Characterization of Vibrio eltor typing phages: properties of the eltor phage e₄

Abstract

Biophysical characteristics of Vibrio eltor phage e₄, a key phage in the Vibrio cholerae typing scheme were studied. This icosahedral phage was found to contain 12 structural polypeptides with mol. wt. ranging from 25,000 to 120,000. One of these polypeptides of mol. wt. 50,000 accounted for most of the structural proteins present and was probably the major phage capsid protein. The phage genome comprised a single linear, double-stranded DNA molecule, 69.2 kbp in length (45.6 × 10⁶ mol. wt.) as determined by electron microscopy and restriction fragment analyses. The G + C content was 34.6%. Electron microscopy data indicated that unlike the DNAs of other cholera phages, phage e₄ DNA is not circularly permuted. Adsorption under normal conditions was biphasic with rate constants of 1.02 × 10⁻⁹/ml/min up to 60% adsorption and 3 × 10⁻¹⁰/ml/min thereafter. Intracellular phage multiplication was characterized by a latent period of 27 min. The burst size was approximately 100 phage particles per infected cell.