The effects of oncolytic reovirus in canine lymphoma cell lines.

Reovirus is a potent oncolytic virus in many human neoplasms that has reached phase II and III clinical trials. Our laboratory has previously reported the oncolytic effects of reovirus in canine mast cell tumour (MCT). In order to further explore the potential of reovirus in veterinary oncology, we tested the susceptibility of reovirus in 10 canine lymphoma cell lines. Reovirus-induced cell death, virus replication and infectivity were confirmed in four cell lines with variable levels of susceptibility. The level of Ras activation varied among the cell lines with no correlation with reovirus susceptibility. Reovirus-susceptible cell lines underwent apoptosis as proven by propidium iodide (PI) staining, Annexin V-FITC/PI assay, cleavage of PARP and inhibition of cell death by caspase inhibitor. A single intratumoral injection of reovirus suppressed the growth of canine lymphoma subcutaneous tumour in NOD/SCID mice. Unlike canine MCT, canine lymphoma is less susceptible to reovirus.