Zasloff et al. showed that squalamine, a compound first isolated from the dogfish shark and known to have antimicrobial properties, also has broad-spectrum antiviral activity against human pathogens. In vitro the compound was effective against dengue virus and hepatitis, and in vivo it was effective against yellow fever, encephalitis virus and cytomegalovirus. The authors postulated that squalamine, a cationic amphipathic sterol, neutralizes the negative electrostatic surface charge of intracellular membranes so that the cell is less able to support viral replication. Squalamine is readily synthesized and is safe in humans, so it could represent a new antiviral agent.