Potential Malaria Vaccine Protects Against Different Strains

A team of U.S. scientists has shown how a malaria vaccine could be more effective by making it work against different strains of the malaria parasite.

The discovery may help develop more effective vaccines for other diseases, too.

Many vaccines are administered in a serum contain adjuvants - substances that enhance the protective effect of the vaccine itself.

Vaccines normally stimulate the production of antibodies which attach to the surface of a bacteria or virus. But if the infection mutates, the antibodies may not be able bind to it, and the immunization won't be effective.

To get around that problem, the researchers focused on finding a malaria vaccine adjuvant that would produce antibodies against numerous strains of the parasite.

Darrick Carter of the non-profit Infectious Disease Research Institute in Seattle, Washington, explained that antibodies become more effective as the body mounts its immune response, a process called antibody maturation.

"And what we found is that certain adjuvants cause maturation at a much higher rate than if you do not include the adjuvant," he says. "And this maturation gives you a diverse set of antibodies that not only protect you against the strains you've been vaccinated against, but that diverse set also seems to start recognizing related sequences."

Using advanced genetic sequencing equipment, the researchers tested a number of adjuvants to identify the one which would result in the most diverse antibody response. More diverse antibodies should be able to fight off more strains of malaria.

Human trials could start next year, and if successful, the adjuvant may also find its way into other vaccines, Carter says.

"So we're working on both pandemic and seasonal flu. We're working on TB and a number of other diseases where we can use the same adjuvant."

Carter and his colleagues are working on a vaccine that is aimed at one of four main types of malaria, caused by the Plasmodium vivax parasite. It's one of the two most common strains but is relatively benign compared to the deadly Plasmodium falciparum.