Validation of a Microsphere-Based Immunoassay for Detection of anti-West Nile Virus and anti-St. Louis Encephalitis Virus Immunoglobulin M antibodies.
Clinical and vaccine immunology : CVI 2007 Jul 3; 14(9):1084-93
Johnson A AJ, Cheshier R RC, Cosentino G G, Masri H HP, Mock V V, Oesterle R R,
Division of Vector-Borne Infectious Diseases, National Center for Zoonotic, Vector-Borne and Enteric
A microsphere-based immunoassay (MIA) was previously developed, capable of determining the presence of anti-West Nile (WN) virus or anti-St. Louis encephalitis (SLE) virus IgM antibodies in human serum or cerebrospinal fluid. The original data set on which the classification rules were based comprised 491 serum specimens obtained from the serum bank at the Division of Vector-Borne Infectious Diseases (DVBID). The classification rules were used to provide a result and to determine whether confirmatory testing was necessary for a given sample. A validation study was coordinated between the DVBID and 5 state health laboratories to determine 1) the reproducibility of the test between different laboratories; 2) the correlation between the MAC-ELISA and the MIA; and 3) whether the initial nonspecific parameters could be refined to reduce the volume of confirmatory testing. Laboratorians were trained in the method, and reagents and data analysis software developed at the DVBID were shipped out to each validating laboratory. Validating laboratories performed tests on approximately 200 samples obtained from their individual states, the collections of which comprised approximately equal numbers of WN-positive, and negative samples, as determined by MAC-ELISA. In addition, 377 samples submitted to the DVBID for arbovirus testing were analyzed using the MIA and by MAC-ELISA at the DVBID only. For the specimens tested at both the state and the DVBID labs, correlation of results indicated that the technology is readily transferable between laboratories. The detection of IgM antibodies to WN virus was more consistent than detection of IgM antibodies to SLE virus. Some changes were made to the analysis software that resulted in improved accuracy of diagnosis.