A Study On HBV Genotypes And Selected HBV X Gene Mutations In Patients With HBV-Induced Liver Diseases

PART ICharacterization and Distribution of HBV GenotypesThere are 8 well-documented genotypes of hepatitis B virus (HBV) at this point in time. There is an association between HBV genotype and the pathogenesis and prognosis of HBV induced liver diseases. Genotype C is associated with severe liver diseases and hepatocellular carcinoma (HCC) prevalence, whereas genotype B is associated with icteric flare-up of chronic HBV infection. A novel, convenient and rapid genotype-specific primers-based PCR was employed for HBV genotype characterization. The genotyping results obtained by the PCR-based method were confirmed/validated by the direct sequencing of PCR amplified pre-S region of 10 samples randomly selected from the cohort. Serum HBV DNA load was determined by Real-Time detection (RTD) PCR. A survey on a cohort of 125 patients with HBV in and around Hangzhou City, Zhejiang Province showed the existence of the following HBV genotypes: A (0.8%), B (48%), C (40.8%), D (0.8%), mixed B and C (9.6%) and an absence of E and F genotypes. Distribution of HBV genotypes in patients with liver diseases revealed a statistically insignificant higher prevalence of genotype B in mild chronic hepatitis (CH). HBV infection in patients with mild CH was more associated with genotype B than C although it was not statistically significant. Among the three genotypes B, C and mixed B/C infections; 11 (73.3%), 3 (20%) and 1 (6.7%), (P< 0.05), respectively in subjects with moderate CH, genotype B was significantly predominant. In subjects with severe CH, the ratio of genotype B, C and mixed B/C infections; 4 (20%), 11 (55.0%) and 5 (25.0%) respectively, showed a predominance of C genotype although the inter-genotypic difference was insignificant. The infection patterns for genotypes B, C and B/C mixed in (i) LC 4 (23.5%), 10 (58.8%) and 3 (17.7%) and (ii) HCC 2 (28.6%), 5 (71.4%) and 0 (0.0%) respectively, revealed a markedly highest association of HBV C genotype with liver disease, albeit insignificant differences (P>0.05).Differences in positive rate of HBeAg for the three genotypes B, 16 (30.8%); C, 27 (51.9%) and mixed B/C, 9 (17.3%) were significant (P<0.05), genotype C showing predominance. Our results show, for the first time and as far as we know, a novel and markedly high prevalence of mixed B/C genotype infections in subjects with severe CH and LC and a possible association of mixed B/C infections with the severity of liver diseases in this region of the Mainland China. In contrast to our finding, previous studieshave reported that super-infection or co-infection was rare and of very minor clinical significance even in endemic areas and also that genotype C was the predominant HBV genotype in the Mainland China. Our results indicate that genotype B is predominant, at least in (Hangzhou and surrounding areas of Zhejiang Province) this region of Mainland China. In addition, the findings also show a higher prevalence of HBV genotype B in patients with mild liver diseases [asymptomatic carrier (ASC), mild CH] while genotype C shows a higher prevalence in patients with LC and HCC. From the findings above, we therefore conclude that there is a variation in the distribution of HBV genotypes in different regions of the Mainland China. Furthermore, we also conclude that HBV mixed B/C genotype infections are indeed frequent and could probably be of clinical significance in HBV-induced liver diseases.PART IICharacterization of HBV X Gene Mutation in Patients with Hepatocellular CarcinomaPrevious studies have shown that HBV X gene (deletion, point) mutations are associatedwith hepatocellular carcinoma (HCC). Truncated versions of X gene or the entire loss ofX gene have been found in patients with HCC. The second part our work involved acohort of 30 patients with HCC and a control of 10 liver cirrhosis and 2 chronic hepatitispatients in the investigation of the relationship between HBV X gene mutations and HCC.Full length HBX gene segments were nested-PCR amplified using the following set ofprimers HX1 and HX2 outer, LX1 and LX2 inner and...