Characteristics of geographic distributions and route of infection for hepatitis B virus genotype D in Ehime area in western Japan

A Recent Prevalence of Hepatitis B Virus (HBV) Genotypes and Subtypes in Asia: A Systematic Review and Meta-Analysis

Background and Aim: Despite introducing the hepatitis B virus (HBV) vaccine, the incidence of the Hepatitis B virus globally is still a major health concern. This systematic review and meta-analysis were conducted to provide detailed information on the prevalence of HBV genotypes and subtypes in circulation in Asia. Methods: A systematic search for articles describing the prevalence of HBV genotypes and subtypes in Asia was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines. Results: Our search returned 207 eligible articles involving 49,279 genotypes and 7457 subtypes representing 28 Asian countries. A meta-analysis was performed on our eligible studies using the Random effect Model. The pooled prevalence of HBV genotypes showed that genotype C (30.9%) (95% CI, 27.5–34.5%; I2 = 97.57%; p < 0.001) was the most common HBV genotype in Asia, followed by genotype B (17.8%) (95% CI, 15.5–20.4%; I2 = 97.26%; p < 0.001) and genotype D (15.4%) (95% CI, 11.8–19.8%). Vietnam had the highest prevalence of genotype B, Lebanon had the highest prevalence of genotypes C, and Jordan had the highest prevalence of genotype D. There was variation in genotypic prevalence with respect to the target genes for HBV genotyping. Reverse dot blot hybridization had the highest estimate of genotypes B and C. HBV subtype C2 (40.0%) (95% CI, 33.3–47.0) is the most prevalent HBV subtype. Conclusion: Evidence from this study reveals that HBV genotypes C and B are the most dominant HBV genotypes in Asia, and HBV subtype C2 is more endemic in Asia.

The Effect of the Hepatitis B Vaccine Derived from Genotype C on Infants Born to Mothers Infected with Genotype D

Objective There is a paucity of information on whether the hepatitis B virus (HBV) vaccine, derived from HBV genotype C, can prevent mother-to-child transmission of HBV genotype D. The aim of this study was to clarify this issue. Methods The subjects consisted of 25 children (8.5±4.1 years old, 7 males, 18 females), born to 17 mothers who were chronically infected with HBV genotype D. Of these, 20 children were inoculated with the genotype C-derived vaccine, one was inoculated with the genotype A-derived vaccine, and one was inoculated with both the A- and C-derived vaccines. Information on the type of vaccine given to the remaining three children was not available. The serum levels of HB surface antigen (HBsAg), antibody to HBsAg (anti-HBs), and antibody to HB core (anti-HBc) of the children, as well as HBV markers of the mothers, were examined. Results All mothers were positive for HBsAg (6,563±11,005 IU/mL), negative for HBeAg, and positive for anti-HBe. HBV-DNA levels (log IU/mL) were <3.3 in 7 mothers, 3.3-4.3 in 9 mothers, and >4.3 in one mother. HBsAg and anti-HBc were negative in all children, regardless of the type of vaccine used. Anti-HBs were positive in 13 children and negative in 12. Conclusion All children born to mothers infected with genotype D, including 20 who were inoculated with the genotype C-derived vaccine, were negative for both HBsAg and anti-HBc. These results suggest that the genotype C-derived HB vaccine is effective in preventing mother-to-child transmission from mothers infected with HBV genotype D.

A 79-year-old Woman with Acute Hepatitis B Caused by the Infection of Subgenotype D1 Hepatitis B Virus in Japan: A Case Study

A 79-year-old Japanese woman was diagnosed with acute hepatitis B based on laboratory tests showing positivity for IgM-class antibody against hepatitis B virus (HBV) core and hepatitis B surface antigen (HBsAg) as well as elevated transaminases. A phylogenetic analysis revealed that the HBV strain obtained from the patient belonged to genotype D/subgenotype D1, similar to strains circulating in foreign countries but different from those in Japan. The clinical course was favorable. HBsAg became negative within 10 weeks after the onset. To our knowledge, this is the first report of acute hepatitis B caused by subgenotype D1 HBV in Japan.

A 96-week randomized trial of switching to entecavir in patients who achieved virological suppression on lamivudine therapy

BACKGROUND AND AIM

There are limited data assessing whether patients who achieved virological suppression on lamivudine but remain hepatitis B "e" antigen-positive should be switched to a more potent antiviral with a high genetic barrier to resistance or continue with lamivudine. We compared the safety and efficacy of switching with entecavir versus continuing lamivudine.

METHODS

This was a Phase IV, randomized, open-label, prospective study in a tertiary care setting. Seventy-three chronic hepatitis B patients who achieved virological suppression on lamivudine (serum hepatitis B virus DNA < 60 International Unit (IU)/mL) were enrolled. Entecavir or lamivudine were administered orally for up to 96 weeks. Virologic and serologic responses were measured throughout the study.

RESULTS

A significantly higher proportion of patients in the entecavir group achieved hepatitis B virus DNA < 60 IU/mL at Weeks 48 (100% [38/38] vs 62.8% [22/35]; P < 0.001) and 96 (97.4% [37/38] vs 57.1% [20/35]; P<0.001). A greater number of patients had virologic breakthrough (Week 96 cumulative incidence 42.9% vs 2.6%; P<0.001) and genotypic lamivudine resistance (28.6% [10/35] vs 0% [0/38]; P<0.001) in the lamivudine group. No serious adverse events or laboratory abnormalities were reported.

CONCLUSIONS

Even after achieving virological suppression on lamivudine therapy, the risk of emergent lamivudine resistance increases over time. Switching to entecavir resulted in a maintained virologic response and superior serologic responses versus continued lamivudine therapy. This study supports a rationale for switching to entecavir in chronic hepatitis B patients with virological suppression on lamivudine.

Current antiviral therapies for chronic hepatitis B

Among current treatment options for chronic hepatitis B, nucleoside/nucleotide analog therapy has better tolerability and most patients respond to the therapy, while interferon (IFN) therapy has rather severe side-effects and a lower response rate. However, nucleoside/nucleotide analog therapies have problems of the emergence of drug resistance and poor sustainability of response after discontinuation. After the first nucleoside/nucleotide analog lamivudine, adefovir and entecavir are now utilized in many countries. Adefovir has efficacy for lamivudine resistant patients and current data suggests that adding adefovir to ongoing lamivudine is better than switching to adefovir in terms of viral suppression and the occurrence of resistance. Entecavir can be the first choice for naïve patients, although cross-resistance has been known for lamivudine resistant patients and mutational screening should take place before using entecavir with such patients. Many other new nucleoside/nucleotide analogs are being developed such as telbivudine, clevudine and tenofovir; the details of each drug will be disclosed in near future.