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PubMed1975

[Morphological manifestation of the action of the complement-antibody system on the surface structures of S. typhimurium].

An electron-microscopic study of the negatively-stained S. typhimurium cells from the culture subjected to the action of a specific hyperimmune antiserum in the presence of a complement (the "complement-antibody" system) pointed to increase in the population of morphological signs of cell destruction--an increase in the number of small bacterial fragments. Many cells which retained the configuration of bacterial cells also had signs of specific affection. The determining sign of specificity of the process was the presence on the surface of the great majority of the mentioned morphological types of accumulations of bacterial fragments of the stain in the form of dark stains surrounded by a lighter ring. The stains were as a rule round with the diameter of the dark zone of about 80 A. The light framing of about 30 A in width consisted of 12 subunits. A conclusion was drawn that further experimental analysis was necessary for detalization of this process and reproduction of a complete picture of bacteriolysis.

Animals↗
PubMedDate not supplied

Lysis of a temperature conditional thiamineless mutant of Salmonella typhimurium by glucose and other hexoses.

The SM-3 mutant of Salmonella typhimurium was isolated as streptomycin resistant and temperature conditional thiamine auxotroph. At 37 C it required thiamine, although it behaves as a leaky mutant at this temperature in minimal liquid medium. At 30 degrees C it was able to growth without thiamine. In minimal-glucose-aminoacids at 37 C after an initial growth, cellular lysis occurred. The same happened with other hexoses, but it was not observable when glycerol or lactate were used as carbon source. Microscopic examination showed clumps of cellular debris, empty bagshapes and swelling of microorganisms, suggesting a cell wall defect. Sucrose 0.5 M protected SM-3 cells from osmotic fragility. At 30 C growth was normal and at 37 C in presence of exogenous thiamine full growth without bacteriolysis was obtained. Preliminary experiments of bacterial conjugation allowed the identification of a new locus involved in thiamine biosynthesis which was tentatively mapped in the pur A - pro B region of the chromosomal map of S. typhimurium.

Bacteriolysis↗
PubMed1988

A synthetic peptide corresponding to the C-terminal 25 residues of phage MS2 coded lysis protein dissipates the protonmotive force in Escherichia coli membrane vesicles by generating hydrophilic pores.

The RNA phage MS2 encodes a protein, 75 amino acids long, that is necessary and sufficient for lysis of the host cell. DNA deletion analysis has shown that the lytic activity is confined to the C-terminal half of the protein. We have examined the effects of a synthetic peptide, covering the C-terminal 25 amino acids of the lysis protein, on the electrochemical potential, generated in Escherichia coli membrane vesicles and in liposomes reconstituted with cytochrome c oxidase. In all cases the peptide dissipates the electrochemical potential. The peptide also induces the release of carboxyfluorescein (376 daltons), but not of inuline (5500 daltons), from protein-free liposomes. The phenomena are observed at a lipid to peptide molar ratio of approximately 100:1. The possible connection between the dissipation of the proton-motive force and bacteriolysis is discussed.

Amino Acid Sequence↗
PubMed1993

The role of toxin-coregulated pili in the pathogenesis of Vibrio cholerae O1 El Tor.

Studies in the infant mouse cholera model have evaluated the significance of toxin-coregulated pili (TCP) in the pathogenesis of Vibrio cholerae strains of El Tor biotype. Four El Tor strains--two which produce TCP during in vitro growth and two which do not--were mutated by the insertion of an antibiotic-resistance cartridge into the tcpA gene (encoding the pilin monomer). The resulting mutants were otherwise indistinguishable from wild-type and in particular were unaltered in their sensitivity to antibody-dependent, complement-mediated bacteriolysis. All were dramatically attenuated and showed a marked impairment in terms of in vivo persistence in mixed-infection competition experiments. Virulence was restored by provision of a functional tcp operon in trans, confirming that the pathogenic potential of El Tor strains is critically dependent upon product(s) of this operon.

Animals↗
PubMed1979

Effect of leukocyte hydrolases on bacteria. XIII. Role played by leukocyte extracts, lysolecithin, phospholipase a2, lysozyme, cationic proteins, and detergents in the solubilization of lipids from Staphylococcus aureus and group A streptococci: relation to bactericidal and bacteriolytic reactions in inflammatory sites.

The bactericidal and bacteriolytic effects of lysolecithin (LL) and egg-white lysozyme (LYZ) on Staph. aureus and group A streptococci and the solubilization of phospholipids from the bacterial membranes by these agents was studied. Low concentrations of lysolecithin (1--10 microgrames/ml) are highly bactericidal for Steph. aureus and group A streptococci, but induce neither bacteriolysis nor solubilization of a substantial amount of membrane phospholipids. On the other hand, while LL at greater than 50 micrograms/ml causes substantial lipid release, a combination of LL and LYZ is absolutely needed to solubilize lipids from streptococci. This combination is, however, not bacteriolytic for this microrganism. The solubilization of lipids from staphylococci by LL is much faster than that induced in streptococci by LL + LYZ. The solubilization of the bulk of membrane lipids from staphylococci can also be achieved by Triton X-100 and by sodium lauryl sulfate and from group A streptococci by Triton X-100 plus LYZ. A variety of other detergents (e.g., Cetavlon, sodium taurocholate, cetyl pyrdinium chloride) have no lipid-releasing properties even in the presence of LYZ. The release of lipids by LYZ (in the presence of LL) from group A streptococci is related to its enzymatic activity, on a still unknown substrate, but not to its cationic nature as this muramidase cannot be replaced by a variety of cation substances (histone, polylysin, leukocyte cationic proteins, polymyxin B, and spermidine). The release of lipids from staphylococci by LL is not inhibited by a variety of anionic and cationic polyelectrocytes (heparin, liquoid, chondroitin sulfate, DNA histone, and polylysine) which markedly inhibit the release of lipids from group A streptococci by LL and LYZ. Streptococci that had been cultivated in the presence of subinhibitory concentrations of penicillin G lose their membrane phospholipids to a larger extent and by much smaller concentrations of LL and LYZ, as compared to controls, suggesting that the interference with the synthesis of the peptidoglycan increases the accessibility of the cell membrane to the lipid-releasing agents. The mechanism by which LL collaborates with LYZ in lipid release is still not known. The possible role of bacterial lipids and lyso compounds in the control of bacterial survival in inflammatory sites is briefly discussed.

Cell Membrane↗
PubMed1990

Increased risk of neisserial infections in systemic lupus erythematosus.

Survival in systemic lupus erythamatosus (SLE) continues to improve because of better ancillary care, earlier diagnosis, and earlier treatment. However, infection remains a leading cause of morbidity and mortality in this disease. Although corticosteroids and immunosuppresives increase the risk of opportunistic infection, the SLE patient is still most at risk from common bacterial pathogens. As the prototypic immune-complex disease, patients with active SLE have low circulating complement as well as a reticuloendothelial system (RES) saturated with immune complexes. It seems intuitive that SLE patients should be most at risk for organisms dependent for their removal on the RES or complement for opsonization or bacteriolysis. The current series presents four patients with SLE and disseminated neisseria infection and brings to 14 the number of patients in the literature with disseminated neisserial infection. They are typically young, female, with renal disease, and either congenital or acquired hypocomplementemia, and may present with all features of a lupus flare. Surprisingly, they are not all on corticosteroids or immunosuppressives and have some features that are unusual for non-SLE patients with these infections. There seems to be an over-representation of Nisseria meningitidis (despite potential reporting bias), and there ironically may be better tolerance with fewer fulminant complications in patients who have complement deficiencies. The best approach for the physician treating SLE is to immunize all SLE patients with available bacterial vaccines to N meningitidis and Streptococcus pneumonia, have a low threshold of suspicion for the diagnosis of disseminated neisserial or other encapsulated bacterial infection in the SLE patient who is sick, and to treat empirically with third generation cephalosporins after appropriate cultures.

Adolescent↗
PubMed1991

Oral immunization with Salmonella typhi Ty21a-based clones expressing Vibrio cholerae O-antigen: serum bactericidal antibody responses in man in relation to pre-immunization antibody levels.

Previous studies have shown that oral immunization with Salmonella typhi Ty21a-based clones expressing Vibrio cholerae O-antigen elicits serum antibody responses against the foreign polysaccharide in human volunteers. These responses are conveniently assayed by complement-dependent bacteriolysis of V. cholerae. In this report the bactericidal responses generated by two such clones are analysed in relation to the pre-immunization titres of various serum antibodies. A significant association was found, in that recipients with higher prevaccine titres of anti-V. cholerae bactericidal antibodies were less likely to register significant bactericidal responses following immunization. These results are discussed in relation to the concept of vaccine exclusion.

Administration, Oral↗
PubMedDate not supplied

Murein chemistry of cell division in Escherichia coli.

The length distribution of the glycan strands of murein has been analysed with a novel method in filamentous and spherical cells of Escherichia coli, as well as during septum formation and cell separation. A shift to the longer glycan strands was observed in the murein of furazlocillin-induced filaments. In contrast, shorter glycan strands were increased in the murein of mecillinam-induced spherical cells. During septum formation in a chain-forming envA mutant that is defective in the splitting process of the septum, a shift to the shorter glycan strands was detected that was not seen in wild type E. coli cells. It is concluded that septum-specific murein structures of rather short glycan strands are released during splitting of the septum. This intermediate material remains present in the septum of the envA mutant. The splitting process of the septum was investigated by analysing the murein during penicillin-induced bacteriolysis, which is known to take place by strictly localized murein degradation in the equatorial zone of the cell. No changes in the length distribution of the glycan strands could be detected during penicillin-induced lysis, with the exception of an increase in disaccharides, the shortest glycan strands possible. This is explained by the action of exo-muramidases progressively digesting glycan strands, leaving disaccharide units covalently linked to the remaining murein at the sites of murein cross-linkage. It is proposed that this "zipper-like" mechanism represents the normal cutting process of the septum during cell separation.

Cell Division↗
PubMed2005

Design of multifunctional peptides expressing both antimicrobial activity and shiga toxin neutralization activity.

We have designed novel short peptides expressing both antimicrobial and Shiga-toxin (Stx) neutralization activities by combining nuclear localization signal (NLS) peptides (RIRKKLR, PKKKRKV, and PRRRK) tandemly with globotriaoside (Gb3) mimic peptide (WHWTWL). These fusion peptides exhibited excellent antimicrobial activity against both gram-positive and gram-negative bacteria. A peptide WHWTWLRIRKKLR (Trp-His-Trp-Thr-Trp-Leu-Arg-Ile-Arg-Lys-Lys-Leu-Arg), especially, exhibited about 100 times higher activity than the original NLS peptide. SPR analysis demonstrated that the binding of this peptide to both Stxs was strong: K(d) = 6.6 x 10(-6) to Stx-1 and 6.8 x 10(-6) to Stx-2. The in vitro assay against Stx-1 using HeLa cells showed that this peptide increased the survival rate of HeLa cells against the infection of Stx-1. The peptide has been found to maintain high antimicrobial activity, Stx neutralization activity, and no cytotoxicity at its concentration of 7.8-31.3 microg/mL (4.2-16.7 microM). The present peptide design has a prospect of developing potent multifunctional drugs to destroy proteinaceous toxin-producing bacteria and to simultaneously neutralize the toxins released by bacteriolysis.

Amino Acid Sequence↗
PubMed2005

Characterization, organization and expression of AmphiLysC, an acidic c-type lysozyme gene in amphioxus Branchiostoma belcheri tsingtauense.

The study on lysozymes remains open in amphioxus, a cephalochordate. Here we show the existence of c-type lysozyme gene (AmphiLysC) in amphioxus, first such data in the basal chordates including urochordate and cephalochordate. This is in contrast to the absence of c-type lysozyme genes in urochordate. It is found that there exist two copies of c-type lysozyme genes in amphioxus genome, and their gene organization is similar to vertebrate c-type lysozyme genes with respect to the number and the size of both exons and introns. AmphiLysC possesses main features characteristic of the digestive c-type lysozyme such as lower number of basic amino acids (low pI values) and pH-optimum in acidic range. Moreover, AmphiLysC is predominantly expressed in the gut. These indicate that AmphiLysC is possibly a digestive c-type enzyme. However, the ubiquitous expression of AmphiLysC in non-digestive tissues such as ovaries, testes, notochord, gill and muscle suggests that it may also play a non-digestive role like antibacterial activity. It is highly likely that AmphiLysC is an enzyme with a combined function of digestion and bacteriolysis.

Amino Acid Sequence↗
PubMed1992

Medical management of ocular malakoplakia.

A 14-year-old girl had a granulomatous conjunctival lesion, proven histologically to be malakoplakia. This is the first reported case of malakoplakia arising from conjunctiva, although three others have involved the ocular adnexa. Malakoplakia is a rare disease often associated with immunodeficiency and is characterized by the presence of intracellular inclusions and organisms due to deficient intracellular bacteriolysis. Medical management is difficult because an effective antibacterial agent requires three properties: activity against the organism involved, good intracellular penetration, and the capacity to maintain its effectiveness in the intracellular milieu. Escherichia coli was isolated from a biopsy specimen and from conjunctival swabs. Treatment with systemic ciprofloxacin, which has good intracellular penetration and activity, led to rapid resolution of the lesion. This is the first report concerning the successful use of this drug to treat malakoplakia of any organ.

Adolescent↗
PubMed2000

Biological activities of antibodies elicited by lipooligosaccharide based-conjugate vaccines of nontypeable Haemophilus influenzae in an otitis media model.

Vaccination of chinchillas with nontypeable Haemophilus influenzae (NTHi) lipooligosaccharide (LOS) conjugates protected against otitis media. Correlations between the levels of conjugate-induced LOS antibodies (Abs) in sera and middle ear fluids (MEFs) and Ab-mediated biological functions and protection were examined. Following parenteral vaccination and middle ear challenge, all vaccinated animals, but none of the controls, had high titers of anti-LOS in their sera and MEFs. There was a correlation between the levels of anti-LOS IgG + M, IgG or IgA in the sera and in the MEFs (P < 0.001). An inverse correlation was found between the level of serum IgG + M and bacterial counts and between the levels of MEF Abs and bacterial counts at the early postchallenge stage (P < 0.05). Of the 39 vaccinated animals, 44% showed complete protection against otitis media, 46% (18/39) of their sera inhibited adherence of NTHi to human epithelial cells, 49% (19/39) demonstrated bactericidal activity and 49% (19/39) showed opsonophagocytic activity. In contrast, none of the controls (19) were protected, none of their sera inhibited bacterial adherence or had bactericidal activity and only 21% showed opsonophagocytosis. Our interpretation is that vaccine-induced LOS Abs transuded into the middle ear and conferred immunity to NTHi by binding to LOS of NTHi, inhibition of NTHi adherence to epithelial cells and complement-mediated bacteriolysis (or opsonophagocytosis).

Animals↗
PubMedDate not supplied

Immunity conferred upon mice by anti-LPS monoclonal antibodies in murine brucellosis.

An immune serum infused into mice prior to intravenous virulent Brucella abortus challenge may reduce initial colonization of the spleen on day 7 post-challenge and increase bacteriolysis in the spleen and liver, as evidenced on day 21. Three monoclonal antibodies (IgG1, IgG3 and IgG2a) directed toward the lipopolysaccharide-A epitope (LPS-A) of B. abortus were studied in this model and compared with three previously studied polyclonal immune sera. The three monoclonals restricted spleen infection on day 7 post-challenge and spleen and liver infections on day 21. These early and late effects were similar to those obtained with the two polyclonal sera of high anti-LPS-A titres, namely, serum from mice either infected by B. abortus or vaccinated with a cell-wall B. abortus fraction. In contrast, serum from mice vaccinated with LPS-M from B. melitensis, which had a high anti-LPS-M but a low anti-LPS-A titre, had lower activity, evidenced at day 7 only. Hence, immune serum protection was mediated by antibodies directed toward the LPS-dominant epitope of the challenge strain.

Animals↗
PubMed2001

Mechanism of complement resistance of pathogenic Borrelia burgdorferi isolates.

Borrelia burgdorferi, the causative agent of Lyme disease, differ in their susceptibility to normal human serum and are consequently classified as complement-resistant, complement-sensitive and intermediate complement-sensitive. Most isolates belonging to the genospecies B. afzelii are complement-resistant, while particularly B. garinii isolates were rapidly killed by complement. In general, isolates of the genospecies B. burgdorferi sensu stricto (s.s.) are intermediate complement-sensitive. Independent of the genospecies, all Borreliae were capable to activate the classical and/or the alternative pathway. Deposition of the activation products C3, C6, and TCC is much stronger by B. burgdorferi s.s. and B. garinii isolates than by B. afzelii isolates. The mechanism(s) on how Borreliae evade complement-mediated bacteriolysis has recently been described by showing that complement-resistant B. afzelii isolates but not the complement-sensitive B. garinii isolates absorb human complement regulators FHL-1/reconectin and factor H. Surface-attached FHL-1/reconectin maintains its complement regulatory activity and supports factor I-mediated C3b cleavage to iC3b. In complement-resistant Borreliae, two outer surface proteins, the 27.5 kDa (CRASP-1, complement regulator-acquiring surface protein 1) and the 20/21 kDa (CRASP-2), are responsible for the surface attachment of the two complement regulators. CRASP-1, which is present in complement-resistant Borreliae, binds preferentially FHL-1/reconectin while CRASP-2, which is restrictively expressed, binds preferentially factor H. Thus, complement-resistant Borreliae bind human complement regulators and control complement activation on their surface and prevent the formation of toxic activation products.

Bacterial Outer Membrane Proteins↗
PubMed1990

Antimicrobial properties of N3-(iodoacetyl)-L-2,3-diaminopropanoic acid-peptide conjugates.

Six peptide conjugates consisting of either norvaline, methionine, or lysine and N3-(iodoacetyl)-L-2,3-diaminopropanoic acid--a strong, irreversible inactivator of bacterial and fungal glucosamine-6-phosphate synthase--were synthesized and their antibacterial and antifungal activities were evaluated. Antimicrobial potencies of these peptides were correlated with their transport and cleavage rates inside the cells. Bacteriolysis of Bacillus pumilus cells and inhibition of [14C]glucose incorporation into cell-wall polysaccharides of Candida albicans as a result of glucosamine 6-phosphate inactivation were also observed. Reversal of growth inhibitory effect of these peptides by N-acetylglucosamine in bacteria and fungi suggests the effective delivery of N3-iodoacetyl-L-2,3-diaminopropanoic acid into the cell by a peptide-transport system.

Anti-Bacterial Agents↗
PubMed2002

Expression of defensin-like peptides in tick hemolymph and midgut in response to challenge with Borrelia burgdorferi, Escherichia coli and Bacillus subtilis.

Challenge of Dermacentor variabilis by hemocoel injection with Borrelia burgdorferi but not Bacillus subtilis or Escherichia coli provoked secretion of two low molecular weight peptides into the hemolymph plasma; the lower band co-migrated with a band previously identified as varisin (a tick defensin). These findings are consistent with reports that D. variabilis controls B. burgdorferi but not B. subtilis or E. coli by defensin-dependent bacteriolysis. Challenge of the tick midgut by capillary artificial feeding with bacteria also provoked expression of multiple low molecular weight peptides. In this case, however, all three bacteria elicited the response. Two bands, including the defensin-like peptide were expressed following challenge with B. subtilis and E. coli, but only the upper band following challenge with B. burgdorferi. Although they appeared intact, these spirochetes were no longer viable suggesting that borreliae in the midgut are controlled by a different method than the lytic response of the D. variabilis hemolymph. DD-RT-PCR revealed multiple mRNAs in the midgut of D. variabilis following challenge with B. burgdorferi, E. coli and Rickettsia montana. Although their identification remains to be determined, the large number of genes expressed in response to bacterial challenge presents intriguing possibilities for explaining the ability of the tick midgut to destroy invading microbes at the cellular level.

Animals↗
PubMed2001

Role and significance of the complement system in mucosal immunity: particular reference to the human breast milk complement.

The complement system plays an important role in a host's defence mechanisms, such as in immune bacteriolysis, neutralization of viruses, immune adherence, immunoconglutination and in enhancement of phagocytosis. The possible role of this important biological system in biological fluids on the mucosal surfaces, including breast milk, has however been largely neglected. Its contribution to the 'common' mucosal immunity is still enigmatic and largely speculative. Assessment of the complement system in human breast milk, which has so far largely been limited to different assays of the individual component proteins, is reviewed. A brief review of the classical and the alternative pathways of complement activation is presented. The potential physiological roles of various complement components and their activation fragments in human milk in particular, and other mucosal surfaces in general, are also presented. It was concluded that the complement system might play a complementary role to other immunological and non-immunological protective mechanisms on the mucosal surfaces.

Complement System Proteins↗
PubMed2001

Survival of Helicobacter pylori From complement lysis by binding of GPI-anchored protectin (CD59).

BACKGROUND & AIMS: Although Helicobacter pylori is sensitive to complement lysis in vitro, chronic infection persists for years. We tested whether H. pylori acquires complement resistance by binding glycolipid-tailed inhibitors from the host. METHODS: Gastric biopsy specimens from H. pylori-infected patients (n = 10) and noninfected controls (n = 6) were analyzed for complement deposition and expression of the complement regulators protectin (CD59) and DAF. Protectin binding and complement sensitivity analyses were performed with the NCTC strain 11637 (CagA(+)) and 2 clinical isolates 9:0 (CagA(+)) and 67:20 (CagA(-)). RESULTS: In the noninfected mucosa, protectin was strongly expressed on the membranes of epithelial cells, but in the infected epithelia the expression was granular and more focused to the mucus. H. pylori bacteria in the gastric pits were often positive for protectin but negative for C5b-9. An opposite pattern was seen on the surface mucosa. In vitro analyses using (125)I-CD59 and bacteriolysis assays showed that protectin bound to H. pylori and protected CagA(+) strains against complement killing. In an enzyme-linked immunosorbent assay, the binding of CD59 correlated inversely with the appearance of the C5b-9 neoantigen. CONCLUSIONS: Binding of protectin inhibits membrane attack complex assembly on H. pylori and may thereby contribute to their survival on the gastric mucosa.

Adult↗