A pilot study of serum microRNA signatures as a novel biomarker for occult hepatitis B virus infection.

The implementation of hepatitis B surface antigen (HBsAg) screening tests has significantly enhanced blood transfusion safety. However, the transmission of HBsAg-negative blood components can still occur in the acute phase of infection during the seronegative window period or during chronic stages of infection such as occult hepatitis virus B infection (OBI). OBI, characterized by the presence of HBV infection without detectable HBsAg, is capable to elude the routine detection with HBV serologic markers and harbor a potential risk of HBV transmission through blood transfusion or organ transplantation. Here, we test the hypothesis that OBI patients have a differentially expressed profile of microRNA (miRNA) in serum, and this unique serum miRNA signature can serve as a biomarker to detect OBI. Employing TaqMan probe-based quantitative reverse transcription polymerase chain reaction (qRT-PCR), we assessed the expression level of miRNAs in serum samples. To control for miRNA quantitation, we added an exogenous plant miRNA, MIR156a, into the samples before RNA extraction and used it as an internal control. After screening 13 previously identified HBV-specific serum miRNAs, we obtained four miRNAs, let-7c, miR-23b, miR-122, and miR-150, which are differentially expressed in OBI sera compared to healthy control sera. This 4-serum miRNA signature shows a high level of accuracy in discriminating both OBI (AUC = 0.999) and HBV (AUC = 0.989) cases from the non-infected controls. Cluster analysis also demonstrates that this 4-miRNA signature can clearly separate OBI patients from the control group. Our results demonstrate for the first time that a profile of serum miRNAs can serve as a sensitive and accurate biomarker for OBI detection.