Activity investigation of pinostrobin towards herpes simplex virus-1 as determined by atomic force microscopy

In the present study, the antiviral activity of pinostrobin towards herpes simplex virus-1 (HSV-1) was investigated by MTT assay and atomic force microscopy. Pinostrobin can inhibit HSV-1 replication with 50% effective concentration (EC(50)) of 22.71 ± 1.72 μg/ml. MTT assay showed HSV-1 was significantly inhibited when pretreated with pinostrobin, with the inhibition of 85.69 ± 2.59%. Significant changes in morphology and size of HSV-1 were observed by atomic force microscopy (AFM) in response to pinostrobin treatment. AFM topography and phase images showed that with increasing time, the envelope was shedded and damaged, finally leading to virus inactivation. With increasing concentration, pinostrobin caused a gradual leakage, also contributing to breakage of the envelope and virus inactivation. Treatment effect of oral pinostrobin in vivo showed that pinostrobin (50mg/kg/dose) possesses definite therapeutical effect in the development of lesion score. In general, the results showed that AFM represents a powerful technique for the investigation of morphology and size of HSV-1 treated by antiviral agents. AFM is applicable to study chemically induced morphological changes at the nanometer level.