Helper-Dependent Adenoviral Vector-Mediated Delivery of Woodchuck-Specific Genes for Alpha Interferon (IFN-α) and IFN-γ: IFN-α but Not IFN-γ Reduces Woodchuck Hepatitis Virus Replication in Chronic Infection In Vivo

摘要

Alpha interferon (IFN-α) and IFN-γ are able to suppress hepadnavirus replication. The intrahepatic expression of high levels of IFN may enhance the antiviral activity. We investigated the effects of woodchuck-specific IFN-α (wIFN-α) and IFN-γ(wIFN-γ) on woodchuck hepatitis virus (WHV) replication in vivo by helper-dependent adenoviral (HD-Ad) vector-mediated gene transfer. The expression of biologically active IFNs was demonstrated in vitro after transduction of woodchuck cells with HD-Ad vectors encoding wIFN-α (HD-AdwIFN-α) or wIFN-γ (HD-AdwIFN-γ). The transduction efficacy of the HD-Ad vector in woodchuck liver in vivo was tested with a vector expressing green fluorescence protein (GFP). Immunohistochemical staining of liver samples on day 5 after injection showed expression of GFP in a high percentage of liver cells surrounding the central vein. The transduction of livers of WHV carriers in vivo with HD-AdwIFN-α or HD-AdwIFN-γ induced levels of biologically active IFN, which could be measured in the sera of these animals. Expression of wIFN-α in the liver reduced intrahepatic WHV replication and WHV DNA in sera of about 1 log step in two of two woodchucks. Transduction with HD-AdwIFN-γ, however, reduced WHV replicative intermediates only slightly in two of three animals, which was not accompanied with significant changes in the WHV DNA in sera. We demonstrated for the first time the successful HD-Ad vector-mediated transfer of genes for IFN-α and IFN-γ in vivo and timely limited reduction of WHV replication by wIFN-α, but not by wIFN-γ.