Differences in herpes virus symptoms may relate to variations in strain gene expression

(Penn State) Why do some people with cold sores around their lips experience painful lesions, while others have no symptoms at all, yet still spread the virus? A new study conducted at Penn State finds that these differences could be due to variations in the way certain strains of herpes simplex (HSV-1) -- the virus that causes cold sores, as well as genital herpes -- activate gene expression in neurons.