Evaluation of the Safety, Tolerability, and Immunogenicity of an Oral, Inactivated Whole-Cell Shigella flexneri 2a Vaccine in Healthy Adult Subjects.

Shigella causes high morbidity and mortality worldwide, but there is no licensed vaccine for shigellosis yet. We evaluated the safety and immunogenicity of a formalin-inactivated whole-cell Shigella flexneri2a vaccine, Sf2aWC, given orally to adult volunteers. In a double-blind, placebo-controlled trial, 82 subjects were randomized to receive three doses of vaccine in dose escalation (2.

A study of different buffers to maximize viability of an oral Shigella vaccine.

Live, whole cell killed and subunit vaccines are being developed for diarrheal diseases caused by V. cholerae, Shigella species, ETEC, and Campylobacter. Some of these vaccines can be administered orally since this route best mimics natural infection.

Combination vaccines against diarrheal diseases.

Diarrheal diseases remain a leading cause of global childhood mortality and morbidity. Several recent epidemiological studies highlight the rate of diarrheal diseases in different parts of the world and draw attention to the impact on childhood growth and survival. Despite the well-documented global burden of diarrheal diseases, currently there are no combination diarrheal vaccines, only licensed vaccines for rotavirus and cholera, and Salmonella typhi-based vaccines for typhoid fever.

Intradermal delivery of Shigella IpaB and IpaD type III secretion proteins: kinetics of cell recruitment and antigen uptake, mucosal and systemic immunity, and protection across serotypes.

Shigella is one of the leading pathogens contributing to the vast pediatric diarrheal disease burden in low-income countries. No licensed vaccine is available, and the existing candidates are only partially effective and serotype specific. Shigella type III secretion system proteins IpaB and IpaD, which are conserved across Shigella spp.

Development and preclinical evaluation of a trivalent, formalin-inactivated Shigella whole-cell vaccine.

Studies were undertaken to manufacture a multivalent Shigella inactivated whole-cell vaccine that is safe, effective, and inexpensive. By using several formalin concentrations, temperatures, and incubation periods, an optimized set of inactivation conditions was established for Shigella flexneri 2a, S. sonnei, and S.

Characterization of a novel fusion protein from IpaB and IpaD of Shigella spp. and its potential as a pan-Shigella vaccine.

Shigellosis is an important disease in the developing world, where about 90 million people become infected with Shigella spp. each year. We previously demonstrated that the type three secretion apparatus (T3SA) proteins IpaB and IpaD are protective antigens in the mouse lethal pulmonary model.

Safety and immunogenicity of a single oral dose of recombinant double mutant heat-labile toxin derived from enterotoxigenic Escherichia coli.

Enterotoxigenic Escherichia coli (ETEC) is a primary cause of traveler's diarrhea for which there is no licensed vaccine. This phase 1 trial determined the safety and immunogenicity of a recombinantly produced double mutant heat-labile enterotoxin (dmLT) of ETEC. It was administered as a single oral dose of dmLT in escalating doses of 5 μg, 25 μg, 50 μg, and 100 μg, followed by a 72-h inpatient observation, outpatient visits at 8, 14, and 28 days, and telephone calls at 2 and 6 months postvaccination.

Vaccines for enteric diseases: a meeting summary.

The 6th Vaccines for Enteric Diseases Symposium was held in Cannes, France, on 14-16 September 2011, drawing approximately 200 vaccine developers, academics and public health experts globally. Infectious diarrhea is a worldwide problem with high mortality and morbidity, particularly among children in the developing world. The WHO estimated approximately 8.

Enteric vaccines for pediatric use. Workshop summary.

Diarrheal diseases remain a major cause of death in children under 5 in less developed countries (LDCs). Vaccine development and implementation offers the best near-term approach to alleviating this problem. For this reason, a workshop to examine the possibilities for making enteric vaccines available to meet the specific needs of children in LDCs was convened in Virginia on April 24-26, 2004.

Safety and immunogenicity of an oral, inactivated, whole-cell vaccine for Shigella sonnei: preclinical studies and a Phase I trial.

Orally delivered, inactivated whole-cell vaccines are safe methods of inducing local and systemic immunity. To increase surface proteins associated with adherence and invasion, Shigella sonnei were grown in BHI broth containing deoxycholate. A whole-cell vaccine (SsWC) was then produced by formalin inactivation.

Protection of mice against brucellosis by intranasal immunization with Brucella melitensis lipopolysaccharide as a noncovalent complex with Neisseria meningitidis group B outer membrane protein.

Intranasal immunization of mice with purified Brucella melitensis lipopolysaccharide (LPS) as a noncovalent complex with Neisseria meningitidis group B outer membrane protein (GBOMP) elicited a high-titer anti-LPS systemic antibody response and a significant mucosal antibody response. The anti-LPS immunoglobulin G (IgG) antibody was predominantly of the IgG1 subtype, although there was some response of the IgG2a, IgG2b, and IgG3 subtypes. The antibody titer remained high for 16 weeks postimmunization.

Experimental gonococcal urethritis and reinfection with homologous gonococci in male volunteers.

Background: Reinfection, a common occurrence with gonorrhea, may result from a lack of protective immune response, or from the tremendous gonococcal strain variation.

Goal: A two-phase study in human volunteers tested whether experimental infection with Neisseria gonorrhoeae MS11mkC would protect against reinfection with the same organisms.

Study Design: In phase 1, an intraurethral inoculum of 57,000 piliated, transparent (opacity protein-negative [Opa-]) MS11mkC N gonorrhoeae infected 14 of 15 (93%) volunteers.

Bacteriologic and histologic features in mice after intranasal inoculation of Brucella melitensis.

Objective: To characterize effects of intranasal inoculation of virulent Brucella melitensis strain 16M in mice.

Animals: Female Balb/c mice, 6 to 8 weeks old.

Procedure: Studies were designed to elucidate gross morphologic lesions, bacterial burden in target organs, and histologic changes in tissues following experimental intranasal inoculation of mice with B melitensis 16M, which could be used to characterize a model for testing vaccine efficacy.

Protection of mice against brucellosis by vaccination with Brucella melitensis WR201(16MDeltapurEK).

Human brucellosis can be acquired from infected animal tissues by ingestion, inhalation, or contamination of the conjunctiva or traumatized skin by infected animal products. A vaccine to protect humans from occupational exposure or from zoonotic infection in areas where the disease is endemic would reduce an important cause of morbidity worldwide. Vaccines currently used in animals are unsuitable for human use.

Native and mutant forms of cholera toxin and heat-labile enterotoxin effectively enhance protective efficacy of live attenuated and heat-killed Shigella vaccines.

Both native and mutant forms of cholera toxin (CT) and heat-labile enterotoxin (LT) are effective adjuvants for antigens and killed whole-cell preparations. To determine whether these toxin molecules could also boost the immunogenicity and efficacy of live attenuated vaccines directed against shigellosis, the guinea pig keratoconjunctivitis model was used to evaluate the adjuvant effect of these toxin molecules on EcSf2a-3, a DeltavirG DeltaaroD Escherichia coli-Shigella flexneri 2a hybrid vaccine strain that was previously found to be less protective than its parent strain in the guinea pig model. Experiments using native and mutant toxin molecules showed that both CT and LT and mutant derivatives were effective as an adjuvant for EcSf2a-3 and that the mutant toxin molecules, which were developed to retain adjuvanticity without the toxicity associated with the native molecules, were as effective as the native toxin molecules as adjuvants.

Outer membrane protein of Neisseria meningitidis as a mucosal adjuvant for lipopolysaccharide of Brucella melitensis in mouse and guinea pig intranasal immunization models.

A mucosal vaccine against brucellosis consisting of the lipopolysaccharide (LPS) of Brucella melitensis complexed with the outer membrane protein (GBOMP) of group B Neisseria meningitidis was tested in small-animal models of intranasal immunization. Mice given two doses of the vaccine developed high levels of immunoglobulin G (IgG) and IgA antibodies specific for B. melitensis LPS in lung lavages and specific IgG and IgA antibody-secreting cells in the lungs and spleen.

Specificity of monoclonal antibodies elicited by mucosal infection of BALB/c mice with virulent Shigella flexneri 2a.

Protective immunity against shigellosis is thought to be determined by the O-antigen side chains of the lipopolysaccharide (LPS) molecule. To study possible common protective epitopes, monoclonal antibodies reacting with Shigella flexneri 2a LPS were generated from BALB/c mice infected ocularly with the virulent serotype 2a strain S. flexneri 2457T and tested against a panel of S.

Cross-reactivity of Shigella flexneri serotype 2a O antigen antibodies following immunization or infection.

To study the cross-reactivity pattern of Shigella flexneri 2a O-antigen antibodies, sera from humans and monkeys challenged with S. flexneri 2a, and from humans and guinea pigs immunized with a recombinant vaccine expressing serotype 2a O-antigen, were tested against a panel of lipopolysaccharide extracted from heterologous S. flexneri.

Cloning of a Brucella melitensis group 3 antigen gene encoding Omp28, a protein recognized by the humoral immune response during human brucellosis.

Brucella group 3 antigens (Ags) are outer membrane proteins (OMPs) with a molecular mass ranging from 25 to 30 kDa. The OMPs are of interest partially because of their potential use as vaccine and diagnostic reagents. We used human convalescent antibody (Ab) to clone a gene that encoded a 28-kDa protein from a lambdagt11 library of Brucella melitensis 16M genomic DNA.

Deletion of purE attenuates Brucella melitensis infection in mice.

We previously showed that a purE mutant (delta purE201) of Brucella melitensis 16M is attenuated for growth in cultured human monocytes (E. S. Drazek, H.

Sialylation lessens the infectivity of Neisseria gonorrhoeae MS11mkC.

In a human challenge experiment, the infectivity of gonococci with sialylated lipooligosaccharide (LOS) was compared with the infectivity of gonococci with unsialylated LOS. Volunteers were intraurethrally inoculated with approximately 5000 sialylated or unsialylated piliated, non-opaque (P+Opa-, transparent) colony type gonococci, strain MS11mkC. Five (83%) of 6 volunteers inoculated with unsialylated gonococci became infected; however, only 1 of 5 volunteers became infected with sialylated gonococci.

Characteristics of Shigella sonnei infection of volunteers: signs, symptoms, immune responses, changes in selected cytokines and acute-phase substances.

Shigella sonnei infection resulting from oral administration of 500 colony-forming units was followed in 11 volunteers with the objective of studying the immune response and pathogenesis. Characterization of infection included recording of signs and symptoms, excretion of S. sonnei in stool, measurement of humoral tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), interferon-gamma (IFN-gamma), C-reactive protein, IL-2 receptor, soluble CD8, antibody-antigen complexes, and endotoxin.

Antibody and cytokine responses in a mouse pulmonary model of Shigella flexneri serotype 2a infection.

A murine pulmonary model was used to study the mucosal immune response to Shigella flexneri serotype 2a infection. Inoculation of BALB/cJ mice with shigellae via the intranasal route resulted in bacterial invasion of bronchial and alveolar epithelia with concomitant development of acute suppurative bronchiolitis and subsequent development of lethal pneumonia. The pathology of pulmonary lesions resembled the colitis that characterizes shigellosis in humans and primates.

Outpatient studies of the safety and immunogenicity of an auxotrophic Escherichia coli K-12-Shigella flexneri 2a hybrid vaccine candidate, EcSf2a-2.

A phase II study was conducted in 244 volunteers at Fort Ord, CA, to determine the safety and immunogenicity of EcSf2a-2, a live, oral Shigella vaccine constructed by transfer of genes from Shigella flexneri to Escherichia coli K-12. In this placebo-controlled study, four doses of vaccine ranging from 2.3 to 9.