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 imported from central Asian countries with three mismatches at the PCR reverse primer (MVN1213R) annealing site. To examine and improve the effectiveness of real-time PCR for detecting this variant, we compared the sensitivity of real-time PCR for MVN1213R and a modified primer using control RNAs, clinical isolates, and clinical specimens. The median difference in the cycle threshold value using the modified primer was 2.92 cycles lower (interquartile range, 1.99-3.38) than when using MVN1213R. Thus, PCR primer sets should be modified to effectively detect measles virus mutations.