Electron microscopic study of measles virus infection: unusual antibody-triggered redistribution of antigens on giant cells

in Journal of Virology (1979), 29(2), 666-676

Vero cells infected with measles virus fuse to form multinucleated cells which incorporated virus- specific antigens in their membrane. The distribution of these antigens was analyzed after a brief ... [more ▼]

Vero cells infected with measles virus fuse to form multinucleated cells which incorporated virus- specific antigens in their membrane. The distribution of these antigens was analyzed after a brief treatment with human anti-measles immunoglobulin G, using autoradiography and immunoperoxidase labeling combined with transmission and scanning electron microscopy. Virus-specific antigens were distributed over the entire surface of giant cells treated at 4°C with human anti-measles immunoglobulin G and labeled Protein A. When cells were shifted to 37°C, labeled antigen-antibody complexes were redistributed in two stages. Patch formation occurred in 5 to 15 min. Later, antigen- antibody complexes became concentrated in a paracentral "ring" rather than typical caps. Patch formation occurred in the presence of metabolic inhibitors, whereas ring formation was inhibited by metabolic inhibitors. These rings contained membrane folds, villi, and viral buds, whereas the rest of the membrane was smooth. In addition, shedding, endocytosis of antigen-antibody complexes, and reexpression of antigens were observed. Antibodies to nonviral membrane antigens induced the same pattern of redistribution. Infected cells treated with anti-measles Fab' fragments maintained a homogeneous distribution of label throughout the experiments. In conclusion, intact immunoglobulins, but not Fab' fragments, were able to induce a dramatic redistribution of viral antigen on the membrane of giant cells infected with measles virus. [less ▲]

Structural basis of hemadsorbing sites during the formation of syncytia in measles-infected cells

in Journal of Cell Biology (1977), 75

The surfaces of cells Infected with measles virus adsorb monkey red blood cells (RBC). In this study, the structure and localization of viral hemadsorbing (HAD) sites and their relationship with antigenic ... [more ▼]

The surfaces of cells Infected with measles virus adsorb monkey red blood cells (RBC). In this study, the structure and localization of viral hemadsorbing (HAD) sites and their relationship with antigenic sites and with cell fusion were investigated in measles virus infected Vero cells. Transmission and scanning electron microscopy were combined with immunolabeling, using human anti-measles IgG (Ab) and protein A from Staph, aureus coupled to peroxidase.. In the early syncytia (50-100 2 in diameter), HAD sites were clustered in the center but scattered at the periphery. In contrast, mature giant cells (400 to 500 2) had all HAD sites in the central area which displayed scattered villi. The periphery of the mature giant cells and the mononucleated cells did not hemadsorb but were covered with numerous villi. In the central area, RBC were firmly attached to villi and ridges over nucleocapsids but rarely to viral buds. Villi and ridges under the RBC were covered with antigenic sites which were not detected at the periphery of the mature syncytia. When living cells were treated with Ab at 4°C, complete inhibition of hemadsorption was only observed when RBC were applied to the cells in the cold. In other experiments, cells reacted with Ab at 4°C were washed, brought to 37°C and treated with RBC immediately or after 1-24 hrs. After 1-2 hrs, some HAD sites were present only at the periphery of immature giant cells, suggesting that RBC receptors had already emerged in membrane areas where fusion started again. After 24 hrs, the distribution of HAD and antigenic sites was the same as on cells not exposed to Ab. It seems that when fusion begins, HAD sites appeared on the periphery of the syncytia and then move spontaneously towards the center. With cessation of fusion, HAD sites disappear from the periphery of the giant cell. Receptors for RBC are closely associated with antigenic sites and correlated with viral induced fusion but not with virus production. [less ▲]

Recherches sur l'organisation de l'enveloppe des myxovirus

Doctoral thesis (1976)

Organization of myxoviruses: structural basis of several biological properties of Newcastle Disease Virus

in Proceedings (1973)