The effects of photodynamic therapy on Vero cells and replication of herpes simplex type 1: an in vitro analysis

Purpose The aim of this study was to perform in vitro assays using epithelial cell culture of monkey kidney (Vero cell line) and herpes simplex virus type 1 (HSV-1) to evaluate the effect of photodynamic therapy in this virus infection. Methods It was used a culture of epithelial cells infected (I) or not infected with HSV-1 (NI). The experimental groups were defined: control cell (G1), cell with methylene blue (G2), the control HSV-1 (G3), photodynamic therapy in the cell by the virus inoculated with laser irradiation 30 J/cm 2 (8 s) (G4) and irradiation 100 J/cm 2 , 70s (G5), cell inoculated by virus with laser irradiation 30 J/cm 2 (8 s) (G6), and cell inoculated by virus with laser irradiation 100 J/cm 2 (70s) (G7). The irradiation was carried out by a GaAlAs diode laser – 660 nm, and methylene blue concentration of 0.0001%. Cell viability was investigated by inverted optical microscope (Leitz). Titer was evaluated using the 50/Ml TCID (the dose that produces cytopathic effect (CPE) in 50% of cell culture) by the method of Reed and Muench. Results The methylene blue and photodynamic therapy were effective in viral inhibiting. The low power laser with energy densities of 30 J/cm 2 and 100 J/cm 2 showed no effect in inhibiting HSV-1. The results of cell viability were G4 > G5 = G6˃G7 > G2. Conclusion Photodynamic therapy proved to be effective in inhibiting HSV-1 virus. The low power laser with wavelength of 660 nm and energy density of 30 J/cm 2 showed better viral inhibition with higher viable cells.