known to be very responsive.
In fact, mice vaccinated with this protein conjugate produced antibodies specific to the Plasmodium protein. A mosquito that bites a vaccinated patient should pick up these antibodies, thereby preventing the parasite from reproducing.
Malaria is still the most common tropical disease on earth. An estimated 500 million people worldwide become ill every year; about a million - mostly children - do not survive the infection. (aj)