Investigation of DNA Sequence in the Basal Core Promoter, Precore, and Core Regions of Hepatitis B Virus from Tunisia Shows a Shift in Genotype Prevalence

authors:

avatar Rym Ayari 1 , * , avatar Yousr Lakhoua-Gorgi 1 , avatar Lamjed Bouslama 2 , avatar Imen Safar 1 , avatar Fatma Houissa Kchouk 1 , avatar Houda Aouadi 1 , avatar Saloua Jendoubi-Ayed 1 , avatar Taoufik Najjar 3 , avatar Kaled Ayed 1 , avatar Taieb Ben Abdallah 1

Laboratory of Immunology Research Center, Kidney Transplantation and Immunopathology (LR03SP01), Charles Nicolle Hospital, University of Tunis El Manar, rym_ayari@yahoo.com, Tunisia
Borj Cedria Center for Biotechnology, Hammam Lif, Tunisia
Department Gastro-Enterology, Charles Nicolle Hospital, Tunisia
Hepatitis Monthly: Vol.12, issue 11; 6191
published online: November 30, 2012
article type: Research Article
received: May 12, 2012
accepted: October 15, 2012
DOI: https://doi.org/10.5812/hepatmon.6191

how to cite: Ayari R, Lakhoua-Gorgi Y, Bouslama L, Safar I, Kchouk F H, et al. Investigation of DNA Sequence in the Basal Core Promoter, Precore, and Core Regions of Hepatitis B Virus from Tunisia Shows a Shift in Genotype Prevalence. Hepat Mon. 2012;12(11):6191. https://doi.org/10.5812/hepatmon.6191.

Abstract

Background:

In this study, we evaluated the prevalence of the most common mutations occurring in Enhancer II (EnhII), Basal Core Promoter (BCP), Precore (PC), and Core (C) regions of hepatitis B virus (HBV) genome.

Objectives:

We also investigated the correlation between HBV variants, their genotypes, and patients HBe antigen (HBeAg: soluble shape of the capsid antigen) status

Patients and Methods:

We retrieved viral DNA from 40 serum samples of Tunisian patients positive for hepatitis B surface antigen (HBsAg) and HBV DNA, amplified the above mentioned regions using specific primers, and sequenced the corresponding PCR (polymerase chain reaction) products. For further analysis purpose, the patients were divided into two groups: Group1 including 34 HBeAg-negative patients and Group2 with 6 HBeAg-positive patients.

Objectives:

We also investigated the correlation between HBV variants, their genotypes,and patients HBe antigen (HBeAg: soluble shape of the capsid antigen) status

Results:

Twenty-one patients (52.5%) showed PC G1896A mutation and 11 (27.5%) carried A1762T/G1764A double mutations. These mutations were more frequent in HBeAg-negative patients than that in HBeAg-positive ones. Indeed, 58.8% of patients bearing G1896A mutation were HBeAg-negative while 16.7% were positive. In patients bearing T1762/A1764 double mutation, 29.4% were positive and 16.7% were negative. In addition, the A1896 mutation was restricted to HBV isolates that had wild-type T1858, while C1858 was rather linked to the occurrence of T1762/A1764 mutation. Interestingly, this study revealed a high frequency of genotype E. This frequency was important as compared to that of genotype D known to be predominant in the country as delineated in previous studies.

Conclusions:

Previous results supported and showed that HBV strains present in Tunisia belonging to genotype D and, to a lesser extent, to genotype E, were prone to mutations in BCP/ PC regions. This observation was more obvious in HBV isolates from asymptomatic chronic carriers (AsC). The high mutational rates observed in our study might result from a mechanism of viral escape that plays an important role in the loss of HBeAg.

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