Prophage, [phi]PV83-pro, Carrying Panton-Valentine Leukocidin Genes, on the Staphylococcus aureus P83 Chromosome

Staphylococcus aureus P83 has Panton-Valentine leukocidin (PVL)-like genes, lukM and lukF-PV. Here, lukM and lukF-PV genes were found on the genome of a prophage, which was designated as φPV83-pro. The precise genome size was 45,636 bp with att core sequences of 10 base pairs. Sixty-four ORFs were identified on the φPV83-pro genome, including two extra operons, lukM-lukF-PV and orfs63-64. The lukM-lukF-PV cluster was located 2.1 kb upstream of the attL site. The most striking feature of the φPV83-pro genome was a constituent of at least 4 regions from φ11, φPVL, and other phages, i.e., (i) att sites identical with those of φ11, (ii) a cos sequence and the genes encoding packaging and head proteins of φPVL (occupied half region of φPV83-pro), and (iii) the other two regions which showed no significant similarity with known phages (occupied about 40% of φPV83-pro). Furthermore, two insertion sequences, ISSA1 and ISSA2 were integrated into attL site and orf44, respectively. φPV83-pro was not induced as phage particles from S. aureus P83 regardless of its treatment with mitomycin C. The insertion of ISSA1 into the attL site was one of the reasons of the failure of the induction of the phage particles by mitomycin C treatment of the strain P83.