Persistent Infection of Cells in Culture by Measles Virus II. Effect of Measles Antibody on Persistently Infected HeLa Sublines and Recovery of a HeLa Clonal Line Persistently Infected with Incomplete Virus

Abstract

The effect of viral antibody on persistent infection of HeLa cells by the Edmonston strain of measles virus was investigated by culturing cells from three persistently infected clones in medium supplemented with human immune globulin. The three infected HeLa clones were isolated from a persistently infected parent line. Two sublines which were grown in the presence of measles antibody developed a nonyielder state, wherein there is no detectable virus infectious for normal HeLa cultures. There is, however, continued synthesis of intraellular viral antigen and formation of viral intracytoplasmic inclusion bodies. The development of a nonyielder state was associated with a marked decrease in the degree of hemadsorption in cultures of both sublines. Further studies of the viral properties of nonyielder He La cell populations were made with a clone obtained from one of these sublines by plating under antibody. Persistent infection in this line was characterized by synthesis of incomplete virus even when the cells were cultured thereafter in antibody-free medium. This was evidenced by (i) failure to recover infectious virus from the clonal population despite continued formation of intracellular viral antigen and viral intractoplasmic inclusion bodies in a majority of the cells, (ii) the presence of only a few cells with surface viral antigen(s) including hemagglutinin, and (iii) the relatively weak antibody response to viral envelope antigen(s) after injection of cells into guinea pigs.