[Molecular epidemiology of hepatitis B virus in Northern Cyprus]

Identification of hepatitis B virus (HBV) strains and understanding of molecular epidemiological characteristics are important for the effective surveillance of HBV infections. Genotype D is dominant in studies performed in Turkey but it is known that cases infected with genotypes A, E, G and H also exists. In contrast, there are no data regarding the molecular epidemiologic characteristics of the HBV in Northern Cyprus. The aim of this study was to determine the distribution of genotypes and subgenotypes of HBV among the people living, educating and working in Northern Cyprus. A total of 160 cases (1.2%) who were HBsAg seropositive out of 13.892 subjects admitted to Nicosia, Near East University Hospital microbiology laboratory for the routine control and to blood center for donor screening tests between November 2011 to September 2014, were included in the study. HBV-DNA levels in the HBsAg positive cases were detected by real-time polymerase chain reaction and genotypes/subgenotypes were determined by sequence analysis of the viral pol gene (reverse transcriptase [rt] region, between 80-250. aminoacids). Sixty samples (60/160, 37.5%) were excluded from sequencing analysis due to negative and/or very low (< 30 IU/ml) HBV-DNA levels, so 100 samples were included in sequence analysis. Ninety-six of those cases (13 female, 87 male; mean age: 35.51 ± 12.88 years) were anti-HBc IgG, 95 were anti-HBe and five were HBeAg positive, with a mean HBV-DNA level of 5.36 x 10(6) ± 3.58 x 10(7) IU/ml. As 32 (32%) samples yielded HBV-DNA level below the threshold of 1000 IU/ml, sequence analyses were unsuccesful, eventually 68 (68/160, 42.5%) samples could be phylogenetically analyzed. The distribution of HBV genotypes/subgenotypes were found as follows: 48 were (70.6%) D/D1; four were (5.9%) D/D2; one was (1.5%) D/D3, five were (7.4%) A/A1, two were (2.9%) A/A2 and eight were (11.8%) genotype E. Among the most frequent D1 strains, 60.4% (29/48) cases were from Turkish; single D/D3 strain from Benguela (Angola) and all eight genotype E strains were from Nigerian national cases. According to the data of this first study performed in TRNC on this subject, genotype D is dominant (53/68, 78%) in Northern Cyprus and consistent with the subgenotype distribution that is similar to Turkey and mediterranean basin. The prevalences of genotype A (7/68, 10.3%) and E (8/68, 11.8%) were also remarkable. In conclusion, although Northern Cyprus is an island country the heterogeneous distribution of HBV genotype/subgenotype may be contributed to the cosmopolitan characteristics of various populations from different countries who have come here for education, work or touristic purposes.