Non-sorbitol-fermenting, ␤-glucuronidase-negative Escherichia coli O157:H7 strains are regarded as a clone complex, and populations from different geographical locations are believed to share a recent common ancestor. Despite their relatedness, high-resolution genotyping methods can detect significant genome variation among different populations. Phylogenetic analysis of high-resolution genotyping data from these strains has shown that subpopulations from geographically unlinked continents can be divided into two primary phylogenetic lineages, termed lineage I and lineage II, and limited studies of the distribution of these lineages suggest there could be differences in their propensity to cause disease in humans or to be transmitted to humans. Because the genotyping methods necessary to discriminate the two lineages are tedious and subjective, these methods are not particularly suited for studying the large sets of strains that are required to systematically evaluate the ecology and transmission characteristics of these lineages. To overcome this limitation, we have developed a lineage-specific polymorphism assay (LSPA) that can readily distinguish between the lineage I and lineage II subpopulations. In the studies reported here, we describe the development of a six-marker test (LSPA-6) and its validation in a side-by-side comparison with octamer-based genome scanning. Analysis of over 1,400 O157:H7 strains with the LSPA-6 demonstrated that five genotypes comprise over 91% of the strains, suggesting that these subpopulations may be widespread.

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Accumulation of extracellular hyaluronan (HA) and its processing enzyme, the hyaluronidase Hyal1, predicts invasive, metastatic progression of human prostate cancer. To dissect the roles of hyaluronan synthases (HAS) and Hyal1 in tumorigenesis and metastasis, we selected nonmetastatic 22Rv1 prostate tumor cells that overexpress HAS2, HAS3, or Hyal1 individually, and compared these cells with co-transfectants expressing Hyal1 ؉ HAS2 or Hyal1 ؉ HAS3. Cells expressing only HAS were less tumorigenic than vector control transfectants on orthotopic injection into mice. In contrast, cells co-expressing Hyal1 ؉ HAS2 or Hyal1 ؉ HAS3 showed greater than sixfold and twofold increases in tumorigenesis, respectively. Fluorescence and histological quantification revealed spontaneous lymph node metastasis in all Hyal1 transfectant-implanted mice, and node burden increased an additional twofold when Hyal1 and HAS were co-expressed. Cells only expressing HAS were not metastatic. Thus, excess HA synthesis and processing in concert accelerate the acquisition of a metastatic phenotype by prostate tumor cells. Intratumoral vascularity did not correlate with either tumor size or metastatic potential. Analysis of cell cycle progression revealed shortened doubling times of Hyal1-expressing cells. Both adhesion and motility on extracellular matrix were diminished in HA-overproducing cells; however , motility was increased twofold by Hyal1 expression and fourfold to sixfold by Hyal1/HAS co-expression , in close agreement with observed metastatic potential. This is the first comprehensive examination of these enzymes in a relevant prostate cancer microenvironment. (Am J

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