Recombinant NhSAG1 ELISA: a sensitive and specific assay for detecting antibodies against Neospora hughesi in equine serum.
Neospora hughesi is a recently identified cause of equine protozoal myeloencephalitis. However, the significance of this parasite is poorly understood. An enzyme-linked immunosorbent assay (ELISA) with a recombinant form of the N. hughesi 29-kDa surface antigen (rNhSAG1) was developed for serodiagnosis of equine N. hughesi infections. Parallel ELISA analysis showed that animals immunized or infected with N. hughesi exhibited greater antibody reactivity with rNhSAG1 than with the Neospora caninum homolog, rNcSAG1. The rNhSAG1 ELISA showed 94.4% sensitivity and 95.0% specificity when compared with N. hughesi western blot results for 1,006 samples. The N. hughesi seroprevalence was 3.4% for the 1,917 samples tested by ELISA, which is less than earlier reports. Importantly, western blot analysis of ELISA-positive sera revealed only 18 true seropositive samples for an even lower seroprevalence of 0.9%. These results imply that Neospora spp. infections are uncommon in horses. The sensitivity and specificity exhibited by the rNhSAG1 ELISA suggest that it has a potential use for serodiagnosis of N. hughesi infection in equids. Furthermore, the high-throughput capability of the ELISA will allow for screening large sample sets, which should provide a better understanding of N. hughesi epidemiology.
Department of Veterinary Science, University of Kentucky, 108 Gluck Equine Research Center, Lexington, Kentucky 40546-0099, USA.
Jessica S
JS
Hoane
Michelle R
MR
Yeargan
Shelby
S
Stamper
William J
WJ
Saville
Jennifer K
JK
Morrow
David S
DS
Lindsay
Daniel K
DK
Howe
D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood*; D000953:Antigens, Protozoan / Q000276:immunology; D015153:Blotting, Western / Q000662:veterinary; D003048:Coccidiosis / Q000175:diagnosis / Q000453:epidemiology / Q000276:immunology / Q000662:veterinary*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods / Q000662:veterinary*; D018397:Equidae / Q000097:blood / Q000276:immunology / Q000469:parasitology*; D006734:Horse Diseases / Q000175:diagnosis / Q000453:epidemiology / Q000276:immunology* / Q000469:parasitology; D006736:Horses; D018688:Neospora / Q000276:immunology*; D015800:Protozoan Proteins / Q000276:immunology; D011817:Rabbits; D011994:Recombinant Proteins / Q000276:immunology; D012680:Sensitivity and Specificity; D016036:Seroepidemiologic Studies
D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D015800:Protozoan Proteins; D011994:Recombinant Proteins; C115390:SAG1 protein, Neospora caninum