Monoclonal antibody-based competitive enzyme-linked immunosorbent assay for detecting and quantifying West Nile virus-neutralizing antibodies in horse sera.
A rapid immunoassay for detecting and quantifying West Nile virus (WNV)-neutralizing antibodies in sera was developed as an alternative to the plaque reduction neutralization test (PRNT), the gold standard test for WNV. The assay is a competitive, enzyme-linked immunosorbent assay using neutralizing monoclonal antibody 5E8 (NT-ELISA). A cutoff percent inhibition (PI) value of 35% (mean PI plus 3 standard deviations), with a specificity of 99%, was established based on analysis of 246 serum samples from horses free of WNV. The NT-ELISA detected neutralizing antibodies in all sera collected 7 or 14 days postinoculation from mice (n = 11) infected with lineage I (strain NY385-99) or II (strain B956) WNV. When sera from WNV-vaccinated horses (n = 212) were tested by NT-ELISA and PRNT, the NT-ELISA gave a positive result for 96.1% (173/180) of the PRNT-positive sera and 3.1% (1/32) of the PRNT-negative sera. Discrepancies between the two tests were observed mainly with sera with low PRNT(90) titers (expressed as the reciprocal of the highest dilution yielding > or = 90% reduction in the number of plaques) for WNV or low PIs by NT-ELISA. The overall agreement (k value) between the two tests was 0.86. A good correlation (r(2) = 0.77) was also observed between the tests for endpoint titration of sera (n = 116). In conclusion, the newly developed NT-ELISA may be a good alternative serologic assay for detecting WNV that can be used for large-scale testing of WNV-neutralizing antibodies in multiple species.
Choi
Kang-Seuk
KS
National Veterinary Research and Quarantine Service, 480 Anyang-6 dong, Anyang, Gyeonggi 430-824, Republic of Korea. choiks@nvrqs.go.kr
Ko
Young-Joon
YJ
Nah
Jin-Ju
JJ
Kim
Yong-Joo
YJ
Kang
Shien-Young
SY
Yoon
Kyoung-Jin
KJ
Joo
Yi-Seok
YS
D000818:Animals; D000906:Antibodies / Q000097:blood*; D000911:Antibodies, Monoclonal; D004797:Enzyme-Linked Immunosorbent Assay; D006736:Horses / Q000097:blood* / Q000276:immunology; D044967:Serum / Q000276:immunology*; D014902:West Nile virus / Q000276:immunology*
D000906:Antibodies; D000911:Antibodies, Monoclonal