
Scientists Steal Parasites Digestive
SecretsBy Jan Suszkiw January 20, 1999Stolen secrets from the barberpole worm may help scientists plot
biochemical sabotage to undermine the tiny blood suckers mischief in
grazing animals like sheep. The secrets include a potent cocktail of digestive secretions
discovered in the intestine of the three-centimeter long worm, Haemonchus
contortus. One find, proteins that help the parasite digest red blood cells, may prove
vulnerable to new drug control strategies or open the door to animal vaccine
research. Thats the hope of zoologist Ray Fetterer and colleagues at the
Parasite Biology and
Epidemiology Laboratory, operated in Beltsville, Maryland, by the
Agricultural Research Service. ARS is
the chief research agency of the U.S. Department
of Agriculture. Administering drugs to livestock is the standard course of action against
Haemonchus, which feeds on blood from its host abomasum (true stomach).
But such chemical control is costly, and the parasite is showing signs of
resistance, especially in sheep in the United States and Australia, where
scientists are searching for natural alternatives. Fetterers search began with cutting into Haemonchus
intestine, where hemoglobin and other nutrients are extracted from red blood
cells. Along with ARS colleagues Marcia Rhoads and Dolores Hill, Fetterer
discovered a key group of proteins, called hemolytic factors, and a cysteine
protease enzyme. Lab analysis showed that the proteins form pores in red blood cells within
30 minutes of contact, causing hemoglobin to escape. The hemoglobin is then
broken down into smaller fragments by the cysteine protease enzyme, aiding the
worms ability to utililize the nutritious blood protein. Fetterers lab is working with Enzyme Systems Products, a Livermore,
Calif., company, to see how well substances called inhibitors thwart the
parasites production of cysteine protease, thus depriving it of a key
digestive tool. A story about the research appears in the January issue of Agricultural Research magazine,
and on the Web at: http://www.ars.usda.gov/is/AR/archive/jan99/worm0199.htm Scientific contact: Scientific contact:
Ray
Fetterer, Parasite Biology and Epidemiology Laboratory, Beltsville, Md.,
phone (301) 504-8300, fax (301) 504-5306,
[email protected]. Story contacts Dolores E Hill Jan R Suszkiw U.S. Department of Agriculture | |