Real-time PCR-based method for measuring the phase variation frequency of flagellin in Salmonella enterica serovar...

Some Salmonella serovars possess two antigenic phases of the H antigen, known as phase 1 and phase 2. These phases reversibly switch between each other at a constant frequency; phase variation frequency. Previously, we focused on the inversion of hin and developed a real-time PCR system, H-qPCR, to quantitatively measure the proportion of bacterial cells expressing each phase of flagellin for Salmonella enterica serovar Typhimurium (S. Typhimurium). In this study, we developed a novel method to analyze the phase variation frequency of H antigen of S. Typhimurium, based on the H-qPCR approach. It was shown that our method offered equivalent accuracy but superior sensitivity compared with the conventional method for measuring the phase variation frequency. Our real-time PCR-based method is expected to contribute to the analysis of phase variation frequency as a useful tool.