Identification of in vitro and in vivo oncolytic effect in colorectal cancer cells by Orf virus strain NA1/11

Orf virus (ORFV) is a favorable oncolytic viral carrier in research, and ORFV strain NZ2 has been revealed to have antitumor effects in animal models mediated by immunoregulation profile. However, the antitumor effects triggered by the ORFV in colorectal cancer (CRC) cells is poorly characterized. The in vivo and in vitro roles of ORFV in CRC were determined using western blotting, colony formation, CCK-8, wound scratch assay, qPCR, and animal models. Furthermore, cytokine antibody chip assay, flow cytometry, western blotting, and immunohistochemical (IHC) assays were conducted to explore the potential mechanism of ORFV. The present data revealed that ORFV strain NA1/11 infected and inhibited the in vitro growth and migration of CRC cells. By establishing a CRC model in Balb/c mice, it was revealed that ORFV strain NA1/11 significantly inhibited the in vivo growth and migration of CRC cells. A cytokine antibody array was utilized to obtain a more comprehensive profile revealing the differentially expressed cytokines in ORFV infection. Cytokines, such as IL-7, IL-13, IL-15, CD27, CD30, pentraxin 3, and B lymphocyte chemoattractant (BLC), were upregulated. Axl, CXCL16, ANG-3, MMP10, IFN-γ R1 and VEGF-B were downregulated. The results indicated that ORFV played roles in the regulation of key factors relevant to apoptosis, autoimmunity/inflammation, angiogenesis, and the cell cycle. Finally, data was presented to validate that ORFV infection induces oncolytic activity by enhancing apoptosis in vivo and in vitro. In conclusion, ORFV could be an oncolytic virus for CRC therapy.