Sensitivity evaluation of a modified real-time reverse-transcription PCR primer to detect a measles virus variant in Japan in 2024

Abstract

A measles outbreak occurred in Japan in February 2024 due to a measles virus variant that was imported from central Asian countries with three mismatches at the PCR reverse primer (MVN1213R) annealing site. To examine and improve the impact of real-time PCR effectiveness for detecting this variant, we compared the sensitivity of real-time PCR between MVN1213R and a modified primer using control RNAs, clinical isolates, and clinical specimens. The median difference in the cycle threshold value was 2.92 (interquartile range, IQR 1.99–3.38) lower using the modified primer compared with MVN1213R. Thus, PCR primer sets should be modified to effectively detect this measles virus mutation.