Cytochemical and Electron Microscopical Observations on the Presence and Origin of Adenosine Triphosphatase-like Activity at the Surface of Two Myxoviruses.

Dawson, C. R. (The Middlesex Hospital Medical School, London, England), M. A. Epstein, and K. Hummeler. Cytochemical and electron microscopical observations on the presence and origin of adenosine triphosphatase-like activity at the surface of two myxoviruses. J. Bacteriol. 89:1526-1532. 1965.-HeLa cells infected with either fowl plague virus (FPV) or Newcastle disease virus (NDV) were examined in thin sections by electron microscopy. Preparations were studied both after direct fixation and embedding and after the application of cytochemical staining for enzymes splitting adenosine triphosphate. Viral particles were identified by their size and characteristic structure, and were found to form at the cell surface by budding out through structurally altered plasmalemma. After cytochemical staining for adenosine triphosphatase activity, extracellular FPV or NDV particles lying close against cell membranes with enzyme activity likewise carried this function, whereas those particles which were associated with cell surfaces without reaction product were themselves free from it. This correspondence between enzyme function in cell membranes and the outer viral membranes of newly formed particles adjacent to them indicates that surface enzymatic capability of the host cell survives even when the cell membrane undergoes morphological and antigenic alteration into myxovirus outer membrane.