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.