Attempts to vaccinate ewes and their lambs against natural infection with Haemonchus contortus in a tropical environment

Author(s)

Bassetto, C. C. ^[1] ; Picharillo, M. E. ^[1] ; Newlands, G. F. J. ^{[2, 3]} ; Smith, W. D. ^{[2, 3]} ; Fernandes, S. ; Siqueira, E. R. ; Amarante, A. F. T. ^[1]

Affiliation

^[1] UNESP Univ Estadual Paulista, Dept Parasitol, Inst Biociencias, BR-18618000 Botucatu, SP - Brazil

^[2] Moredun Res Inst, Edinburgh EH26 0PZ, Midlothian - Scotland

^[3] UNESP Univ Estadual Paulista, Dept Prod Anim, Fac Med Vet & Zootecnia, Fazenda Expt Lageado, BR-18618000 Botucatu, SP - Brazil

• Document type: Journal article
• Source: International Journal for Parasitology; v. 44, n. 14, p. 1049-1054, DEC 2014.
• Web of Science Citations: 12

Abstract

A vaccine containing integral membrane glycoproteins from the intestine of Haemonchus contortus was evaluated in three groups of grazing sheep each containing 13 ewes and their 16 lambs naturally infected with gastrointestinal nematodes. Two groups were vaccinated with either 5 or 50 mu g of the antigen per immunisation, while the third, the control group, received adjuvant alone. The sheep were immunised six times at 3 week intervals, partly because the vaccine antigens are hidden and thus no immunological boost would be delivered by subsequent infection and partly because the level of Haemonchus spp. challenge was expected to be high. The vaccinated ewes, first immunised approximately 1 month before lambing, showed a circulating antibody response but no signs of reduced anaemia or Haemonchus spp. egg counts, compared with control ewes. Several ewes with severe haemonchosis in all three groups had to be given precautionary treatment with anthelmintic drugs. In contrast, vaccinating their lambs with either 5 or 50 mu g of the antigen per immunisation resulted in 10 fold higher antibody titres. In the case of the lower antigen dose this was associated with significantly less anaemia, 72% reduction in the overall number of Haemonchus spp. eggs produced and significantly fewer worms compared with control lambs. It is hypothesised that the heavily pregnant or lactating ewes did not have sufficient physiological reserves to mount a protective response following vaccination in the tropical weather and high challenge conditions that prevailed. Nevertheless, the vaccine could afford useful protection for lambs against H. contortus. (C) 2014 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved. (AU)

• FAPESP's process: 10/18678-5 - Protection of sheep and cattle against haemoncose after immunization with antigens from the intestinal membrane of Haemonchus contortus.
• Grantee: César Cristiano Bassetto
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 11/03806-0 - Immunization of sheep against Haemonchus contortus: effect of vaccination on weight gain of animals and pasture contamination by infective larvae
• Grantee: Maria Erika Picharillo
• Support Opportunities: Scholarships in Brazil - Scientific Initiation