Structural changes in cells of Clostridium sporogenes infected with a long-tailed bacteriophage

Abstract

The infective process of phage F1 in Clostridium sporogenes has been studied by the electron microscopy of negatively stained preparations and, mainly, of thin sections. The phages adsorbed to the host wall by their tails. The first visible cytological changes accompanying intracellular multiplication were in the nucleoplasm, which became progressively fragmented into smaller units. Phage particles developed within the nuclear regions forming regular arrays of heads. When sectioned longitudinally, the elongated heads occurred in several rows; in transverse section, they were hexagonal and formed "crystalline" aggregates. Lysis occurred gradually, and was caused by the breaking away of portions of the cell envelope (cell wall and plasma membrane). During early lysis the rows of phage heads remained intact, only dispersing with time. The contents, and presumably free phage, leaked out through holes in the cell.