title: Naturally Occurring Surface Antigen Variants of Hepatitis B Virus in Tunisian Patients.
abstract: In Tunisia, the prevalence of naturally occurring surface (S) gene variants of hepatitis B virus (HBV) has not been determined. In the present study, the prevalence of these variants was examined in terms of the clinical and viral state in a series of 99 Tunisian patients with HBV infection. The S genes were amplified and directly sequenced. Genotype D was predominant (98%), 40.4% isolates belonged to subgenotypes D7 and 1 to subgenotype D2. The most common subtype was ayw2 (95.9%). In total, 60.6% of the studied strains harbored S mutations. Several novel mutation patterns were detected. Interestingly, the presence of S mutations was significantly correlated with the D7 subgenotype, low HBV DNA and advancing age (≥35 years), and tended to be higher in liver cirrhosis than in chronic infection. The global prevalence of the major hydrophilic region variants was 12.1%, with substitution S143L/T as the most frequent (4%). Only 33.9% of S substitutions produced amino acid changes in the polymerase gene. In conclusion, a high prevalence of naturally occurring HBsAg variants was observed among Tunisian HBV carriers. Natural viral variability in a geographical region and duration of infection are among the major factors associated with the occurrence of S mutations.
authors.affiliation: Department of Infectious Diseases, Viral Hepatitis Research Unit (UR12SP35), University Hospital Farhat Hached, Sousse, Tunisia.
authors.forename: Houda
authors.initials: H
authors.lastname: Chaouch
authors.forename: Stefania
authors.initials: S
authors.lastname: Taffon
authors.forename: Umbertina
authors.initials: U
authors.lastname: Villano
authors.forename: Michele
authors.initials: M
authors.lastname: Equestre
authors.forename: Roberto
authors.initials: R
authors.lastname: Bruni
authors.forename: Manel
authors.initials: M
authors.lastname: Belhadj
authors.forename: Naila
authors.initials: N
authors.lastname: Hannachi
authors.forename: Mahjoub
authors.initials: M
authors.lastname: Aouni
authors.forename: Amel
authors.initials: A
authors.lastname: Letaief
authors.forename: Anna Rita
authors.initials: AR
authors.lastname: Ciccaglione
mesh_terms: D000328:Adult; D000368:Aged; D001483:Base Sequence; D002353:Carrier State / Q000821:virology; D004279:DNA, Viral / Q000235:genetics; D005260:Female; D014644:Genetic Variation; D005838:Genotype; D006514:Hepatitis B Surface Antigens / Q000235:genetics*; D006515:Hepatitis B virus / Q000145:classification / Q000235:genetics*; D019694:Hepatitis B, Chronic / Q000453:epidemiology / Q000208:ethnology / Q000821:virology*; D006801:Humans; D008103:Liver Cirrhosis / Q000821:virology; D008297:Male; D008875:Middle Aged; D009154:Mutation; D010802:Phylogeny; D015995:Prevalence; D017422:Sequence Analysis, DNA; D014416:Tunisia / Q000453:epidemiology / Q000208:ethnology; D055815:Young Adult
chemical_list: D004279:DNA, Viral; D006514:Hepatitis B Surface Antigens