Establishment of Simple Cell-based Screening Assay and the Identification of Potent Antiviral Activity of a Plant Extract against HSV-1

Abstract

Herpes simplex virus (HSV) is one of the viruses which cause medical problems in human. 9,10 There are two distinct serotypes of HSV, type 1 (HSV-1) and type 2 (HSV-2). The transmission of HSV-1 through contact with infected lesions or other parts of the body is much easier than HSV-2 which is transmitted through genital contact. It has been reported that the HSV-1 infection rate is two times higher than HSV-2. 9-11 In immunocompromised individuals such as cancer, HIV or organ transplant patients, the clinical manifestation may be more complicated resulting in HSV encephalitis, damage of temporal lobes, pneumonitis, esophagitis, and hepatitis. The HSV-1 infection is also related to the establishment of latent infection in the trigeminal area, where it can be reactivated and cause recurrent ABSTRACT Backgrounds: Drug screening is a time-consuming and costly process confronted with low productivity and challenges in using animals, which limits the discovery of new drugs. The cellbased assay allows the minimization of using the animal models and can provide more relevant in vivo biological information than biochemical assay. Objective: We aimed to establish a simple cell-based screening assay for the discovery of lead extract against HSV-1. Materials and Methods: Assay setting up was performed by optimization of the cell, incubation time, virus titer, and determination of Z value. Results: We have successfully established reproducible methods, by setting up assay plate including determination: 1) Vero cells as a model for HSV-1 infection, 2) Incubation for 5 days as sufficient time for CPE endpoint at monolayer cells, 3) 100 TCID 50 /well HSV-1 as infection titer which caused high percentage of cell detachment, 4) determination of Z value of 100 TCID 50 /well infection > 0.5. In addition, the established system was tested using ACV as the most common anti-HSV drug. Furthermore, we demonstrated the current system to screen extracts from Acacia nilotica, Uncaria gambir and Aspalathus linearis against HSV-1. It was observed that the alkaline extract of Uncaria gambir exhibited the highest SI (12.5) compared to other extracts. Conclusion: We demonstrated current cellbased screening system was reproducible and able to identify lead extracts against HSV-1 infection.