Detection of Neospora spp. antibodies in horses from La Pampa, Argentina

Abstract

Neospora caninum and N. hughesi are apicomplexan parasitesaffecting several animal species worldwide. Horses have beenreported as intermediate hosts of these protozoans. Neosporacaninum is an important cause of bovine abortion and neurologicalsigns in dogs while N. hughesi is reported as potential cause ofequine protozoal myeloencephalitis (EPM). Little is known aboutneosporosis in Argentinean horses. The aim of the present studywas to indentify antibodies against Neospora spp. in horses fromLa Pampa, Argentina. Serum samples (n¼42) were randomlyselected from a group of 300 horses belonging to rural areas fromLa Pampa province, Argentina. All animals were clinically healthy.The samples were processed by 4 serological tests using N. caninumantigen: indirect ELISA (CIVTEST HIPRA) with G protein asconjugate; a competitive ELISA (VMRD) proceeding according tomanufacturer instructions; indirect fluorescence antibody test(IFAT) and Immunoblot (IB) both using Nc1 strain as antigen.Serum sample from an experimentally infected (Nc1 strain)young horse was used as positive control. Positive serologicalresults were detected as follows: 30% of samples (n¼13) by ELISAHIPRA,28% (n¼12) by IFAT, 26% (n¼11) by IB and 16% (n¼7) byELISA-VMRD. A total of 12 samples resulted positive to 2 or moretests. Most of the positive samples (n ¼ 9) were seropositive byIFAT and IB. Considering the positivity to these 2 tests as ?truepositive?, 21.4% of horses showed antibodies against N. caninumantigens. Since potential cross reactions between Neospora spp.are plausible we considered the detected antibodies as genusspecific.Further studies should be conducted with specific N.hughesi serological tests for specific differentiation of the immunologicalresponses observed. The present study is the first reportof Neospora spp. antibodies detection in Argentinean horses. Theseropositivity rate detected suggests that horses from La Pampahave a frequent contact with Neospora spp. Future studies will beconducted in horses with clinical signs.