Hepatitis B Virus Genotype G: First Report of Complete Genomic Analysis from the African Continent

Hepatitis B virus can be divided into 10 genotypes based on sequence heterogeneity. HBV genotype G (HBV-G) has little genetic variation and often co-exists with another HBV genotype. HBV-G infections have been detected around the world, but rarely from Africa. Over a 9 year period, 3 patients were identified with HBV-G infection while attending a specialist Liver Clinic at a tertiary hospital in Cape Town, South Africa. The aim of this study was to describe the clinical and laboratory features of the patients and sequence the full HBV-G genome to determine the phylogenetic relationship with other HBV-G isolates from around the world. Further, co-infection with other HBV genotypes was determined using a multiplex type- specific PCR and cloning. All patients (2 of Caucasian and 1 of Asian ethnicity) belonged to a high risk group of men who have sex with men and were HBeAg positive. Two patients were co-infected with HIV and HBV co-infection (HBV-A) could only be identified in one case. The 2 South African complete genomes, from patients of Caucasian and Asian ethnicity, showed the characteristic features of HBV-G, including the 36 nucleotide insert at the 5' end of the core gene, 2 stop codons in the precore region and low genetic variability (0.5%). Phylogenetically the genomes clustered together with reference HBV-G strains. This is the first report of the full characterization of HBV-G in South Africa.