A lubricant derived from the mucus of cow salivary glands has shown promise at preventing the human immunodeficiency virus (HIV) and a herpes virus from infecting healthy human cells.

Mucus is a protective gel that lubricates the epithelial tissues that cover our organs and line our body cavities, as well as acting as a first line of defence against microorganisms. The main component of mucus, a protein called mucin, may have antiviral properties.