INHIBITION OF HUMAN-IMMUNODEFICIENCY-VIRUS REPLICATION BY THE HERPES-SIMPLEX VIRUS VIRION HOST SHUTOFF PROTEIN

The herpes simplex virus (HSV) virion host shutoff gene (vhs) encodes a protein which nonspecifically accelerates the degradation of mRNA mo lecules, leading tea inhibition of protein synthesis. This ability to inhibit a critical cellular function suggested that vhs could be used as a suicide gene in certain gene therapy applications. To investigate whether vhs might be useful for treatment of AIDS, we tested the abil ity of both HSV type 1 (HSV-1) and HSV-2 vhs to inhibit replication of human immunodeficiency virus (HIV). Replication of HIV was substantia lly inhibited when an infectious HIV proviral clone was cotransfected into HeLa cells together with vhs under the control of the cytomegalov irus (CMV) immediate-early promoter. HSV-2 vhs was more active than HS V-1 vhs in these experiments, consistent with previously published stu dies on these genes. Since expression of vhs from the CMV promoter is essentially unregulated, we also tested the ability of vhs expressed f rom the HN long terminal repeat (LTR) promoter to inhibit HIV replicat ion. Wild-type HSV-1 vhs inhibited HIV replication more than 44,000-fo ld in comparison to a mutant vhs gene encoding a nonfunctional form of the Vhs protein. Production of Vhs in transfected cells was verified by Western blot assays, A larger amount of Vhs was observed in cells t ransfected,vith plasmids expressing vhs from the HIV LTR than from the CMV promoter, consistent with the greater inhibition of HIV replicati on observed with these constructs, Mutant forms of Vhs were expressed at higher levels than wild-type Vhs, most likely due to the ability of wild-type Vhs to degrade its own mRNA. The strong inhibitory activity of the vhs gene and its unique biological properties make vhs an inte resting candidate for use as a suicide gene for HIV gene therapy.