Abstract:
Acyclovir and Clinacanthus nutans extract were tested for antiviral activities against Koi Herpesvirus (KHV) which has caused global epizootic in common carp and koi. Acyclovir and C. nutans extract were tested for pre and post infection antiviral activities. The mean ED50 of plant extract post-infection was 0.475 mg/ml and pre-infection at 1 hr, 2hr, 3hr and 4hr were 0.475 mg/ml. While acyclovir at the maximum concentration 1 0 ~g/ml was not have antiviral activity in pre and post infection tests. The cytotoxicity results indicated that acyclovir at the concentration of 25, 50 and 100 ug/ml and C. nutans plant extract at 4.75 mg/ml damaged Koi fin cell line and had the cytotoxic effect to the cells. 10r non-toxic concentration of acyclovir was at 11 .60 ug/ml and C. nutans plant extract at 1.9 mg/ml. The cellular pathological study under Transmission electron microscope indicated that the intracellular virion exposed to C. nutans extract was degenerated. Therefore, the incomplete development of these virions effected the infectivity of the virus. The results showed that C. nutans extract showed antiviral activity against Koi herpesvirus in Koi fin cell line which may be applied as therapeutic agents in common carp and koi in the future