Hepatitis B virus genotype: What should the clinician know?

Characterization of hepatitis B virus molecular genotypes in Chongqing and quantitative serological markers in patients during natural phases of chronic hepatitis B infection

BACKGROUND/AIMS

The present study was launched to systematically characterize the molecular genotypes and quantitative serological biomarkers during the natural course of chronic hepatitis B (CHB) infection in a patient population from Chongqing, China.

METHODS

A total of 140 patients were enrolled and grouped according to the natural phases of HBV infection: HBeAg (+) immune tolerance, immune clearance, HBeAg (-) low replicative and reactivation phase. Nested PCR was used for HBV molecular genotyping and chemiluminescent microparticle immunoassay for quantitative serological detection.

RESULTS

Subgenotypes B2 and C2 were found to be most prevalent with genotype B patients showing more potent viral activity. HBsAg level was found to be significantly correlated with HBV DNA, HBeAg, age, ALT and AST levels during some phases of CHB.

CONCLUSION

These results indicated that molecular genotyping and quantitative serological detection might be helpful for earlier prediction of the long-term disease outcomes.

Diagnosis of hepatitis B virus infection through serological and virological markers

Hepatitis B virus (HBV) infection is an important health problem and the major cause of chronic hepatitis, cirrhosis and hepatocellular carcinoma (HCC) worldwide. The natural history of chronic HBV infection can be divided into four dynamic phases in HBV carriers who acquire the virus early in life. Diagnosis of HBV infection is usually through serological and virological markers. Hepatitis B surface antigen (HBsAg) is the hallmark of HBV infection and is the first serological marker to appear in acute hepatitis B, and persistence of HBsAg for more than 6 months suggests chronic HBV infection. Hepatitis B e antigen (HBeAg) usually indicates active HBV replication and risk of transmission of infection. Recently, occult HBV infection is recognized as the absence of circulating HBsAg in individuals positive for serum or tissue HBV DNA, irrespective of other HBV serological markers. Meanwhile, monitoring the serum HBV DNA level is valuable for assessing liver disease activity, differentiating other etiologies of hepatitis activity in HBV carriers, predicting risk of HCC development or liver-related mortality, deciding to administer antiviral therapy, determination of the response to antiviral treatment, predicting the risk of developing drug resistance, and detecting the emergence of drug-resistant mutants. On the other hand, HBV genotype C, basal core promoter mutant and pre-S deletion mutant are reported to be associated with increased risk of HCC development. The roles of quantitative HBV serology and intrahepatic HBV covalently closed circular (ccc)DNA deserve further studies. In conclusion, it is particularly important for physicians to screen for HBV infection in HBV-endemic areas and to monitor liver disease progression in HBV carriers by using both serological and virological markers, so that effective treatment can be initiated early before the development of advanced liver disease.

Hepatitis B virus (HBV) infection in Asian and Pacific Islander Americans (APIAs): how can we do better for this special population?

Hepatitis B virus(HBV) infection is one of the major global public health problems. Based on the second National Health and Nutrition Examination Survey (NHANES II), it is estimated that 1.25 million people are HBV infected in the United States. However, Asian and Pacific Islander Americans (APIAs) were underrepresented in this survey, and studies on the community HBV screening reported 6-15% of HBV infection in this special population. This article systematically reviews recent research advances in the possible barriers of hepatitis B care in APIAs that can be classified into three major categories, i.e., provider-, patient-, and resource-related barriers. The article also provides an overview of multiple approaches to effectively reduce these barriers so that we can evolve better strategy and deliver appropriate care to this special population and eventually reduce health disparity of CHB in APIAs.

[Natural history of chronic hepatitis B]

An estimated 350 million people worldwide are chronically infected with hepatitis B virus (HBV). Three phases of chronic hepatitis B virus infection is are recognized: the immune tolerant phase (HBeAg-positive, high levels of serum HBV-DNA, normal ALT, and no evidence of active liver diseases), the immune clearance phase or chronic hepatitis phase (HBeAg-positive, high levels of serum HBV-DNA, elevated ALT, and active liver disease ), and the inactive carrier state or asymptomatic phase (HBsAg-positive in serum without HBeAg, HBV-DNA levels than < 10(5) copies/mL, and normal ALT levels). Chronic hepatitis B is classified into 2 major forms: HBeAg-positive disease (wild-type HBV) and HBeAg negative disease (pre-core/core promoter HBV variant). Both forms can lead to liver cirrhosis, hepatic decompensation and liver cancer. The purpose of this article is to review the principal aspects of natural history of chronic hepatitis B.

Role of viral factors in the natural course and therapy of chronic hepatitis B

Hepatitis B virus (HBV) infection is a global health problem that causes a wide spectrum of liver disease, including acute or fulminant hepatitis, inactive carrier state, chronic hepatitis, cirrhosis, and hepatocellular carcinoma (HCC). The pathogenesis of hepatocyte damage associated with HBV is mainly through immune-mediated mechanisms. On the basis of the virus and host interactions, the natural history of HBV carriers who are infected in early life can be divided into four dynamic phases. The frequency, extent, and severity of hepatitis flares or acute exacerbation in the second immune clearance and/or fourth reactivation phase predict liver disease progression in HBV carriers. In the past decade, hepatitis B viral factors including serum HBV DNA level, genotype, and naturally occurring mutants predictive of clinical outcomes have been identified. The higher the serum HBV DNA level after the immune clearance phase, the higher the incidence of adverse outcomes over time. In addition, high viral load, genotype C, basal core promoter mutation, and pre-S deletion correlate with increased risk of cirrhosis and HCC development. As to the treatment of chronic hepatitis B, patients with high HBV DNA level and genotype C or D infection are shown to have a worse response to interferon therapy. In conclusion, serum HBV DNA level, genotype, and naturally occurring mutants are identified to influence liver disease progression and therapy of chronic hepatitis B. More investigations are needed to clarify the molecular mechanisms of the viral factors involved in the pathogenesis of each stage of liver disease and the response to antiviral treatments.