HERPESVIRUS VECTOR-MEDIATED GENE DELIVERY TO HUMAN MONOCYTES

In vitro delivery of interferon-alpha (IFN-alpha) to cultured human mo nocytes by means of a replication-incompetent herpesvirus vector inhib its human immunodeficiency virus (HIV) replication. To explore the pos sibility of IFN-alpha gene delivery by vector-infected human monocytes , monocytes were isolated and the culture conditions necessary for eff icient vector infection and gene expression were examined. Monocytes w ere efficiently infected between 1 and 7 days after isolation. Express ion of IFN-alpha was greater in cells infected 7 days after isolation compared to 1 day after isolation, but the levels of expression were e quivalent regardless of whether cells were maintained in suspension or monolayer culture. When suspension-cultured monocytes were treated wi th vd120/IFN-alpha and added to monolayer cultures of HIV-infected mon ocytes, IFN-alpha was expressed and replication of HIV was inhibited. HIV replication was arrested even when HIV had spread through much of the monolayer. The persistence of the viral vector in infected cells w as examined by a superinfection rescue assay using a second replicatio n-incompetent herpes simplex virus, 5d/1.2. The initial replication-in competent vector remained in a recoverable form for at least 7 days af ter delivery, even though foreign gene expression was transient.