New high for global molybdenum production and use in 2014

Abstract

Dawkins H. J. S., Windon R. G., Outteridge P. M. and Dineen J. K. 1988. Cellular and humoral responses of sheep with different levels of resistance to Trichostrongylus colubriformis. International Journal for Parasitology18: 531–537. A selective breeding programme, based on faecal egg counts, has produced lines of sheep which are either resistant (high responder) or susceptible (low responder) to challenge infection with T. colubriformis after vaccination with irradiated larvae. Peripheral blood cellular and humoral responses were examined in third generation lambs at fortnightly intervals beginning 1 week after birth. All lambs had complement-fixing antibodies to T. colubriformis 1 week after birth due to maternal colostrum. Vaccination and challenge infections induced increased antibody titres, with high responder lambs having higher mean antibody titres than the low responder lambs. The mitogens Con A, leucoagglutinin, PHA and Protein A induced increased lymphocyte transformation in ewes prior to secondary vaccination. Cells from low responder ewes had higher stimulation indices than cells from high responder ewes. Blastogenic responses of high and low responder rams were similar for each of the mitogens tested. LPS and Dextran sulphate were poor ovine lymphocyte mitogens. Cells from high and low responder lambs did not differ in their blastogenic response to antigen from T. colubriformis larvae. It was concluded that for the assay conditions employed in this study, humoral and cellular parameters did not differentiate between high and low responder lambs.