The Correlation Between Hepatitis B Virus Precore/Core Mutations and the Progression of Severe Liver Disease

Abstract

Viral mutations acquired during the course of chronic hepatitis B virus (HBV) infection are known to be associated with the progression and severity of HBV-related liver disease. This study of HBV-infected Saudi Arabian patients aimed to identify amino acid substitutions within the precore/core (preC/C) region of HBV, and investigate their impact on disease progression toward hepatocellular carcinoma (HCC). Patients were categorized according to the severity of their disease, and were divided into the following groups: inactive HBV carriers, active HBV carriers, liver cirrhosis patients, and HCC patients. Two precore mutations, W28^* and G29D, and six core mutations, F24Y, E64D, E77Q, A80I/T/V, L116I, and E180A were significantly associated with the development of cirrhosis and HCC. Six of the seven significant core mutations that were identified in this study were located within immuno-active epitopes; E77Q, A80I/T/V, and L116I were located within B-cell epitopes, and F24Y, E64D, and V91S/T were located within T-cell epitopes. Multivariate risk analysis confirmed that the core mutations A80V and L116I were both independent predictors of HBV-associated liver disease progression. In conclusion, our data show that mutations within the preC/C region, particularly within the immuno-active epitopes, may contribute to the severity of liver disease in patients with chronic hepatitis. Furthermore, we have identified several distinct preC/C mutations within the study population that affect the clinical manifestation and progression of HBV-related disease. The specific identity of HBV mutations that are associated with severe disease varies between different ethnic populations, and so the specific preC/C mutations identified here will be useful for predicting clinical outcomes and identifying the HBV-infected patients within the Saudi population that are at high risk of developing HCC.

Keywords: HBV; HCC; cirrhosis; core gene; hepatitis; mutations.

Figure 1

Different amino acid position variations between Active HBV carrier's vs. Liver Cirrhosis of core protein.

Figure 2

Sliding-window analysis for the differences in amino acid changes between the Inactive and active+ cirrhosis+ HCC groups in HBV infected patients. The first panel shows the mean number of amino acid mutations of inactive (thick line) and active+ cirrhosis+HCC (shaded area) in each sliding window of30 amino acids. Second panels show the probability of observed differences in the amino acid mutations between inactive and active+ cirrhosis+ HCC was calculated for each window by t-test and was plotted for an inverted logarithmic scale. Significant differences observed in amino acid changes from 147 to 176.

Figure 3

Sliding-window analysis for the differences in amino acid changes between the active and liver cirrhosis patients. The ftrst panel shows the mean number of amino acid mutations of active (thick line) and cirrhosis (shaded area) in each sliding window of 30 amino acids. Second panels show the probability of observed differences in the amino acid mutations between active and cirrhosis was calculated for each window by t-test and was plotted for an inverted logarithmic scale. No Significant differences observed in amino acid.

Figure 4

Sliding-window analysis for the differences in amino acid changes between the active and liver cirrhosis + HCC patients. The ftrst panel shows the mean number of amino acid mutations of active (thick line) and cirrhosis + HCC (shaded area) in each sliding window of 30 amino acids. Second panels show the probability of observed differences in the amino acid mutations between active and cirrhosis + HCC was calculated for each window by t-test and was plotted for an inverted logarithmic scale. No significant differences observed in amino acid.

Figure 5

Sequence logos depicting the variations in frequency of identified mutations at different positions of the core protein between the active HBV carriers and HBV -related liver cirrhosis + hepatocellular carcinoma patients. Statistically significant differences between active HBV carriers vs. liver cirrhosis + HCC.