Cross-species oncolytic virotherapy in vitro: BoHV4EGFPΔTK as a novel candidate against canine osteosarcoma and histiocytic sarcoma

Canine osteosarcoma (cOSA) and histiocytic sarcoma (cHS) are aggressive tumors characterized by poor prognoses and limited therapeutic options. Oncolytic viruses represent a promising treatment option for these tumors. Based on this hypothesis, this study aimed to evaluate direct and indirect oncolytic effects of Bovine Herpes virus type 1 (BoHV1) and a recombinant type 4 (BoHV4EGFPΔTK). Here we used cOSA, cHS and cutaneous fibroblast (FDOG) cell lines. BoHV1 and BoHV4EGFPΔTK can successfully infect cOSA and cHS cell lines with 1 multiplicity of infection (MOI). Notably, BoHV4EGFPΔTK displayed a less prominent ability to infect FDOG, whereas BoHV1 showed the highest percentage of infected cells in FDOG. Flow cytometry results showed that BoHV4EGFPΔTK, unlike BoHV1, induces a high percentage of dead and infected cells in all tumor cell lines. BoHV4EGFPΔTK infected FDOG showed over time a stable low percentage of dead and infected cells. Moreover, BoHV4EGFPΔTK infection of canine tumor cell lines triggered apoptosis and increased (Gasdermin-D) GSDM-D levels. Furthermore, both viruses exerted indirect oncolytic effects like influence on tumor cell motility. Efficacy varied by tumor cell line and time point. In conclusion, BoHV4EGFPΔTK compared to BoHV1, showed a prominent tropism for cancer cells and deserve future investigation to confirm its oncolytic potential.