Detection of Hepatitis B Virus Covalently Closed Circular DNA in the Plasma of Iranian HBeAg-Negative Patients With Chronic Hepatitis B

Droplet digital PCR technique is ultrasensitive for the quantification of covalently closed circular DNA in the blood of chronic HBV-infected patients

BACKGROUND

Covalently closed circular DNA (cccDNA) is a stable, episomal form of HBV DNA. cccDNA is a true marker for the intrahepatic events in controlled CHB infection. Quantifying cccDNA is critical for monitoring disease progression, and efficacy of anti-viral therapies.

METHODS

To standardize the method, total HBV DNA was isolated from HepAD38 cells and digested with three exonuclease enzymes to remove linear and relaxed circular HBV DNA. Purified cccDNA quantification used ddPCR with specific primers. Treatment-naive chronic hepatitis B virus patients (nCHBV, n=36) with detectable HBV DNA and HBsAg were grouped by HBsAg levels: Group I (HBsAglo < 2000 IU/ml, n=11) and Group II (HBsAghi > 2000 IU/ml, n=25). cccDNA, HBV DNA and HBsAg were quantified in plasma and compared between groups. Correlation with clinical/histopathological features was done.

RESULTS

Non-digested 3.6^10⁶ tet-ve HepAD38 cells showed 316 copies/µl of total viral DNA. After digesting the linear, integrated, and relaxed circular DNA with triple enzymes, 15 copies/µl of cccDNA were detected. Similarly, after DNA digestion, HBsAglo patients showed a median of 8.5 copies/µl (IQR 2.75-9.75 copies/µl), and HBsAghi gave a median of 11 copies/µl (IQR 4-16 copies/µl) but with no significant difference between groups (p=0.093). Further, HBsAglo patients with low cccDNA copy numbers showed significantly higher fibrosis grades than HBsAghi (p=0.036).

CONCLUSIONS

We conclude that employing a combined approach utilizing three exonucleases, cccDNA-specific primers, and ddPCR enables the detection of cccDNA copies even in patients exhibiting low levels of HBsAg and HBV DNA. This integrated method offers additional validation as a surrogate diagnostic tool.

Prevalence of HCV and/or HBV coinfection in Iranian HIV-infected patients

Aim: HIV-infected patients risk coinfection with HBV and HCV. This study aimed to investigate molecular epidemiology of HBV and HCV coinfection in Iranian HIV-infected individuals. Materials & methods: In this cross-sectional study, serological markers of HBV and HCV infection (hepatitis B surface antigen [HBsAg], hepatitis B e-antigen [HBeAg], hepatitis B e-antibody [HBeAb] and hepatitis B core antibody [HBcAb]) and anti-HCV antibodies [anti-HCV Abs] were tested in 198 Iranian HIV-infected patients. From plasma, HBV viral load was determined using COBAS TaqMan 48, and HCV-RNA was detected by reverse transcriptase-nested PCR. Results: 85 out of 198 (42.9%) patients were anti-HCV Ab positive and 42/198 (21.2%) had detectable HCV-RNA. Eight (4.0%) had traceable HBV-DNA. All these patients were infected by HBV genotype D. 55 (27.8%) were HBcAb positive. Nine (4.4%) were HBsAg and anti-HCV Ab positive. Conclusion: None were HIV-RNA/HCV-RNA/HBV-DNA positive, 21.2% were HIV-RNA/HCV-RNA positive and 4.0% were HIV-RNA/HBV-DNA positive. Therefore, studies on diagnosing these infections in HIV-infected individuals may be valuable.

Detection of HBV genome in the plasma and peripheral blood mononuclear cells of Iranian HBsAg negative patients with HIV infection: occult HBV infection

The presence of hepatitis B virus (HBV) DNA in the absence of traceable hepatitis B surface antigen (HBsAg) in the plasma specimen of patients is defined as occult HBV infection (OBI). This study aimed to detect HBV-DNA in the plasma and peripheral blood mononuclear cells (PBMCs) of Iranian HBsAg negative patients with human immunodeficiency virus (HIV) infection. This cross-sectional study was conducted on 172 patients with HIV infection from September 2015 to August 2017. The patients were tested for serological parameters (HBsAg, HBcAb, HBeAg and HBeAb) against HBV infection. Moreover, they were tested for HBV viral load (using COBAS TaqMan 48 Kit, Roche, USA) in plasma and the presence of the HBV genome in PBMC specimens using real-time PCR. The mean age of the patients was 35.4 ± 13.4 years. Of the 172 studied patients, 109 (63.4%) were male. In this study, 151 (87.8%) patients were negative for HBsAg, 111 (64.5%) patients were negative for all HBV infection serological markers, 9 (5.2%) patients were only positive for HBsAg and 29 (16.9%) patients were only positive for HBcAb. Moreover, five (3.3%) patients with HBsAg negative had OBI (in the plasma sample of four patients and PBMC specimens of all five patients, HBV-DNA was detected). The present study revealed that 3.3% of the patients with HIV infection had occult HBV infection. Presumably, designing prospective studies to identify this infection in patients with HIV infection is informative and valuable.

Detection of HBV Covalently Closed Circular DNA

Chronic hepatitis B virus (HBV) infection affects approximately 240 million people worldwide and remains a serious public health concern because its complete cure is impossible with current treatments. Covalently closed circular DNA (cccDNA) in the nucleus of infected cells cannot be eliminated by present therapeutics and may result in persistence and relapse. Drug development targeting cccDNA formation and maintenance is hindered by the lack of efficient cccDNA models and reliable cccDNA detection methods. Southern blotting is regarded as the gold standard for quantitative cccDNA detection, but it is complicated and not suitable for high-throughput drug screening, so more sensitive and simple methods, including polymerase chain reaction (PCR)-based methods, Invader assays, in situ hybridization and surrogates, have been developed for cccDNA detection. However, most methods are not reliable enough, and there are no unified standards for these approaches. This review will summarize available methods for cccDNA detection. It is hoped that more robust methods for cccDNA monitoring will be developed and that standard operation procedures for routine cccDNA detection in scientific research and clinical monitoring will be established.