Novel Subgenotypes of Hepatitis B Virus Genotypes C and D in Papua, Indonesia

Departments of Microbiology, and Biochemistry, Faculty of Medicine, Tropical Disease Center, Airlangga University, Surabaya, Indonesia; Department of Microbiology, Cenderawasih University School of Medicine, Jayapura, Indonesia; Division of Microbiology, and International Center for Medical Research and Treatment, Kobe University Graduate School of Medicine, Kobe, Hyogo 650-0017, Japan

^* To whom correspondence should be addressed. Email: hotta{at}kobe-u.ac.jp.

	Abstract

Eight genotypes (A to H) and nine subtypes (adw2, adw4, ayw1, ayw2, ayw3, ayw4, adrq+, adrq– and ayr) of hepatitis B virus (HBV) have been identified worldwide. They appear to be associated with geographical distribution, virological characteristics, and possibly clinical outcomes. We performed sequence analysis of part of the S gene and the entire precore/core gene of HBV isolates obtained from HBsAg-positive blood donors in Papua Province, Indonesia. Phylogenetic analysis of the S gene sequences revealed that 23 (85.2%) of the 27 HBV isolates tested belonged to genotype C (HBV/C), and 2 (7.4%) each to HBV/B and HBV/D. Interestingly, 19 (82.6%) of the 23 isolates of HBV/C clustered in a branch that was distinct from the previously reported subgenotypes C1 (HBV/C1) to HBV/C5. Similarly, two isolates of HBV/D clustered in a branch distinct from the reported subgenotypes HBV/D1 to HBV/D5. Phylogenetic analysis of the entire precore/core gene confirmed the consistent presence of the distinct branches in HBV/C and HBV/D. We therefore propose the novel subgenotypes, designated HBV/C6 and HBV/D6. The majority of HBV/C6 isolates in Papua had alanine at positions 159 and 177 (A159/A177) in the HBsAg. A159/A177 is different from the determinants for adrq+ (A159/V177) found in the other part of Asia and adrq– (V159/A177) found in New Caledonia and Polynesia, possibly representing a unique antigenic group (provisionally referred to as adrq-indeterminate). In conclusion, we have identified two novel HBV subgenotypes, HBV/C6 and HBV/D6, the former of which is the most prevalent subgenotype of HBV in Papua, Indonesia.