Collaborative study for the characterization of a chikungunya virus RNA reference reagent for use in nucleic acid testing

Background and Objectives Infections with the mosquito‐borne chikungunya virus ( CHIKV ) can cause febrile illness or be asymptomatic. Laboratory diagnosis of CHIKV is often made with laboratory‐developed nucleic acid amplification technology ( NAT ) assays because there are no U.S. Food and Drug Administration ( FDA )‐approved diagnostic or blood screening assays. We aimed to produce a well‐characterized CHIKV RNA reference reagent ( CHIKV ‐ RR ) for use in NAT assays. Materials and Methods A CHIKV RNA ‐ RR consisting of cell culture‐grown, heat‐inactivated CHIKV diluted in human plasma was assessed by 8 laboratories in a collaborative study. The participants were asked to test the CHIKV ‐ RR using their NAT assay(s) by qualitative testing (determination of RNA end‐point by testing log and half‐log dilutions followed by calculation of estimated NAT ‐detectable units/ml, after adjustment for the sample volume used for testing), and by quantitative testing, when available. Results Results from the testing showed that the CHIKV ‐ RR had an estimated overall mean of 7·56 log 10 detectable units/ml, ranging from 6·2 log 10 to 8·6 log 10 . Conclusions The Center for Biologics for Evaluation and Research/ FDA CHIKV RNA ‐ RR for NAT was established with a concentration of 7·56 log 10 detectable units/ml.