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J Med Virol. 2017 Mar;89(3):469-475. doi: 10.1002/jmv.24665. Epub 2016 Aug 24.

Evolutionary dynamics of HBV-D7 subgenotype in Tunisia.

Author information

1
Department of Infectious, Parasitic and Immune-Mediated Diseases, Epidemiology Unit, Istituto Superiore di Sanità, Rome, Italy.
2
University Hospital Campus Bio-Medico, Rome, Italy.
3
Department of Infectious Diseases, Viral Hepatitis Research Unit (UR12SP35), University Hospital Farhat Hached, Sousse, Tunisia.
4
Faculty of Pharmacy, Laboratory of Infectious Diseases and Biological Agents, University of Monastir, Monastir, Tunisia.
5
Department of Infectious, Parasitic and Immune-Mediated Diseases, Viral Hepatitis Unit, Istituto Superiore di Sanità, Rome, Italy.
6
Department of Cell Biology and Neurosciences, Clinical Diagnostics and Therapy of Degenerative Diseases of the Central Nervous System Unit, Istituto Superiore di Sanità, Rome, Italy.
7
Public Health and Infectious Diseases, Sapienza University, Rome, Italy.

Abstract

Hepatitis B virus (HBV) is the main cause of diseases liver related infecting more than 200 milion persons worldwide. HBV infection shows high level of prevalence in South-East Europe and in Mediterranean basin. In Tunisia, a country with an intermediate level endemicity, HbsAg prevalence ranges from 2 to 5%. Most of the HBV isolates from Tunisia were classified as subgenotype D7 whose circulation is restricted to a specific area of North Africa including Maghreb region. In this paper, the phylogeny of HBV-D7 isolated from 38 Tunisian patients was investigated by analyzing the S gene region of HBV. A Bayesian coalescent-based framework was used to estimate the origin of the HBV-D7 in the country. The Tunisian D7 isolates were found to share a common ancestor whose origin was traced back to 1958. Population dynamics indicated that HBV-D7 epidemic in Tunisia grew exponentially from 1960s to 1990s. After that, the curve reached a plateau around the years 2000 likely due to the implementation of the infant vaccination program in 1996. Epidemiological data suggested that the exponential growth phase was likely sustained by intra-familial transmission events occurring during infancy. Further characterization of HBV-D7 isolates should be performed to evaluate, in the post-vaccination era, the emergence of new transmission routes, and to monitor the efficacy of the vaccination program. J. Med. Virol. 89:469-475, 2017.

KEYWORDS:

epidemiology; evolution; hepatitis B virus

PMID:
27543368
DOI:
10.1002/jmv.24665
[Indexed for MEDLINE]

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