Antiviral activity of the Indian medicinal plant extract Swertia chirata against herpes simplex viruses: a study by in-vitro and molecular approach.

PURPOSE: The antiviral activity of Indian Medicinal plant extract Swertia chirata was tested against Herpes simplex virus (HSV) type-1, using multiple approaches both at cellular and molecular level. METHODS: Cytotoxicity, plaque reduction, virus infectivity, antigen expression and polymerase chain reaction (PCR) assays were conducted to test the antiviral activity of the plant extract. RESULTS: Swertia plant crude extract (1 gm/mL) at 1:64 dilution inhibited HSV-1, plaque formation at more than 70% level. HSV antigen expression and time kinetics experiments conducted by indirect immunofluorescence (IFA) test, revealed a characteristic pattern of small foci of single fluorescent cells in Swertia extract treated HSV-1 infected cells at 4 hours post infection dose, suggested drug inhibited viral dissemination. Infected cell cultures treated with Swertia extract at various time intervals, tested by PCR, failed to show amplification at 12, 24-72 hours. HSV-1 infected cells treated with Acyclovir (antiviral drug) did not show any amplification by PCR. CONCLUSIONS: In this preliminary study, the Indian medicinal plant extract, Swertia chirata showed antiviral properties against Herpes simplex virus type-1.