Study On The Quasispecies Of Hepatitis B Virus Within Pre-Core / Core Gene In Acute On Chronic Liver Failure

Objective: To investigate the quasispecies distribution of hepatitis B virus within pre-Core/Core gene in acute on chronic liver failure patients and to learn the pathogenesis of liver failure from the perspective of HBV population heterogeneity.Methods: Ten acute on chronic liver failure patients were studied and ten chronic hepatitis B patients were enrolled as control. HBV DNA was extracted from serum sample and the pre-Core/Core gene of hepatitis B virus was amplified by nested PCR. The PCR products were purified and then cloned and sequenced. The differences of quasispecies characteristics between the acute on chronic liver failure group and chronic hepatitis B group, which including quasispecies complexity and diversity, were analyzed using bioinformatics methods. The correlation between the quasispecies complexity and diversity and viral load was analyzed. Phylogenetic trees were constructed to compare the differences of HBV evolution between the two groups.Results: The composition of HBV quasispecies is different between the two groups. Quasispecies complexity (including the nucleotide and amino acid level) and quasispecies diversity (including dS and dN) in the liver failure group were higher than the chronic hepatitis B group(P <0.05). The quasispecies complexity and diversity has no significant correlation with viral load (P>0.05). Phylogenetic tree showed that the sequences from the same patients always assemble together, and only a few sequences gomphosis in sequence clusters of other patients. The branch length of sequences from liver failure group is longer than that from the chronic hepatitis B group . Conclusions: Quasispeciese composition in the ACLF group is more complex than in the CHB group. Quantitative indicators of quasispecies heterogeneity (including the quasispecies complexity and quasispecies diversity) in the liver failure group were higher than in the chronic hepatitis B group. Complex quasispecies distribution of HBV may cause severe infection of HBV, even liver failure. HBV showed different evolution patterns between the two group, may have different biological functions. Increasing virus quasispecies heterogeneity is not only related to high viral load, but also may be related to the virus genetic background, the immune pressure and external pressure and so on.