Impact of treatments on fecal microbiota and fecal metabolome in symptomatic uncomplicated diverticular disease of the colon: a pilot study

Symptomatic uncomplicated diverticular disease (SUDD) affects 50% of people having diverticulosis. We performed a pilot study assessing the effect of current treatments on fecal microbiota and metabolome in SUDD. Thirteen consecutive females with SUDD were treated with a 2-week therapeutic trial of 30 g/day fiber supplementation (3 patients), 1.6 g/day of mesalazine (3 patients), 900 billion/day of probiotic mixture VivoMixx® (3 patients), or 800 mg/day of rifaximin (4 patients). Stool samples were collected at entry (T0), at the end of the 2-week therapeutic course (T1), and 30 (T2) and 60 days (T3) after the end of the therapeutic course. Real-time PCR quantified targeted microorganisms. Fecal metabolome patterns were studied by high-resolution proton NMR spectroscopy. At cumulative analysis, symptoms significantly decreased at each time point during follow-up (p less than 0.0001), and only left-lower quadrant pain increased again at T3. The overall bacterial quantity was not altered by the treatments. The amount of Akkermansia muciniphila species was significantly reduced at T1 (p=0.017) and at T2 (p=0.026), while at T3 the reduction was not significant in comparison to enrollment (p=0.090). Fecal molecular profile showed significant changes at T1 and T2, while at T3 it became similar to that of T0. Differences were found for 18 of the quantified molecules (tryptophan, phenylalanine, tyrosine, 4-hydroxyphenylacetate, urocanate, X-6.363, X-5.779, uridylate, galactose, X-4.197, threonine, sarcosine, methionine, 2-oxoisocaproate, 5-aminolevulinate, alanine, leucine, valerate). Metabolome and microbiota changed in patients with SUDD under treatment, confirming a possible role of dysbiosis/dysmetabolome in the pathology.

Biological control of vaginosis to improve reproductive health

The human vaginal microbiota plays an important role in the maintenance of a woman's health, as well as of her partner's and newborns'. When this predominantly Lactobacillus community is disrupted, decreased in abundance and replaced by different anaerobes, bacterial vaginosis (BV) may occur. BV is associated with ascending infections and obstetrical complications, such as chorioamnionitis and preterm delivery, as well as with urinary tract infections and sexually transmitted infections. In BV the overgrowth of anaerobes produces noxious substances like polyamines and other compounds that trigger the release of pro-inflammatory cytokines interleukin (IL)-1 β and IL-8. BV can profoundly affect, with different mechanisms, all the phases of a woman's life in relation to reproduction, before pregnancy, during fertilization, through and at the end of pregnancy. BV can directly affect fertility, since an ascending dissemination of the involved species may lead to tubal factor infertility. Moreover, the increased risk of acquiring sexually transmitted diseases contributes to damage to reproductive health. Exogenous strains of lactobacilli have been suggested as a means of re-establishing a normal healthy vaginal flora. Carefully selected probiotic strains can eliminate BV and also exert an antiviral effect, thus reducing viral load and preventing foetal and neonatal infection. The administration of beneficial microorganisms (probiotics) can aid recovery from infection and restore and maintain a healthy vaginal ecosystem, thus improving female health also in relation to reproductive health.

Vaginal microbiota and viral sexually transmitted diseases

Healthy vaginal microbiota is an important biological barrier to pathogenic microorganisms. When this predominantly Lactobacillus community is disrupted, decreased in abundance and replaced by different anaerobes, bacterial vaginosis (BV) may occur. BV is associated with prevalence and incidence of several sexually transmitted infections. This review provides background on BV, discusses the epidemiologic data to support a role of altered vaginal microbiota for acquisition of sexually transmitted diseases and analyzes mechanisms by which lactobacilli could counteract sexually transmitted viral infections.

Chlamydia Pneumoniae and Cardiovascular Disease in End-Stage Renal Disease Patients: An Update

Cardiovascular diseases (CVD), due to accelerated atherosclerosis, are responsible for approximately 50% of mortality in End Stage Renal Disease (ESRD) patients undergoing haemodialysis (HD). Over the last decade, Chlamydia pneumoniae, a respiratory pathogen, has been involved in the pathogenesis of atherosclerosis and several reports have suggested the association between C. pneumoniae infection and CVD in HD patients. This report reviews the contribution of C. pneumoniae infection in cardiovascular diseases in ESRD patients, in light of recent studies on cardiovascular risk factors; we hypothesize that C. pneumoniae-infection may contribute to mineral bone disorder and, consequently, vascular calcification. However, further studies are needed to define the relationship between C pneumoniae and bone and vascular disorders in HD patients.

Inhibition of herpes simplex virus type 2 by vaginal lactobacilli

The protective effect of selected vaginal Lactobacillus strains (L. brevis CD2, L. salivarius FV2, L. plantarum FV9) towards herpes simplex virus type 2 (HSV-2) infection in vitro has been analyzed. Living bacterial cells affect different steps of virus multiplication. The effect on the early phases of virus infection appeared related to the bacterial adhesive potential to the cell membrane while all the strains strongly reduced intracellular events of virus multiplication. The anti HSV-2 activity was not mediated by a virucidal effect. Instead it was exerted through bacterial soluble factors able to down regulate the production of infective virions. In fact HSV-2 yield was significantly reduced in infected cells fed with cell-free supernatants of lactobacilli grown in cell culture medium. Purified lactic acid and H(2)O(2), Lactobacillus metabolites with known antimicrobial activity, produced a dose-dependent virucidal effect. Lactic acid successfully interfered with viral intracellular antigen synthesis and both the virucidal activity and the inhibition of replication were correlated to acidic pH values. L. brevis CD2, the most active strain, does not produce H(2)O(2) and neutralized lactic acid had no effect, thus indicating that factors other than H(2)O(2) and lactic acid could be responsible for the antiviral effect.

Does hospital work constitute a risk factor for Helicobacter pylori infection?

The aim of this study was to assess whether clinical work constitutes a risk factor for Helicobacter pylori infection among employees in hospitals. The prevalence of H. pylori infection was analysed in 249 individuals employed in a university teaching hospital according to three categories of hospital workers: (A) personnel from gastrointestinal endoscopy units (N=92); (B) personnel from other hospital units with direct patient contact (N=105); and (C) staff from laboratories and other units with no direct patient contact (N=52). Stool samples from each subject were examined with a validated enzyme-linked immunosorbent assay for the presence of H. pylori antigens. A questionnaire inquiring about sociodemographic and occupational characteristics was completed by each participant. The prevalence of H. pylori infection was 37.0% in group A, 35.2% in group B and 19.2% in group C (P<0.05). Among the different healthcare categories, nurses had a significant higher prevalence of H. pylori infection (P<0.01). No significant association was found between the length of employment or exposure to oral and faecal secretions, and H. pylori infection. Hospital work involving direct patient contact seems to constitute a major risk factor for H. pylori infection compared with hospital work not involving direct patient contact.

Precision measurement of the weak mixing angle in Møller scattering

We report on a precision measurement of the parity-violating asymmetry in fixed target electron-electron (Møller) scattering: A(PV) = [-131 +/- 14(stat) +/- 10(syst)] x 10(-9), leading to the determination of the weak mixing angle sin2(thetaW(eff) = 0.2397 +/- 0.0010(stat) +/- 0.0008(syst), evaluated at Q2 = 0.026 GeV2. Combining this result with the measurements of sin2(thetaW(eff) at the Z0 pole, the running of the weak mixing angle is observed with over 6sigma significance. The measurement sets constraints on new physics effects at the TeV scale.

Observation of parity nonconservation in møller scattering

We report a measurement of the parity-violating asymmetry in fixed target electron-electron (Møller) scattering: A(PV)=[-175+/-30(stat)+/-20(syst)] x 10(-9). This first direct observation of parity nonconservation in Møller scattering leads to a measurement of the electron's weak charge at low energy Q(e)(W)=-0.053+/-0.011. This is consistent with the standard model expectation at the current level of precision: sin((2)theta(W)(M(Z))((-)MS)=0.2293+/-0.0024(stat)+/-0.0016(syst)+/-0.0006(theory).

Characterization and selection of vaginal Lactobacillus strains for the preparation of vaginal tablets

AIMS

To characterize and select Lactobacillus strains for properties that would make them a good alternative to the use of antibiotics to treat human vaginal infections.

METHODS AND RESULTS

Ten Lactobacillus strains belonging to four different Lactobacillus species were analysed for properties relating to mucosal colonization or microbial antagonism (adhesion to human epithelial cells, hydrogen peroxide production, antimicrobial activity towards Gardnerella vaginalis and Candida albicans and coaggregation with pathogens). The involvement of electrostatic interactions and the influence of bacterial metabolic state in the binding of lactobacilli to the cell surface were also studied. Adherence to epithelial cells varied greatly among the Lactobacillus species and among different strains belonging to the same Lactobacillus species. The reduction in surface negative electric charge promoted the binding of several Lactobacillus strains to the cell membrane whereas lyophilization reduced the adhesion capacity of many isolates. The antimicrobial activity of lactobacilli culture supernatant fluids was not directly related to the production of H2O2.

CONCLUSIONS

Three strains (Lactobacillus brevis CD2, Lact. salivarius FV2 and Lact. gasseri MB335) showed optimal properties and were, therefore, selected for the preparation of vaginal tablets. The selected strains adhered to epithelial cells displacing vaginal pathogens; they produced high levels of H2O2, coaggregated with pathogens and inhibited the growth of G. vaginalis.

SIGNIFICANCE AND IMPACT OF THE STUDY

The dosage formulation developed in this study appears to be a good candidate for the probiotic prophylaxis and treatment of human vaginal infections.

Technological and biological evaluation of tablets containing different strains of lactobacilli for vaginal administration

Ten strains of lactobacilli were evaluated for the administration of viable microorganisms to restore the normal indigenous flora in the treatment of urogenital tract infections (UTI) in women. As the strains considered are facultative anaerobes, optimization of the production process was particularly critical to preserve bacterial viability. The microorganisms were formulated in single- and double-layer vaginal tablets. The two layers were characterized by different release properties: one is an effervescent composition that ensures a rapid and complete distribution of the active ingredient over the whole vaginal surface; while the second is a sustained release composition capable of releasing the lactobacilli over a longer period of time. Three different retarding polymers were tested, and all the formulations and tablets were evaluated in terms of technological processability, bacterial viability and stability, and cell adhesion properties of the microorganisms. From the results obtained, three out of ten strains appear particularly suitable for their application in the treatment of UTI. A larger batch of tablets made with a mixture of the three strains was then evaluated, confirming the feasibility of their industrial production and a good bacterial viability in the final dosage form.

Synthesis and anti-rhinovirus activity of 2-styrylchromones

2-Styrylchromones were synthesized as vinylogues of 2-phenylchromones (flavones), a broad class of anti-rhinovirus compounds. The antiviral activity of 2-styrylchromones and 3-hydroxy-1-(2-hydroxyphenyl)-5-phenyl-2,4-pentadien-1-ones, which are intermediates in the synthesis, was evaluated against two selected serotypes of human rhinovirus, 1B and 14, by a plaque reduction assay in HeLa cell cultures. All of the compounds interfered with HRV 1B replication, with the exception of 3-hydroxy-1-(2-hydroxyphenyl)-5-(4-methoxyphenyl)-2,4-pentadien-1-one. The majority of derivatives were also found to be effective against serotype 14, often with a higher potency.

Synthesis and biological evaluation of 2-methoxy- and 2-methylthio-6-[2'-alkylamino)ethyl]-4(3H)-pyrimidinones with anti-rubella virus activity

The synthesis of a new family of antiviral compounds, 2-methoxy-, and 2-methylthio-6-[(2'-alkylamino)ethyl]-4(3H)-pyrimidinones, has been accomplished. The activity of these agents against positive strand (rubella virus and sindbis virus) and negative strand (vesicular stomatitis virus) RNA viruses is reported. Some of these compounds are efficient and selective inhibitors of rubella virus.

Antiviral effect of hyperthermic treatment in rhinovirus infection

Human rhinoviruses (HRV) are recognized as the major etiologic agents for the common cold. Starting from the observation that local hyperthermic treatment is beneficial in patients with natural and experimental common colds, we have studied the effect of brief hyperthermic treatment (HT) on HRV replication in HeLa cells. We report that a 20-min HT at 45 degrees C is effective in suppressing HRV multiplication by more than 90% when applied at specific stages of the virus replication cycle. Synthesis of virus proteins is not affected by HT, indicating that the target for treatment is a posttranslational event. The antiviral effect is a transient cell-mediated event and is associated with the synthesis of the 70-kDa heat shock protein hsp70. Unlike poliovirus, rhinovirus infection does not inhibit the expression of hsp70 induced by heat. The possibility that hsp70 could play a role in the control of rhinovirus replication is suggested by the fact that a different class of HSP inducers, the cyclopentenone prostaglandins PGA1 and delta 12-PGJ2, were also effective in inhibiting HRV replication in HeLa cells. Inhibition of hsp70 expression by actinomycin D prevented the antiviral activity of prostaglandins in HRV-infected cells. These results indicate that the beneficial effect of respiratory hyperthermia may be mediated by the induction of a cytoprotective heat shock response in rhinovirus-infected cells.

Anti-picornavirus activity of synthetic flavon-3-yl esters

The in vitro antiviral activity against picornaviruses (rhinovirus serotype 1B and 14, and poliovirus type 2) of new synthetic 3-hydroxyflavones, 3-acetoxyflavones, and substituted cinnamic and benzoic acid flavon-3-yl esters was evaluated. The maximum non-toxic concentration of compounds was determined in a human cell line (HeLa) suitable for the replication of the three viruses. Their antiviral potency was measured by a plaque reduction assay. Generally, rhinoviruses exhibited a higher sensitivity to the new flavonoids than poliovirus. Flavones, with sterically small substituents in position 3, showed good activity against both rhinoviruses tested. However, the introduction of bulky substituents in the same position resulted in analogues with a higher toxicity and often with a lower efficacy.

Antiviral activity of natural and semisynthetic polysaccharides on the early steps of rubella virus infection

The natural and semisynthetic carbohydrates scleroglucan, locust bean gum, tamarind gum (glyloid) and its three sulphate derivatives (GP4311, GP4327 and GP4324), glycogen and its two sulphate derivatives (GP4427 and GP4435), alginic acid and dextran sulphate, were investigated for their inhibitory effect on rubella virus (RV) infection of Vero cells. The neutral polymer scleroglucan and two highly negatively charged compounds, glyloid sulphate 4324 and dextran sulphate, had the highest inhibitory effect on RV antigen synthesis. The antiviral properties of active molecules appears to be dependent on the shape of the macromolecule and/or on the electric charge, while saccharide units play a minor role. The results indicated that polysaccharides blocked a step in virus replication subsequent to virus attachment, such as internalization and/or uncoating. Confirmation that the inhibitory activity of the compounds was directed at the early steps of RV multiplication, was that none of the polysaccharides had any effect on infection initiated by transfection of cells with RVRNA.

Inhibition of poliovirus replication by prostaglandins A and J in human cells

Cyclopentenone prostaglandins (PGs) inhibit the replication of a wide variety of enveloped DNA and RNA viruses. The antiviral activity is associated with alterations in the synthesis, maturation, and intracellular translocation of viral proteins. In the present report, we describe the effects of cyclopentenone PGs PGA1 and delta 12-PGJ2 on poliovirus (PV) replication in HeLa cells. Both PGs were found to inhibit PV replication dose dependently. Virus yield was significantly reduced at nontoxic concentrations, which did not suppress RNA or protein synthesis in uninfected or PV-infected cells. Both the pattern of PV proteins synthesized and the kinetics of viral protein synthesis and degradation appeared to be similar in PGA1-treated cells and control cells. Antiviral PGs have been shown to selectively inhibit virus protein synthesis during the replication of several viruses, including vesicular stomatitis virus (VSV), and this effect has been recently associated with the induction of a 70-kDa heat shock protein (HSP70). PGA1 and delta 12-PGJ2 were found to induce HSP70 synthesis in uninfected or VSV-infected HeLa cells. PV infection was found to inhibit PG-induced HSP70 synthesis in these cells, suggesting that the lack of ability of cyclopentenone PGs to block PV protein synthesis could be related to an impaired heat shock response in PV-infected cells. The finding that PV protein synthesis was not inhibited by PGs suggests that cyclopentenone PGs could interfere with a late event in the virus replication cycle, such as protein assembly and maturation of PV virions.

Pathway of rubella virus infectious entry into Vero cells

The mechanism and the kinetics of rubella virus (RV) penetration into Vero cells were studied. By using pronase or acid treatment to inactivate virus which had adsorbed to cell membrane but had not been internalized, it was found that a period of 7 h was required in order for all of the adsorbed virus to enter the host cells. Lysosomotropic agents (monensin, methylamine, ammonium chloride and chloroquine) were used to study the mechanism by which RV penetrates host cells. Virus replication was inhibited if treatment of cells with these compounds was performed for at least 9 h after infection. However, if extracellular adsorbed virions were eliminated by acid treatment following removal of the lysosomotropic compounds, RV replication was completely inhibited by treatment with these drugs for any time period after adsorption. This indicated that the prolonged period of treatment with these compounds necessary to inhibit virus replication is due to the slow rate of RV internalization. None of the compounds had any effect on infection initiated by transfection of RV RNA, confirming that these drugs were exerting their inhibitory activity at penetration. The inhibition of RV replication by lysosomotropic compounds indicates that RV penetrates host cells by the endosomal pathway.

Inhibition of herpes simplex, rabies and rubella viruses by lectins with different specificities

A series of eleven lectins were investigated for their inhibiting activity towards herpes simplex type 1, rabies and rubella viruses. Herpes simplex virus adsorption was inhibited by Limulus polyphemus (LPA), Canavalia ensiformis (ConA) and wheat germ (WGA) agglutinins, whereas Bauhinia purpurea (BPA) and soybean agglutinins were more effective if present during viral replication; rabies virus attachment to susceptible cells was prevented by LPA and Narcissus pseudonarcissus (NPA) agglutinin whereas WGA and BPA were inhibitory at a later step; rubella virus multiplication was affected only after the attachment step by NPA, ConA and WGA.

Inhibition of Sindbis virus replication by cyclopentenone prostaglandins: a cell-mediated event associated with heat-shock protein synthesis

Cyclopentenone prostaglandins (PGs) have been shown to inhibit the replication of several DNA and RNA viruses. Here we report on the effect of prostaglandin A1 (PGA1) on the multiplication of a positive strand RNA virus, Sindbis virus, in Vero cells under one-step multiplication conditions. PGA1 was found to inhibit Sindbis virus production dose-dependently, and virus yield was reduced by more than 90% at the concentration of 8 micrograms/ml, which was non-toxic to the cells and did not inhibit DNA, RNA or protein synthesis in Vero cells. The cyclopentenone prostaglandin delta 12-PGJ2 was also shown to be a potent inhibitor of Sindbis virus replication. Virus-induced reduction of [3H]uridine uptake by cells was partially prevented by PGA1 treatment, which also caused a 1 h delay in the peak of virus RNA synthesis. SDS-PAGE analysis of [35S]methionine-labeled proteins showed that PGA1 moderately inhibited the synthesis of the viral structural proteins E1, E2 and C, and induced the synthesis of a 72 kDa M(r) protein, identified as a heat-shock protein related to the HSP70 group, in both virus-infected and uninfected cells. Actinomycin D treatment completely prevented PGA1-antiviral activity, indicating that a cellular product is responsible for this action. PGA1-induced HSP70 is a good candidate for this role.

Effect of electric charged molecules on Sindbis virus hemagglutination and hemolysis

The role of electrostatic interactions in the attachment and fusion at acidic pH of Sindbis virus (SNV) with goose erythrocytes was studied, investigating the effect of several anionic and cationic polyelectrolytes on SNV hemagglutination and hemolysis. In order to establish the target of active drugs, the compounds were incubated either with the virus particles or with the erythrocytes. Dextran sulfate was the only compound able to inhibit the attachment of SNV to the erythrocytes. Fusion of virus with red cells was reduced dose-dependently by the polyanions dextran sulfate, mucin and polygalacturonic acid. On the contrary two polycations, polylysine and polybrene, enhanced viral hemolytic activity. However the effect of polyions is not exclusively related to the electric charge since ineffective molecules were found in both classes of compounds.

Influence of polyions on the early steps of enterovirus infection

The influence of electric charged molecules on the early phases of enterovirus infection was studied in order to select antiviral compounds able to prevent viral attachment. The effect of different polyelectrolytes on the multiplication of coxsackie virus B3, echovirus 6 and hepatitis A virus was investigated in susceptible cells by adding the drug before, during or after the viral adsorption period. Among polyanions, the polysaccharides heparin and dextran sulfate inhibited viral infectivity, dextran sulfate being the most effective mainly towards hepatitis A virus infection. DEAE-dextran and protamine sulfate, generally recognized as enhancers of infectivity of naked and enveloped viruses, exhibited an inhibitory effect towards the three picornaviruses tested. Only in the case of hepatitis A did DEAE-dextran slightly improve viral antigen synthesis. The inhibitory effect shown by compounds belonging to positive and negative polyions suggests that the electric charge is not sufficient by itself to explain the antiviral activity of these drugs.

Effect of polyions on the early events of Sindbis virus infection of Vero cells

To clarify the role of electrostatic interactions in the binding of Sindbis virus (SNV) to cell membrane receptors, we investigated the effect of different polyions on the initial steps of infection of Vero cells by the virus. Several polyanions (mucin, heparin, polygalacturonic acid) and polycations (polylysine, protamine, polybrene) were able to reduce the replication of SNV when present in the viral adsorption period, whereas others (chondroitin sulfate, polymyxin B sulfate, histone) were devoid of any activity. Therefore the electric charge alone is not sufficient to explain the action of compounds. The effects of polyions on receptor binding, on bound virus, and on internalized virus have been examined. All the drugs inhibited SNV infection by affecting its binding to the cellular receptor. The results indicated that heparin and mucin act directly on the virus particle while polycations bind to the cell membrane receptor for the virus, protamine being effective on both targets. Since among polyanions glycosaminoglycans showed a strong inhibiting activity, the involvement of these molecules in the virus surface receptor was assessed by enzyme digestion of cell membrane with heparinase and chondroitin ABC lyase.

Role of membrane phospholipids and glycolipids in cell-to-cell fusion by VSV

To identify membrane components of CER cells interacting with vesicular stomatitis virus (VSV) during fusion at acidic pH (fusion from without, FFWO) two different approaches have been used, i.e. (i) treating the whole cells with enzymes and (ii) testing the ability of isolated membrane molecules to interfere with FFWO. Phospholipase A2 and C digestion of cells greatly reduced syncytia formation, pointing towards the involvement of lipid structures as target sites for VSV. Cell susceptibility to FFWO was also reduced after neuraminidase, beta-galactosidase or periodate treatment, suggesting that carbohydrate residues may participate in a complex receptor structure required for virus fusion. When membrane molecules were examined separately for their ability to inhibit viral FFWO, phosphatidylserine, phosphatidylinositol, sphingomyelin, cholesterol and GM3 ganglioside were found to be active, confirming the role of membrane lipid moiety in the cell surface structures involved in the early phases of VSV infection.

Electrostatic interactions in the early events of VSV infection

The importance of electrostatic interactions in the early phases of vesicular stomatitis virus (VSV) infection has been investigated in susceptible cells of different origin, human (HeLa) and avian (CER), by using some polyanions (heparin, polygalacturonic acid and mucin) and polycations (polymyxin B sulphate, poly-L-lysine, protamine, histone and polybrene). In HeLa cells, the attachment of VSV was enhanced by polymers having a positive charge and inhibited by those having a negative charge. In CER cells, all the polyanions tested reduced virus infection. Among the polycations, histone, polymyxin B sulphate and poly-L-lysine enhanced virus plaque formation while protamine and polybrene reduced virus attachment. The effect of polyions on VSV particles and on cell membrane receptors has also been investigated. The analysis of the results obtained suggest that, although electrostatic interactions play an essential role in the binding of VSV to the cell membrane, more specific structural features appear to be required for viral attachment to occur.

Effect of antibiotics on polycation-treated Escherichia coli HB101 (pRI203)

In the present paper, we demonstrated that low concentrations of various polycationic agents sensitize E. coli HB 101 harboring the plasmid pRI203, containing the Y. pseudotuberculosis invasion region, to antibiotics rifampicin, amikacin, ceftazidime and cefotaxime. These antibiotics, known to be excluded, to various degrees, by the bacterial outer membrane, resulted several-fold more active towards polycation-treated bacteria by comparison with controls. This increased permeability to antibiotics of E. coli HB 101 (pRI203) probably depends upon the binding of polycations to the acidic moieties of lipopolysaccharide, as already suggested for other gram-negative bacteria.

Effect of polyelectrolytes on entry of Escherichia coli HB101 (pRI203) into HeLa cells

The role of charged molecules in the entry mechanism of enteroinvasive bacteria was studied using Escherichia coli HB101 harboring a plasmid (pRI203) containing the Yersinia pseudotuberculosis invasion region as an experimental model. We investigated the effect of several anionic and cationic polyelectrolytes on the initial steps of infection of HeLa S3 cells by E. coli HB101 (pRI203). Experiments in which the polyions were added to cell monolayers together with bacteria showed that invasion was only slightly influenced by anions whereas cations strongly enhanced bacterial entry. DEAE-dextran, histone and poly-L-lysine were the most effective enhancers producing an up to five-fold increase in the number of both infected cells and internalized bacteria. Moreover, addition of the active polycations at different stages of infection demonstrated that their action took place during the attachment step, whereas internalization was not affected.

Role of membrane phospholipids and glycolipids in the Vero cell surface receptor for rubella virus

Membrane receptors for rubella virus (RV) in Vero cells were studied by means of two different approaches: (i) by enzyme treatment of the whole cell membrane and (ii) by testing the ability of isolated plasma membrane molecules to compete with cells for virus binding. The replication of RV was studied with both indirect immunofluorescence assay and molecular hybridization techniques. Phospholipases A2 and C digestion of cells greatly reduced the infectivity by the virus, pointing towards the involvement of lipid structures as receptor sites for RV. Furthermore, susceptibility of Vero cells to virus infection was also reduced after beta-N-acetyl-D-glucosaminidase, alpha-glucosidase and beta-galactosidase treatment, suggesting that carbohydrate residues may participate in a complex cellular receptor structure for RV. When the major membrane lipids were examined separately for their ability to inhibit viral infectivity, several phospholipids (phosphatidylserine, phosphatidylinositol, phosphatidylethanolamine, phosphatidylcholine, sphingomyelin) and glycolipids (gangliosides, lactosylceramide, cerebroside sulphate) showed a strong neutralizing activity, confirming the role of membrane lipid moiety in the cell surface receptor for RV.

Role of membrane glycosphingolipids as Pseudomonas aeruginosa adhesin receptor in rabbit bladder mucosa

The adhesiveness of a mucous strain of Pseudomonas aeruginosa to rabbit bladder mucosa was studied after preincubation of the microorganism with several glycolipids with different carbohydrate moieties to investigate their importance in the interaction with bacterial adhesins. Vesical cells were also treated with lectins (limulin and soybean) to confirm the role of saccharides as membrane receptor. The results obtained showed that galactose-containing glycolipids were able, in varying degrees, to reduce bacterial binding. The most active compounds were glycosphingolipids with negatively charged terminal groups. Lectin treatment of bladder mucosal cells confirmed the importance of galactose and sialic acid as mucosal cell membrane receptors for P. aeruginosa.

Involvement of carbohydrates in vesicular stomatitis virus-cell early interaction

The role of N-acetylneuraminic acid and N-acetyl-D-glucosamine containing molecules in vesicular stomatitis virus-cell interaction was studied using specific lectins (limulin and wheat germ agglutinin) and esoglycosidases (neuraminidase, beta-galactosidase, alpha-mannosidase, alpha-fucosidase, beta-N-acetyl-D-glucosaminidase). Lectin treatment of vesicular stomatitis virus (VSV) indicated that carbohydrates of the VSV G envelope glycoprotein were not required for virus infectivity, whereas sialic acid appeared directly involved in the attachment of virus to erythrocytes. The comparative results obtained after enzymatic digestion of cell membrane carbohydrates or their cross linking by lectins demonstrated that whereas VSV infectivity was strongly reduced by pretreatment of chick embryo cells, virus binding to erythrocytes was unaffected by such treatments. We conclude that sugar residues may participate at the host cell attachment site which differs, at least in part, from the membrane binding site of erythrocytes.

Involvement of lipids in the interaction of Sindbis virus with goose erythrocytes

The chemical nature of Sindbis virus receptors on goose erythrocytes was investigated by means of two different experimental approaches: by testing the capacity of human serum lipoproteins (HDL, LDL, VLDL) to compete with erythrocytes for virus binding and by enzymatic and chemical modifications of the cell membrane. Each class of lipoproteins was separated into its protein and lipid components which were tested for hemagglutination and hemolysis inhibiting activity. Only the lipid moieties were able to inhibit binding and fusion activities of the virus. Enzymatic treatments of the erythrocyte surface showed that sialic acid and trypsin-sensitive proteins were not involved in Sindbis virus membrane receptor and that some phospholipids probably represent important components of the cellular binding site.

Binding sites for rubella virus on erythrocyte membrane

To identify molecule(s) with the properties of rubella virus (RV) receptor, goose erythrocyte membranes were isolated and tested for their ability to complete with whole cells for viral binding and fusion. Solubilized membranes showed a dose-dependent inhibiting activity on either rubella virus attachment or its fusion with erythrocytes at acidic pH. The inhibitory activity was enhanced by trypsin and neuraminidase, and inactivated by phospholipase A2 digestion, pointing towards the involvement of lipid structures as receptor sites for RV. After isolation of the different membrane components, only the lipid moiety, specifically phospholipids and glycolipids, was found to inhibit viral biological activities. When the major membrane lipids were examined separately, phosphatidylserine and cerebroside sulfate showed a strong inhibiting activity on viral hemagglutination and subsequent hemolysis. The capacity of several pure phospholipids (phosphatidylinositol, phosphatidylcholine and sphingomyelin) to inhibit the hemolysis but not the binding of the virus to the erythrocytes indicated that different membrane lipid components are involved in the attachment and the fusion step. Enzymatic and chemical modifications of whole erythrocytes confirmed the role of membrane lipid molecules in the cell surface receptor for RV.

Adhesiveness of Pseudomonas aeruginosa to rabbit vesical mucosa effect of glycosidases on cellular binding

The adhesiveness of a mucous strain of Pseudomonas aeruginosa to rabbit bladder mucosa has been investigated after pretreatment of the vesical mucosa with different glycosidases. Using a simple apparatus the study was carried out in parallel on samples of untreated and pre-treated mucosa. The results obtained showed that the cleavage of terminal sugar by addition of neuraminidase, N-acetyl-beta-D-glucosaminidase, alpha-mannosidase, alpha-L-fucosidase and beta-galactosidase produced a decrease in the number of adhered bacteria. A more drastic enzymatic action due to the combined effect of neuraminidase + alpha-L-fucosidase and neuraminidase + beta-galactosidase produced, on the other hand, an increased adhesion of bacteria, probably due to an unmasking of new receptor sites.

Identification of lipid components of human serum lipoproteins involved in the inhibition of Sindbis virus infectivity, hemagglutination, and hemolysis

Human serum high density lipoproteins (HDL), low density lipoproteins (LDL) and very low density lipoproteins (VLDL) were isolated and tested for their ability to inhibit Sindbis virus infectivity, hemagglutination and hemolysis. VLDL and LDL produced a strong reduction on both viral infectivity on Vero cell monolayers and attachment and fusion with erythrocytes, whereas HDL appeared to be only a weak inhibitor. Lipid and protein components were extracted from each class of lipoproteins to identify the molecules responsible for the inhibiting activity. Only the lipid moiety was found to inhibit Sindbis virus biological activities. Among the individual lipid components of lipoproteins, neutral lipids (cholesterol, oleic acid and palmitic acid) and negatively charged phospholipids (phosphatidylserine and phosphatidylinositol) and glycolipids (GM 3 ganglioside and cerebroside sulphate) were able to neutralize the virus suggesting that either hydrophobic or electrostatic interactions are involved in the inhibition.

Characterization of rat brain cellular membrane components acting as receptors for vesicular stomatitis virus. Brief report

The chemical nature of the binding sites for vesicular stomatitis virus (VSV) was studied by measuring the ability of solubilized rat brain cell membranes (SRBM) to compete with cultured cells for viral binding. SRBM significantly reduced both binding and infectivity of VSV. After separation of protein and lipid components from membranes, VSV infection was unaffected by the protein fraction, whereas the lipid moiety, specifically phospholipids and glycolipids, showed a dose-dependent inhibitory effect. The essential role of phospholipid and sialic acid-containing glycolipid molecules as receptors for VSV was also suggested by the sensitivity of the inhibitory activity of SRBM and lipid components to phospholipase C and neuraminidase digestion.

Characterization of membrane components of the erythrocyte involved in vesicular stomatitis virus attachment and fusion at acidic pH

Goose erythrocyte membranes were isolated and tested for their ability to compete with red cell receptors for vesicular stomatitis virus (VSV) attachment and fusion at acidic pH. Crude membranes, solubilized with Triton X-100, Tween 80 and octyl-beta-D-glucopyranoside, showed a dose-dependent inhibitory effect on virus binding and haemolysis. The chemical nature of the active molecules was investigated by enzyme digestion and by separation of purified components. Only the lipid moiety, specifically phospholipid and glycolipid, was found to inhibit VSV attachment; a more detailed analysis of these molecules showed that phosphatidylinositol, phosphatidylserine and GM3 ganglioside were responsible for the inhibitory activity and could therefore represent VSV binding sites on goose erythrocyte membranes. Removal of negatively charged groups from these molecules by enzymic treatment significantly reduced their activity, suggesting that electrostatic interactions play an important role in the binding of VSV to the cell surface. Enzymic digestion of whole erythrocytes confirmed the involvement of membrane lipid molecules in the cell surface receptor for VSV.

Effect of concanavalin A on early interactions of Sindbis virus with goose erythrocytes and BHK 21 cells

The role of mannose containing molecules in Sindbis virus envelope glycoproteins and cell membrane receptors was investigated by means of concanavalin A (con A). Treatment of virus or BHK 21 cells with the lectin before infection reduced viral infectivity. Hemagglutination and hemolysis showed a different sensitivity to con A. Hemagglutination was not affected by the lectin and treatment of erythrocytes with con A produced an enhancement of agglutinability by the virus. Hemolytic activity was, on the contrary, strongly reduced by the lectin. The inhibition observed is due to an action on viral structures and not to an interaction with erythrocyte receptors because con A did not affect the hemolysis when preincubated with erythrocytes.

A study on the erythrocyte structures involved in the interaction with mannose-resistant E. coli adhesins

Research has been carried out on the role of different chemical groups present on human group A erythrocyte membranes and involved in the interaction with mannose-resistant (MR) adhesins of a uropathogenic E. coli strain. For this purpose several enzymes specifically acting on protein, lipid and carbohydrate components have been used to modify the erythrocyte surface structures and the effect produced by these treatments on the agglutinability of red blood cells by E. coli has been studied. Moreover different biological compounds have been tested as possible competitive inhibitors for erythrocyte receptors involved in MR agglutination by E. coli.

Activity of human serum lipoproteins on the infectivity of rhabdoviruses

The inhibiting activity of various human serum lipoprotein classes and their lipid components on the infectivity of rhabdoviruses has been studied. The research has been carried out according to different experimental procedures on both the vesicular stomatitis virus (Indiana strain), and the fixed rabies virus (CVS strain). The results obtained have shown an inhibition of the infectivity of VSV and CVS, mainly linked to the very low and low density lipoprotein classes. It has also been demonstrated that the inhibitors act directly on viruses causing a decrease in their attachment to host cells.

Receptors for BK virus on human erythrocytes

The chemical nature of BK virus receptors on human erythrocytes was investigated. Glycosidases, KIO4, proteases, phospholipases and other substances acting specifically on different structures of plasma membranes were used to ascertain the role of surface cell components in the interaction with BK virus. The results obtained indicate an analogy between BK virus receptors on red cells and non-antibody serum inhibitors active against haemagglutination by the same virus.

Separation by affinity chromatography of human very low and low density lipoproteins inhibiting Sindbis virus haemagglutination

The haemagglutination-inhibiting activity of human serum towards Sindbis virus is linked to very low and low density lipoprotein classes, in particular to their lipid component. To investigate the specific role played in this inhibition by carbohydrates contained in the molecule, inhibitor separation was carried out by Concanavalin A-Sepharose affinity chromatography. A different behaviour among the inhibiting molecules in relation to the carbohydrate content was observed. The importance of mannose for the biological activity of the inhibitor is discussed.

Capacity of staphylococci to grow in the presence of ovotransferrin or CrCl3 as a character of potential pathogenicity

A total of 150 strains of staphylococci, clinically isolated, were tested for sensitivity to ovotransferrin (conalbumin). Among these, all the 50 coagulase-positive, mannitol-positive, and deoxyribonuclease-positive staphylococci appeared to be resistant to conalbumin, i.e., capable of growing in the presence of this transferrin. Among the other 100 strains, which were not classified as S. aureus, some appeared to be resistant and some were sensitive. The different behavior toward conalbumin is related to varying degrees of efficiency of the bacterial iron transport systems and, to test this, a simple method can be used, based on the addition of CrCl3 to the culture medium. The precipitation of iron produced by chromium salts has an effect on the growth of staphylococci similar to that produced by conalbumin and reveals the differences in the iron transport systems which occur in the genus Staphylococcus.

Role of cell surface receptor mobility in concanavalin A-induced agglutination of Novikoff hepatoma and normal rat liver cells

The relationshio between Con A-receptor mobility and Con A-induced agglutination of Novikoff hepatoma and normal rat liver cells was investigated. Novikoff cells, incubated with fluorescein-labelled Con A at 3 degrees C displayed uniform, ring-like surface fluorescence. Increasing the temperature of the cells to 37 degrees C caused capping of Con A receptors in approximately 65% of the cells, a phenomenon that could be prevented by prefixing the cells with glutaraldehyde. In spite of these variations in Con A-receptor distribution, Con A-induced agglutination was remarkably constant over a temperature range from 3 to 37 degrees C. In contrast to Novikoff cells, normal hepatocytes displayed a uniform, ringlike surface fluorescence at both 3 and 37 degrees C. No capping was observed. However, hepatocytes, similar to Novikoff cells, were agglutinable by low concentrations of Con A. These findings indicate that, in this model system, Con A-induced cytoagglutination is not dependent upon long-range lateral mobility of Con A receptors. The qualitative differences in the lateral mobility of cell-surface Con A receptors of normal and malignant rat liver cells may represent a marker for neoplastioc transformation during hepatocarcinogenesis, adaptation to growth in ascitic form, or progression of a tumour to a more malignant state.

Relationship between enzymatic modifications of serum low density lipoproteins and their haemagglutination inhibiting activity towards Sindbis virus

The chemical structure of human serum low density lipoproteins (LDL) involved in the inhibition of the haemagglutination by Sindbis virus was studied. Separation of lipoproteins into their protein and lipid components demonstrated that the inhibiting activity is almost completely due to the lipid moiety. The treatment of LDL and extracted lipoprotein lipids by phospholipase A2, C and D produced different effects and in particular a marked increase in the HI titre by the action of phospholipase A2. Moreover treatment with glycosidases significantly reduced the HI titre of LDL, thus suggesting the importance of carbohydrate moiety in the inhibiting lipoprotein molecule.