Evaluation of Commercially Available Chikungunya Virus Immunoglobulin M Detection Assays

Abstract

Commercial chikungunya virus (CHIKV)-specific IgM detection kits were evaluated at the Centers for Disease Control and Prevention (CDC), the Public Health Agency of Canada National Microbiology Laboratory, and the Caribbean Public Health Agency (CARPHA). The Euroimmun Anti-CHIKV IgM ELISA kit had ≥ 95% concordance with all three reference laboratory results. The limit of detection for low CHIK IgM+ samples, as measured by serial dilution of seven sera up to 1:12,800 ranged from 1:800 to 1:3,200. The Euroimmun IIFT kit evaluated at CDC and CARPHA performed well, but required more retesting of equivocal results. The InBios CHIKjj Detect MAC-ELISA had 100% and 98% concordance with CDC and CARPHA results, respectively, and had equal sensitivity to the CDC MAC-ELISA to 1:12,800 dilution in serially diluted samples. The Abcam Anti-CHIKV IgM ELISA had high performance at CARPHA, but at CDC, performance was inconsistent between lots. After replacement of the biotinylated IgM antibody controls with serum containing CHIKV-specific IgM and additional quality assurance/control measures, the Abcam kit was rereleased and reevaluated at CDC. The reformatted Abcam kit had 97% concordance with CDC results and limit of detection of 1:800 to 1:3,200. Two rapid tests and three other CHIKV MAC-ELISAs evaluated at CDC had low sensitivity, as the CDC CHIKV IgM in-house positive controls were below the level of detection. In conclusion, laboratories have options for CHIKV serological diagnosis using validated commercial kits.

Figure 1.

Performance of CHIKV IgM detection assays compared with CDC results as the reference standard. *CDC CHIKV IHPC had negative result in test. **CDC CHIKV IHPC had positive result in test. CDC = Centers for Disease Control and Prevention; CHIKV = chikungunya virus; IHPC = in-house positive control; ND = not done; RT = rapid test.

Figure 2.

Abcam CHIK MAC-ELISA performance assessment with CDC CHIKV IHPC, by lot number. CDC = Centers for Disease Control and Prevention; CHIKV = chikungunya virus; IHPC = in-house positive control.

Figure 3.

Comparison of sensitivity by serum titration. Chikungunya virus (CHIKV) IgM+ samples from the Caribbean were diluted 2-fold to 1:12,800 in sample dilution buffer. The revised Abcam kit with CHIKV-specific IgM serum controls was used for the evaluation.