Flow cytometric evaluation of antiviral agents against human herpesvirus 6

Antiviral activities of acyclovir (9-[(2-hydroxyethoxy) methyl] guanine, AC V), penciclovir (9-[4-hydroxy-3-(hydroxymethyl) butyl] guanine, PCV), ganci clovir ([9-(1,3-dihydroxy-2-propoxy) methyl] guanine, GCV), and foscarnet ( phosphonoformic acid, PFA) were determined against Human Herpesvirus 6 (HHV -6) by flow cytometric technique. The technique is based on the detection o f gp116 antigen expression in virus infected cells. Susceptibility was defi ned in terms of drug concentration which reduced the number of cells expres sing HHV-6 gp116 antigen with a mean fluorescent intensity (MFI) by 50% as compared to virus infected untreated cells. GCV was found to be most effect ive against HHV-6 followed by PFA, PCV and ACV, For HHV-6A, the mean 50% in hibitory concentrations (IC50) of GCV and PFA were found to be 3.4 muM and 34.7 muM respectively, whereas the IC50 of ACV and PCV were found to be 53. 7 muM and 37.9 muM respectively, For HHV-6B, the IC50 of GCV and PFA were f ound to be 5.7 muM and 71.4 muM respectively, whereas the IC50 of ACV and P CV were found to be 119.0 muM and 77.8 muM respectively, Flow cytometry is a valuable technique for the evaluation of antiviral compounds against viru ses including HHV-6.