Deep sequencing analysis of serum hepatitis B virus‐RNA during nucleot(s)ide analogue therapy

AIM Recently, serum hepatitis B virus (HBV)-RNA has been reported to be detectable even when HBV particle production is inhibited by nucleot(s)ide analogues (NAs). However, the dynamics of the HBV-RNA sequence compared with those of HBV-DNA during the emergence of antiviral resistance are yet to be elucidated. METHODS First, we quantified serum HBV-RNA in 181 infected patients, and its relationships with clinical characteristics as well as HBV markers were investigated. Next, we undertook simultaneous deep sequencing of HBV-RNA/HBV-DNA and their dynamics among four patients receiving NA therapy who were experiencing viral breakthrough. RESULTS Serum HBV-RNA was detected in 25% (31/123) of cases among patients with HBV without NAs, and the detection rate was significantly high in hepatitis B e antigen-positive cases with high viral activity. In patients with chronic hepatitis, hepatitis B core-related antigen was significantly correlated with serum HBV-RNA irrespective of NA use. In the analysis of the four patients experiencing viral breakthrough, no NA resistance mutation was detected in the serum HBV-RNA immediately before the breakthrough. However, NA-resistant sequences appeared at the rates of 0%, 3%, 14%, and 100%, and the NA-resistant HBV-RNA sequence rate was correlated with the peak HBV-DNA titer multiplied by the HBV-DNA detection duration during the breakthrough (R2 = 0.978) observed before redisappearance of HBV-DNA following the addition of new NA. CONCLUSION Serum HBV-RNA could reflect the transcriptional activity of covalently closed circular DNA and hepatitis B core-related antigen. The dynamics of HBV-RNA could help understanding of the turnover process of HBV covalently closed circular DNA in the liver.