Herpes simplex virus type 1 thymidine kinase-armed bovine herpesvirus type 4-based vector displays enhanced oncolytic properties in immunocompetent orthotopic syngenic mouse and rat glioma models

Gliomas are devastating tumors of the brain resistant to therapies. Although some therapies can prolong the survival time among the affected persons, gliomas are not curable and new therapeutic approaches need to be investigated. Oncolytic viruses seem to represent an interesting alternative, because anticancer agents and new viral agents have to be explored to identify the one with the best characteristics. Bovine herpesvirus type 4 (BoHV-4) is a gammaherpesvirus with a striking tropism and permissive replication toward cancer cells and rat, mouse, and human glioma cells. However, BoHV-4 does not replicate into the normal brain parenchyma. The BoHV-4 genome was cloned as a bacterial artificial chromosome to easily manipulate this large genome and be used as a viral vector platform. In the present study, a herpes simplex virus type 1 thymidine kinasc suicide gene armed BoHV-4 was constructed, characterized, and proven to be highly efficient in killing by apoptosis glioma cells in vitro when co-administered with the pro-drug ganciclovir (GCV). When the armed BoHV-4/GCV therapeutic approach was tested in immunocompetent orthotopic syngenic mouse and rat glioma models in vivo, a significant increase in survival among the treated animals was achieved, and some animals were completely cured. The BoHV-4 based vector represents a promising alternative oncolytic virus for glioma and, perhaps, other types of cancer treatment that merit further investigation. This article represents the result of a mutual interaction between human medical science and veterinary science, a combination of scientific knowledge often neglected.