| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2002: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 2001: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Research Abstract |
Staphylococcus aureus is known as community-accuired, nosocominal pathogen. It produces bi-component toxin, called Panton-Valentine leukocidin (PVL) which acts to polymorphonuclear lukocytes and macrophages. The epidemiological studies of PVL shows that PVL producing strains were isolated from limited clinical samples, most of cotenous necrotic lesions, such as furuncles, however, PVL cluster was seen only few % of clinical isolated strain while almost all S. aureus has hlg/luk cluster. The aim of this study is clarification of the mechanism of these uneven distribution of PVL producing strains among the clinical isolated S. aureus.
(1) Phage conversion of PVLP Previously, we found that gene cluster of two components for PVL are encoded in the prophages φPVL and φSLT. Therefore we assumed that phage conversion of PVL is related to the uneven distribution of PVL gemes. In this *y, we isolated 10 novel PVL-carrying phages and whole genome sequence of three of them were determined. We showed that these PVL carrying phages are divided into two groups, φPVL and φSLT types. In addition, each type phage divided into several subtypes by difference of lysogenic and replication regions. These data shows that PVL genes are carried by several different temperate phases and these deference were reflected to host ranges of PVL converting phages. We tested 257 S. aureus isolates from food poisoning origins, and only few percent of strains were infected by these phages.
(2) Regulation of PVL expression. Regulation of expression of PVL is important factor for the infection of S. aureus in the high-level PVL producer related lesions. We found several indicator strains which could not produce PVL components when PVL genes were transduced by φSLT. Now we are studying about the effect of the well known global regulators, such as agr and sigB to the expression of PVL.
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