Epidemiology, risk factors, and molecular characterization of occult hepatitis B infection among anti‐hepatitis B core antigen alone subjects

Abstract

Objectives Features of occult hepatitis B virus (HBV) infection among the anti‐hepatitis B core antigen (anti‐HBc) positives have yet to be described in more details. This study aimed to determine the molecular prevalence of occult HBV infection (OBI), and association to risk factors among seropositives for anti‐HBc. Methods This was part of a community‐based screening project that included 5234 cases. All participants completed a questionnaire on demographic and socio‐epidemiological information. Then, the blood samples were collected and tested for anti‐HBc and HBsAg using ELISA method. To identify OBI, nested‐polymerase chain reaction (PCR) assays were performed for HBV‐S and X genes, and viral load was determined using an in‐house real‐time PCR. Sequencing and phylogenetic analysis have been implemented for genotyping. Results Overall, 596 cases, positive only for anti‐HBc were included in the study. OBI was detected among 61 cases (10.2%). The genotype and subgenotype of HBV among all of them was D1, except one that was D4. Most of them had low viral loads ranged from 1.2 × 102 to 1.34 × 10 3 copies/mL; 19.6% had undetectable viral loads. Important mutations in surface protein and reverse transcriptase were sI92T, sQ129H, rtL80I, rtS85F, rtL91I. The prevalence of OBI was related to some risk factors, such as tattooing (P = 0.02), sexual activities (P = 0.009), and diabetes (P = 0.031). Conclusion Our study suggests that OBI should be considered among anti‐HBc seropositive subjects. This form of HBV infection was accompanied with some mutations, risk factors, and diseases. However, further investigations are needed to determine virological importance of documented mutations.

Molecular and serological characterization of occult hepatitis B virus infection among patients with hemophilia

“…In the present study, 62.5% of the subjects who were determined as OBI case had detectable viral load; the mean viral load was 4.5 × 10 2 copies/mL. This result is consistent with most of the reported viral loads among the OBI cases . Very low and undetectable viral loads of OBI along with some mutations that may decrease viral secretion represent a repressive force.…”

“…Functional in vitro evidence revealed some reduced level of antigenicity for P127T, and same effects were also established for Q129H, the most prevalent escape mutant observed in the present study. It has also been prevalent in previous reports carried out in Iran . The G130R mutant has been found to be defective for viral secretion .…”

“…As previously explained, we attempted to detect HBx and S genes (Table shows the sequence of primers). Appropriate considerations were exerted to avoid carryover contamination.…”

“…Quantification of HBV‐DNA was performed using an in‐house SYBR green‐based real‐time PCR assay, as described previously . Briefly speaking, 20 pmole/mL of each primer (BSqF and BSqR; Table ), 10 µL of SYBR green master mix 2X (Applied Biosystems, Thermo Fisher Scientific, MA), and 3 µL of extracted DNA made the total reaction volume of 20 µL.…”

“…For quantification of real‐time PCR and construction of standard curve, serial dilutions of a synthesized cloned of HBsAg coding region were used (Figure S1). The LLOD of this approach has already been determined to be 1.2 × 10 2 copies/mL . The quantitative PCR tests were performed in triplicate and twice for each OBI positive subject.…”