Researchers in America believe they may have the key to malaria prevention, engineering algae to produce potential candidates for a vaccine that would prevent transmission of protozoan parasites from the genus Plasmodium.

Biologists at the University of California, San Diego came up with the idea for the vaccine, which could pave the way for the development of an inexpensive way to protect billions of people from a disease that affects 225 million people worldwide.

Even though there are preventative treatments on the market, a vaccine offering a high level of protection from the disease does not yet exist. This is primarily because a system of three-dimensional proteins must be made that resemble those made by the parasite, thus eliciting antibodies that disrupt malaria transmission. Most vaccines aren’t that complex, and until now, making treatments that work on this level has been very costly and inefficient.

Stephen Mayfield, a professor of biology at University of California, San Diego who headed the research effort, said: “Malaria is caused by a parasite that makes complex proteins, but for whatever reason this parasite doesn’t put sugars on those proteins.

“If you have a protein covered with sugars and you inject it into somebody as a vaccine, the tendency is to make antibodies against the sugars, not the amino acid backbone of the protein from the invading organism you want to inhibit. Researchers have made vaccines without these sugars in bacteria and then tried to refold them into the correct three-dimensional configuration, but that’s an expensive proposition and it doesn’t work very well.”

The researchers therefore looked for an alternative by producing proteins with the help of an edible green alga, Chlamydomonas reinhardtii, which is used widely in research laboratories as a genetic model organism, much like the fruit fly Drosophila and the bacterium E. coli.

James Gregory, a postdoctoral researcher in Mayfield’s laboratory, collaborated on the research, and believes it holds the key to cost-effective preventative treatments. He said: “It’s hard to say if these proteins are perfect, but the antibodies to our algae-produced protein recognise the native proteins in malaria and, inside the mosquito, block the development of the malaria parasite so that the mosquito can’t transmit the disease."