Jinlin Hou

Hepatitis B virus genotypes and subgenotypes in China

Eight Hepatitis B virus (HBV) genotypes (A to H) have been identified based on an intergenotype divergence of 8% or more in the entire nucleotide sequence. Subgenotypes have also been identified in different HBV genotypes. As a highly endemic area for HBV infection, the prevalence of chronic HBV infection in China is between 8 and 20% of the general population. Genotypes B and C were identified as the most common HBV strains and account for approximately 95% of Chinese patients. Further study confirmed all genotype B strains belong to subgenotype Ba. Two of genotype C subgenotypes, C1 (Cs) and C2 (Ce), were found in China and they showed different geographic distributions. Genotype A was very rarely found, while genotypes E, F, G and H have not beenreported until now. Two types of HBV C/Drecombinant viruses have been identified in west China and distinct geographic and ethnic distributions were observed. Significant differences were observed (Pu2003<u20030.001) in the prevalence of A1896 and T1762/A1764 mutations among HBV Ba, C1 and C2 subgenotypes in Chinese patients. Accumulating evidence showed the response rate to antiviral therapy in Chinese patients is higher in genotype B than genotype C patients on interferon treatment, but no difference was observed on nucleoside/nucleotide analog treatment.

Role of hepatitis B virus genotypes and quantitative HBV DNA in metastasis and recurrence of hepatocellular carcinoma

Identification of risk factors for recurrence and metastasis of HCC is important for the prognosis of HCC surveillance in chronic HBV infection. In this article, 125 HCC patients recruited were followed up prospectively for tumor metastasis and recurrence for a median of 104 (10–130) weeks. HBV DNA level was detected by LightCycler‐based real‐time fluorescence quantitative polymerase chain reaction‐restriction system. HBV genotypes were determined by using PCR restriction‐fragment length polymorphism. BCP and PC mutations were performed by PCR and direct sequencing of amplified products. Among 125 HCC patients, 19 patients were excluded because of the lack of follow‐up data and the remaining 106 patients were followed up of 2 years and entered into analysis. Sixty‐nine patients had tumor metastasis or recurrence during the follow‐up and the cumulative probability of HCC metastasis or recurrence was 65.1%. On multivariate analysis, genotype C and HBV DNA level were the risk factors for HCC recurrence or metastasis. The incidence of recurrence or metastasis increased with baseline HBV DNA level in a dose‐response relationship ranging from 22% for HBV DNA level of less than 3 log10 copies/ml to 80% for HBV DNA level of 5 log10 copies/ml or greater (Pu2009=u20090.012). Fifty‐seven (74.0%) and 12 (41.4%) patients had metastasis or recurrence in patients with genotype C and B, respectively. The adjusted OR of recurrence or metastasis for genotype C compared with genotype B was 9.755 (Pu2009=u20090.009). In conclusion, elevated HBV DNA level and genotype C are strong risk predictors of HCC metastasis or recurrence. J. Med. Virol. 80:591–597, 2008.

Interleukin-21 is upregulated in hepatitis B-related acute-on-chronic liver failure and associated with severity of liver disease.

Summary.u2002 The immune mechanism(s) that lead to hepatitis B‐related acute‐on‐chronic liver failure (HB‐ACLF) are poorly understood. Interleukin‐21 is a newly discovered cytokine that is involved in autoimmune and inflammatory diseases. Its potential role in HB‐ACLF remains unknown. The serum levels of 12 immune cytokines measured by cytometric bead arrays and the frequency of IL‐21‐secreting CD4+ T cells in peripheral blood mononuclear cells (PBMC) measured by intracellular cytokine staining were compared in moderate chronic hepatitis B (M‐CHB, nu2003=u200320), severe chronic hepatitis B (S‐CHB, nu2003=u200320), HB‐ACLF (nu2003=u200339) and healthy controls (nu2003=u200310). PBMC from M‐CHB patients or healthy subjects were stimulated with rhIL‐21 in vitro, and cytokines in supernatants were measured by FlowCytomix. The frequencies of IL‐21‐secreting CD4+ T cells were higher in HB‐ACLF (both Pu2003<u20030.001) and S‐CHB (Pu2003=u20030.002 and 0.001) as compared to M‐CHB patients and controls. Serum IL‐21 levels were highest (Pu2003<u20030.001) in HB‐ACLF and positively associated with high MELD score (Pu2003=u20030.001) and mortality (Pu2003=u20030.038). Recovery from HB‐ACLF was associated with reduced serum IL‐21 levels (Pu2003=u20030.003) and lower CD4+IL‐21+ T‐cell frequency (Pu2003=u20030.006). The secretions of IL‐1β (Pu2003<u20030.001), IL‐6 (Pu2003<u20030.001), IL‐10 (Pu2003<u20030.001), IFN‐γ (Pu2003=u20030.001) and TNF‐α (Pu2003=u20030.042) from PBMC were significantly increased with rhIL‐21 stimulation. In summary, IL‐21 has a causal role in the development of severe liver inflammation, which is upregulated in HB‐ACLF and associated with severity of liver disease.

Distribution and characteristics of hepatitis B virus genotype C subgenotypes in China.

Summary.u2002 Genetic diversity within the same hepatitis B virus (HBV) genotype indicates the presence of several subgenotypes. We have found that genotype C is the most common in China, and this study aimed to determine the geographical distribution and characteristics of HBV‐C subgenotypes in the country. A cohort of 534 patients with chronic HBV genotype C infection, collected across China, was analysed by nucleotide sequencing or polymerase chain reaction‐restriction fragment length polymorphism. HBV‐C1/Cs (nu2003=u2003112, 21%) and HBV‐C2/Ce (nu2003=u2003397, 74%) were the most common HBV‐C subgenotypes and showed different geographical distribution in China. No significant differences were found between patients infected with HBV‐C1 and HBV‐C2 when comparing liver function tests, hepatitis B e antigen positive rate and clinical manifestations. We identified two other types of HBV‐C provisionally designated as HBV‐CD1 and HBV‐CD2, which have particular virological features and clustered in one geographic area. These two types of C/D hybrids have emerged through recombination with genotype D and encode serotype ayw2 hepatitis B surface antigen. In conclusion, there are at least four subtypes of HBV genotype C: subgenotypes C1, C2 and two types of C/D recombinants CD1 and CD2 in China, which have a distinct geographic distribution. Whether HBV‐C subgenotypes differ in their impact on liver disease progression requires prospective studies.

Management of chronic hepatitis B: experience from China

Summary.u2002 Chronic hepatitis B infection is a significant health problem throughout the world, and particularly in China. It is estimated that more than half a million Chinese people die annually from end‐stage hepatitis B complications, which is associated with huge healthcare costs and a heavy socioeconomic burden. In China, the implementation of a hepatitis B vaccination programme has come into effect, and there has been a one‐third decrease of the hepatitis B virus (HBV) carrier population since 1992. This great achievement changes China from a highly endemic area for HBV infection to an intermediate one. The predominant HBV genotypes in China are B and C, which might predispose patients to a poor antiviral response. Patients and physicians from China have been actively involved in the global research into and development of new antiviral agents. Patients have been recruited for global and domestic clinical trials on antiviral agents, including lamivudine, adefovir dipivoxil, entecavir, telbivudine and two pegylated interferon‐α. In the future, more important data, focussing on optimization of the efficacy of antiviral agents, will be released from China, based on the newly launched National Eleven Five Plan Project on Hepatitis Research. Both economic development and healthcare system reform, including a new reimbursement policy, will make antiviral agents more accessible to Chinese patients. Ultimately, this will allow physicians greater opportunities to follow international and Chinese treatment recommendations.

Hepatitis B virus genotype B with G1896A and A1762T/G1764A mutations is associated with hepatitis B related acute-on-chronic liver failure.

The existence of statistical associations between hepatitis B‐related acute‐on‐chronic liver failure and both hepatitis B virus (HBV) genotype and mutations in the basal core promoter (BCP) and precore (PC) regions needs to be confirmed. A total of 322 patients with a chronic HBV infection, including 77 with hepatitis B‐related acute‐on‐chronic liver failure, 109 with hepatocellular carcinoma (HCC) and 136 with chronic hepatitis B (CHB) were enrolled. The HBV genotype and the presence of mutations in the BCP/PC regions were determined by direct sequencing, and the frequencies were compared in the three patient groups. Overall, 198/322 (61.5%) were infected with genotype B and 124/322 (38.5%) with genotype C. Genotype B was significantly more frequent in patients with acute‐on‐chronic liver failure than CHB (92.2% vs. 60.3%, Pu2009<u20090.001). As a contrast, genotype C was more common in patients with HCC than CHB (58.7% vs. 39.7%, Pu2009=u20090.003). In genotype B patients, the A1762T/G1764A, A1846T, and G1896A mutations were significantly more prevalent in patients with acute‐on‐chronic liver failure than CHB (50.7% vs. 28.0%, Pu2009=u20090.004; 59.2% vs. 34.1%, Pu2009=u20090.002; 69.0% vs. 41.5%, Pu2009=u20090.001, respectively). In multivariate analysis, the risk factors for acute‐on‐chronic liver failure were genotype B, A1762T/G1764A, and G1896A. In conclusion, CHB patients with genotype B, G1896A, and A1762T/G1764A had a higher tendency to develop liver failure than patients with genotype C. Therefore, HBV genotyping and detecting G1896A and A1762T/G1764A mutations might have important clinical implications as predictive risk factors for hepatitis B‐related acute‐on‐chronic liver failure. J. Med. Virol. 83:1544–1550, 2011.

Hepatitis B virus genotypes, subgenotypes, precore, and basal core promoter mutations in the two largest provinces of Pakistan

Background and Aim:u2002 Hepatitis B virus (HBV) genotyping has been done in most countries, but unfortunately, in Pakistan, HBV genotypic distribution is still unclear. The aim of the present study was to determine the prevalent genotype and subgenotype in the two most populated provinces in Pakistan: Punjab and Sind.

Serum HBsAg changes in HBeAg positive chronic hepatitis B patients with continuous viral load reductions during treatment with adefovir or peg-interferon-α-2a.

Hepatitis B surface antigen (HBsAg) loss under antiviral therapy is rare in chronic hepatitis B patients and the dynamics of serum HBsAg in these patients are not available. The changes in serum HBsAg following treatment with adefovir (n=31) or peg-interferon-alpha-2a (n=23) were studied in hepatitis B e-antigen (HBeAg) positive chronic hepatitis B patients. Abbott Architect HBsAg assay was used to quantify serum HBsAg. HBsAg levels were significantly decreased during the first 12 weeks of treatment with median change of -397.0 IU/ml and -555.4 IU/ml, respectively for adefovir and peg-interferon-alpha-2a (p=0.005 and 0.001, respectively). Beyond 12 weeks, no further significant HBsAg reductions were found even in patients with sustained viral replication inhibition in either group. Three distinct patterns of HBsAg changes were observed in most patients in both treatment groups: biphasic pattern (rapid HBsAg reduction from baseline to week 12); assurgent pattern (higher HBsAg level at week 12 than at baseline); and wavy pattern (HBsAg reduction from baseline to week 12, followed by relapse at week 24 or week 28). These results might offer insights into the possible mechanism(s) underlying the unusual occurrences of HBsAg loss under antiviral therapy.

GTPase activity is not essential for the interferon-inducible MxA protein to inhibit the replication of hepatitis B virus

Multiple studies have established that GTPase activity is critical for MxA to act against RNA viruses. Recently, it was shown that MxA can also restrict the replication of hepatitis B virus (HBV), a DNA virus, but the requirements for GTPase activity in inhibition of HBV by MxA remain unknown. Here, we report that GTPase-defective mutants (K83A, T103A, and L612K) can downregulate extracellullar HBsAg and HBeAg and reduce the expression of extra- and intracellular HBV DNA in HepG2 cells to levels similar to that achieved by wild-type MxA. Furthermore, TMxA and T103, two nuclear forms of wild-type MxA and a GTPase-defective mutant (T103A) could only slightly decrease the expression of extra- and intracellular HBV DNA in HepG2 cells. In conclusion, GTPase activity is not essential for MxA protein to inhibit HBV replication, and MxA may have only a minimal effect on the replicative cycle of HBV in the nucleus.

Prevention and management of drug resistant hepatitis B virus infections

In the past decade, broadened therapeutic options of oral direct antiviral agents for the treatment of chronic hepatitis B infection include: Lamivudine, Adefovir Dipivoxil, Telbivudine, Entecavir and Tenofovir Disoproxil Fumarate. These direct oral antiviral agents effectively suppress the replication of the virus and reduce the risk of potential liver‐related complications. However, prolonged use of these nucleos(t)ide analogues has been associated with drug resistance that compromises the initial clinical benefits. Moreover, the oncogenic risk of mutations due to prolonged nucleos(t)ide analogue therapy needs to be further investigated by in vitro and in vivo studies. In the current era of potent nucleotide analogues, new data are emerging, we are still facing the pool of patients who have developed resistance to the prior generation of nucleos(t)ide analogues. This paper aims to focus on incidence of antiviral drug resistance and virological breakthrough, prudent selection of initial therapy, on‐treatment monitoring for drug resistance and revise treatment strategies for patients with resistant virus.