Harvard Scientists Analyze Genes of Malaria Parasite

Scientists have recently mapped the genome of the parasite that causes malaria, and a researcher at the Harvard School of Public Health (HSPH) is hoping this information will lead to more effective forms of treatment.

The genome sequencing of Plasmodium falciparum and the initial lessons that scientists have learned about the parasite are outlined in two new journal articles by Dyann F. Wirth, director of the Harvard Malaria Initiative and professor of immunology and infectious diseases at HSPH.

One paper appeared in Thursday's issue of the journal Nature, and the other article was published in Friday's issue of the journal Science.

"The goal is to use this blueprint to find the Achilles heel, or weak point, of the parasite and use drugs to attack that," Wirth said.

P. falciparum causes the most lethal form of human malaria, which is the world's most serious parasitic tropical illness, killing 1 million to 3 million people each year.

One key that researchers found is the genetic variability of the parasite.

Some genes are specifically targeted by the human body's immune system, and these genes exhibit very high variability that allows them to evade the immune response, according to Wirth.

"It seems as if the parasite has evolved a mechanism to be one step ahead of the host immune system," Wirth said.

She said the first step in identifying potential new drug targets for treating the disease is to see if there are enzymes present in the parasite that also exist in other systems. Drugs that are currently available to treat other diseases could then be tested for immediate use in treating malaria.

Scientists also hope to use the genome sequence to find out more about the parasite's metabolism. The parasite has a special organ that is not present in humans, and which may yield new targets for drug treatment.

Another goal of the research is to use population biology to compare the parasite genome with the genome of the mosquito, which has already been published, and the genome of the human, a draft of which has been completed. This will allow scientists to better understand the interaction between the parasite and its two hosts, according to Wirth.

Scientists and doctors have been growing more concerned about the disease-for which one quarter of the world's population is at risk-as malaria is showing increasing resistance to the most common forms of treatment.

The parasite lives off mosquito hosts that spread the disease to humans.

Although pesticide use has essentially eradicated the disease in the United States and other areas outside of the tropics, two teenagers in Virginia contracted malaria just last month.

In Africa, however, infection levels are at an all-time high. The disease is a particular concern in frontier areas with new agricultural and irrigation projects, including the Amazon, Southeast Asia and Sub-Saharan Africa.

Malaria is curable if it is caught and treated early, but once the parasite establishes itself in the body, it is much more difficult to treat.