Use of the herpes amplicon system as a vehicle for somatic gene transfer

Oncolytic Herpes Simplex Viral Therapy: A Stride toward Selective Targeting of Cancer Cells

Oncolytic viral therapy, which makes use of replication-competent lytic viruses, has emerged as a promising modality to treat malignancies. It has shown meaningful outcomes in both solid tumor and hematologic malignancies. Advancements during the last decade, mainly genetic engineering of oncolytic viruses have resulted in improved specificity and efficacy of oncolytic viruses in cancer therapeutics. Oncolytic viral therapy for treating cancer with herpes simplex virus-1 has been of particular interest owing to its range of benefits like: (a) large genome and power to infiltrate in the tumor, (b) easy access to manipulation with the flexibility to insert multiple transgenes, (c) infecting majority of the malignant cell types with quick replication in the infected cells and (d) as Anti-HSV agent to terminate HSV replication. This review provides an exhaustive list of oncolytic herpes simplex virus-1 along with their genetic alterations. It also encompasses the major developments in oncolytic herpes simplex-1 viral therapy and outlines the limitations and drawbacks of oncolytic herpes simplex viral therapy.

Herpes simplex virus 1 (HSV-1) for cancer treatment

Cancer remains a serious threat to human health, causing over 500 000 deaths each year in US alone, exceeded only by heart diseases. Many new technologies are being developed to fight cancer, among which are gene therapies and oncolytic virotherapies. Herpes simplex virus type 1 (HSV-1) is a neurotropic DNA virus with many favorable properties both as a delivery vector for cancer therapeutic genes and as a backbone for oncolytic viruses. Herpes simplex virus type 1 is highly infectious, so HSV-1 vectors are efficient vehicles for the delivery of exogenous genetic materials to cells. The inherent cytotoxicity of this virus, if harnessed and made to be selective by genetic manipulations, makes this virus a good candidate for developing viral oncolytic approach. Furthermore, its large genome size, ability to infect cells with a high degree of efficiency, and the presence of an inherent replication controlling mechanism, the thymidine kinase gene, add to its potential capabilities. This review briefly summarizes the biology of HSV-1, examines various strategies that have been used to genetically modify the virus, and discusses preclinical as well as clinical results of the HSV-1-derived vectors in cancer treatment.

Viral-based gene transfer to the mammalian CNS for functional genomic studies

A fundamental problem in neuroscience has been the creation of suitable in vivo model systems to study basic neurological phenomena and pathology of the central nervous system (CNS). Somatic cell genetic engineering with viral vectors provides a versatile tool to model normal brain physiology and a variety of neurological diseases.

Tumor growth inhibition by intratumoral inoculation of defective herpes simplex virus vectors expressing granulocyte-macrophage colony-stimulating factor

To evaluate the potential of defective herpes simplex virus (HSV) amplicon vectors as in vivo cytokine gene transfer vehicles for active immunotherapy, we generated a defective HSV vector that encodes the murine granulocyte-macrophage colony-stimulating factor (GM-CSF) gene, using a replication-defective HSV as helper virus. A variety of murine tumor cell lines were efficiently infected in vitro with the defective GM-CSF vector (dvGM), and this led to the synthesis and secretion of murine GM-CSF. In an established bilateral subcutaneous tumor model with Harding-Passey murine melanoma, unilateral intratumoral inoculation of dvGM significantly inhibited tumor growth of both the inoculated and noninoculated contralateral tumors. This tumor inhibition was dose-dependent and resulted in increased survival of the dvGM-treated mice. Inoculation of a lacZ-expressing defective vector had no effect on tumor growth. We conclude that this defective HSV vector system offers an effective method for cytokine gene delivery in vivo and that GM-CSF expression in tumors has antitumor activity.