Association of the Core Clustering Mutations Codon 21-34 and the Severity of Chronic Hepatitis B in Korean Patients

Abstract

Objectives:There are regions in the core gene of hepatitis B virus (HBV) where missense mutations are clustered, and mutations in that region are related to severe liver disease. However, there were some differences of the major regions for mutation clustering among ethnic groups. To explore the phenomenon of clustering mutations in Korean patients with chronic HBV infection and to elucidate the correlation between clustering mutation region of the core gene and the severity of liver damage, we analyzed the precore/core gene sequence of HBV in the sera from fifteen chronic hepatitis B (CH-B) patients.Methods:We analysed the HBV precore and core sequences in the sera obtained from fifteen patients (14 males and 1 female, mean age 30.0 years) with biopsy-proven CH-B. The patients were divided into two groups according to the pathological severity of CH-B; namely, group I consisted of 8 patients with chronic persistent hepatitis (CPH), and group II included 7 patients with chronic active hepatitis (CAH). After extraction of HBV DNA from each serum by proteinase K and phenol-chloroform solution, the entire precore and core region of HBV was amplified by PCR, and then the PCR products were subjected to direct sequencing using thermostable DNA polymerase. Fisher’s exact test and Mann-Whitney U test were used for statistical analysis.Results:A total of 181 nucleotide substitutions were found in the HBV core gene from the 15 CH-B patients, of which 23 were missense and 158 were silent. The nucleotide and amino acid substitution rates were not significantly different between the two groups (p>0.05). Two mutational hot spots (MHS), codons 21–34 (MHS1) and codons 85–100 (MHS2), were found in the deduced amino acid alignment of the core gene. The alteration rate of amino acid residue in these regions were 2.857×10−2 and 5.000×10−2, respectively. Of 8 CPH patients, 5 showed missense mutations only in MHS2. In comparison, of 7 CAH patients, 3 showed them both in MHS1 and MHS2, 1 only in MHS1, and 1 only in MHS2; thus, missense mutation in MHS1 was exclusively found in patient with CAH.Conclusions:There were two mutation clusterings in the core region of adr subtype of HBV from Korean CH-B patients. Mutations in MHS1 (codon 21–34), but not in MHS2 (codon 85–100), are more likely to be related to the severity of CH-B. A longitudinal study using sequential samples is warranted to further clarify the role of MHS1 in the pathogenesis of more severe CH-B.

A novel primer‐extension assay for the detection of a G to A mutation in the distal precore region of hepatitis B virus DNA

“…However, subsequent studies have failed to prove any consistent relationship between the precore stop codon mutation and the severity of the liver disease [8,[10][11][12]. More recently, mutations of the core gene and the core promoter gene have been investigated and many studies have reported that core gene or core promoter gene mutations are more closely associated with severity of HBV infection and responsiveness to interferon-α treatment than the precore stop codon mutation [13][14][15][16][17]. However, a recent well-designed study failed to correlate core promoter sequence variations with SUMMARY.…”

Molecular Epidemiology and Immunology of Hepatitis B Virus Infection – An Update

“…Numerous unique mutations were found in the region 48-60 in fulminant [67][68][69] and severe exacerbation hepatitis B patients [64][65][66][67][70][71][72]. In addition, mutation clustering regions at aa 21-34 [73] and 31-49 [74] were detected.…”

Analysis of the core gene of hepatitis B virus in Korean patients

“…Recently, a number of groups have described mutations/deletions that were selected in the core gene during the HBeAg‐negative phase and altered B‐ and T‐cell responses (7–9). Most HBV core gene mutations have been reported to be clustered in mid‐core regions (10–12). Among these regions where mutations cluster, several missense mutation hot spots in HBV have been identified in HBV chronic carriers, such as mutations at codons 5, 13, 59, 60, 87, 97, 130 and 182.…”