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July 03, 2013

Promising Malaria Vaccine Headed for Trials in Australia

by Jessica Berman

An experimental malaria vaccine, poised to undergo human clinical trials, seems to protect against all types of the disease.  The Australian researchers who developed the drug say it can be simply and inexpensively made in countries where it is most needed.  

There's a reason most malaria vaccines do not work, says Michael Good, an immunologist at Griffith University in Queensland, Australia.  It's because the drugs now in clinical trials try to stimulate an immune response against the infection by using surface proteins from the mosquito-borne parasite.  

But Good says those proteins are highly changeable, allowing the parasite to evade destruction by the body’s protective white blood cells.

The vaccine approach taken by Good and colleagues uses the entire parasitic worm, which they bathe in chemicals that bind to the organism’s DNA so it cannot reproduce.  
 
”It’s completely weakened.  It can’t actually cause an infection.  But it fools the body into thinking that there has been an infection," said Good.

After the parasites are essentially neutered by the chemicals, Good says they are processed into a vaccine that, in experiments with mice, triggered a very strong protective response by the body's T cells.  

In a Skype interview, Good said the inoculated mice were shielded for more than six months when researchers tried to infect them with different strains of a rodent version of malaria.  

This indicates that the “whole parasite” vaccine approach, as Good calls it, could potentially protect against infection by any number of human malaria strains, by targeting proteins common to all of them.

“To get protection against multiple strains to us was extremely encouraging because that has been to date one of the major issues...about making vaccines for humans," he said.

Researchers also found that even the deadliest human malaria parasite, Plasmodium falciparum, was weakened by the drug compounds they tested to make the vaccine.

Human clinical trials to test the safety and immune response of the novel malaria vaccine are expected to get under way in the coming months.  Good says the vaccine is simple to make and could easily be produced locally in malaria-endemic countries, including those in sub-Saharan Africa, where the disease claims upwards of three-quarters of a million lives each year.

An article on the malaria parasite vaccine by Australian researcher Michael Good and colleagues is published in the Journal of Clinical Investigation.