Anti-Neospora caninum and anti-Sarcocystis spp. specific antibodies cross-react with Besnoitia besnoiti and influence the serological diagnosis of bovine besnoitiosis

GARCIA LUNAR, P.; MORÉ, G.; CAMPERO, L.; ORTEGA-MORA, L.; ALVAREZ-GARCÍA, G.

VETERINARY PARASITOLOGY

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2015 vol. 214 p. 49 - 54

0304-4017

Bovine besnoitiosis control remains a challenge because the disease continues to spread and controlrelies solely on accurate diagnosis coupled to management measures. However, recent studies havereported that routinely used ELISAs may raise a high number of false-positive results. Herein, cross-reactions between Besnoitia besnoiti antigens and anti-Neospora caninum and/or anti-Sarcocystis spp.-specific antibodies were studied in an in house ELISA since N. caninum and Sarcocystis spp. are closelyrelated parasites, and both infections are highly prevalent in cattle worldwide. The serum panel wascomposed of the following categories: sera from B. besnoiti-seronegative (n = 75) and -seropositive cattle(n = 66), B. besnoiti-based-ELISA false-positive reactors (n = 96) together with N. caninum (n = 36) andSarcocystis spp. (n = 42) -seropositive reference cattle sera. B. besnoiti tachyzoite based western blot (WB)results classified animals as seropositive or seronegative. Sera were analyzed for the detection of anti-N.caninum by WB and ELISA and anti-Sarcocystis spp.-specific antibodies by WB and IFAT. Those samplesrecognizing a Sarcocystis spp. 18?20 kDa antigenic region and N. caninum 17?18 kDa immunodominantantigen were considered to be Sarcocystis spp. and N. caninum seropositive, respectively. The categoryof B. besnoiti based-ELISA false-positive reactors showed the highest number of sera with specific anti-Sarcocystis spp. and anti-N. caninum antibodies (74%; 71/96), followed by the N. caninum-seropositivecattle category (52.8%; 19/36). In contrast, few B. besnoiti-seronegative and -seropositive cattle showedantibodies against Sarcocystis spp. and N. caninum (10.7%; 8/75 and 1.5%; 1/66), respectively). This studyrevealed that B. besnoiti false-positive ELISA results were associated not only with the presence of anti-N.caninum and anti-Sarcocystis spp. antibodies (2: 78.36; p < 0.0001; OR: 34.6; CI: 14?88) but also withhigh antibody levels against them using ELISA and IFAT tests, respectively (p < 0.05; t-test). These resultsmay explain why only some animals seropositive to Sarcocystis spp. and/or N. caninum are Besnoitia false-positive reactors. Therefore, sera meeting these requirements should be included in future validations ofserological tests for bovine besnoitiosis.