Abstract
Summary: The antigenic relationship between human measles virus and canine distemper virus has been analysed. Neutralization titrations of antisera produced by dogs in response to homologous and heterologous inoculation producedures indicated that the capsids of the viruses have similar antigens, but that there is no common identical antigen. Adsorption of antibody onto, and elution from, preparations of purified virus indicated that at least part of the antibody produced during the heterologous secondary response comprises antibody molecules that can react with both viruses.