Abstract
By combining infectivity titration, direct immunofluorescent, acridine orange and hematoxylin-eosin staining methods, the sequential morphologic changes of tissue culture cells infected with Edmonston measles virus were followed. The initial site of measles virus multiplication appeared to be in the perinuclear region of the cell cytoplasm. As the infection progressed, viral antigen spread into the nucleus first as small granules and later coalesced into large masses. During the end stage of infection, the content of measles antigen and nucleic acid decreased markedly, leaving a morphologic residue represented by intranuclear eosinophilic inclusion bodies. In this study the direct immunofluorescent staining method is found to be superior to the indirect technique in demonstrating the antigenic development within the measles infected cells.