Differences Within Churra Breed Sheep in the Early Immune Response to the Infection by Teladorsagia circumcincta

Trabajo presentado al: 27th International Conference of the World Association for the Advancement of Veterinary Parasitology. Abstract book, Oral Session OA41.05, pp. 155. Madison (USA), 7-11 julio 2019.In the present study, the mechanisms by which Churra breed sheep can present di@erent resistance phenotypes were studied in adults during the early stage of the infection by Teladorsagia circumcincta. For that, 12 animals were classified as resistant (6) or susceptible (6) to the infection by T. circumcincta based on their cumulative faecal egg count after an initial experimental infection. A negative correlation was found between the cumulative FEC at the end of the infection and the level of IgA in serum at day 3 pi (r=-0.764; P= 0.004), when IgAs reached the highest values in the resistant group. Sheep were dewormed and were infected again to be slaughtered at day 7 post infection. At slaughter, level of IgA in serum and gastric mucus was higher in the resistant group although only showing slight significant di@erences in serum samples (P=0.1). At the necropsy, abomasum tissue samples were collected for histological and immunohistochemistry analysis. A positive correlation was found between CD4+ and %&+ T cells (r= 0.714; P= 0.04), suggesting that both cell populations could participate in the early immune response. Moreover, we found an association between the number of %&+ T cells and eosinophils (r= 0.600; P=0.05); this association was even stronger in the resistant group (r= 0.900; P= 0.037), but absent in the susceptible animals, suggesting that the activation of this mechanism could play an important role in the resistance to the infection. On the other hand, the susceptible group showed a negative correlation between globule leukocytes and %&+ T cells (r= -0.812; P=0.05) but also slight with CD4+ T cells (r= -0.800; P=0.1). Therefore, it is possible that in the susceptible group the immune response was not strong enough to activate the recruitment of a higher number of globule leukocytes to protect against the infection.Peer reviewe