Monoclonal antibodies to equine IgM improve the sensitivity of West Nile virus-specific IgM detection in horses.
West Nile virus (WNV) is a zoonotic pathogen of global importance. In horses with neurological signs, detection of WNV-specific immunoglobulin M (IgM) in serum is widely used to identify clinical cases of WNV encephalitis. Here, we describe the development of two monoclonal antibodies (mAbs) to equine IgM which were used in a WNV IgM-specific enzyme-linked immunosorbent assay (ELISA). Their performance was compared to an established assay based on polyclonal anti-IgM. Check test serum samples from the National Veterinary Service Laboratory (NVSL) were used to evaluate the performance of the three anti-IgM antibodies. The anti-IgM 1-22 mAb correctly identified all NVSL samples. Both the polyclonal antibody and monoclonal anti-IgM 2B-63 identified eight out of ten samples correctly. The three assays were then compared using serum samples from clinically healthy animals (n=33) and horses with neurological signs (n=21). High Spearman rank correlations (0.76-0.86) were found among the ELISA results. Inter-test agreements (weighted kappa) for assay interpretation resulted in strong agreement (0.95) of the results obtained by the mAbs and moderate agreements when monoclonal and polyclonal anti-IgM-based assays were compared. To determine the analytical sensitivities of anti-WNV IgM detection, serial dilutions of WNV IgM-positive serum samples were analyzed. The highest sensitivity was obtained by using the anti-IgM 1-22 mAb to capture IgM from equine serum. In conclusion, the use of monoclonal anti-IgM antibodies can improve the sensitivity of IgM detection in the acute phase of WN disease.
Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA. bw73@cornell.edu
Bettina
B
Wagner
Amy
A
Glaser
Julia M
JM
Hillegas
Hollis
H
Erb
Carvel
C
Gold
Heather
H
Freer
D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000276:immunology; D000911:Antibodies, Monoclonal / Q000276:immunology*; D000914:Antibodies, Viral / Q000097:blood*; D004797:Enzyme-Linked Immunosorbent Assay; D006736:Horses / Q000276:immunology*; D007074:Immunoglobulin G / Q000097:blood; D007075:Immunoglobulin M / Q000097:blood*; D012680:Sensitivity and Specificity; D014902:West Nile virus / Q000276:immunology*
D000888:Antibodies, Anti-Idiotypic; D000911:Antibodies, Monoclonal; D000914:Antibodies, Viral; D007074:Immunoglobulin G; D007075:Immunoglobulin M; C044203:anti-IgM