Herpes simplex virus (HSV) causes genital, orolabial, or cutaneous lesions, keratitis, and encephalitis. Recently cellular receptors for HSV were isolated. The purpose of this study is to identify polymorphisms in the sequence of HSV receptor, cytokines or chemokines and to determine whether these polymorphisms correlate with susceptibility to infection by HSV or with symptoms of HSV. Blood samples from individuals who are seronegative, or seropositive (with or without symptoms of infection) for HSV-2 will be analyzed to determine the sequences of the HSV receptors, cytokines, chemokines, or related proteins. If a new genetic polymorphism is found, additional blood samples from individuals who are seropositive for HSV and from random blood donors will be analyzed to determine the frequency of the polymorphisms in seropositives and in the general population. Knowledge gained from this study should provide important insights into mechanisms of infection by HSV and may lead to novel therapies to block infection.