In the complicated life cycle of ancient flatworms that cause schistosomiasis, Case Western Reserve University researchers have identified a gene activator crucial to development of the parasites within humans a potential target for a vaccine.
A description of the activator, which turns on rapid growth, is in the online journal PLoS Neglected Tropical Diseases.
Schistosomiasis, which causes organ damage and failure, afflicts more than 200 million people worldwide, killing 280,000 annually. Another 400 million people are at risk for the disease.
For decades, a single drug, praziquantel, has been used to kill the worms, and scientists are concerned the drug may become useless. The worms, called schistosomes, have shown they can develop resistance to praziquantel in the lab and there is currently no other drug to treat the disease.
Beyond that concern, the lack of a vaccine leaves human hosts in a cycle of their own: becoming infected, taking praziquantel, becoming reinfected - multiple times - due to the prevalence and ease of contracting the parasite in rivers and ponds in Asia, Africa and South America. Repeated exposure can add up to illness and death.
"This is really a disease of poor people," said Emmitt Jolly, professor of biology at Case Western Reserve and senior author of the paper. "The strategy to combat the disease cannot be expensive."
Jolly and John Milligan, a technician in Jolly's lab and lead author, spent two years studying, identifying and characterizing the protein, and gene activator, myocyte enhancer factor 2, commonly referred to at Mef2, in the flatworm's life cycle.
Depending on the phase of development, the schistosome lives in snails, in freshwater or in humans. From the snail, it becomes a tiny free swimmer that penetrates human skin. The parasite enters blood vessels and feeds on blood cells.
Sexually mature schistosomes congregate in blood vessels in
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Case Western Reserve University