Lambda interferon inhibits hepatitis B and C virus replication

Abstract

Lambda interferon (IFN-lambda) induces an intracellular IFN-alpha/beta-like antiviral response through a receptor complex distinct from the IFN-alpha/beta receptor. We therefore determined the ability of IFN-lambda to inhibit hepatitis B virus (HBV) and hepatitis C virus (HCV) replication. IFN-lambda inhibits HBV replication in a differentiated murine hepatocyte cell line with kinetics and efficiency similar to IFN-alpha/beta and does not require the expression of IFN-alpha/beta or IFN-gamma. Furthermore, IFN-lambda blocked the replication of a subgenomic and a full-length genomic HCV replicon in human hepatocyte Huh7 cells. These results suggest the possibility that IFN-lambda may be therapeutically useful in the treatment of chronic HBV or HCV infection.

FIG. 1.

IFN-λ inhibits HBV replication and induces expression of IFN-stimulated genes. (A) Differentiated HBV-Met cells were untreated (−; lanes 1, 5, and 9) or treated with 200 U of murine IFN-β (β; lanes 2, 6, and 10) per ml, 1 ng of murine IFN-λ2 (λ₁; lanes 3, 7, and 11) per ml, or 10 ng of murine IFN-λ2 (λ₁₀; lanes 4, 8, and 12) per ml and harvested at the indicated time points. HBV replication was monitored by Southern blot (SB) analysis of the HBV relaxed circle (RC) and single-stranded (SS) DNA replication forms. Tg, integrated transgene. (B) Quantitative RT-PCR analysis of two representative IFN-induced genes, Isg15 and Ifit3. Data are expressed as increases in induction (n-fold) relative to untreated cells and are normalized to GAPDH (glyceraldehyde-3-phosphate dehydrogenase) expression levels.

FIG. 2.

Inhibition of HBV replication by IFN-λ does not require IFN-α/β or IFN-γ. (A) Differentiated HBV-Met cells were untreated (lanes 1 to 4) or treated with 100 ng of murine IFN-λ2 (lanes 5 to 8) per ml in the presence of 1,000 neutralization units of antibody to murine IFN-α (α; lanes 2 and 6), IFN-β (β; lanes 3 and 7), or IFN-γ (γ; lanes 4 and 8) per ml and harvested 24 h later. HBV replication was monitored by Southern blot (SB) analysis of the HBV relaxed circle (RC) and single-stranded (SS) DNA replication forms. Tg, integrated transgene; neut Ab, neutralizing antibody. (B) Quantitative RT-PCR analysis of changes in IFN-γ, IFN-α2, and IFN-β expression levels induced by IFN-β (500 U/ml), IFN-λ (10 and 100 ng/ml), or transfection with an irrelevant double-stranded RNA (dsRNA). Data are expressed as the change in induction (n-fold) relative to untreated cells and are normalized to GAPDH (glyceraldehyde-3-phosphate dehydrogenase) expression levels.

FIG. 3.

IFN-λ inhibits HCV replication. (A) Huh7 cells containing HCV subgenomic (lanes 1 to 12) or full-length genomic (lanes 13 to 24) replicons were untreated (−; lanes 1, 5, 9, 13, 17, and 21) or treated with 500 U of human IFN-α(A/D) (α; lanes 2, 6, 10, 14, 18, and 22) per ml, 100 ng of human IFN-λ1 (λ1; lanes 3, 7, 11, 15, 19, and 23) per ml, or 100 ng of human IFN-λ2 (λ2; lanes 4, 8, 12, 16, 20, and 24) per ml. Cells were harvested 1, 3, or 5 days after IFN treatment, and Northern blot (NB) analysis (on 5 μg of total RNA from subgenomic and 8 μg of total RNA from genomic HCV replicons) was performed for HCV plus-strand RNA and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) levels. (B) Quantitative RT-PCR analysis of HCV plus-strand RNA from the same experiment. Data are expressed as HCV RNA levels relative to untreated controls and are normalized to GAPDH levels. (C) Quantitative RT-PCR analysis of MxA expression. Data are expressed as the increase in induction (n-fold) relative to untreated controls and are normalized to GAPDH levels.