Impacts of breed type and vaccination on Teladorsagia circumcincta infection in native sheep in Gran Canaria

Abstract

Vaccines and genetic resistance offer potential future alternatives to the exclusive use of anthelmintics to control gastrointestinal nematodes (GIN). Here, a Teladorsagia circumcincta prototype vaccine was administered to two sheep breeds which differ in their relative levels of resistance to infection with GIN. Vaccination of the more susceptible Canaria Sheep (CS) breed induced significant reductions in worm length and numbers of worm eggs in utero (EIU) when compared to control CS sheep. In the more resistant Canaria Hair Breed (CHB), although vaccination induced a reduction in all parasitological parameters analysed, differences between vaccinated and control sheep were not statistically significant. Such interactions between sheep breed and vaccination may allow better integrated control of GIN in future.

Reduced egg shedding in nematode-resistant ewes and projected epidemiological benefits under climate change

“…Despite the relatively smaller reduction in FECs in the present study, the predicted benefits of this reduction in the context of reduced pasture contamination and reduced lamb exposure to infection lend support to the future role of vaccination in controlling gastrointestinal nematodes. Selective breeding might also enhance vaccine effectiveness in the field, as indicated by breed differences in responsiveness to a T. circumcincta vaccine (Gonzalez et al, 2019).…”

Cellular and humoral immune responses associated with protection in sheep vaccinated against Teladorsagia circumcincta

“…The experimental design was previously described in details in [ 11 ]. Briefly, 24 male lambs of CHB and another 24 male lambs of CS, all of them weaned, were dewormed and kept worm-free until they were six months-old.…”

“…Faecal egg counts (FEC) were performed using modified McMaster technique [ 12 ] three times per week from day 56 after the start of immunisations, until the end of the experiment. At the end of the trial (days 82–85), lambs were euthanised, and adult and immature worms from aliquots of the abomasal content were obtained, counted and measured following standard techniques [ 11 ].…”

“…IBM SPSS Statistics version 24.0 software was used for statistical analysis of parasitological, immunohistochemical and serum antibody data. Differences in FEC, cumulative FEC, worm counts, worm length and EIU were estimated as described in [ 11 ]. The data relative to specific immunoglobulin levels in serum were analysed using generalised linear models (GENLIN), using the estimation method Newton–Raphson and Pearson Chi-square scale.…”

“…In a recent study [ 11 ], parasitological data was collected for evaluating the effects of this vaccine in two sheep breeds, the Canaria Sheep (CS) and the Canaria Hair Breed (CHB), which have different susceptibilities to T. circumcincta . Whereas in vaccinated CS animals there were significant reductions in worm length and numbers of worm intrauterine eggs, vaccination in CHB also induced reductions in parasitological variables, but these were not statistically significant.…”