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