Abstract
The antigenic relationship between the viruses of varicella-zoster and herpes simplex was studied by complement-fixation, fluorescent antibody staining and neutralization tests. Twenty-three of 75 patients with herpes simplex infections showed significant heterologous increases in complement-fixing antibody titre to varicella-zoster virus. These heterologous increases occurred in patients with serological evidence of a prior infection with varicella-zoster virus, and the greatest proportion occurred in patients in the younger age groups who had probably experienced the most recent varicella-zoster virus infections. Five of 42 patients with varicella-zoster infections showed heterologous complement-fixing antibody responses to herpes simplex virus; all were patients with serological evidence of a prior herpes simplex virus infection. The patients with herpes simplex infection who showed heterologous complement-fixing antibody responses to varicella-zoster virus also showed marked increases in neutralizing antibody and antibody demonstrable by immunofluorescent staining. However, none of the patients with varicella-zoster infection who showed heterologous increases in complement-fixing antibody titre to herpes simplex virus had significant increases in neutralizing antibody.