Structural changes in the bovine nematode Haemonchus placei, that may be associated with host immune response

Abstract

The structure of H. placei adult worms, obtained from calves at 4, 7, 10 or 11–13 weeks after primary infection, has been studied. A reorganization of rough endoplasmic reticuhim in the cytoplasm of the gut cells was seen at 10 weeks and this was followed by marked vacuolation of many of these cells, associated with an increase in lipid production. Increases of lipid were also found in the hypodermis, lateral cords and occasionally muscle cells of worms examined at 11–13 weeks after infection.It is suggested that these changes are the result of the host immune response, because they resemble changes which occur in the rat nematode Nippostrongylus brasiliensis and which are known to be caused by host immunity.