HIV infection of dendritic cells subverts the IFN induction pathway via IRF-1 and inhibits type 1 IFN production

Many viruses have developed mechanisms to evade the IFN response. Here, HIV-1 was shown to induce a distinct subset of IFN-stimulated genes (ISGs) in monocyte-derived dendritic cells (DCs), without detectable type I or II IFN. These ISGs all contained an IFN regulatory factor 1 (IRF-1) binding site in their promoters, and their expression was shown to be driven by IRF-1, indicating this subset was induced directly by viral infection by IRF-1. IRF-1 and -7 protein expression was enriched in HIV p24 antigen-positive DCs. A HIV deletion mutant with the IRF-1 binding site deleted from the long terminal repeat showed reduced growth kinetics. Early and persistent induction of IRF-1 was coupled with sequential transient up-regulation of its 2 inhibitors, IRF-8, followed by IRF-2, suggesting a mechanism for IFN inhibition. HIV-1 mutants with Vpr deleted induced IFN, showing that Vpr is inhibitory. However, HIV IFN inhibition was mediated by failure of IRF-3 activation rather than by its degradation, as in T cells. In contrast, herpes simplex virus type 2 markedly induced IFNβ and a broader range of ISGs to higher levels, supporting the hypothesis that HIV-1 specifically manipulates the induction of IFN and ISGs to enhance its noncytopathic replication in DCs.

Modulation of epithelial biology by rhinovirus infection: role in inflammatory airway diseases

The human airway epithelial cell is the primary site of human rhinovirus (HRV) infection in both the upper and lower airways, but HRV infection does not cause overt epithelial cytotoxicity at either location. Therefore, it is thought that HRV infections induce symptoms of the common cold or exacerbate lower airway diseases, such as asthma and chronic obstructive pulmonary disease, by altering epithelial cell biology. This premise has led to intense investigation of the interactions of HRV with epithelial cells. This article reviews current knowledge regarding how HRV induces epithelial induction of proinflammatory cytokines and chemokines. In addition, the contributions of epithelial cells to host antiviral responses will be reviewed along with evidence that HRV-infected epithelial cells may contribute to the airway remodeling that is a characteristic feature of asthma.