West Nile virus infection induces interferon signalling in human retinal pigment epithelial cells.

PURPOSE: In addition to neuroinvasive disease, West Nile virus (WNV) infection is frequently associated with self-limiting chorioretinitis and vitritis. However, the mechanisms of ophthalmic WNV infection are rarely investigated, in part because of the lack of reliable in vitro models. The authors therefore established the first model of ocular WNV infection and investigated interaction of WNV with IFN signal-transduction mechanisms. METHODS: Human retinal pigment epithelial (RPE) cells were infected with WNV strain NY385-99 at a multiplicity of infection of 5. Virus replication was evaluated by virus titers at different times after infection. The susceptibility of RPE cells to WNV infection was confirmed by transmission electron microscopy. IFN-beta expression was assessed by quantitative real-time PCR and by measurements of antiviral activity in cell culture supernatants. IFN signaling was evaluated by phosphorylation of transducer and activator of transcription 1 and 2 (STAT1/2) proteins, with immunoblot analysis. RESULTS: RPE cells appeared to be highly sensitive to WNV infection. Maximum viral titers were found 24 hours after infection, followed by a continuous decline during the course of infection. WNV infection of RPE cells was followed by increased IFN-beta expression associated with IFN signaling and subsequent inhibition of WNV replication. CONCLUSIONS: In this study, the first cell culture model of ophthalmic WNV infection was developed and characterized in RPE cells, and the molecular mechanisms of WNV infection were studied. The data suggest that WNV induces a general antiviral state in RPE cells. This general antiviral state correlates with WNV-induced IFN signaling in retinal cells.

Potent oncolytic activity of multimutated herpes simplex virus G207 in combination with vincristine against human rhabdomyosarcoma.

Replication restricted oncolytic viruses such as multimutated herpes simplex virus type 1 (HSV-1) G207 represent a novel and attractive approach for cancer therapy, including pediatric solid tumors. Rhabdomyosarcoma is the most common soft-tissue sarcoma of childhood and is often diagnosed already as an advanced disseminated disease. Despite aggressive therapeutic approaches, the prognosis for patients with metastatic rhabdomyosarcoma remains grim. Therefore, there is a need for novel effective drugs with superior safety and efficacy profile. In this study, we showed marked in vitro activity of HSV-1 G207 against embryonal and alveolar rhabdomyosarcoma cells. All human embryonal (KF-RMS-1, RD, and CCA) and alveolar RMS (KFR, Rh28, Rh30, and Rh41) cell lines were highly sensitive to cytotoxic and replicative effects of G207 even at a multiplicity of infection of 0.01, except embryonal Rh1 rhabdomyosarcoma cells, which were efficiently killed only upon multiplicity of infection of 1.0. i.v. G207 treatment of xenotransplanted KFR and KF-RMS-1 tumors in mice led to significant tumor growth inhibition of both tumor entities, whereas intraneoplastic G207 treatment additionally resulted in complete tumor disappearance in 25% of animals. No difference has been found between alveolar and embryonal types of rhabdomyosarcoma. Combination treatment of both cell lines with G207 and vincristine led to strongly enhanced in vitro cytotoxicity without affecting infection efficiency and replication of G207 in KFR as well as in KF-RMS-1 cells. In vivo combination treatment using i.v. G207 and vincristine resulted in complete regression of alveolar rhabdomyosarcoma in five of eight animals and significant growth inhibition of embryonal rhabdomyosarcoma. Taking into consideration the proven safety of G207 in humans, we suggest that G207 alone and in combination with vincristine should be additionally evaluated as a potential agent against human rhabdomyosarcoma.