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Gastroenterology. 2000 Dec;119(6):1649-55.

Two PKR inhibitor HCV proteins correlate with early but not sustained response to interferon.

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Department of Clinical and Experimental Medicine, University of Padua, Padua, Italy.



The NS5A and the E2 proteins of hepatitis C virus (HCV)-1b can bind and inhibit in vitro the interferon (IFN)-induced cellular kinase PKR. The role of such interaction in modulating the antiviral effect of IFN is still controversial. We have analyzed the E2 and the NS5A sequences in HCV-1b-infected patients treated with IFN to assess whether and how different combinations of wild-type and mutant proteins correlated with early and long-term virological response.


In 30 patients, sequences of pretreatment and on-treatment E2-PePHD and NS5A-PKR binding domain (including the putative ISDR) were analyzed in parallel by sequencing cDNA-polymerase chain reaction products and up to 25 independent clones.


The E2-PePHD sequence was highly conserved with a homogeneous quasispecies and was identical in 29 of 30 cases with no association with the pattern of response and no evidence of evolution during therapy. Patients with a mutated NS5A-ISDR had a higher rate of early virological response (67%) than cases with wild-type ISDR (17%). This association was lost in long-term responders (33% vs. 17%).


Although the highly conserved E2-PePHD motif might contribute to reduce IFN responsiveness, variations within this region do not seem to play a role in modulating IFN sensitivity. The NS5A-ISDR sequence influenced the early, but not the sustained response, to IFN, suggesting that other factors may be more important for the long-term outcome of therapy.

[Indexed for MEDLINE]

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