title: A polysaccharide fraction from medicinal herb Prunella vulgaris downregulates the expression of herpes simplex virus antigen in Vero cells.
abstract: Herpes simplex viruses (HSV) are pathogenic. With the emergence of drug-resistant strains of HSV, new antiviral agents, especially those with different modes of action, are urgently needed. Prunella vulgaris L. (Labiatae), a perennial plant commonly found in China and Europe, has long been used as a folk medicine to cure ailments. In this study, a polysaccharide fraction was prepared from Prunella vulgaris (PPV), and its effects on the expressions of HSV-1 and HSV-2 antigens in their host Vero cells were investigated with flow cytometry. The HSV antigen increased time-dependently in the infected cells, and PPV reduced its expression. The effective concentrations of PPV with 50% reductions of the HSV-1 and HSV-2 antigens were 20.6 and 20.1 microg/ml, respectively. The novelty of PPV is that it also reduces the antigen expression of acyclovir-resistant strain of HSV-1. After incubations with 25-100 microg/ml of PPV the HSV antigen-positive cells were reduced by 24.8-92.6%, respectively, showing that this polysaccharide fraction has a different mode of anti-HSV action from acyclovir. Results from this study show that PPV is effective against both the HSV-1 and HSV-2 infections, and flow cytometry offers a quantitative and highly reproducible anti-HSV drug-susceptibility assay.
authors.affiliation: Department of Biology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China. chimingchiu@graduate.hku.hk
authors.forename: Lawrence Chi-Ming
authors.initials: LC
authors.lastname: Chiu
authors.forename: Wen
authors.initials: W
authors.lastname: Zhu
authors.forename: Vincent Eng-Choon
authors.initials: VE
authors.lastname: Ooi
mesh_terms: D000818:Animals; D000956:Antigens, Viral / Q000096:biosynthesis* / Q000276:immunology; D002522:Chlorocebus aethiops; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects* / Q000502:physiology; D015967:Gene Expression Regulation, Viral / Q000187:drug effects / Q000502:physiology; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology; D011134:Polysaccharides / Q000302:isolation & purification / Q000494:pharmacology*; D031347:Prunella; D018139:Simplexvirus / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D014709:Vero Cells
chemical_list: D000956:Antigens, Viral; D010936:Plant Extracts; D011134:Polysaccharides