Interferon epsilon protects primary macrophages against HIV infection

Abstract

Abstract Interferon epsilon (IFNe) is a unique type I IFN that is not induced by pattern-recognition response elements. IFNɛ is constitutively expressed in mucosal tissues including the female genital mucosa. Although the direct anti-viral activity of IFNe was thought to be weak compared to IFNa, IFNe controls Chlamydia muridarum and herpes simplex virus 2 in mice, possibly through modulation of immune response. We show here that IFNe induces an antiviral state in human macrophages that blocks HIV-1 replication. IFNe had little or no protective effect in activated CD4+ T cells or transformed cell lines unless activated CD4+ T cells were infected with replication competent HIV-1 at a low MOI. The block to HIV infection of macrophages was maximal after 24 h of treatment and was reversible. IFNe acted on early stages of the HIV life cycle including viral entry, reverse transcription and nuclear import. The protection did not appear to operate through known type I IFN-induced HIV host restriction factors such as APOBEC3A and SAMHD1. IFNe-stimulated immune mediators and pathways had the signature of type I IFNs but were distinct from IFNα2. IFNe induced significant phagocytosis and reactive oxygen species, which contributed to the block to HIV replication in macrophages. These findings indicate that IFNe induces an antiviral state in macrophages that is mediated by different factors than those induced by IFNa2. Understanding the mechanism of IFNe-mediated HIV inhibition through immune modulation has implications for prevention.