Polar appearance and nonligand induced spreading of measles virus hemagglutinin at the surface of chronically infected cells.

Fixation with glutaraldehyde (GA) and paraformaldehyde (PFA) preserved measles virus hemagglutinin at the surface of chronically infected cells. Cells fixed with PFA but not with GA exhibited hemadsorption with green monkey cells. PFA fixation, in contrast to GA fixation, also preserved the immunogenicity of measles virus hemolysin. These fixatives and the removal of the measles virus hemagglutinin from the cell surface by trypsin enabled studies of the appearance of the hemagglutinin at the surface membrane. Results obtained by immunofluorescence technique and by hemadsorption indicated that measles virus hemagglutinin appeared polarly at the cell membrane and then spread around the surface. This was substantiated by measurements of the immunofluorescence intensity at the single cell level per membrane unit and per cell, and by measuring the binding of iodinated immunoglobulins per 10(6) cells. The appearance was inhibited by sodium azide and cytochalasin B. The spreading was not inhibited by sodium azide, but was influenced by cytochalasin B. The spreading did not proceed at 4 degrees C. On the basis of these findings, a hypothetical model for appearance and spreading of measles virus hemagglutinin was proposed.