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United States Department of Agriculture

Agricultural Research Service


item Fetterer, Raymond
item Rhoads, Marcia

Submitted to: Veterinary Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/15/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: The stomach worm Haemonchus contortus is a blood feeding parasite that infests grazing ruminants. Infection with the parasite causes anemia which often results in death of the host. In order to derive nutrition from ingested red blood cells (RBCs) the parasites require a mechanism to lyse or otherwise disrupt cells. The current study examined the effect of hemolytic factors on the structure of host RBCs. Electron micrographs of sheep RBCs indicate that the hemolytic factor causes, initially distortion and then complete disruption of the cells. RBCs from other mammals are similarity altered by the hemolytic factor. These results suggest that the hemolytic activity of H. contortus is important in the disruption of host cells and may be an suitable target for development of new controls.

Technical Abstract: A hemolytic factor from adult H. contortus lysed sheep red blood cells (RBCs) causing distinct morphological changes in the cell surface. After 15 min exposure to the hemolytic factor cells were spherical in shape with numerous surface projections. After 30 minute exposure echinocytes were formed and after 90 minute incubation cells were severely disrupted with many visible holes in membranes. No RBC ghost were observed. RBCs from four other mammalian species were also lysed by the H. contortus hemolytic factor. However the rate of hemolysis varied with a relative order of rabbit>pig>goat>calf. The morphology of RBCs from all four species was significantly altered after 30 minute incubation with the degree of morphological changes related to the degree of hemolysis. These results suggest support a hypothesis that hemolytic factor may act as a pore forming agent although a phospholipase or other enzyme may play a role in solubilization of cell membranes.

Last Modified: 10/20/2017
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