Infection of transformable cells ofHaemophilus influenzae by bacteriophage and bacteriophage DNA

Summary A phage HP1, infecting transformable cells ofHaemophilus influenzae Rd, has been isolated. The general properties of the wild type and of a clear plaquemutantc1 employed for most of the experiments are described. Phage DNA is infective for transformableHaemophilus cells with an efficiency (plaqueforming units of the original phage recovered as DNA-infected cells) of up to 6×10^–3. The competence ofHaemophilus cells for infection with phage DNA parallels the competence for transformation with bacterial DNA.Both HP1 and thec1 mutant are able to lysogenize their host, and the lysogenic cells are readily induced by UV. Competent non-lysogenicHaemophilus cells can be infected by DNA of lysogenic cells, thereby giving rise to phage progeny. Thus, the phage genetic material can be introduced into competentHaemophilus cells in three different ways: injection from intact phage, and infection with either phage DNA or with bacterial DNA carrying the prophage.The UV inactivation curves for infectious phage DNA and for complete phages are similar, both indicating the occurrance of host-cell reactivation. Photoreactivationin vitro of infectious phage DNA takes place to about the same high extent as observed with bacterial transforming DNA.The usefulness of this system for investigating bacterial transformation and biological effects ofin vitro treatment of DNA is discussed.with the technical assistance ofSandra J. Antoine With 4 Figures in the TextPreliminary report presented at the 7th Annual Bacterial Transformation Meeting, Aspen, Colorado, June 17–19, 1963.Supported by a travel grant from the Deutsche Forschungsgemeinschaft.Supported by Research Carreer Development Award GM-K3-7500 and Research Grant RH 00221 from the U.S. Public Health Service.