Rehabilitation of distal radioulnar joint instability

Distal radioulnar joint (DRUJ) instabilities are common and often combined with other injuries of the interosseous membrane and/or the proximal radioulnar joint. Once they are diagnosed and the treatment is chosen, physiotherapists have limited choices due to the lack of validated protocols. The benefits of proprioception and neuromuscular rehabilitation have been brought to light for the shoulder, knee and ankle joints, among others. However, no program has been described for the DRUJ. The purpose of this article is to study the muscular elements responsible for active DRUJ stability, and to propose a proprioceptive rehabilitation program suited to this condition.

Formulations of single or multiple H. pylori antigens with DC Chol adjuvant induce protection by the systemic route in mice. Optimal prophylactic combinations are different from therapeutic ones

The ability to induce a protective response against Helicobacter pylori infection has been investigated by systemic immunization of mice with urease formulated with the cationic lipid DC Chol. This compound acts both as a formulating agent and as an adjuvant and induces a balanced Th1/Th2 response shown to be more effective for protection in our previous studies. Urease-DC Chol induced a significant protection in prophylaxis but not in therapeutic immunization. The protection level was between 1.5 and 2 log reduction of bacterial density measured by quantitative culture compared to unimmunized-infected mice. In parallel, the protective efficacy of other H. pylori antigens formulated in a similar way and administered with DC Chol was tested. These antigens were tested alone or in combination in prophylactic and therapeutic regimens. Some combinations of antigens induced a better prophylactic or therapeutic activity than urease alone (0.5-1.5 log further reduction in prophylaxis and therapy respectively, P<0.05). The combinations that induced the best protection were different in prophylaxis and therapy. In conclusion, DC Chol provides a convenient and efficient method to formulate different antigens even when they are present in non-compatible buffers initially. Moreover, the results obtained in protection against H. pylori with such formulations should lead the way to future clinical trials.

Formulations of single or multiple H. pylori antigens with DC Chol adjuvant induce protection by the systemic route in mice. Optimal prophylactic combinations are different from therapeutic ones

The ability to induce a protective response against Helicobacter pylori infection has been investigated by systemic immunization of mice with urease formulated with the cationic lipid DC Chol. This compound acts both as a formulating agent and as an adjuvant and induces a balanced Th1/Th2 response shown to be more effective for protection in our previous studies. Urease-DC Chol induced a significant protection in prophylaxis but not in therapeutic immunization. The protection level was between 1.5 and 2 log reduction of bacterial density measured by quantitative culture compared to unimmunized-infected mice. In parallel, the protective efficacy of other H. pylori antigens formulated in a similar way and administered with DC Chol was tested. These antigens were tested alone or in combination in prophylactic and therapeutic regimens. Some combinations of antigens induced a better prophylactic or therapeutic activity than urease alone (0.5-1.5 log further reduction in prophylaxis and therapy respectively, P<0.05). The combinations that induced the best protection were different in prophylaxis and therapy. In conclusion, DC Chol provides a convenient and efficient method to formulate different antigens even when they are present in non-compatible buffers initially. Moreover, the results obtained in protection against H. pylori with such formulations should lead the way to future clinical trials.

Dobutamine stress echocardiography identifies anthracycline cardiotoxicity

BACKGROUND

Anthracyclines are effective anti-cancer agents, but their therapeutic value is limited by their myocardial toxicity. We assessed the physiological responses of stress echocardiography at low doses of dobutamine (DSE) in patients treated with anthracycline.

METHODS AND RESULTS

In a prospective study, 28 patients were studied before and 1 month after the end of chemotherapy. All patients had normal ejection fraction (EF) at rest before therapy and the mean dose of anthracycline was 212+/-15 mg/m(2). Echocardiographic Doppler studies were performed before and during dobutamine infusion (5 and 10 microg/kg per min). Rest echocardiography demonstrated a significant decrease of EF between the two examinations in ejection fraction (67+/-3% vs. 61+/-3%, P<0.001). The increase of the EF during dobutamine infusion was higher after chemotherapy compared to the initial examination (19+/-3% vs. 29+/-3%: P<.05). No difference in EF was observed at 10 microg/kg per min between before and after chemotherapy. In contrast, at rest no difference in diastolic parameters was observed between the two examinations. Moreover, a significant decrease of the peak E and the ratio E/A was observed during dobutamine infusion after chemotherapy (93+/-4 cm/s vs. 79+/-5 cm/s and 1.3+/-0.1 vs. 1.0+/-0.1, respectively;P<0.05).

CONCLUSION

Stress echocardiography may prove to be a sensitive technique and useful non-invasive approach for evaluating subclinical anthracycline cardiotoxicity.

Streptococcal pyrogenic exotoxin A, streptolysin O, exoenzymes, serotype and biotype profiles of Streptococcus pyogenes isolates from patients with toxic shock syndrome and other severe infections

The determination of protein M and T serotypes, biotypes and pyrogenic (erythrogenic) exotoxin A (SPE A), streptolysin O (SLO), streptokinase (SK), hyaluronidase (HA) and cysteine proteinase release by 212 S. pyogenes isolates from patients with severe invasive group A streptococcal (GAS) infections, among them 74 cases of streptococcal toxic shock syndrome (STSS) has been investigated. M1 or M3 serotypes were expressed by 25% of the isolates (53/212), whereas 59% (125/212) belonged to 15 other different serotypes and 16% (34/212) were untypeable. Of the 74 isolates from STSS patients, 42% (31/74) expressed M1 and to a lesser extent M3 serotypes versus 19% of the non STSS isolates (26/138). Among the ten different biotypes known, biotypes 1 and 3 were prevalent, particularly the former in the case of STSS isolates. SPE A was detectably produced by about 25% (54/212) of the strains. However, as high as 40.5% of the STSS isolates (30/74) versus 17.4% of non STSS isolates (24/138) released SPE A. Moreover, 67% of the SPE A producing strains were of serotype M1 or M3. SK and HA were released by 71% and 10% of the isolates respectively. All strains released SLO (4 to 256 HU/ml) and 85% cysteine proteinase. No relationship between toxin or enzyme titer and the type of disease or clinical origin of the strains was found. Culture supernatants of all isolates showed moderate to high lymphocyte transforming activity with index values ranging from 14.5 to 50.3 including those strains which did not release detectable amounts of SPE A suggesting that SPE C and other mitogenic factor(s) are released by the isolates investigated.

The sulphydryl-activated cytolysin and a sphingomyelinase C are the major membrane-damaging factors involved in cooperative (CAMP-like) haemolysis of Listeria spp

The negative mutant approach was used in this study to identify listerial cytolytic factors involved in cooperative haemolysis (CAMP-like phenomenon) with Staphylococcus aureus and Rhodococcus equi. A Listeria monocytogenes non-haemolytic mutant specifically impaired in listeriolysin O (LLO) production gave no CAMP reaction with S. aureus, and was virtually CAMP-negative with R. equi, indicating that the listerial sulphydryl-activated toxin played a major role in cooperative haemolysis. This was confirmed by direct evidence using purified LLO and alveolysin (from Bacillus alvei) in diffusion CAMP assays. To our knowledge, this is the first evidence of involvement of a sulphydryl-activated toxin in cooperative lytic processes. Phosphatidylcholine- and phosphatidylinositol-specific phospholipases C from L. monocytogenes did not seem to significantly contribute to cooperative haemolysis, as the corresponding mutants displayed wild-type CAMP reactions. In contrast, the sphingomyelinase C from Listeria iva-novii was the cytolytic factor responsible for the characteristic shovel-shaped CAMP reaction shown by this listerial species with R. equi. Possible mechanisms of lytic cooperation are discussed.

Staphylococcus aureus toxic shock syndrome toxin 1 and Streptococcus pyogenes erythrogenic toxin A modulate inflammatory mediator release from human neutrophils

We studied the influence of staphylococcal toxic shock syndrome toxin 1 and streptococcal erythrogenic (pyrogenic) toxin A (ETA) on intact and digitonin-permeabilized human polymorphonuclear granulocytes (PMNs). As was shown by reversed-phase high-performance liquid chromatography analysis, toxic shock syndrome toxin 1 or ETA alone, in the absence of any additional stimulus, did not induce the generation of the chemoattractant leukotriene B4 (LTB4) from PMNs in a wide range of concentrations. In addition, pretreatment of intact PMNs with either toxin potentiated formyl-methionyl-leucyl-phenylalanine (fMLP)- and washed Staphylococcus aureus cell-induced generation of LTB4 in a time- and dose-dependent manner. This increase included LTB4 as well as its inactive omega-oxidated compounds. Further studies revealed evidence that toxin exposure was accompanied by enhanced cellular receptor expression for fMLP as well as for LTB4. The intrinsic GTPase activity of membrane fractions was modulated by both toxins. Short-term incubation with ETA increased the GTPase activity of PMNs up to 141%. Inhibitory effects were obtained when GTP-binding protein functions were stimulated with sodium fluoride (NaF). In addition, specific binding of Gpp(NH)p to GTP-binding protein was inhibited by both toxins during the first 10 min of incubation and was restored at later times of incubation. Our data therefore suggest that both toxins significantly affect the signal transduction pathways of human PMNs, which results in immunomodulatory functions.

The phosphoinositide pathway of lymphoid cells: labeling after permeabilization by alveolysin, a bacterial sulfhydryl-activated cytolysin

An improved method allowing incorporation of [3H]myo-inositol into the phosphoinositide pool of human lymphoid cells is described. The procedure devised involves cell permeabilization with a thiol-activated membranolytic toxin, alveolysin, and optimization of the phosphoinositide labeling and extraction. In these conditions 4 to 10% of the added [3H]myo-inositol is found intracellularly and half of this amount (2-5%) is incorporated into the phosphoinositide pool in only 1 h as compared to the classical 0.2 to 0.3% incorporation obtained after 10 to 20 h. The integrity of coupling between receptors and phospholipase C was assessed by the inositol phosphate production after cell stimulation by various agonists.

One-step purification of the serotonin transporter located at the human platelet plasma membrane

A 68-kDa glycoprotein bearing the biological activity of the plasma membrane serotonin (5-hydroxytryptamine, 5-HT) transporter has been purified from human blood platelets, a classical cell model for the study of 5-HT uptake. After treatment of the whole platelet population or its plasma membrane fraction by sulfhydryl-dependent bacterial protein toxins or by digitonin, purification was reproducibly obtained by a one-step affinity chromatography using two different columns with 5-HT or 6-fluorotryptamine as ligands and elution by 5-HT or Na(+)-free buffer. The purified fraction migrated on sodium dodecyl sulfate-polyacrylamide gel electrophoresis as a single band with an apparent molecular mass of 68 kDa and exhibited an apparent isoelectric point of 5.6-6.2. Two sialic acid residues were detected in the purified material. The purified glycoprotein bound the 5-HT uptake blocker [3H]paroxetine with a Kd (0.25 nM) similar to the one observed for intact human platelets. It also bound [3H] 5-HT but neither [3H]hydroxytetrabenazine nor [3H] ouabain, the respective markers of the granular monoamine transporter and of the Na+,K(+)-ATPase associated to the plasma membrane 5-HT transporter. 5-HT derivatives and 5-HT uptake inhibitors exhibited similar Ki values for 5-HT uptake and paroxetine binding in intact human platelets and in the purified glycoprotein. Under laser UV irradiation, 40% of this purified glycoprotein could be labeled by either [3H]paroxetine or [3H]cyanoimipramine. No labeling was detected with either [3H] gamma-aminobutyric acid or [3H]GBR 12783, the respective markers of gamma-aminobutyric acid and dopamine carriers. The purified 68-kDa protein is therefore likely to correspond at least to the binding domain of the 5-HT transporter located at the human platelet plasma membrane.

Reduced virulence of a Listeria monocytogenes phospholipase-deficient mutant obtained by transposon insertion into the zinc metalloprotease gene

A phospholipase-deficient mutant, termed JL762, was obtained from a virulent strain of Listeria monocytogenes by screening a bank of 5,000 Tn1545 transposon-induced mutants on 2.5% egg yolk brain heart infusion agar. As previously shown (J. Mengaud, C. Geoffroy, and P. Cossart, Infect. Immun. 59:1043-1049, 1991), the transposon insertion took place inside the gene mpl, which encodes a zinc metalloprotease. By Western blot (immunoblot) analysis, we showed that loss of phospholipase activity was associated with loss of a 29-kDa zinc-dependent phosphatidylcholine-phospholipase C (PC-PLC) in culture supernatant of JL762 and of EGD-SmR incubated with ion chelator. As the parental strain, JL762 still produced in supernatants approximately 33-kDa proteins antigenically closely related to the 29-kDa PC-PLC. These results strongly suggest that the zinc metalloprotease of L. monocytogenes might play a role in the maturation of the 29-kDa PC-PLC. Although the uptake and the intracellular growth of bacteria were not affected in vitro, we found that the virulence of mutant JL762 was strongly impaired in the mouse.

Nucleotide sequence of the lecithinase operon of Listeria monocytogenes and possible role of lecithinase in cell-to-cell spread

The lecithinase gene of the intracellular pathogen Listeria monocytogenes, plcB, was identified in a 5,648-bp DNA fragment which expressed lecithinase activity when cloned into Escherichia coli. This fragment is located immediately downstream of the previously identified gene mpl (prtA). It contains five open reading frames, named actA, plcB, and ORFX, -Y, and -Z, which, together with mpl, form an operon, since a 5.7-kb-long transcript originates from a promoter located upstream of mpl (J. Mengaud, C. Geoffroy, and P. Cossart, Infect. Immun. 59:1043-1049, 1991). A second promoter was detected in front of actA which encodes a putative membrane protein containing a region of internal repeats. plcB encodes the lecithinase, a predicted 289-amino-acid protein homologous to the phosphatidylcholine-specific phospholipases C of Bacillus cereus and Clostridium perfringens (alpha-toxin). plcB mutants produce only small plaques on fibroblast monolayers, and an electron microscopic analysis of infected macrophages suggests that lecithinase is involved in the lysis of the two-membrane vacuoles that surround the bacteria after cell-to-cell spread. On the opposite DNA strand, downstream of the operon, three more open reading frames, ldh, ORFA, and ORFB, were found. The deduced amino acid sequence of the first one is homologous to lactate dehydrogenases. Low-stringency Southern hybridization experiments suggest that these three open reading frames lie outside of the L. monocytogenes virulence region: mpl and actA were specific for L. monocytogenes, sequences hybridizing to plcB were detected in L. ivanovii and L. seeligeri, and sequences hybridizing to ORFX, -Y, and -Z were found in L. innocua. In contrast to this, sequences hybridizing to ldh or ORFB were detected in all Listeria species (including the nonpathogenic ones).

Production and characterization of neutralizing and nonneutralizing monoclonal antibodies against listeriolysin O

Listeriolysin O (LLO) is a thiol-activated toxin secreted by the facultative intracellular pathogen Listeria monocytogenes. LLO is essential for the survival of the bacterium in the infected cell because it promotes lysis of the phagosome membrane and escape of the bacterium into the cytosol. LLO was used as an antigen for the production of nine monoclonal antibodies (MAbs) in mice. Three of these could inhibit the hemolytic activity of LLO. One of them inhibited binding of LLO to erythrocyte membranes. The two other antibodies blocked the activity of LLO at a step subsequent to membrane binding. Only two of the nine MAbs recognized three other purified SH-activated toxins, streptolysin O, alveolysin, and pneumolysin. Western blot (immunoblot) analysis of culture supernatants of Listeria ivanovii and Listeria seeligeri, two hemolytic species of the genus Listeria, revealed that two MAbs recognized ivanolysin and seeligerolysin. The latter was also recognized by two other MAbs, including one of the neutralizing antibodies. MAbs raised against a peptide, ECTG LAWEWWR, present in all thiol-activated toxins sequenced to date, recognized all toxins and were not neutralizing. Taken together, these results demonstrate the existence of regions important for hemolytic activity that are unique to hemolysins of the genus Listeria and show that regions outside the conserved peptide are important for activity of LLO.

Antibody levels and in vitro lymphoproliferative responses to Streptococcus pyogenes erythrogenic toxin A and mitogen of patients with rheumatic fever

We investigated the in vitro lymphoproliferative responses to a streptococcal mitogen and erythrogenic toxin A of children with acute rheumatic fever (ARF) and patients with chronic rheumatic heart disease (CRHD). Antibody levels to the streptococcal products were also analyzed in the sera of those with ARF or chronic rheumatic heart disease as well as in the sera of children with streptococcal pharyngitis or poststreptococcal glomerulonephritis. Our results demonstrated that the individuals had depressed lymphoproliferative responses during the active stage of rheumatic fever. The depressed responses were not found either to be induced by time-sensitive mitogen-specific suppressor cells or to be related to a dose-response phenomenon. On the other hand, antibody levels to the extracellular mitogens were significantly elevated in the sera of children with ARF compared with the levels in the rest of the groups. The hyperresponsiveness noted among children with ARF was found to be at a quantitative level and was not due to recognition of more epitopes, as determined by Western blotting (immunoblotting). The profile of immune responsiveness in children with ARF to the streptococcal extracellular mitogens is discussed in relation to the pathogenesis of disease.

Purification and characterization of an extracellular 29-kilodalton phospholipase C from Listeria monocytogenes

We purified and characterized an extracellular phospholipase produced by Listeria monocytogenes. This enzyme was separated as a homogeneous protein of 29 kDa by chromatography on DEAE-52 cellulose and Bio-Gel P100 columns. It is a zinc-dependent phospholipase C (PLC) that is mainly active at pH 6 to 7 and expresses lecithinase activity and a weaker sphingomyelinase activity. The exoenzyme also hydrolyzed phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, and sphingomyelin but not phosphatidylinositol. It was distinct from the 36-kDa phosphatidylinositol PLC produced by L. monocytogenes and from the L. ivanovii sphingomyelinase. The pure protein expressed a weak, calcium-independent hemolytic activity and was not toxic in mice. Western immunoblot analysis using a rabbit immune serum raised against the enzyme showed that all virulent strains of L. monocytogenes tested produced in the culture supernatant a 29-kDa PLC. In contrast, no proteins antigenically related to the 29-kDa PLC were detected in supernatants of L. ivanovii, L. seeligeri, L. innocua, or L. welshimeri. The role in virulence of the 29-kDa PLC specifically produced by L. monocytogenes remains to be established.

Identification of a new operon involved in Listeria monocytogenes virulence: its first gene encodes a protein homologous to bacterial metalloproteases

The region flanking the transposon in a Tn1545-induced lecithinase-negative mutant of Listeria monocytogenes EGD was cloned and sequenced. The transposon had inserted in ORF D, the open reading frame previously identified downstream from hlyA, the gene encoding listeriolysin O. The complete sequence of ORF D from strain EGD has been determined as well as that of two other strains: LO28, a clinical isolate; and LM8, an epidemic strain. ORF D is 1,533 bp long and encodes a protein highly homologous to metalloproteases of bacilli, Serratia sp., Legionella pneumophila, and Pseudomonas aeruginosa. It was renamed prtA. Northern RNA blot analysis indicated that prtA is the first gene of a 6-kb operon, suggesting that the lecithinase-negative phenotype of the mutant might be due to a polar effect of the transposon insertion.

Alveolysin, the thiol-activated toxin of Bacillus alvei, is homologous to listeriolysin O, perfringolysin O, pneumolysin, and streptolysin O and contains a single cysteine

The gene coding for alveolysin, the thiol-activated toxin produced by Bacillus alvei, has been cloned by means of an oligonucleotide based on the known N-terminal sequence of the secreted protein. The complete nucleotide sequence of the gene has been determined. The deduced amino acid sequence of alveolysin shows that alveolysin shares homologies with listeriolysin O, perfringolysin O, pneumolysin, and streptolysin O. Alveolysin, like the other members of the family, contains a single cysteine in the conserved peptide sequence ECTGLA WEWWR.

Detection of anti-listeriolysin O for serodiagnosis of human listeriosis

To see whether detection of antibodies against listeriolysin O (LLO) could be used to diagnose human listeriosis, sera from 28 patients infected with Listeria monocytogenes and 101 controls were tested by dot-blot titration with purified LLO. 27 patients (96.4%) with listeriosis produced specific anti-LLO. Anti-LLO was detected in 8 (15.6%) of 51 healthy controls and in 6 (12.0%) of 50 controls who had various bacterial, fungal, and viral infections. Anti-LLO titres did not exceed 100 in these two control groups. Anti-LLO could be detected soon after clinical onset of listeriosis, and antibodies persisted for at least several months. This test might be useful for epidemiological surveys and for serodiagnosis of listeriosis, especially when bacteria cannot be isolated.

Interaction of staphylococcal delta-toxin and synthetic analogues with erythrocytes and phospholipid vesicles. Biological and physical properties of the amphipathic peptides

Staphylococcal delta-toxin, a 26-residue amphiphilic peptide is lytic for cells and phospholipid vesicles and is assumed to insert as an amphipathic helix and oligomerize in membranes. For the first time, the relationship between these properties and toxin structure is investigated by means of eight synthetic peptides, one identical in sequence to the natural toxin, five 26-residue analogues and two shorter peptides corresponding to residues 1-11 and 11-26. These peptides were designed by the Edmundson wheel axial projection in order to maintain: (a) the hydrophilic/hydrophobic balance while rationalizing the sequence, (b) the alpha-helical configuration and (c) the common epitopic structure. The fluorescence of the single Trp residue was used to monitor the behaviour of the natural toxin and analogues. All 26-residue analogues were hemolytically active although to a lesser extent than natural toxin. The peptide of residues 11-26 bound lipids weakly and was hemolytic at high concentration. The peptide of residues 1-11 did not bind lipids and was hemolytically inactive. All peptides except the latter cross-reacted in immunoprecipitation tests with the natural toxin. The study of a 26-residue analogue by circular dichroism revealed an alpha-helical configuration in both the free and lipid-bound state. Changes in the fluorescence of the peptides in the presence of lipid micelles and bilayers varied according to the position of the reporter group. When bound to lipids, Trp5, Trp16 and the Fmoc-1 positions of the analogues became buried while Trp15 of the natural toxin and its synthetic replicate remained more exposed. All changes are rationalized by the proposal of an amphipathic helix whose hydrophobic face is embedded within the apolar core of bilayers while the hydrophilic and charged face remains more exposed to solvent.

Production of thiol-dependent haemolysins by Listeria monocytogenes and related species

Twenty-six strains belonging to the five main species of the genus Listeria were examined for production of thiol-dependent exotoxins. All strains of L. monocytogenes cultured in charcoal-treated broth secreted a haemolytic factor at a level ranging from 200 to 800 haemolytic units (HU) ml-1, except for the strain EGD (1500 HU ml-1) and the type strain CIP 82110T (10 HU ml-1). The haemolytic activity reached a maximum level by 8-10 h and then rapidly declined as soon as bacterial exponential growth ceased. The titres of haemolytic activity were markedly reduced when bacteria were grown in charcoal-untreated broth. The haemolytic factor produced by L. monocytogenes strains was characterized as listeriolysin O (Mr about 60,000), a member of the group of thiol-dependent exotoxins. Strains of Listeria ivanovii also produced high levels of thiol-dependent exotoxin (about 2500 HU ml-1), in both charcoal-treated and untreated broth. Small amounts of haemolytic factor (about 9-30 HU ml-1) were also produced by Listeria seeligeri in charcoal-treated broth. The haemolysin produced by L. seeligeri was identified for the first time as a thiol-dependent exotoxin of Mr about 60,000, antigenically related to listeriolysin O. As expected, we failed to detect thiol-dependent exotoxin in the two nonhaemolytic species, Listeria innocua and Listeria welshimeri.

Molecular cloning and characterization of Bacillus alvei thiol-dependent cytolytic toxin expressed in Escherichia coli

A chromosomal DNA fragment from Bacillus alvei, encoding a thiol-dependent haemolytic product known as alveolysin (Mr 60,000, pI 5.0) was cloned in Escherichia coli SK1592, using pBR322 as the vector plasmid. Only a single haemolysin-positive clone was identified, by testing for haemolysis on blood agar plates. The haemolytic material was associated with the host bacterial cell. It was released by ultrasonic disruption and purified 267-fold. A 64 kDa polypeptide of pI 8.2 cofractionated with haemolytic activity during gel filtration chromatography and isoelectric focusing. It behaved identically to alveolysin in its activation by thiols, inactivation by thiol group reagents, inhibition by cholesterol, and neutralization, immunoprecipitation and immunoblotting by immune sera raised against alveolysin and streptolysin O.

Expression in Escherichia coli and sequence analysis of the listeriolysin O determinant of Listeria monocytogenes

To evaluate the role of hemolysin production in the virulence of Listeria monocytogenes, we have undertaken the analysis of the chromosomal region containing hlyA, the gene coding for listeriolysin O. A recombinant cosmid, conferring a hemolytic phenotype to Escherichia coli, was shown to express listeriolysin O, by immunoblotting with a specific antiserum against listeriolysin O. The presence of hlyA on the cosmid was demonstrated by DNA hybridization with a probe previously shown to contain part of hlyA. The complete nucleotide sequence of hlyA has been determined. The deduced protein sequence reveals the presence of a putative 25-amino-acid signal sequence: the secreted form of listeriolysin O would have 504 amino acids, in agreement with the molecular weight of purified listeriolysin O (58,000). The protein sequence is highly homologous to those of streptolysin O and pneumolysin. A peptide of 11 amino acids conserved in the three proteins contains the unique cysteine known to be essential for lytic activity. By DNA-DNA hybridization, the listeriolysin O gene was detected in all L. monocytogenes strains tested, even in the nonhemolytic type strain. The gene was absent in other species of the genus Listeria.

Identification of the structural gene encoding the SH-activated hemolysin of Listeria monocytogenes: listeriolysin O is homologous to streptolysin O and pneumolysin

By immunoblotting with an antiserum raised against purified listeriolysin O, we have detected the presence of a truncated protein of 52 kilodaltons in culture supernatants of a Tn1545-induced nonhemolytic mutant of Listeria monocytogenes (J.L. Gaillard, P. Berche, and P. Sansonetti, Infect. Immun. 52:50-55, 1986). The region of insertion of the transposon has been cloned and sequenced. The transposon had inserted in an open reading frame the listeriolysin O gene. The deduced amino acid sequence of this open reading frame revealed that listeriolysin O is homologous to streptolysin O and pneumolysin, although homologies were not detectable at the DNA level.

T cell recognition of listeriolysin O is induced during infection with Listeria monocytogenes

During bacterial multiplication, Listeria monocytogenes (strain EGD) secretes sulfhydryl-dependent cytotoxin, termed listeriolysin O, a virulence factor presumable promoting intracellular growth of this ubiquitous pathogen. The role of this exotoxin in the process of T cell activation was studied in vivo during the course of an experimental infection in the mouse. By using highly purified listeriolysin O, it was found that infection with viable, replicative bacteria induced in vivo the emergence of T cells specifically reacting against this exotoxin, as demonstrated by eliciting the expression of delayed-type hypersensitivity to listeriolysin O in Listeria-immune mice. The kinetics of this inflammatory reaction followed the same pattern as that observed with crude Listeria antigenic preparation classically used for the detection of delayed-type hypersensitivity, with a peak of expression by day 6 and a slow decline over the next 3 wk to a residual level, indicating the presence of memory T cells reacting with the exotoxin. This result, therefore, allowed us to identify for the first time that a pure immunogenic molecule secreted by L. monocytogenes is specifically recognized by sensitized T cells induced during the course of infection by L. monocytogenes. The expression of T cell-mediated immunity to listeriolysin O was generated by very low amounts of replicative bacteria, indicating that the exotoxin released in host tissues during the process of intracellular growth is highly immunogenic. Our data favor the view that the binding of listeriolysin O to the membrane cholesterol might be a critical event potentiating the in vivo expression of delayed sensitivity against this exotoxin. Indeed, the insertion of listeriolysin O into the cell membrane induced resistance to enzymatic proteolysis and membrane-bound listeriolysin O was significantly more effective in inducing delayed inflammatory reaction in Listeria-immune mice.

T cell recognition of listeriolysin O is induced during infection with Listeria monocytogenes

During bacterial multiplication, Listeria monocytogenes (strain EGD) secretes sulfhydryl-dependent cytotoxin, termed listeriolysin O, a virulence factor presumable promoting intracellular growth of this ubiquitous pathogen. The role of this exotoxin in the process of T cell activation was studied in vivo during the course of an experimental infection in the mouse. By using highly purified listeriolysin O, it was found that infection with viable, replicative bacteria induced in vivo the emergence of T cells specifically reacting against this exotoxin, as demonstrated by eliciting the expression of delayed-type hypersensitivity to listeriolysin O in Listeria-immune mice. The kinetics of this inflammatory reaction followed the same pattern as that observed with crude Listeria antigenic preparation classically used for the detection of delayed-type hypersensitivity, with a peak of expression by day 6 and a slow decline over the next 3 wk to a residual level, indicating the presence of memory T cells reacting with the exotoxin. This result, therefore, allowed us to identify for the first time that a pure immunogenic molecule secreted by L. monocytogenes is specifically recognized by sensitized T cells induced during the course of infection by L. monocytogenes. The expression of T cell-mediated immunity to listeriolysin O was generated by very low amounts of replicative bacteria, indicating that the exotoxin released in host tissues during the process of intracellular growth is highly immunogenic. Our data favor the view that the binding of listeriolysin O to the membrane cholesterol might be a critical event potentiating the in vivo expression of delayed sensitivity against this exotoxin. Indeed, the insertion of listeriolysin O into the cell membrane induced resistance to enzymatic proteolysis and membrane-bound listeriolysin O was significantly more effective in inducing delayed inflammatory reaction in Listeria-immune mice.

Purification, characterization, and toxicity of the sulfhydryl-activated hemolysin listeriolysin O from Listeria monocytogenes

We purified and characterized an extracellular hemolysin produced by Listeria monocytogenes. Hemolysin production was greatly enhanced by growing bacteria in resin (Chelex)-treated medium. This hemolysin was separated as a homogeneous protein of 60,000 daltons by using thiol-disulfide exchange affinity chromatography. This protein was a sulfhydryl-activated toxin, termed listeriolysin O, which shared the classical properties of other bacterial sulfhydryl-activated toxins: inhibition by very low amounts of cholesterol; activation by reducing agents and suppression of the lytic activity by oxidation; antigenic cross-reactivity with streptolysin O. However, listeriolysin O differed remarkably from the other sulfhydryl-activated toxins in that its cytolytic activity towards erythrocytes from various animal species was maximum at low pH (approximately 5.5) and was undetectable at pH 7.0. This suggests that the lytic activity of the toxin in host tissues might be better expressed in the acidic microenvironment, including macrophage phagosomes where bacteria presumably replicate. Listeriolysin O was lethal to mice (50% lethal dose of ca. 0.8 microgram) and induced a rapid inflammatory reaction when injected intradermally. These results favor the view that listeriolysin O might play a major role during intracellular replication of L. monocytogenes, ultimately promoting death of infected macrophages.

High production of the acquired immunodeficiency syndrome virus (lymphadenopathy-associated virus) by human T lymphocytes stimulated by streptococcal mitogenic toxins

Purified streptococcal mitogens (SMs) including erythrogenic exotoxin were compared with phytohemagglutinin (PHA) for their ability to sustain lymphadenopathy-associated virus (LAV) replication after the stimulation of normal human peripheral blood mononuclear cells and purified CD4+ and CD8+ T cells infected with LAV. Both SM and PHA supported LAV production in peripheral blood mononuclear and CD4+ cells but not in CD8+ cells. LAV production assessed by the assay of reverse transcriptase in cell supernatants appeared earlier after stimulation with SM and was 6- to 10-fold greater than after stimulation by PHA.

Surface properties of bacterial sulfhydryl-activated cytolytic toxins. Interaction with monomolecular films of phosphatidylcholine and various sterols

Sulfhydryl-activated cytolysins are a group of bacterial protein toxins which, in the reduced state, lyse eukaryotic cells by disruption of the cytoplasmic membrane. Cell surface cholesterol is thought to be the target of the toxins. In the present work, the monolayer technique was used to investigate the interaction of four SH-activated toxins (streptolysin 0, alveolysin , perfringolysin 0, pneumolysin ) with various lipid films as a model for studying toxin-induced membrane disruption. A surface pressure increase up to very high values was elicited by reduced toxins (approximately equal to 10 nM) on films of cholesterol, other toxin-binding 3 beta-hydroxy-sterols, thiocholesterol and cholesterol-phosphatidylcholine mixtures suggesting deformation or penetration of the films. The surface-active potency of the toxins was of the same order as that of melittin and snake cardiotoxins at similar concentrations. No pressure increase was observed on films made of pure phosphatidylcholine, lanosterol and other sterols lacking the 3 beta-OH group. Optimal efficiency was at cholesterol/phosphatidylcholine molar ratio of 1 to 1. The critical pressures for toxin interaction with phosphatidylcholine and cholesterol monolayers were 25 mN X m-1 and 45 mN X m-1 respectively. Toxin interaction with phosphatidylcholine [14C]-cholesterol films did not modify monolayer radioactivity, indicating no cholesterol desorption. No pressure increase was elicited by toxins inactivated by SH-group reagents, heating or neutralization with antibody. Toxin effect was dependent temperature and pH. The overall potency of the four toxins tested was streptolysin 0 greater than alveolysin approximately equal to perfringolysin 0 greater than pneumolysin . The monolayer system mimicked in several respects toxin interaction with eukaryotic cells.

Purified -SH-activated toxins (streptolysin O, alveolysin): New tools for determination of platelet enzyme activities

The purpose of this study was to examine the lytic effect on human platelet preparations (washed, gel-filtered and dextran-isolated) of two sulfhydryl-activated bacterial protein toxins, streptolysin 0 and and alveolysin, and to compare their efficacy with that of other disruptive procedures (freezing and thawing, ultrasonic, mechanical, or nystatin-toluene treatment) as a method for the determination of various platelet enzyme activities. The enzymes assayed were alkaline and acid phosphatases, monoamine oxidase, phenolsulfotransferase, N-acetyltransferase, hydroxyindole-O-methyltransferase, glutathione peroxidase and lactate dehydrogenase. In all cases, the lowest activities were found after freezing and thawing and/or ultrasonic disruption. The highest activities were always observed in the platelet lysates obtained after toxin, and in some instances after nystatin-toluene treatment. Intermediate values were obtained for mechanical disruption. The -SH-activated cytolysins thus appear to be appropriate and gentle tools for the assay of platelet enzymes when compared to the physical or chemical procedures generally employed.

Selective purification by thiol-disulfide interchange chromatography of alveolysin, a sulfhydryl-activated toxin of Bacillus alvei. Toxin properties and interaction with cholesterol and liposomes

Alveolysin has been purified in milligram quantities to apparent immunochemical and electrophoretic homogeneity from the supernatant culture fluid of Bacillus alvei. Purification involved ultrafiltration with concomitant molecular sieving on Amicon hollow fibers, thiol-disulfide interchange chromatography on thiopropyl-Sepharose 6B, and gel filtration on Sephacryl S-200 and Bio-Gel P-100. The purified toxin was found to be a single polypeptide chain of 582 amino acids (Mr = 63,000) free of carbohydrate, with alanine as NH2-terminal amino acid. Nonpolar amino acids accounted for 40% of the total residues. Immunochemical analysis of the precipitation curve of the toxin with anti-alveolysin immune sera indicated the presence of approximately 13 epitopes. The toxin exhibited a specific activity of 10(6) hemolytic units/mg of protein and behaved as an amphiphilic protein as inferred from charge-shift electrophoresis in a three-detergent system, suggesting the presence of substantial hydrophobic region(s). The inhibitory effects of various thiol reagents and that of cholesterol and related 3 beta-hydroxysterols with aliphatic side chains at carbon 17 indicated that alveolysin is a typical member of the group of bacterial--SH-activated toxins. The stoichiometry of cholesterol-toxin interaction was apparently equimolar. The complexes between alveolysin and [3H]cholesterol were characterized by sucrose gradient ultracentrifugation. Cholesterol-containing liposomes were disrupted by the toxin.

Two different modes of membrane damaging action by bacterial thiol-activated haemolysins

The mode of action to cause membrane damage to human diploid fibroblasts by streptolysin 0 is not typical for that of all thiol-activated cytolysins. Theta-toxin and alveolysin, on the other hand, share all properties investigated and may thus, with regard to mechanisms of membrane damaging action, constitute a subgroup among thiol-activated haemolysins.

Membrane-damaging action of alveolysin from Bacillus alvei

We investigated membrane damage to human diploid, embryonic lung fibroblasts caused by highly purified alveolysin by measuring leakage of cytoplasmic markers and uptake of various metabolites, and we observed a leakage pattern typical of SH-activated cytolysins. However, the mode of membrane interaction resembled the mode of membrane interaction of theta-toxin from Clostridium perfringens rather than that of streptolysin O in the following respects: the activity on fibroblast membranes was high compared with the activity on sheep erythrocytes; the toxin did not bind irreversibly to fibroblast cytoplasmic membranes; considerable membrane damage was caused at 0 degrees C; and inhibition of amino acid uptake occurred in the absence of significant structural membrane damage. These findings imply that data on membrane effects caused by streptolysin O cannot be related indiscriminately to other SH-activated cytolysins. With regard to the mode of membrane interaction, two apparently different groups of SH-activated cytolysins exist.

Binding of cholesterol by sulfhydryl-activated cytolysins

The binding of cholesterol by pneumolysin, alveolysin, and streptolysin O has been demonstrated. The properties of the cytolysin-cholesterol interaction parallel those of cytolysin-erythrocyte interaction in that the reaction is rapid, temperature independent, decreased at elevated pH, and shows the same specificity with respect to other related sterols. However, oxidized or p-hydroxymercuribenzoate-treated thoxin showed no decrease in cholesterol-binding activity, whereas the ability of cytolysin to bind to erythrocytes was modified by such treatment.

[Assay of human anti-exoproteins to group A streptococci by microhaemagglutination: correlation with anti-streptolysin O and various anti-enzymes (author's transl)]

A microhaemagglutination test in disposable U plates has been devised for rapid, quantitative evaluation in antistreptococcal antibodies in human sera. Fresh or freeze-dried glutaraldehyde-treated sheep erythrocytes sensitized with over fifteen extracellular proteins released by group A Streptococcus pyogenes including streptolysin O, deoxyribonucleases, hyaluronatelyase, streptokinase and nicotinamide dinucleotide glycohydrolase were used. Haemagglutination and anti-streptolysin O (ASLO) titers were determined in parallel on 434 serum specimens from 123 healthy subjects ("controls") and 311 patients with a history of supposed or evident streptococcal infection. The titration of the four above-mentioned anti-enzyme antibodies has also been made on about 100 sera from both groups. Haemagglutination titre (HT) was less than 800 in control sera. By contrast it was greater than 800 up to 12 800 in patients specimens. Very good correlation was found between HT on the one hand and ASLO or anti-SK, anti-HA and anti-NADase antibodies on the other hand. HT and anti-DNase B antibodies were less correlated. Haemagglutination titres appear to rise earlier than serological titres of conventional streptococcal antibodies. The haemagglutination test described may be particularly helpful as a rapid serologic indicator of streptococcal infections and more reliable than the titration of ASLO alone, or of any one of anti-enzyme antibodies.

[Purification of an extracellular thiol-dependent hemolysin from Bacillus alvei]

Alveolysin a sulfhydryl-dependent cytolytic extracellular protein released by Bacillus alvei has been purified by salting-out by ammonium sulfate, gel filtration, isoelectric focusing on pH gradient and chromatography on DEAE-cellulose. The purified protein after reduction by thiols (active hemolytic form) proved homogeneous by disc polyacrylamide gel electrophoresis and by gel immunodiffusion. The molecular weight was 60,000 daltons, Two molecular forms of pI 5.1 and 7.0 were detected by gel isoelectrofocusing. The toxin was lethal to the mouse. Lytic activity was inhibited by cholesterol and antistreptolysin O anstisera. Immunological cross-reaction was observed between alveolysin and streptolysin O.