Scientists uncover mystery behind failure of DNA-based anti-malaria vaccines

Washington, Apr 24 : Florida State University biologists claimed to have solved the mystery behind the failure of DNA-based anti-malaria vaccines to protect children suffering from the disease.

They have discovered an autoimmune-like response in blood drawn from malaria-infected African children that can speed the development of new treatments and vaccines for effective treatment.

The study involved children in remote Nigerian villages who were younger than 6 and infected with Plasmodium falciparum, the most virulent form of the malarial parasite.

The study led by Virginia Baker, an assistant professor at Chipola College in Marianna, Fla. found that the white blood cell remnants actually are Neutrophil Extracellular Traps or "NETs" that both capture malaria parasites and stimulate unique, often deadly responses in the immune systems of these young children.

Baker had spent several weeks in Nigeria directing the sample collection by Nigerian medical collaborators.

The team measured the levels of cytokines, molecules that are released in response to infection and circulate in the blood stream to function as signals in the immune system, both before and after the treating children with an effective anti-malarial drug.

"We also took a fresh look at some unusual white blood cells that appeared to have exploded in the children's blood smears," said Keller.

"Although scientists had observed these structures for years in malaria-infected blood samples, they remained very poorly understood.

"From our interpretations of the existing literature, we suspected that an autoimmune-like response may have contributed to the severity of malaria in young children.

"Nevertheless, we were completely surprised to find that the strange white blood cell structures characterized by previous researchers as artifacts or an extraordinary response to other types of infections were in fact circulating 'NETs' of DNA, which form as a result of the immune system's response to malaria," he added.

Baker said that protocols designed to treat the accompanying autoimmune-like response will be more effective in preventing severe malaria in young children than treatments directed only at clearing the parasites.

The findings appear in the February 2008 edition of the journal Malaria.

ANI