Seventy three marine plant extracts were tested in vitro in chick embr
yo fibroblast cell culture and their antivaccinia virus activity was e
valuated in terms of reduction in number of plaques by the extracts. O
nly seven extracts were found to show the activity. Sargassum wightii,
a seaweed had the highest activity, reducing 65 per cent of plaques f
ormed by vaccinia virus.