In vitro effect of phototherapy with low-intensity laser on HSV-1 and epithelial cells

The effects of phototherapy on herpes lesions have been clinically demonstrated by either preventing the lesion formation or speeding their repair. The aim of this in vitro study was analyze the effect of phototherapy on epithelial cells and HSV-1 in culture. Cultures of HSV-1 and epithelial cells (Vero cell line) were used. The irradiations were done using a GaAlAs laser (660 e 780 nm, 4.0 mm2). One, two and three irradiations with 6 h-intervals were done. The experimental groups were: Control: non-irradiated; 660 nm and 3 J/cm2 (2.8 sec); 660 nm and 5 J/cm2 (3.8 sec); 780 nm and 3 J/cm2 (1.9 sec), and 780 nm and 5 J/cm2 (2.5 sec). The HSV-1 cytopatic effect and the cell viability of irradiated cultures and controls were analyzed in four different conditions: irradiation of non-infected epithelial cells; epithelial cells irradiated prior infection; virus irradiated prior infection; irradiation of HSV infected cells. The mitochondrial activity and cytopathic effects were assessed. The number of irradiations influenced the cell growth positively and proportionally, except for the 660 nm/ 3 J/cm2 group. Any variation in cytopathic effects was observed amongst the experimental groups. The viability of infected cells prior irradiation was significantly higher than that of non-irradiated cultures when 2 irradiations were done. Under the experimental conditions of this study we concluded that phototherapy is capable of enhancing epithelial cell growth and prolonging cell viability of HSV-1 infected cells. Positive benefits of phototherapy could be resultant from prolongation of infected cells viability, corroborating with host defenses.