title: Immunoglobulin M-capture enzyme-linked immunosorbent assay testing of cerebrospinal fluid and serum from horses exposed to west nile virus by vaccination or natural infection.
abstract: The West Nile (WN) virus, present in the United States since 1999, is a cause of encephalomyelitis in birds, alligators, humans, and horses. No data exist regarding detection of anti-WN virus immunoglobins in equine cerebrospinal fluid (CSF). The aims of this study were to evaluate the blood-brain barrier (BBB) in WN virus-infected (WNE) horses, to compare diagnostic testing in serum and CSF, and to describe the immunoglobulin M (IgM) response in serum and CSF of vaccinated horses. CSF was collected from the lumbosacral (LS) space (n = 13) or the allanto-occipital (AO) space (n = 14) of WNE horses. The albumin quotient (AQ) and IgG index were calculated, and the IgM-capture-enzyme-linked immunosorbent assay (MAC-ELISA) was used to detect anti-WN virus IgM in serum and CSF. CSF collected from the LS site had a higher (P < .02) IgG index compared to the AO site (0.34 +/- 0.04 versus 0.22 +/- 0.04 [mean +/- SE], respectively). The mean AQ, irrespective of collection site, did not exceed reference values. There was 100% agreement between CSF and serum testing for IgM by MAC-ELISA testing. However, the positive to negative antigen ratios were higher (P < .001) in CSF (34.5) versus serum (8.5), indicating lower nonspecific reactivity in CSF samples. Horses vaccinated against WN virus did not develop an IgM response at 1:400 mg/dL in serum; however, a few horses developed a weak IgM response in serum but not in CSF. In conclusion, MAC-ELISA testing of serum and CSF were equivocal. Also, examination of CSF data from WNE horses suggests a normal BBB integrity and increased intrathecal production of antibodies.
authors.affiliation: Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Gainesville, FL, USA. portermi@mail.vetmed.ufl.edu
authors.forename: Michael B
authors.initials: MB
authors.lastname: Porter
authors.forename: Maureen
authors.initials: M
authors.lastname: Long
authors.forename: David G
authors.initials: DG
authors.lastname: Gosche
authors.forename: Harold M
authors.initials: HM
authors.lastname: Schott
authors.forename: Melissa T
authors.initials: MT
authors.lastname: Hines
authors.forename: Mary
authors.initials: M
authors.lastname: Rossano
authors.forename: Debra C
authors.initials: DC
authors.lastname: Sellon
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000276:immunology*; D002555:Cerebrospinal Fluid / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D005260:Female; D006734:Horse Diseases / Q000097:blood / Q000134:cerebrospinal fluid / Q000517:prevention & control*; D006736:Horses; D007075:Immunoglobulin M / Q000097:blood / Q000134:cerebrospinal fluid; D008297:Male; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D014765:Viral Vaccines; D014901:West Nile Fever / Q000517:prevention & control / Q000662:veterinary*; D014902:West Nile virus / Q000276:immunology*
chemical_list: D000914:Antibodies, Viral; D007075:Immunoglobulin M; D014765:Viral Vaccines