Epidemiology of HBV genotypes by nested PCR with multi-paired primers

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 influence of HLA alleles and HBV subgenotyes on the outcomes of HBV infections in Northeast China

Hepatitis B virus (HBV) infection has a wide variety of clinical outcomes, it could be spontaneouly recovered and also could develop fulminant liver failure or cirrhosis with hepatocellular carcinoma. Human leukocyte antigen (HLA) polymorphism and HBV (sub)genotypes have been speculated to associate with the outcome of HBV infection because the data obtained from various populations who bear different HLA alleles have shown a HLA polymorphism associated outcome of HBV infection. However, as the most important viral and host genetic factors, the impact of HBV (sub)genotypes in combination with HLA polymorphism on the clinical outcomes of HBV infections remains unclear. To demonstrate the association of HLA allele polymorphism in combination with HBV subgenotypes with the outcome of HBV infection in Northeastern Han Chinese population, a total of 230 HBV-infected individuals (Infection group) were compared to 210 random selected controls (Control group) who are negative for HBV infection for their HLA alleles frequency as well as the associations with the virus infection, clearance and persistence in combination with HBV subgenotypes. Of the 230 HBV-infected subjects, 54 were acute self-limited hepatitis (ASH) with HBV subgenotype C2 (ASH-C2), 144 were chronic hepatitis (CH) with HBV subgenotype C2 and B2 (CH-C2 and CH-B2), and 32 were spontaneously recovered (SR) without subgenotype results. When two groups are compared, the results suggest that B*48, B*51 and DRB1*12 carrier may have a high risk for HBV infection, but B*51 is likely association with spontaneous recovery and DRB1*07, 12 may be implied in viral persistence. HLA-B*15, DRB1*11 and 14 associated with viral clearance in the cases of HBV-C2 infection; HLA-B*54 carriers in chronic group are more sensitive to with the infection of HBV subgenotype B2; HLA-B*07 and DRB1*13 may protect subjects from HBV infection. The data presented a link between HLA polymorphism and HBV pathogenesis and suggested potential therapeutic targets for hepatitis B.

Hepatitis B virus subgenotype C2 is the most prevalent subgenotype in northeast China

The geographical distribution of hepatitis B virus (HBV) subgenotypes and their clinical implications in patients with acute and chronic hepatitis B in the Heilung-kiang province of northeast China were investigated. Nested PCR and multiplex PCR were performed with genotype-specific primers and with subgenotype-specific primers to identify genotypes and subgenotypes from serum samples of 412 HBV infections including 69 with acute self-limited hepatitis (ASH) and 343 with chronic hepatitis (CH). A total of 361 samples were genotyped and 304 were further subgenotyped. The most common HBV genotype was C (93.63%, 338/361), with subgenotype group C2 (83.73%, 283/338) predominating. Genotype B was also found and subgenotype B2 predominated within this genotype. Out of 69 infected patients with ASH, 48 were identified as genotype C and all belonged to subgenotype C2. Of 343 infected patients with CH, 313 were genotyped and 256 were subgenotyped; amongst these, C2 (91.80%, 235/256), B2 (7.42%, 19/256) and mixed subgenotypes B2 and C2 (0.78%, 2/256) were found. In HBV subgenotype C2 infections, ASH had a higher ratio of women than CH patients. These results show that HBV subgenotypes C2 and B2 were found in Heilung-kiang province of northeast China. In ASH and CH groups, the distributions of subgenotypes were coincident with C2, the predominant subgenotype. Analysis of the association between subgenotype and the outcomes of HBV infection was inconclusive in our study.

Construction and expression of eukaryotic plasmids containing lamivudine-resistant or wild-type strains of Hepatitis B Virus genotype C

AIM: To construct eukaryotic expression plasmids of full-length Hepatitis B Virus (HBV) genotype C genome, which contain lamivudine-resistant mutants (YIDD, YVDD) or wild-type strain (YMDD), and to observe the expression of HBV DNA and antigens [hepatitis B surface antigen (HBsAg) and hepatitis B e antigen (HBeAg)] of the recombinant plasmids in HepG2 cells.

METHODS: Three HBV full-length genomes were amplified from the plasmids pMD18T-HBV/YIDD, pMD18T-HBV/YVDD and pMD18T-HBV/YMDD, using PCR. Three recombinant plasmids were generated by inserting each of the PCR products into the eukaryotic expression vector pcDNA3.1 (+), between the EcoRI and HindIII sites. After being characterized by restriction endonuclease digestion, and DNA sequence analysis, the recombinant plasmids were transfected into HepG2 cells. At 48 and 72 h post-transfection, the levels of intracellular viral DNA replication were detected by real-time PCR, and the expression of HBsAg and HBeAg in the cell culture supernatant was determined by ELISA.

RESULTS: Restriction endonuclease digestion and DNA sequence analysis confirmed that the three recombinant plasmids were correctly constructed. After transfecting the plasmids into HepG2 cells, high levels of intracellular viral DNA replication were observed, and HBsAg and HBeAg were secreted into the cell culture supernatant.

CONCLUSION: Eukaryotic expression plasmids pcDNA3.1 (+)-HBV/YIDD, pcDNA3.1 (+)-HBV/YVDD or pcDNA3.1 (+)-HBV/YMDD, which contained HBV genotype C full-length genome, were successfully constructed. After transfection into HepG2 cells, the recombinant plasmids efficiently expressed HBV DNA, HBsAg and HBeAg. Our results provide an experimental basis for the further study of HBV lamivudine-resistant mutants.

Association of hepatitis B virus genotypes with clinical phenotypes of hepatitis B virus infection in Beijing

AIM: To investigate the relationship between the genotypes of hepatitis B virus (HBV) and the clinical outcomes of HBV infection in Beijing area.

METHODS: A total of 1 321 patients, including those with self limited HBV infection (n = 245), chronic hepatitis B (n = 668), liver cirrhosis (n = 108) and asymptomatic carriers (n = 300), were concluded in this study. Serum samples were collected for the detection of HBV markers by enzyme linked immunosorbent assay (ELISA). A simple and precise genotyping system based on polymerase chain reaction (PCR) using type-specific primers was developed for the determination of the genotypes of HBV.

RESULTS: Of the 1 321 serum samples, 804 (60.1%) were HBV DNA positive. HBV with the genotype of B, C, and B+C covered a larger percent. The percentage of HBV with genotype A, B, C, and B+C were 0.25% (2/804), 20.77% (167/804), 69.53% (559/804) and 9.45% (78/804), while none of HBV with genotype D, E, and F was found. Of all the patients with self limited HBV infection, 14 were HBV DNA positive, and the rates of genotype B, C, and B+C were 28.6% (4/14), 64.3% (9/14) and 7.1% (1/14), respectively. Of the samples from asymptomatic carriers, 128 were HBV DNA positive, and the rates of genotype B, C, and B+C were 28.1% (36/128), 68.8% (88/128), and 3.1% (4/128), respectively. Of the patients with in chronic hepatitis B, 608 cases were positive for HBV DNA, and the percentage of genotype B, C, B+C, and A were 19.9% (121/608), 68.6% (417/608), 10.4% (68/608), and 0.3% (2/608), respectively. Of the patients with liver cirrhosis, 54 were HBV DNA positive, and the percentage of genotype B, C, and B+C were 11.1% (6/54), 88.3% (45/54), and 5.6% (3/54), respectively. The rate of genotype C in liver cirrhosis patients was markedly higher than that in the patients with chronic hepatitis B, self limited HBV infection, and asymptomatic carriers (all P <0.05). In addition, genotype distribution showed no significant differences between the age and sex of patients.

CONCLUSION: Genotype B and C are major genotypes in Beijing. HBV with genotype C is predominant in patients with HBV infection, and it may be associated with the development of liver cirrhosis.

Evaluation of fluorescent hybridization biprobe PCR and melting curve assay

AIM: To evaluate a fluorescent hybridization biprobe PCR and melting curve assay for detection of (hepatitis B virus) YMDD mutation associated with lamivudine therapy.

METHODS: HBV DNA and YMDD mutations in the 217 clinical serum specimens from patients with chronic HBV infection who were treated with lamivudine (100 mg/d) were detected by the fluorescence quantitative polymerase chain reaction (PCR) using TaqMan probe (FT-PCR) and the fluorescent hybridization biprobe PCR and melting curve assay (FH-PCR-MC), respectively. Seventy-eight positive sera were then genotyped by nested PCR with six pairs of HBV genotype-specific primes (A to F), and the cloned DNA fragments derived from conventional PCR of HBV YMDD of 30 positive sera were sequenced.

RESULTS: Among 217 samples, 75.6%(164/217) were HBV DNA positive, and 67.7% (147/217) were HBV YMDD positive, including YMDD 44.9%(66/147), YIDD 22.5%(33/147),YVDD 17.7%(26/147),YI/VDD 10.9%(16/147), and others 4.0%(6/147). In HBV DNA≥10⁷copies/L, all the positive and mutant rates of YMDD have no significant difference in different HBV DNA levels. Among 78 genotype samples (genotype C 89.8%, B 8.9% and D 1.3%), the positive and mutant rates of YMDD were 100%(78/78) and 58.97%(46/78) respectively. One genotype D was YIDD/YVDD. The mutant rates of YMDD in genotype B and C were 71.4% and 55.7% respectively, but have no marked difference (P >0.5). Using the results by DNA sequencing as reference standard, the relative specificity, sensitivity and over-all accordance of FH-PCR-MC were 96.3% (26/27), 100% (3/3) and 96.7% (29/30) respectively. The results of YMDD typing by FH-PCR-MC were confirmed by the sequencing of clones.

CONCLUSION: The fluorescent hybridization biprobe PCR and melting curve assay kit in detection of HBV YMDD mutation has high sensitivity and specificity. It is a convenient and rapid test kit, and may be used in YMDD genotyping.