Suppressor of Cytokine Signaling (SOCS) 1 & 3 Expression in HSV-1- Infected and Interferon-γ-treated Neuro-2A Cells

This study examined the effects of HSV-1 infection and IFN-γ treatment on Neuro-2A cells. HSV-1 induces expression of SOCS1 and SOCS3 in infected cells, inhibiting the ability of these cells to produce the pro inflammatory, antiviral cytokine IFN-γ (Nowoslawski and Benveniste, 2011). SOCS1 and SOCS3 levels were determined in IFN-γ-treated cells, virus-infected cells, and cells that were both IFN-γ-treated and virus-infected. Results were compared with untreated, uninfected control cells. Flow cytometry data analysis showed a slight decrease in SOCS1 and SOCS3 protein levels in cells treated with IFN-γ for 6 hours compared to control cells. A significant decrease in SOCS1 and SOCS 3 levels was found in cells treated with IFN-γ for 18 hours. Up regulation of SOCS1 and SOCS3 expression was established in virus-infected Neuro-2A cells but this increase was not statistically significant when compared to control cells. However, culturing cells with IFN-γ for 6 hours prior to virus infection led to a significant (50%) decrease in SOCS1 and SOCS3expression compared to cells treated with IFN-γ alone. This showed that HSV-1 was not able to overcome the antiviral effects of IFN-γ to up regulate SOCS1 and SOCS3 expression. Cytopathic effects assays were performed to determine cell viability among cells treated with IFN-γ for 18 hours, cells infected with virus for 48 hours, and cells treated with IFN-γ for 18 hours followed by 48 hour HSV-1 infection. Pre-treating cells with IFN-γ for 18 hours prior to infection with HSV-1 (0.1 MOI) yielded a cell viability level similar to that of control cells (untreated/uninfected). This indicates that IFN-γ is providing antiviral protection to most, if not all of the cells. Applying these studies in a human cell line and eventually in an animal model would be necessary to find the efficacy of IFN-γ as a HSV-1 therapeutic.