LMMUNOHISTOCHEMICAL STUDIES ON T H E INTERACTION BETWEEN EHRLICH ASCITES TUMOR CELLS AND NEWCASTLE DISEASE VIRUS

Evidence has been presented which supports the hypothesis that Newcastle disease virus interacts with Ehrlich ascites tumor cells in a manner similar to the reactions of a virus with its susceptible host cells in a normal infection, except that replication of hemagglutinating, complement fixing, or infectious particles could not be demonstrated (2, 3). That virus penetrated into tumor cells was supported only by evidence of an indirect nature. I t was, therefore, important to attempt to study this problem by more direct means. The fluorescent antibody technique of Coons and Kaplan offered such a possibility (4). This technique permits visualization of viral antigen within infected cells by union of antigen and labelled specific antibody. Infections by mumps, canine hepatitis, influenza, herpes zoster, varicella, vaccinla, and Egypt 101 viruses have been studied by this method (5-10). I t is the purpose of this paper to present additional evidence in support of the postulate that Newcastle disease virus (NDV), or a portion of this agent, in order to induce cell damage, penetrates the Ehflich ascites tumor cell. The data to be described suggest that penetration of cells initially involves the loss of the ability of viral antigen to combine with antibody, and that penetration is followed by the synthesis of a viral antigen which appears to be non-infectious, unable to agglutinate chicken erythrocytes, or to fix complement with homologous antibody.