Veterinary Students in Research

Viral-mediated oncolysis of cancer cells isolated from canine tumors

Kirsha B Fredrickson and Amy L MacNeill

Department of Microbiology, Immunology and Pathology, Colorado State University

The three classic arms of cancer therapy are surgical resection, chemotherapeutics, and radiation. As these fields have progressed we have greatly improved cancer survival rates in both companion animals and humans. However, with the complexities of neoplastic disease and their ability to further mutate due to genomic instability, these classic approaches are not always successful and often have undesirable adverse effects. Oncolytic virotherapy has the potential to be highly effective with minimal adverse effects due to targeted lysis of neoplastic cells. Studies were performed to evaluate the oncolytic effects of recombinant myxoma virus (MYXV) on canine osteosarcoma and soft tissue sarcoma primary cell cultures. The tumor samples were obtained following surgical excision. Once cultured, cells were evaluated for vimentin using

immunocytochemistry and for alkaline phosphatase activity using nitroblue tetrazolium chloride/5-bromo- 4-chloro- 3- indolyl phosphate toluidine solution. The cancer cell-lines were then inoculated with recombinant myxoma virus expressing a red fluorescent protein and collected after 48-hours. Cytopathic effects were assessed at 24-hour and 48- hour time points via fluorescent microscopy. Ability of the virus to replicate within the cancer cells was confirmed via Western immunoblot detection of late MYXV protein production. The findings of this study suggest that canine osteosarcoma and soft tissue sarcoma primary cell cultures are lacking antiviral mechanisms and susceptible to MYXV infection leading to oncolysis. Viral-mediated oncolysis of cancer cells isolated from canine tumorsKirsha B Fredrickson and Amy L MacNeillDepartment of Microbiology, Immunology and Pathology, Colorado State UniversityThe three classic arms of cancer therapy are surgical resection, chemotherapeutics, andradiation. As these fields have progressed we have greatly improved cancer survival ratesin both companion animals and humans. However, with the complexities of neoplasticdisease and their ability to further mutate due to genomic instability, these classicapproaches are not always successful and often have undesirable adverse effects.Oncolytic virotherapy has the potential to be highly effective with minimal adverseeffects due to targeted lysis of neoplastic cells. Studies were performed to evaluate theoncolytic effects of recombinant myxoma virus (MYXV) on canine osteosarcoma and soft tissue sarcoma primary cell cultures. The tumor samples were obtained followingsurgical excision. Once cultured, cells were evaluated for vimentin usingimmunocytochemistry and for alkaline phosphatase activity using nitroblue tetrazoliumchloride/5-bromo- 4-chloro- 3- indolyl phosphate toluidine solution. The cancer cell-lineswere then inoculated with recombinant myxoma virus expressing a red fluorescentprotein and collected after 48-hours. Cytopathic effects were assessed at 24-hour and 48-hour time points via fluorescent microscopy. Ability of the virus to replicate within thecancer cells was confirmed via Western immunoblot detection of late MYXV proteinproduction. The findings of this study suggest that canine osteosarcoma and soft tissuesarcoma primary cell cultures are lacking antiviral mechanisms and susceptible toMYXV infection leading to oncolysis.