Shigella flexneri cell-to-cell spread, and growth and inflammation in mice, is limited by the outer membrane protease IcsP.

The Shigella flexneri autotransporter protein IcsA is essential for intra- and intercellular spread, and icsA mutants are attenuated in several models. However, the pathogenic significance of the outer membrane protease IcsP, which orchestrates the polar distribution of IcsA on the bacterial surface, remains unclear. To further examine this point, we constructed icsP mutants in the two most commonly studied S.

Fluticasone Induces Epithelial Injury and Alters Barrier Function in Normal Subjects.

Objective: The airway epithelium has a number of roles pivotal to the pathogenesis of asthma, including provision of a physical and immune barrier to the inhaled environment. Dysregulated injury and repair responses in asthma result in loss of airway epithelial integrity. Inhaled corticosteroids are a corner stone of asthma treatment.

Impact of dynasore an inhibitor of dynamin II on Shigella flexneri infection.

Shigella flexneri remains a significant human pathogen due to high morbidity among children < 5 years in developing countries. One of the key features of Shigella infection is the ability of the bacterium to initiate actin tail polymerisation to disseminate into neighbouring cells. Dynamin II is associated with the old pole of the bacteria that is associated with F-actin tail formation.

Efficacy of a low-cost, inactivated whole-cell oral cholera vaccine: results from 3 years of follow-up of a randomized, controlled trial.

Background: Killed oral cholera vaccines (OCVs) have been licensed for use in developing countries, but protection conferred by licensed OCVs beyond two years of follow-up has not been demonstrated in randomized, clinical trials.

Methods/principal Findings: We conducted a cluster-randomized, placebo-controlled trial of a two-dose regimen of a low-cost killed whole cell OCV in residents 1 year of age and older living in 3,933 clusters in Kolkata, India. The primary endpoint was culture-proven Vibrio cholerae O1 diarrhea episodes severe enough to require treatment in a health care facility.

Conjugated linoleic acid improves airway hyper-reactivity in overweight mild asthmatics.

Background: Conjugated linoleic acids (CLA) are naturally occurring fatty acids that have multiple biological properties including the regulation of metabolic, proliferative and immune processes.

Objective: The aim of this study was to investigate the efficacy and safety of CLA as a dietary supplement in mild asthma.

Methods: This was a prospective, randomized, double-blind, placebo-controlled study.

Vibrio cholerae O139 capsular polysaccharide confers complement resistance in the absence or presence of antibody yet presents a productive target for cell lysis: implications for detection of bactericidal antibodies.

Vibrio cholerae O139 variants with different surface phenotypes have been compared for their resistance to complement and also for their susceptibility to antibody-dependent, complement-mediated bacteriolysis (ACB). While both capsular polysaccharide (CPS) and lipopolysaccharide (LPS) contribute to complement resistance in the absence of antibody, the relative survival of variants expressing only one of these surface polysaccharides reveals CPS to be of much greater significance in this respect. Variants with LPS+/CPS- or LPS-/CPS+ surface phenotypes were both susceptible to ACB, showing that antibody binding to either of the O139 polysaccharides can initiate ACB.

Immune responses following one and two doses of the reformulated, bivalent, killed, whole-cell, oral cholera vaccine among adults and children in Kolkata, India: a randomized, placebo-controlled trial.

Immune responses after one and two doses of the reformulated killed oral cholera vaccine were measured in a double-blind, randomized, placebo-controlled trial of 77 adults aged 18-40 years and 77 children aged 1-17 years residing in Kolkata, India. 65% of adults and 87% of children and 46% of adults and 82% of children exhibited a > or =4-fold rise in serum Vibrio cholerae O1 vibriocidal antibody titers from baseline following dose 1 and 2, respectively. Responses to V.

Establishment of an adult mouse model for direct evaluation of the efficacy of vaccines against Vibrio cholerae.

We describe here a new animal model that offers the prospect of using conventional adult mice for direct evaluation of the protective potential of new cholera vaccines. Pretreatment of adult mice with oral streptomycin allowed intestinal colonization by streptomycin-resistant Vibrio cholerae strains of either the O1 or the O139 serogroup. Bacteria were recovered in greatest numbers from the cecum and large intestine, but recoveries from all regions of the gut correlated significantly with bacterial excretion in fresh fecal pellets, which thus provides a convenient indicator of the extent and duration of gut colonization.

Differential immunogenicity of Vibrio cholerae O139 variants expressing different combinations of naturally occurring and atypical forms of the serogroup polysaccharide.

Field testing of an inactivated bivalent O1/O139 cholera vaccine suggests that Vibrio cholerae O1 is more immunogenic than V. cholerae O139. To investigate whether this might be partly attributable to the production of capsular polysaccharide (CPS) by O139 isolates, we have compared the immunogenicity of variant strains expressing different combinations of lipopolysaccharide (LPS) and CPS.

Murine antibody responses following systemic or mucosal immunization with viable or inactivated Vibrio cholerae.

Protocols are described for the induction of strong, consistent serum and mucosal antibody responses to Vibrio cholerae O1 or O139 lipopolysaccharide (LPS) following intranasal or oral immunization of adult mice with viable or formalin-killed bacteria. A simplified two-dose schedule for intranasal immunization has been identified, whereby viable bacteria elicit strong serum responses and, most importantly, also induce significant, sustained intestinal IgA responses. Using higher doses of bacteria it was also possible to generate consistently high intestinal and serum anti-LPS responses by the oral route.

A randomized, placebo-controlled trial of the bivalent killed, whole-cell, oral cholera vaccine in adults and children in a cholera endemic area in Kolkata, India.

Objectives: An effective vaccine against cholera has been used for public health purposes in Vietnam since the 1990s. This vaccine was reformulated to meet WHO requirements. We assessed the safety and immunogenicity of the reformulated bivalent (Vibrio cholerae 01 and 0139) killed whole cell oral vaccine in a cholera endemic area in Kolkata, India.

Wood smoke exposure induces a pulmonary and systemic inflammatory response in firefighters.

Epidemiological studies report an association between exposure to biomass smoke and cardiopulmonary morbidity. The mechanisms for this association are unclear. The aim of the present study was to characterise the acute pulmonary and systemic inflammatory effects of exposure to forest fire smoke.

Safety and immunogenicity of a reformulated Vietnamese bivalent killed, whole-cell, oral cholera vaccine in adults.

Vietnam currently produces an orally administered, bivalent (O1 and O139) killed whole-cell vaccine and is the only country in the world with endemic cholera to use an oral cholera vaccine in public health practice. In order to allow international use, the vaccine had to be reformulated to meet World Health Organization (WHO) requirements. We performed a randomized, placebo controlled, safety and immunogenicity studies of this reformulated vaccine among Vietnamese adults.

Altering the length of the lipopolysaccharide O antigen has an impact on the interaction of Salmonella enterica serovar Typhimurium with macrophages and complement.

A panel of isogenic Salmonella enterica serovar Typhimurium strains that vary only in the length of the O antigen was constructed through complementation of a wzz double mutant (displaying unregulated O-antigen length) with one of two homologous (wzzST and wzzfepE) or three heterologous (wzzO139 of Vibrio cholerae and wzzSF and wzzpHS-2 of Shigella flexneri) wzz genes. Each gene was functional in the S. enterica serovar Typhimurium host and specified production of O-antigen polymers with lengths typical of those synthesized by the donor bacteria (ranging from 2 to >100 O-antigen repeat units).

Inducible serum resistance in Salmonella typhimurium is dependent on wzz(fepE)-regulated very long O antigen chains.

Salmonella typhimurium possesses two wzz genes conferring long (wzz(ST)) and very long (wzz(fepE)) lipopolysaccharide O antigen modal chain lengths. While the long O antigen modal length was essential for complement resistance, the very long modal length was found to have a minor role. However, when grown in the presence of serum, S.

Vector-primed mice display hypo-responsiveness to foreign antigen presented by recombinant Salmonella regardless of the route of delivery.

Our previous studies have shown that mice which have been orally primed with an attenuated Salmonella vector [S. enterica serovar Stanley] are hypo-responsive to foreign antigens later delivered orally by the same vector strain, responding with significantly impaired serum and intestinal antibody responses compared with those seen in unprimed controls. Initial vector priming of the gut-associated lymphoid tissue (GALT) is likely to result in impaired persistence of recombinant Salmonella later administered orally.

Detection of antibodies to toxin-coregulated pili in sera from cholera patients.

Monoclonal antibodies (MAbs) were prepared against toxin-coregulated pili (TCP) isolated from Vibrio cholerae O1 El Tor. Despite their limited bactericidal potential, two MAbs were able to mediate biotype-specific protection against experimental cholera in infant mice. These MAbs were used in immunoblotting studies to assess seroconversion to El Tor TCP following cholera.

Vector priming reduces the immunogenicity of Salmonella-based vaccines in Nramp1+/+ mice.

The present studies in Nramp1(-/-) BALB/c and Nramp1(+/+) CBA mice question the significance of this genotype as a determinant of the level of gut colonization following oral administration of naturally attenuated or highly virulent Salmonella strains. In line with previous results in BALB/c hosts, vector priming of CBA mice with Salmonella enterica serovar Stanley was found to significantly compromise the immunogenicity of a recombinant construct expressing a foreign pilus protein.

Regulation of Salmonella typhimurium lipopolysaccharide O antigen chain length is required for virulence; identification of FepE as a second Wzz.

Wzz proteins regulate the degree of polymerization of the O antigen (Oag) subunits in lipopolysaccharide (LPS) biosynthesis. Although the pathogenic relevance of Oag is well recognized, the significance of Oag chain length regulation is not well defined. In this report, Salmonella typhimurium was shown to possess two functional wzz genes resulting in a bimodal Oag length distribution.

Impact of vector priming on the immunogenicity of recombinant Salmonella vaccines.

There are conflicting reports concerning the impact of prior vector priming on the immunogenicity of recombinant-Salmonella-based vaccines. A comparison of experimental protocols identified two variables which might account for this inconsistency: the potential of the vector strain to colonize the murine gut-associated lymphoid tissue (GALT) and the nature of the foreign antigen subsequently delivered by the recombinant Salmonella construct. The former was investigated by constructing an aroA mutant of the Salmonella enterica serovar Stanley vector previously used in our laboratory.

Cloning and characterization of a novel haemolysin in Vibrio cholerae O1 that does not directly contribute to the virulence of the organism.

A previously undescribed haemolysin, distinct from the major Vibrio cholerae O1 El Tor haemolysin, HlyA, was cloned from the O1 classical biotype strain Z17561. This novel haemolysin showed 71.5% overall similarity to the delta-thermostable direct haemolysin of Vibrio parahaemolyticus, and so it has been termed V.

Sensitive microplate assay for detection of bactericidal antibodies to Vibrio cholerae O139.

A microplate assay for the detection of bactericidal antibodies to Vibrio cholerae O139 is described. The assay is sensitive, highly reproducible, specific, and convenient to perform. It has been used to demonstrate the induction of serum bactericidal antibodies in Vietnamese recipients of an oral, inactivated, bivalent O1/O139 vaccine, as well as in Bangladeshi patients with O139 disease.

Isolation and characterization of bacteriophage-resistant mutants of Vibrio cholerae O139.

Vibrio cholerae O139 strains produce a capsule which is associated with complement resistance and is used as a receptor by bacteriophage JA1. Spontaneous JA1-resistant mutants were found to have several phenotypes, with loss of capsule and/or O-antigen from the cell surface. Determination of the residual complement resistance and infant mouse colonization potential of each mutant suggested that production of O-antigen is of much greater significance than the presence of capsular material for both of these properties.

Characterization and immunogenicity of Vibrio cholerae ghosts expressing toxin-coregulated pili.

Bacterial ghosts are attractive for use as non-living vaccines and as carriers of heterologous antigens of vaccine relevance. Ghosts were prepared from Vibrio cholerae strains of O1 or O139 serogroup after growth under culture conditions, which favor or repress the production of toxin-coregulated pili (TCP). Immunoblotting confirmed the TCP status of these V.

Susceptibility of Vibrio cholerae O139 to antibody-dependent, complement-mediated bacteriolysis.

Volunteer studies with Vibrio cholerae O1 have shown that the best correlate of a vaccine's protective efficacy is its propensity to elicit serum bactericidal responses in its recipients. Attempts to detect such responses following infection with V. cholerae O139, however, have met with varying success.