title: A hemolytic factor from Haemonchus contortus alters erythrocyte morphology.
abstract: A hemolytic factor from adult Haemonchus contortus caused distinct morphological changes in the surface of sheep red blood cells (RBCs). After a 15 min exposure to the hemolytic factor, hemolysis was not detected in incubation media, but RBCs were spherical in shape with numerous surface projections compared to control cells that were smooth-surfaced biconcave disks. After 30 min, a time at which significant hemolysis occurred, echinocytes were formed, and after 90 min, cells were severely disrupted with many visible holes in membranes. No RBC ghosts were observed. RBCs from four other mammalian species were lysed by the H. contortus hemolytic factor. However, the rate of hemolysis varied with a relative order of sheep approximately rabbit>goat>pig>calf. The morphology of RBCs from all four species was significantly altered after 30 min incubation with the degree of morphological changes related to the degree of hemolysis. These results support the hypothesis that the hemolytic factor acts as a pore-forming agent, although a phospholipase or other enzyme might play a role in solubilization of cell membranes.
authors.affiliation: Parasite Biology and Epidemiology Laboratory, Livestock and Poultry Sciences Institute, Beltsville Agricultural Research Center, MD 20705, USA. rfetterer@ggpl.arsusda.gov
authors.forename: R H
authors.initials: RH
authors.lastname: Fetterer
authors.forename: M L
authors.initials: ML
authors.lastname: Rhoads
mesh_terms: D000818:Animals; D002417:Cattle; D004912:Erythrocytes / Q000648:ultrastructure*; D006041:Goats; D006189:Haemonchus / Q000737:chemistry*; D006461:Hemolysis / Q000502:physiology*; D006462:Hemolytic Plaque Technique / Q000662:veterinary; D008855:Microscopy, Electron, Scanning; D011817:Rabbits; D012756:Sheep; D013552:Swine