Evolutionary dynamics of HBV‐D7 subgenotype in Tunisia

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. © 2016 Wiley Periodicals, Inc.

Hepatitis B virus and hepatitis delta virus subtypes circulating in Algeria and seroprevalence of HDV infection

“…28 The HBV/D7 is restricted to a specific area of North Africa including Tunisia and Morocco. 20,22,23,25,28 In the case of genotype A, only a single subgenotype (A2) was found in this study.…”

“…Our results showed the predominance of subgenotype D7 (43.5%) which was identified for the first time in Tunisia . The HBV/D7 is restricted to a specific area of North Africa including Tunisia and Morocco . In the case of genotype A, only a single subgenotype (A2) was found in this study.…”

“…19,21 Most of the HBV isolates from Tunisia and Morocco were classified as genotype D and the HBV/D7/D1 subgenotypes are predominant in these countries. 20,[22][23][24][25][26][27][28] In Mauritania, the genotype distribution appears more diverse including D, E and A, and subgenotyping revealed HBV/D1/D7, and the recently described/ D8. 29 While HDV infection is low endemic in Tunisia and Libya, 24,30,31 Mauritania is a highly endemic region for this virus, and HDV-1 is a predominant genotype.…”

“…HBV infection represents an especially important health problem in the Maghreb countries. This infection is intermediately endemic in Morocco and Tunisia, whereas it is highly endemic in Mauritania . Most of the HBV isolates from Tunisia and Morocco were classified as genotype D and the HBV/D7/D1 subgenotypes are predominant in these countries .…”

Variable Proportions of Phylogenetic Clustering and Low Levels of Antiviral Drug Resistance among the Major HBV Sub-Genotypes in the Middle East and North Africa

“…Another interesting observation was the dominance of SGT D7 in the Arab Maghreb (Northwest Africa). The sustained presence of SGT D7 in the Maghreb was linked to intra-familial transmission in early childhood [ 91 ]. The dominance of SGT D7 in the Maghreb was previously reported by several original and review papers and is consistent with the results of this study [ 49 , 91 , 92 , 93 , 94 ].…”