NASA Scientists Gain Insight Into Deadly Disease

"We were able to determine a three-dimensional atomic structure of an important enzyme from one of four species of parasites known to cause schistosomiasis," explained Dr. Daniel Carter, research director and chief of Marshall's Biophysics and Advanced Materials Branch of the Space Sciences Laboratory. "That allowed us to identify critical parts of the enzyme's surface structure which elicit the immune responses to the disease. This important step seems to offer the most potential for developing vaccines that protect people against the entire species of schistosomiasis parasites, not just one species," said Carter.

Using highly specialized X-ray equipment and protein crystallization techniques developed for space-based microgravity research, biophysics researchers were able to locate key positions of individual atoms in the enzyme, also a major target for drugs used in the treatment of schistosomiasis, and build a computer picture or blueprint of the schistosoma enzyme structure.

The determination of the enzyme structure offers the possibility of combining such techniques as the use of disease fighting drugs with the development of preventative vaccines to form an effective barrier against the transmission of schistosomiasis.

"Building a person's immunity is one way to fight schistosomiasis," explained Carter. "Many people are repeatedly infected with the disease. If we can break the life cycle of the parasite by vaccinating people against transmission of the disease, we can make a major step toward eliminating the threat of schistosomiasis in those parts of the world where it poses a major health hazard."

The research has paid dividends in other areas as well, said Carter. "Information gained in the search for a particular atomic structure often helps us learn more quickly about other research targets," he said. "For instance, a three-dimensional crystal structure of a schistosomiasis enzyme joined with atomic structural components of Human Immunodeficiency Virus type 1 (HIV-1) has also been resolved. This structural, building- block approach to HIV research has helped us learn more about the structure of HIV proteins, which have proven very difficult to crystallize and thus study more thoroughly," said Carter.

Schistosomiasis research at Marshall was performed in collaboration with the Institute of Applied Microbiology in Vienna, Austria, and the Center For Advanced Research in Biotechnology of the National Institute of Standards in Washington, DC.

Also known as bilharzia, schistosomiasis is a disease caused by any of four parasitic flatworms or flukes. Persons can become infected with schistosomiasis when they wade or swim in contaminated fresh water by exposure to skin-penetrating, free-swimming larvae. Schistosomiasis is known to occur in parts of Brazil, Egypt, sub-Saharan Africa, southern China, the Philippines and Southeast Asia. There is no vaccine against the disease.