Endogenous antisense RNA modulates biofilm organization and pathogenicity of .

() is regarded as the major pathogen for persistent periapical periodontitis. The aim of the present study was to investigate the role of antisense RNA in the regulation of adjacent downstream genes. Reverse transcription-PCR assays were performed to validate . Adjacent downstream genes , EF1195, EF1196, and EF1197 were co-transcribed and detect antisense RNA. Northern blotting and 5'-rapid amplification of cDNA ends (5'-RACE) assays were conducted to detect and confirm a novel antisense (AS) RNA. AS overexpression mutants were constructed, and the biofilm biomass was determined using a crystal violet microtiter assay. The present study detected and confirmed a 550-bp noncoding antisense RNA with the potential to attenuate the activities of the essential response regulator . The levels of antisense RNA transcripts were inversely associated with the production of protein. It was showed that overexpression of AS leads to reduced biofilm formation and exopolysaccharide synthesis. Furthermore, the pathogenicity of was markedly decreased by AS overexpression in an periapical periodontitis model. In summary, the present study detected a novel antisense RNA that leads to a reduction in biofilm formation and the pathogenicity of . Collectively, the data suggest a role for AS as a post-transcriptional modulator of the regulator in .