An altered cellular response to interferon and up-regulation of interleukin-8 induced by the hepatitis C viral protein NS5A uncovered by microarray analysis.
There is evidence for an inhibition of interferon-alpha antiviral activity by the hepatitis C viral protein, NS5A. To identify the mechanisms through which NS5A blocks interferon activity, we compared the gene expression profile of interferon-treated Huh7 cells, stably expressing NS5A with control, using microarrays. Following interferon treatment, 50 genes were up-regulated by at least twofold in control clones, whereas induction of 9 of the 50 genes was significantly reduced in NS5A-expressing clones. The strongest effect of NS5A on interferon response was observed for the OAS-p69 gene. Remarkably, Huh7 cells expressing NS5A showed an up-regulation of interleukin-8. Up-regulation of interleukin-8 was also observed upon transient expression of NS5A mutants isolated from patients responsive or resistant to interferon therapy. Addition of interleukin-8 to Huh7 cells inhibited the antiviral activity of interferon and, similarly to NS5A, reduced the induction by interferon-alpha of selective genes including OAS-p69. Our findings provide a mechanism for NS5A-mediated interferon resistance.
Girard
Sophie
S
Department of Microbiology and Immunology, University of Michigan, Ann Arbor 48109-0666, USA.
Shalhoub
Philip
P
Lescure
Pascal
P
Sabile
Abdelmajid
A
Misek
David E
DE
Hanash
Samir
S
Bréchot
Christian
C
Beretta
Laura
L
D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D016174:Hepacivirus / Q000235:genetics / Q000378:metabolism*; D022781:Hepatocytes / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology*; D016209:Interleukin-8 / Q000235:genetics / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014407:Tumor Cells, Cultured; D015854:Up-Regulation; D017361:Viral Nonstructural Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D012324:RNA-Dependent RNA Polymerase
D007371:Interferon-gamma; D016209:Interleukin-8; D012333:RNA, Messenger; D017361:Viral Nonstructural Proteins; C087036:NS-5 protein, hepatitis C virus; D012324:RNA-Dependent RNA Polymerase