Malaria beats immune system by causing it to self-sabotage

The new understanding of malaria infection may help development of more effective vaccines, researchers said.
By Stephen Feller  |  Dec. 28, 2015 at 12:21 PM
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MELBOURNE, Dec. 28 (UPI) -- Scientists have had trouble developing a malaria vaccine because it takes so long to develop immunity. Researchers in Australia may have figured out the culprit for preventing immunity: the immune system itself.

Researchers at the Walter and Eliza Hall Institute found inflammatory molecules that drive the immune response to malaria also prevent the creation of immune cells that kill the micro-organism Plasmodium falciparum, which causes malaria.

Longtime immunity from infection requires an antibody response from the immune system, which is why a malaria vaccine has been so elusive, said the researchers. A vaccine approved for use by the European Union in July, and expected to be available by 2017, is not universally effective and its ability to protect against the infection starts to fade after a year.

"We didn't know whether it was the malaria parasite itself or the inflammatory reaction to malaria that was actually inhibiting the ability to develop protective immunity," Dr. Diana Hansen, a researcher at the Walter and Eliza Hall Institute, said in a press release. "We have now shown that it was a double-edged sword: the strong inflammatory reaction that accompanies and in fact drives severe clinical malaria is also responsible for silencing the key immune cells needed for long-term protection against the parasite."

In a study with mice, published in Cell Reports, researchers tested the effects of malaria infection on the immune system. They found inflammatory molecules prevent the creation of cells responsible for making antibodies that fight the parasite.

Hansen said the new understanding could help researchers develop better way to treat malaria, as well as help stalled vaccine development.

"Until now, malaria vaccines have had disappointing results," Hansen said. "We can now see a way of improving these responses, by tailoring or augmenting the vaccine to boost development of helper T cells that will enable the body to make protective antibodies that target the malaria parasites."

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