Incomplete but infectious vaccinia virions are produced in the absence of oncolysis in feline SCCF1 cells

How Viruses Hijack and Modify the Secretory Transport Pathway

Eukaryotic cells contain dynamic membrane-bound organelles that are constantly remodeled in response to physiological and environmental cues. Key organelles are the endoplasmic reticulum, the Golgi apparatus and the plasma membrane, which are interconnected by vesicular traffic through the secretory transport route. Numerous viruses, especially enveloped viruses, use and modify compartments of the secretory pathway to promote their replication, assembly and cell egression by hijacking the host cell machinery. In some cases, the subversion mechanism has been uncovered. In this review, we summarize our current understanding of how the secretory pathway is subverted and exploited by viruses belonging to Picornaviridae, Coronaviridae, Flaviviridae,Poxviridae, Parvoviridae and Herpesviridae families.

Myxoma virus therapy for human embryonal rhabdomyosarcoma in a nude mouse model

Rhabdomyosarcoma (RMS) is a devastating tumor of young people that is difficult to cure. To determine if oncolytic virus therapy can improve outcomes in individuals with RMS, myxoma virus expressing a red fluorescent protein (MYXV-red) was evaluated for antitumoral effects using a murine model of RMS. Fluorescent protein was expressed in four RMS cell lines inoculated with MYXV-red, indicating that these cells were semipermissive to MYXV infection. MYXV-red replication and cytopathic effects were further evaluated using human embryonal RMS (CCL-136) cells. Logarithmic growth of MYXV-red and significant cell death were observed 72 hours after inoculation with MYXV. The oncolytic effects of MYXV-red were then studied in nude mice that were injected subcutaneously with CCL-136 cells to establish RMS xenografts. Once tumors measured 5 mm in diameter, mice were treated with multiple intratumoral injections of MXYV-red or saline. The average final tumor volume and rate of tumor growth were significantly decreased, and median survival time was significantly increased in MYXV-red-treated mice (P-values =0.0416, 0.0037, and 0.0004, respectively). Histologic sections of MYXV-red-treated tumors showed increased inflammation compared to saline-treated tumors (P-value =0.0002). In conclusion, MXYV-red treatment of RMS tumors was successful in individual mice as it resulted in decreased tumor burden in eight of eleven mice with nearly complete tumor remission in five of eleven mice. These data hold promise that MYXV-red treatment may be beneficial for people suffering from RMS. To our knowledge, this is the first report of successful treatment of RMS tumors using an oncolytic poxvirus.