The release of influenza virus from the infected cell

Abstract

1. When detached portions of the chorioallantoic membranes of normal fertile eggs are examined in the dark-field microscope spherical and tubular cytoplasmic protrusions are seen to develop from the margins of the cells and to become detached from them. This is probably a normal physiological phenomenon which occurs to some extent in the intact egg.2. Similar cell protrusions occur from chorioallantoic membranes of eggs infected with influenza virus. The phenomenon appears to be more pronounced in the infected egg than in the normal egg and in particular tubular cytoplasmic protrusions are much more frequent in the infected egg than in the normal.3. Tubular cytoplasmic protrusions may fragment into small spherical particles or may contract into filaments. All types of cell protrusion become detached from the cells and undergo contraction in size probably as a result of loss of water. The infective elementary bodies and filaments present in the allantoic fluid of eggs infected with influenza virus are derived from the cells in this way.4. It is concluded that the infective particle of the influenza virus is a fragment of the cell cytoplasm and consists of a closely aggregated mass of virus protein enclosed in cell membrane.The author is indebted to Prof. W. T. Astbury and Dr R. Reed for the electron photomicrographs reproduced in this paper.