Respiratory Enteric Orphan virus (reovirus) is widely prevalent in the human population but not associated with any known human disease. Reovirus has been isolated from the respiratory and gastrointestinal tracts and is described as an "orphan" virus because the infection is asymptomatic. The family Reoviridae is composed of nonenveloped, double-stranded (ds) RNA viruses with 9 to 12 genome segments, an icosahedral capsid, and range in size from 60 to 80 nm in diameter. Reovirus is 80 nm in diameter and has a 24 kb RNA genome. Unlike viruses with a dsDNA genome, like adenoviruses and herpes simplex viruses, the decreased genomic stability provided by an RNA backbone makes genetic engineering more difficult and more prone to hazardous mutation. In DNA viruses, genetic manipulation provides a method to suppress pathogenicity and increase oncolytic potency and tumor-targeting specificity. However, even without engineered capabilities, reovirus is pathologically benign and tumor cytotoxic, making it an appealing oncolytic virus (OV) for therapeutic development.
It has been more than 30 years since wild-type reovirus was demonstrated to replicate preferentially in transformed cell lines but not in normal cells. The means by which reovirus oncolysis occurred remained elusive until rodent cell lines transformed with genes encoding the epidermal growth factor receptor (EGFR) and a truncated form of the EGFR, possessing constitutive tyrosine kinase activity but lacking the extracellular ligand-binding domain, demonstrated increased susceptibility to reovirus infection and thereby proposing that EGFR-mediated pathways facilitated reovirus infection. In fact, transfection with constitutively activated Ras oncogenes or son of sevenless in NIH-3T3 fibroblasts led to increased vulnerability to reovirus infection and expounded the involvement of activated Ras signaling pathways in reovirus oncolysis.
Figure 1. The effect of the Ras signaling pathway on reovirus infection.
Although our understanding of the host and viral determinants which underlie reovirus replication and killing of transformed cells is progress, many gaps in knowledge remain. Reovirus engineering with improved targeting and cytotoxicity in transformed cells and tissues is in its infancy. Recombinant reoviruses that impair cancer cell growth while also enhancing antitumor immune responses are probably to have enhanced oncolytic effects in vivo. Besides, determining how reovirus navigates the altered environment of cancer cells is important for refining existing reovirus therapeutic regimens and development of new reovirus-based oncolytic.
For years of experience in immunology and oncology, Creative Biogene has established a comprehensive QVirus™ platform for providing oncolytic virus development service. By QVirus™ platform, we are able to design, engineering and generate the most efficacious oncolytic reovirus vector and reovirus particles.
➢ Construction of recombinant reoviruses
➢ Recombinant reoviruses amplification
➢ Recombinant reoviruses concentration and titration
➢ Northern and Western blot analysis
➢ Cell killing assay to examine viral oncolytic activity
➢ Data analysis
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