ABSTRACT
<p><b>OBJECTIVE</b>To study the antiviral effect and mechanisms of the liquid extract from Ceratostigma willmattianum against herpes simplex virus type 1 (HSV-1) in vitro.</p><p><b>METHOD</b>C. willmattianum in various concentration was applied to different steps of HSV-1 replication cycle. 50% Tissue culture infective dose (TCID50), cytopathic effect (CPE), MTT staining method, dot blotting and Northern blotting analysis were used to estimate index of antiviral activity.</p><p><b>RESULT</b>50% Toxic concentration (TC50) was 1077 mg x L(-1), IC50 29.46 mg x L(-1) and therapeutic index (TI) 36.56 in C. willmattianum. TC50 330 mg x L(-1), 50% Inhibiting concentration (IC50) 9.12 mg x L(-1) and TI 36.18 in ACV by MTT staining method. The liquid extract from C. willmattianum had remarkable effect on inhibiting HSV-1 in vitro. Ceratostigma could interfere absorption of HSV-1 to Vero cells to prevent HSV-1 infectivity, inhibit HSV-1 gD DNA replication and HSV-1 gD mRNA expression.</p><p><b>CONCLUSION</b>C. willmattianum possesses strong anti-HSV-1 activity in vitro. The antiviral mechanisms are related to inhibiting virus absorption, HSV-1 gD gene replication and HSV-1 gD gene transcription.</p>