Precore mutation enhances viral replication to facilitate persistent infection especially in HBeAg-negative patients

Naturally occurred precore (PC, G1896A) and/or basal core promoter (BCP, A1762T/G1764A) mutations are prevalent in chronic HBV-infected patients, especially those under HBeAg-negative status. However, the replicative capacity of HBV with PC/BCP mutations remains ambiguous. Herein, meta-analysis showed that, only under HBeAg-negative status, the serum HBV DNA load in patients with PC mutation was 7.41-fold higher than those without the mutation. Both PC mutation alone and BCP ​+ ​PC mutations promoted HBV replication in cell and hydrodynamic injection mouse models. In human hepatocyte chimeric mouse model, BCP ​+ ​PC mutations led to elevated replicative capacity and intrahepatic core protein accumulation. Mechanistically, preC RNA harboring PC mutation could serve as mRNA to express core and P proteins, and such pgRNA-like function favored the maintenance of cccDNA pool under HBeAg-negative status. Additionally, BCP ​+ ​PC mutations induced more extensive and severe human hepatocyte damage as well as activated endoplasmic reticulum stress and TNF signaling pathway in livers of chimeric mice. This study indicates that HBeAg-negative patients should be monitored on HBV mutations regularly and are expected to receive early antiviral treatment to prevent disease progression.

Acute hepatitis B in pregnancy with surprisingly rapid clearance of serum HBs antigen associated with a favourable outcome

Acute hepatitis B (AHB) is usually asymptomatic, but it can progress to chronic hepatitis B (HB) defined by HB surface antigen (HBsAg) persisting beyond 6 months. Nevertheless, the delay of HBsAg seroclearance is not well-defined. During pregnancy, the immune system of the pregnant women is altered and delayed HBsAg loss can be observed, leading to chronic infection. Here, we present an uncommon case of AHB in a pregnant woman in whom rapid HBsAg seroclearance (52 days after AHB) was associated with a favourable outcome (no injury to liver). This patient received tenofovir disoproxil fumarate promptly after diagnosis. The case raises questions about the use of antiviral treatment in AHB. This is generally not recommended in AHB, but it would be potentially useful in pregnant women to reduce the risk of chronic HB infection and could also prevent the transmission of the maternal precore mutation, thus reducing the significant risk of fulminant hepatitis in the infant. This case also highlights the impact of the hepatitis B virus (HBV) genotype and precore/core mutations on the clinical course of the disease.

Spontaneous reactivation of hepatitis B virus with a frameshift mutation in the precore region in an elderly hepatitis B virus carrier with lifestyle-related diseases

A 76-year-old woman with spontaneous reactivation of hepatitis B virus (HBV) without any immunosuppressants who had been successfully treated with tenofovir alafenamide fumarate (TAF) was reported. The patient was admitted to our hospital because of acute exacerbation of the liver function and jaundice. She had been found to have chronic HBV infection with a normal liver function and had been treated for lifestyle-related diseases, such as diabetes mellitus, dyslipidemia and hypertension, for over 10 years at a local clinic. At admission, her serum HBV DNA was high (7.3 log IU/mL), and anti-hepatitis B core protein immunoglobulin M was slightly elevated (1.47 S/CO). Due to the absence of known risk factors for HBV reactivation, the reactivation was regarded as "spontaneous". After the initiation of the nucleotide analog TAF, her liver function gradually improved with a decrease in the HBV DNA load. Her HBV genome was typed as subgenotype B1 and possessed a frameshift mutation due to an insertion of T after nucleotide (nt) 1817 and G to A mutations at nt 1896 and nt 1899 (G1896A/G1899A) in the precore region as well as serine to glutamine substitution of amino acid 21 in the core protein. In addition to these viral mutations, aging and complications of lifestyle-related diseases in the present case may have been responsible for the spontaneous HBV reactivation. Careful observation and management of aged HBV carriers with underlying diseases are needed even when persistent HBV infection is free from symptoms and liver dysfunction and no immunosuppressive conditions are involved.

Prevalence and clinical significance of hepatitis B Basal core promoter and precore gene mutations in southern Iranian patients

BACKGROUND AND AIMS

To investigate the prevalence and pattern of PC and BCP mutations and their clinical significance in patients with genotype D chronic hepatitis B infection in the Fars province of southern Iran.

MATERIALS AND METHODS

From January 2007 to March 2008, we evaluated 44 patients with chronic hepatitis B infection who were referred to our hepatology clinics affiliated with the Shiraz University of Medical Science. All Patients were HBeAg Negative and HBeAb positive. Basal core promoter and precore mutations in these patients were evaluated with clinical phenotype and laboratory tests.

RESULTS

The mean age of the patients was 37.21 ± 10.54 years. Twenty-seven patients (61.4%) had no mutations, whereas 17 patients (38.6%) had mutations in the precore or basal core promoter regions or both. The mean serum ALT level in mutation-free patients was 59.74 ± 55.86 IUL, whereas patients with PC and BCP mutations had a mean serum ALT level of 71.35 ± 59.49 IUL. The mean serum AST level in patients with mutations was higher than for patients without mutations (59.53 ± 41.35 IUL vs. 40.65 ± 25.21 IUL, respectively). There was no statistically significant difference between the mutation and mutation-free groups in terms of age, sex, and liver enzyme levels (P > 0.05). Fourteen of the 44 patients (31.8%) had mutations in the precore region (G 1896A). 17 patients (38.6%) had mutations in basal core promoter region.

CONCLUSION

This study revealed a high prevalence of precore and basal core promoter mutations in southern Iran. Although no statistically significant difference was noted in liver enzymes, patients with mutations had higher liver enzymes in comparison with mutation-free patients.