Molecular relationships among serogroup B bacteriophages of Staphylococcus aureus

Abstract

The typing bacteriophages 55, 80, 83A, and 85 of Staphylococcus aureus, representative of the three major lytic groups of serological group B aureophages, have been examined for relatedness of their genomes and virion proteins. Phages 11 and 80a were also examined to determine the relationship of phage 80a to phages 11 and 80. Total genome hybridization measurements divided the phages into two groups. Phages 55 and 80, in the first group, had DNA homology of 50%. Phages 11, 80a, 83A, and 85 formed a second group with 27 to 65% homology. Homology between the two groups was in the range of 14 to 22%. Phage 80a is more closely related to phage 11 than to phage 80, though it is probably not a simple recombinant of phages 11 and 80. Restriction enzyme digestion and phage [32PJDNA hybridization analysis of the endonuclease-generated fragments from each phage DNA confirmed the findings of the DNA homology measurements. The endonuclease fragment patterns generated by EcoRI and HindlIl were distinctive for eacb phage, confirming that none of the phages are closely related. Common sequences were present in most fragments from the phage DNAs when the labeled probe DNA was from a different phage in the same group. Cross-group probing of endonuclease fragments revealed both a diminished level of homology when similar sequences were present and the probable absence of some sequences. Virion proteins, examined by polyacrylamide gel electrophoresis, were similar in number and molecular weight for phages 11, 80a, 83A, and 85, reflecting the DNA homology analyses. The virion proteins from phages 55 and 80, however, were more distinctive, and both differed from the phages in the other group.

The gene for toxic shock toxin is carried by a family of mobile pathogenicity islands in Staphylococcus aureus

“…This strain is naturally lysogenic for three known phages, φ11, φ12 and φ13 (Novick, 1967), and is insensitive to phage 80. Phage 80α was later shown by Southern blot hybridization to be much more closely related to φ11 than to its progenitor, 80 (Stewart et al ., 1985), suggesting that it is probably a recombinant between 80 and φ11; it is probably also a restriction–modification variant, as it does not plate on NCTC9789, the propagating strain for phage 80. We thus addressed two questions: (i) which phage(s) contributed the 80α genes that are involved in the excision, replication and transfer of SaPI1; and (ii) can other phages be shown to express one or more of these functions?…”

“…Thus far, we have detected SaPI transfer only by phage‐mediated transduction; as the circular form would have a molecular size of 15 or 18 kb, depending on whether the 3 kb tetM fragment has been inserted, and as typical staphylococcal transducing phages have genomes of approximately 45 kb (Stewart et al ., 1985), the PI could be packaged as part of a 45 kb chromosomal transducing fragment or, if excised, as a PI–phage recombinant or a PI multimer. Thus, the encapsidation mechanism may be a reflection of whether SaPI1 replicates autonomously as a plasmid or passively upon (reversible) integration into the phage genome.…”

Antimicrobial resistance of Staphylococcus aureus: genetic basis.

“…The current Basic Set of human S. aureus typing phages contains representatives of three serological groups, A, B, and F (413). There are few reports of molecular comparisons of phage within the same lytic or serological group (365,478).…”

“…Where examined, staphylococcal transducing phage have genome sizes of approximately 45 kilobase pairs (kb) (18,289,366,478). This limitation on the amount of DNA that can be packaged in the phage head could explain the much higher transduction frequencies obtained with plasmids of 30 to 40 kb or less (72,308,423) and may be the rationale for the majority of staphylococcal plasmids having molecular sizes of <45 kb.…”

The Cloning of Chromosomal DNA Associated with Methicillin and Other Resistances in Staphylococcus aureus

“…After at least 4 h pre-hybridization the labelled probe DNA was added. The probe consisted of 0.5 pg DNA labelled with f3*P]dCTP (Amersham) by nick translation as described previously (Stewart et al, 1985). For normal (non-competitive) hybridization, the labelled DNA was freed from unincorporated nucleotides by adding 40 pg sheared salmon sperm DNA and precipitating with ethanol.…”