Genetic and Serological Analysis of Salmonella-Coli Phage Hybrids and Development of New Mutator Phages with Expanded Host Ranges.

摘要

We have isolated hybrid phages between the evolutionary distant phages Salmonella phage 22 and E. coli mutator phage Mu. The MuimmP22 hybrid class carries the entire late genes of Mu and some early genes, at least att-c-12 regions, of P22. MuimmP22 hybrid class is divided into two types, MuimmP22 and MuimmP22dis, with respect to their immunity pattern. P22 infects and grows in strains lysogenic for MuimmP22 though it carries the c region of P22. MuimmP22dis is able to grow in MuimmP22 lysogens, indicating that MuimmP22dis type carries second immunity region (immI) of P22. Indeed strains lysogenic for MuimmP22 is immune to P22. MuimmP22dis confers the hosts for 0-1 antigen conversion because of the inheritance of the al gene which is situated between immI and c region of P22. Both MuimmP22 and MuimmP22dis types are unable to infect E. coli strains K12 and C while they infect smooth derivatives of E. coli - S. typhimurium WR4028. This observation suggests that the G(+) segment for the Mu tail fiber region is inverted in the MuimmP22 hybrid class and the Mu tail fiber region is inverted in the MuimmP22 hybrid class and transcribed in inverse G(-) orientation. This hypothesis is supported by a reduced neutralizing activity of an anti-Mu serum. Furthermore, P22immMu hybrid class containing the entire late genes of P22 and some early genes at least the c region of Mu has been isolated. P22immMuc+ is, however, unable to establish stable lysogens. Keywords: High specialized transducing phage; Mutator phage; Recombination tail fiber; Host range; Tail antigen; Serological neutralization; Invertible segment. (kt)