Evidence for reduced selection pressure on the hepatitis B virus core gene in hepatitis B e antigen-negative chronic hepatitis B

• Published in: Journal of general virology 2011-08, Vol.92 (Pt 8), p.1800-1808
• Main Authors: WARNED, Brook G, TSAI, Peter, RODRIGO, Allen G, OFANOA, Malakai, GANE, Edward J, MUNN, Stephen R, ABBOTT, William G. H
• Format: Article
• Language: English
• Subjects: Adult; Amino Acid Sequence; Biological and medical sciences; Female; Fundamental and applied biological sciences. Psychology; Hepatitis B Core Antigens - genetics; Hepatitis B Core Antigens - metabolism; Hepatitis B e Antigens - genetics; Hepatitis B e Antigens - metabolism; Hepatitis B virus - classification; Hepatitis B virus - genetics; Hepatitis B virus - isolation & purification; Hepatitis B virus - physiology; Hepatitis B, Chronic - virology; Humans; Male; Microbiology; Middle Aged; Miscellaneous; Molecular Sequence Data; Mutation; Phylogeny; Selection, Genetic; Virology
• ISSN: 0022-1317; 1465-2099
• DOI: 10.1099/vir.0.030478-0

The mechanisms underlying the high levels of hepatitis B virus (HBV) replication that cause hepatitis B e antigen (HBeAg)-negative chronic hepatitis B (e-CHB) are unknown. Impaired anti-HBV immunity, which may be measurable as a relaxation of selection pressure on the virus, is possible. A group of Tongans (n = 345) with a chronic HBV infection, including seven with e-CHB, were genotyped at HLA class I. The repertoire of HBV core-gene codons under positive selection pressure was defined by phylogenetic analysis (by using the paml program) of 708 cloned sequences extracted from the 67 of these 345 subjects with the same repertoire of HLA class I alleles as the seven e-CHB individuals and matched controls (see below). The frequency of non-synonymous mutations at these codons was measured in longitudinal data from 15 subjects. Finally, the number of non-synonymous mutations at these codons was compared in seven groups comprised of one subject with e-CHB and 1-3 HLA class I-matched controls with an inactive, HBeAg-negative chronic HBV infection (e-InD). Nineteen codons in the core gene were under positive selection pressure. There was a high frequency of new non-synonymous mutations at these codons (P