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The calcium requirement for hemolytic activity of Escherichia coli hemolysin was investigated by using hemolytic assays and immunoblotting of toxin-treated erythrocytes. The hemolytic activity of cell culture supernatants obtained during growth of E. coli in Luria-Bertani (LB) broth or calcium-free LB broth was calcium dependent. The hemolytic activity of(More)
To gain further evidence that Escherichia coli alpha-hemolysin has a role in pathogenesis, its effect on human peripheral leukocyte viability was studied in vitro. Viability of leukocytes exposed to low doses of alpha-hemolysin decreased nearly 10-fold within 15 min of exposure. This response was dose and time dependent and was neutralized by antiserum,(More)
The primary structure of Escherichia coli hemolysin (HlyA) contains a 9-amino-acid sequence which is tandemly repeated 13 times near the C terminus and which is essential for hemolytic activity. Hemolysin also requires an unknown modification by an accessory protein, HlyC, for hemolytic activity. The role of calcium in the interaction of HlyA with(More)
Escherichia coli alpha-hemolysin (AH) purified from culture supernatants by gel filtration and ion-exchange chromatography was heterogeneous in charge and size. A 107,000-dalton protein was identified as the product of the hlyA gene by its reactivity with anti-AH monoclonal antibodies. Proteolysis of the product of the hlyA gene occurred but was not(More)
This study was undertaken to determine the frequency of Legionella infection in a dental clinic setting. Serum samples from 270 dental clinic personnel were evaluated using an enzyme-linked immunosorbent assay to detect Legionella-specific IgM and IgG antibodies. The pooled-species whole-cell-antigen preparation used in these assays was derived from six(More)
Alpha haemolysin, produced by Escherichia coli, grown in a chemically defined medium, was purified 19-fold and the endotoxin content reduced 2176-fold by ultrafiltration and glycerol-gradient ultracentrifugation. Immunodiffusion of purified alpha haemolysin (PH) against antiserum to crude haemolysin (CH) revealed only one precipitation line. PH was(More)
Twelve monoclonal antibodies (MAbs) produced against the Escherichia coli hemolysin (HlyA) encoded by the hemolysin recombinant plasmid pWAM04 were studied. HlyA derivatives from recombinant strains with different plasmids encoding HlyA amino-terminal and carboxy-terminal truncates, HlyA in-frame deletions, and HlyA frameshift mutations were used in(More)
To gain further evidence for the role of the Escherichia coli alpha-hemolysin in pathogenesis, its in vitro effects on human peripheral leukocyte function were studied. Leukocytes exposed to low doses of alpha-hemolysin responded with a marked chemiluminescence response, indicating activation of oxidative metabolism. This response was time and dose(More)