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At least 73 records · Page 4Linked to original sources
PubMed1978

Comparison of bacterial cardiotoxins: thermostable direct hemolysin from Vibrio parahaemolyticus, streptolysin O and hemolysin from Listeria monocytogenes.

Some properties of the bacterial cardiotoxins, thermostable direct hemolysin from Vibrio parahaemolyticus (vibriolysin), and streptolysin O and hemolysin from Listeria monocytogenes (listeriolysin), were compared. These toxins had rapid lethal effects on mice when injected intravenously. The electrocardiographic changes of rats after intravenous injections of these toxins were very similar, showing bradycardia and inhibition of atrio-ventricular conduction. These toxins also caused cessation of the spontaneous beating and degeneration of cultured foetal mouse heart cells. When equal hemolytic units of these three toxins were administered, vibriolysin had the most potent effects on mice and cultured mouse heart cells. Differences in the kinetics of the hemolysis by each toxin and in the effects of cholesterol of their hemolytic actions suggest that the mode of action of vibriolysin is different from those of streptolysin O and listeriolysin.

Bacterial Toxins↗
PubMed1995

Bacterial hemolysins and leukotoxins affect target cells by forming large exogenous pores into their plasma membrane: Escherichia coli hemolysin A as a case example.

Many bacteria include among their virulence factors exoproteins which exert leukocidal and cytolytic functions and have the ability to form pores in model membranes. We show that, at least in the case of the RTX hemolysin produced by Escherichia coli (HlyA), formation of pores in planar lipid membranes is parallelled by opening of strikingly similar channels in the plasma membrane of exposed macrophages. Formation of such lesions in leukocytes can give rise to a variety of effects leading altogether to a diminished immune response towards the invasive bacteria.

Bacterial Proteins↗
PubMed1989

Incomplete warm hemolysins. II. Corresponding antigens and pathogenetic mechanisms in autoimmune hemolytic anemias induced by incomplete warm hemolysins.

The pathogenesis of autoimmune hemolytic anemias induced by incomplete warm hemolysins (IWHs) is only poorly understood. Sera from eight patients with mostly severe IWH-related autoimmune anemias allowed us to address some key elements of the pathogenetic process. With the use of a modified enzyme-linked immunoassay we could show that (i) IWHs bound to native RBCs and (ii) IWHs initiated the activation of the complement cascade on native RBCs up to the level of C3. The interaction of IWHs with their corresponding antigens on red blood cell membranes, which were pretreated with different enzymes, showed that despite serological uniformity there are at least two different types of IWHs: (i) IWHs reacting with phospholipase susceptible antigens (six of the studied sera) and (ii) IWHs reacting with antigens which are hardly, if at all, phospholipase susceptible (two of the studied sera). Aside from Rh antibodies, most IWHs apparently belong to a second category of RBC antibodies whose corresponding antigens can be inactivated by phospholipase treatment of the cell membranes. IWHs showed no specificity for Rh antigens or the antigens of the I/i-system.

Anemia, Hemolytic, Autoimmune↗
PubMed2003

Cloning and molecular characterization of a unique hemolysin gene of Vibrio pommerensis sp. nov.: development of a DNA probe for the detection of the hemolysin gene and its use in identification of related Vibrio spp. from the Baltic Sea.

A group of hemolytic Vibrio strains was isolated from surface water of the Baltic Sea in 1995. A typical representative strain, CH-291, was found to lyse washed human and animal erythrocytes. Hemolysis was found to be calcium-dependent and occurred over a temperature range from 25 to 37 degrees C. The hemolysin-encoding genes were identified by screening a genomic library of total DNA from strain CH-291. A cloned chromosomal DNA fragment of 15.6 kb conferred to Escherichia coli DH5alpha a hemolytic phenotype. Hybridization and sequence analysis showed the cloned sequence to be unique to these Baltic Sea Vibrio isolates and therefore provides a useful marker for their identification. Moreover, the cloned 15.6-kb DNA fragment possessed structural features typical for genetic islands, including a decreased GC content and a flanking cryptic insertion sequence element.

Baltic States↗
PubMed1988

Production of gamma-hemolysin and lack of production of alpha-hemolysin by Staphylococcus aureus strains associated with toxic shock syndrome.

The hemolytic activity of toxic shock syndrome isolates of Staphylococcus aureus is enhanced when agarose is substituted for agar in blood plates or when strains are grown in liquid culture in the presence of 20% (vol/vol) CO2 in air. Hemolytic activity of a representative panel of toxic shock syndrome isolates was rigorously assessed both on blood agar and in liquid culture to unequivocally identify the predominant hemolysins produced. As determined by isoelectric focusing and Western immunoblotting, 15 of 15 TSS isolates produced gamma-lysin and 10 of 15 produced delta-lysin. None produced beta-lysin, and only 2 of 15 produced alpha-lysin. The low rate of alpha-lysin production was a most striking characteristic, since all strains were found to have the alpha-lysin gene by Southern blot hybridization.

Bacterial Proteins↗
PubMed1990

Properties of a hemolysin related to the thermostable direct hemolysin produced by a Kanagawa phenomenon negative, clinical isolate of Vibrio parahaemolyticus.

A hemolytic toxin (Vp-TRH) produced by a Kanagawa phenomenon negative, clinical isolate of Vibrio parahaemolyticus was further characterized. The purified Vp-TRH showed various biological activities, such as fluid accumulation in rabbit ileal loops, increase of rabbit skin vascular permeability, and cardiotoxicity on cultured myocardial cells, all of which are essentially similar to the activities found with thermostable direct hemolysin (Vp-TDH), a pathogenic toxin produced by Kanagawa phenomenon positive V. parahaemolyticus. Immunological similarities of Vp-TRH not only to Vp-TDH but also to hemolytic toxins produced by Vibrio hollisae and Vibrio cholerae non-O1, both of which are also enteropathogens closely related to V. parahaemolyticus, were demonstrated. The amino acid composition and sequence of N-terminal amino acids of Vp-TRH were determined. These results suggest that Vp-TRH has biological and immunological characters similar to Vp-TDH, although they are distinct molecules.

Amino Acid Sequence↗
PubMed2000

Bacillus cereus group strains, their hemolysin BL activity, and their detection in foods using a 16S RNA and hemolysin BL gene-targeted multiplex polymerase chain reaction system.

Hemolysin BL (HBL) is a major virulence factor for Bacillus cereus group strains. It is also a target enterotoxin for the most commonly used B. cereus detection kit, i.e., the B. cereus enterotoxin (diarrheal type) reversed passive latex agglutination (BCET-RPLA) test kit. A survey of the HBL activities and the cytotoxicities to the Chinese hamster ovary (CHO) cells for the B. cereus group strains, however, showed that although only part of the B. cereus group strains are HBL active, all strains show cytotoxicity to the CHO cells. Thus, methods that allow the detection of not only the HBL but also of the B. cereus group strains are important. In this study, by comparison of the gene sequences of the 16S rRNA for B. cereus group and other bacteria strains, we designed primers B16S1 and B16S2 specific to all the B. cereus group strains. In addition, because HBL is a major enterotoxin, we also designed HBL gene-specific polymerase chain reaction (PCR) primers, i.e., Hm1 and Hm2, that generated the same results as those of the hemolysis and BCET-RPLA assays. Primers B16S1/B16S2 and Hm1/Hm2 could be combined into a multiplex PCR system for the simultaneous detection of B. cereus group cells and the possible presence of their HBL enterotoxins. Also, all these PCR systems allowed the detection of n x 10(0) CFU B. cereus cells per g of food sample if an 8-h enrichment step was performed prior to the PCR.

Animals↗
PubMed1993

Complementation of transport-deficient mutants of Escherichia coli alpha-hemolysin by second-site mutations in the transporter hemolysin B.

Hemolysin B (HlyB) is a membrane-bound transport protein composed of an amino-terminal multiple membrane-spanning portion followed by a conserved ATP binding sequence. Together with the inner membrane protein HlyD and the outer membrane protein TolC, HlyB is responsible for transport of the 107-kDa toxin HlyA from the cytoplasm, across both membranes of the cell envelope of Escherichia coli, directly to the medium. We have used a mutational approach to investigate a postulated interaction between HlyA and HlyB. We have isolated transport-deficient mutants of HlyA altered in the C-terminal signal sequence and used one of these, a deletion of 29 amino acids, to select compensatory mutants in the transporter protein HlyB. Fifteen mutants located at six different sites, all mapping within the amino-terminal multiple membrane-spanning domain of HlyB, were identified. All of the mutations are clustered into three groups located close to the predicted inner face of the cytoplasmic membrane. We propose that these locations are close to sites on HlyB that interact with the C-terminal signal sequence of HlyA. This interaction is likely to involve either binding of HlyA to HlyB or activation of the transport mechanism. The compensatory mutants also display different patterns of specificity in terms of their ability to transport different HlyA mutants. The fact that point mutations are able to compensate for drastic changes in the signal sequence of HlyA suggests that substrate specificity of transporters such as HlyB may shift dramatically during evolutionary history. This could account for the diversity of substrates observed for the ABC transporter superfamily in nature.

Amino Acid Sequence↗
PubMed2004

Real-time PCR detection of the thermostable direct hemolysin and thermolabile hemolysin genes in a Vibrio parahaemolyticus cultured from mussels and mussel homogenate associated with a foodborne outbreak.

Molecular methods have become vital epidemiological tools in the detection and characterization of bacteria associated with a foodborne outbreak. We used both culture and real-time PCR to detect a Vibrio parahaemolyticus isolate associated with a foodborne outbreak. The outbreak occurred in July 2002 in Polk County, Florida, and originated at a Chinese buffet, with one person being hospitalized. The hospital isolated V. parahaemolyticus from the patient but destroyed the sample after diagnosis. From an onsite visit of the restaurant, food samples that possibly contributed to the outbreak were collected and sent to the Florida Department of Health, Tampa Branch Laboratory. Crab legs, crabsticks, and mussel samples were homogenized and incubated according to the Food and Drug Administration Bacteriological Analytical Manual culture protocol. Three sets of primers and a TaqMan probe were designed to target the tdh, trh, and tlh genes and used for real-time PCR. This study was successful in isolating V. parahaemolyticus from a mussel sample and detecting two of its genes (tdh and tlh) in food and pure culture by real-time PCR.

Animals↗