Regulation of interferon-alpha-inducible cellular genes in human immunodeficiency virus-infected monocytes

Cellular mechanisms that control susceptibility to opportunistic infection in human immunodeficiency virus (HIV)-infected individuals remain poorly understood. HIV may induce certain cellular genes that restrict HIV replication and protect cells against other superinfecting viral pathogens. Indeed, HIV-infected monocytes resist infection by vesicular stomatitis virus (VSV). HIV-induced VSV interference in monocytes increases with time after HIV infection. Such interference was evident 6 h after HIV infection and reached maximal levels at 14 days. Monocytotropic but not T cell-tropic HIV strains elicited these effects, signaling a requirement for viral entry and/or replication. Viral interference was independent of interferon (IFN) and was unaffected by addition of neutralizing IFN-alpha and -beta antibodies. The well-described IFN-alpha-inducible antiviral pathways were examined to determine their relationship to the cellular mechanism(s) underlying VSV interference. HIV and IFN-alpha both induced the expression of 2-5A synthetase and Mx gene. In contrast, the guanylate-binding protein (GBP), 6-16, and 9-27 cellular genes were up-regulated by IFN-alpha but not HIV. MxA was detected in HIV-infected monocytes but not in uninfected monocytes. The association between Mx expression and resistance to VSV, coupled with previously described anti-VSV activities by human MxA, suggested that Mx may be an effector molecule for the HIV-induced anti-VSV activities. These results, taken together, suggest that HIV can induce antiviral cellular gene expression, independent of IFN.