High Throughput Quantitative Colorimetric Microneutralization Assay for the Confirmation and Differentiation of West Nile Virus and St. Louis Encephalitis Virus

• Published in: The American journal of tropical medicine and hygiene Vol. 82; no. 3; pp. 501 - 504
• Main Authors: Taketa-Graham, Michael, Powell Pereira, Jaime L, Baylis, Elizabeth, Cossen, Cynthia, Oceguera, Leopoldo, Patiris, Peter, Chiles, Robert, Hanson, Carl V, Forghani, BagHer
• Format: Journal Article
• Language: English
• Published: United States ASTMH 01-03-2010; The American Society of Tropical Medicine and Hygiene
• Subjects: Animals; Cercopithecus aethiops; Colorimetry - methods; Encephalitis Virus, St. Louis - isolation & purification; Neutralization Tests - methods; Short Report; Vero Cells; West Nile virus - isolation & purification
• ISSN: 0002-9637; 1476-1645
• DOI: 10.4269/ajtmh.2010.09-0297

An automated colorimetric micro-neutralization assay (CmNt) was developed for confirmation and differentiation of West Nile Virus (WNV)-positive human sera as a higher throughput alternative to the standard six-well plaque-reduction neutralization test (PRNT). CmNt was performed in high-capacity 96-well micro-titer plates and required 4-6 days to complete. Inhibition of infection was determined by reduced neutral red-dye retention and conveniently recorded by a colorimetric plate reader. Human sera previously confirmed by PRNT as either negative (N = 52), WNV positive (N = 81), or St. Louis encephalitis virus positive (N = 12) were tested by CmNt; interpreted results were virtually identical to PRNT with a reduced turnaround time and higher throughput. Additionally, a handful of dengue virus positive and negative specimens (four each) were tested by CmNt; interpreted results were identical to PRNT.