Contribution of genome-wide HCV genetic differences to outcome of interferon-based therapy in Caucasian American and African American patients.
BACKGROUND
Hepatitis C virus (HCV) has six major genotypes, and patients infected with genotype 1 respond less well to interferon-based therapy than other genotypes. African American patients respond to interferon alpha-based therapy at about half the rate of Caucasian Americans. The effect of HCV's genetic variation on treatment outcome in both racial groups is poorly understood.


METHODS
We determined the near full-length pre-therapy consensus sequences from 94 patients infected with HCV genotype 1a or 1b undergoing treatment with peginterferon alpha-2a and ribavirin through the Virahep-C study. The sequences were stratified by genotype, race and treatment outcome to identify HCV genetic differences associated with treatment efficacy.


RESULTS
HCV sequences from patients who achieved sustained viral response were more diverse than sequences from non-responders. These inter-patient diversity differences were found primarily in the NS5A gene in genotype 1a and in core and NS2 in genotype 1b. These differences could not be explained by host selection pressures. Genotype 1b but not 1a African American patients had viral genetic differences that correlated with treatment outcome.


CONCLUSIONS
Higher inter-patient viral genetic diversity correlated with successful treatment, implying that there are HCV genotype 1 strains with intrinsic differences in sensitivity to therapy. Core, NS3 and NS5A have interferon-suppressive activities detectable through in vitro assays, and hence these activities also appear to function in human patients. Both preferential infection with relatively resistant HCV variants and host-specific factors appear to contribute to the unusually poor response to therapy in African American patients.
Department of Molecular Microbiology and Immunology, Saint Louis University School of Medicine, St. Louis, Missouri, United States of America.
Maureen J
MJ
Donlin
Nathan A
NA
Cannon
Rajeev
R
Aurora
Jia
J
Li
Abdus S
AS
Wahed
Adrian M
AM
Di Bisceglie
John E
JE
Tavis
D000328:Adult; D001741:Black or African American / Q000706:statistics & numerical data; D000998:Antiviral Agents / Q000627:therapeutic use; D004359:Drug Therapy, Combination; D005260:Female; D005787:Gene Frequency; D014644:Genetic Variation; D016679:Genome, Viral; D005838:Genotype; D016174:Hepacivirus / Q000145:classification / Q000235:genetics*; D006526:Hepatitis C / Q000188:drug therapy* / Q000208:ethnology / Q000235:genetics; D006801:Humans; D000077190:Interferon alpha-2; D016898:Interferon-alpha / Q000627:therapeutic use*; D008297:Male; D035683:MicroRNAs / Q000235:genetics; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D010802:Phylogeny; D011092:Polyethylene Glycols / Q000627:therapeutic use*; D011994:Recombinant Proteins; D012254:Ribavirin / Q000627:therapeutic use; D014758:Viral Core Proteins / Q000235:genetics; D017361:Viral Nonstructural Proteins / Q000235:genetics; D044465:White People / Q000706:statistics & numerical data; D012324:RNA-Dependent RNA Polymerase
D000998:Antiviral Agents; D000077190:Interferon alpha-2; D016898:Interferon-alpha; D035683:MicroRNAs; D011092:Polyethylene Glycols; D011994:Recombinant Proteins; D012254:Ribavirin; D014758:Viral Core Proteins; D017361:Viral Nonstructural Proteins; C097010:NS2 protein, Hepatitis C virus; C069130:nucleocapsid protein, Hepatitis C virus; C087036:NS-5 protein, hepatitis C virus; D012324:RNA-Dependent RNA Polymerase; C100416:peginterferon alfa-2a