Gigartina skottsbergii carrageenan 18 Carrageenan 14 Rhodophyta 14 seaweed 14 article 12 Gigartinaceae 10 nonhuman 10 Animals 8 Antiviral Agents 8 Simplexvirus 8 algae 8 controlled study 8 red alga 8 Gigartina 6 Herpes simplex virus 2 6 Herpesviridae 6 Human herpesvirus 1 6 Mice 6 Support, Non-U.S. Gov't 6 animal model 6 antiviral activity 6 carrageenans 6 chemistry 6 drug mechanism 6 mouse 6 Algae, Red 4 Animalia 4 Antiviral 4 Carbohydrate Sequence 4