Progress Made In Possible Vaccine Against Malaria
May 17, 2012

Progress Made In Possible Vaccine Against Malaria

Connie K. Ho for

Malaria, a mosquito-borne disease, affects more than 225 around the world, particularly in tropical and subtropical areas. Those who contract malaria report symptoms like fever and headaches, which can sometimes lead to severe coma and death. While there are a few different medications to protect against infections, there have not been any vaccines available that offer a high amount of protection against the disease. Recently, biologists at the University of California, San Diego (UCSD) revealed their progress in engineering algae for a vaccine that could possibly counter transmission of the parasite that causes malaria.

The research was done by two groups at UCSD. The Division of Biological Sciences and San Diego Center for Algae Biotechnology, which has worked to engineer algae for biofuels and bio-products, along with the Center for Tropical Medicine and Emerging Infectious Diseases in the School of Medicine, which has focused on prevention and treatment of malaria, collaborated on the project. They looked at how algae could produce malaria proteins and gather antibodies against Plasmodium falciparum in laboratory mice. The study, published in the journal PLoS ONE, discussed how biologists produced proteins with Chlamydomonas reinhardtii, an edible green alga used as a genetic model organism.

Researchers believe that one of the difficulties in creating a vaccine is that there´s currently no system that can create the complex, three-dimensional proteins that mimic the ones made by the parasite. If produced, these proteins would be able to divert the transmission of malaria by the parasite. Many of the vaccines created by engineered bacteria are simple proteins that assist the body´s immune system to produce antibodies against harmful bacteria.

“Malaria is caused by a parasite that makes complex proteins, but for whatever reason this parasite doesn´t put sugars on those proteins,” noted Dr. Stephen Mayfield, lead researcher and a professor of biology at UC San Diego, in a prepared statement. “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.”

James Gregory, a postdoctoral researcher in Mayfield´s laboratory, was inspired by a past UCSD study by Mayfield that showed how Chlamydomonas, an algae, could produce complex human therapeutic proteins like growth hormones and monoclonal antibodies. Gregory decided to determine if Chlamydomonas could produce complex proteins cheaply. It was his hope that the malaria proteins could inhibit malaria infection.

“It´s too costly to vaccinate two billion people using current technologies,” explained Mayfield in the statement. “Realistically, the only way a malaria vaccine will ever be used is if it can be produced at a fraction of the cost of current vaccines. Algae have this potential because you can grow algae any place on the planet in ponds or even in bathtubs.”

Gregory worked with Dr. Joseph Vinetz, a professor of medicine at UCSD, on the project and found that the proteins by the algae, when injected into lab mice, could block malaria transmissions from mosquitoes.

“It´s hard to say if these proteins are perfect, but the antibodies to our algae-produced protein recognize 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,” remarked postdoctoral researcher Gregory in the statement.

The scientists will continue research on the malaria vaccine by testing to see if the algae proteins can protect humans from malaria and then, if so, determining if they can modify the proteins to be eaten rather than injected into humans.

“This paper tells us two things: The proteins that we made here are viable vaccine candidates and that we at least have the opportunity to produce enough of this vaccine that we can think about inoculating two billion people,” commented lead researcher Mayfield in the statement. “In no other system could you even begin to think about that.”