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Genotype D of hepatitis B virus and its subgenotypes: An update
Author(s) -
Yousif Mukhlid,
Kramvis Anna
Publication year - 2013
Publication title -
hepatology research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.123
H-Index - 75
eISSN - 1872-034X
pISSN - 1386-6346
DOI - 10.1111/j.1872-034x.2012.01090.x
Subject(s) - phylogenetic tree , genotype , divergence (linguistics) , biology , genetics , genetic divergence , combinatorics , mathematics , gene , genetic diversity , demography , population , linguistics , philosophy , sociology
Aim The aim of the present study was to systematically and comparatively analyze the subgenotypes of genotype D of hepatitis B virus. Methods In total, 304 complete genomes of all genotype D subgenotypes were downloaded from the public databases. The sequences were analyzed using nucleotide divergence calculations, phylogenetic analysis and bioinformatics to detect amino acids signature motifs for each subgenotype and to define their geographical distribution. Results Intragroup divergence ranged from 0.8 ± 0.5 (% standard deviation) for subgenotype D 6 to 3.0 ± 0.3 for D 8. Inter‐subgenotype divergence mostly ranged 4–7.5%. Phylogenetic analysis of genotype D showed separation into six distinct clusters (subgenotypes D 1, D 2, D 3/ D 6, D 4, D 5 and D 7/ D 8) with good bootstrap support. The mean intergroup divergence between D 3 and D 6 was the lowest and fell below the threshold of 4%, which is required to define a subgenotype, suggesting that subgenotypes D 3 and D 6 belong to one subgenotype. “ D 8” is a genotype D / E recombinant, which clusters with D 7. A number of signature amino acids were found in all four open reading frames that could differentiate the subgenotypes, which also showed distinct geographical distribution. Conclusion There are six and not eight subgenotypes of D , D 1– D 6, which can be differentiated by distinct clustering with high bootstrap support and signature amino acids. Subgenotypes D 3 and “ D 6” should be reclassified as a single subgenotype D 3 and it would be more correct to classify “ D 8” as a genotype D/E recombinant rather than a subgenotype.