IMMUNIZATION OF SHEEP WITH AN INTEGRAL MEMBRANE GLYCOPROTEIN COMPLEX OF HAEMONCHUS-CONTORTUS AND WITH ITS MAJOR POLYPEPTIDE COMPONENTS

Sheep were immunised against Haemonchus contortus with an integral mem brane glycoprotein complex isolated from the intestines of the parasit e as antigen. This antigen has been termed Haemonchus galactose-contai ning glycoprotein complex. Sodium dodecyl sulphate (SDS) polyacrylamid e gel analysis has shown that it is composed of several polypeptides b ut so far these have proved refractory to separation when in the nativ e state. However when dissociated by sos, it was found to be as effica cious as in its native stare, although it was less consistently protec tive when tested after being dissociated and reduced. An attempt was t herefore made to identify the protective ingredient(s) of the dissocia ted complex by testing its major polypeptides individually after they had been separated on SDS polyacrylamide gels under non-reducing condi tions. Partial protection was induced by protein bands with molecular weights of about 200 kD and less than 50 kD, but none of the individua l fractions tested was as efficacious as the unseparated complex, sugg esting that either more than one component was essential for a consist ent effect or that the separation technique had damaged crucial protec tive epitopes.