Some interesting research
From a site I subscribe to...acyclovir is the active ingredient in anti-viral creams like Denavir and Zovirax...
Tea Tree Oil/Melaleuca
Tea tree oil has some interesting research demonstrating it to be an effective antimicrobial agent. The Journal of Applied Microbiology (January 2000, pages 170–175) stated that "The essential oil of Melaleuca alternifolia (tea tree) exhibits broad-spectrum antimicrobial activity. Its mode of action against the Gram-negative bacterium Escherichia coli AG100, the Gram-positive bacterium Staphylococcus aureus NCTC 8325, and the yeast Candida albicans has been investigated using a range of methods.... The ability of tea tree oil to disrupt the permeability barrier of cell membrane structures and the accompanying loss of chemiosmotic control is the most likely source of its lethal action at minimum inhibitory levels." In addition, "In a randomized, placebo-controlled pilot study of tea tree oil in the treatment of herpes cold sores, tea tree oil was found to have similar degree of activity as 5% acyclovir" (Source: Journal of Antimicrobial Chemotherapy, May 2001, page 450).