Extracellular Matrix Proteolysis by MT1-MMP Contributes to Influenza-Related Tissue Damage and Mortality.

Mounting an effective immune response, while also protecting tissue integrity, is critical for host survival. We used a combined genomic and proteomic approach to investigate the role of extracellular matrix (ECM) proteolysis in achieving this balance in the lung during influenza virus infection. We identified the membrane-tethered matrix metalloprotease MT1-MMP as a prominent host-ECM-remodeling collagenase in influenza infection.

Revisiting the Concept of Targeting Only Bacillus anthracis Toxins as a Treatment for Anthrax.

Protective antigen (PA)-based vaccines are effective in preventing the development of fatal anthrax disease both in humans and in relevant animal models. The Bacillus anthracis toxins lethal toxin (lethal factor [LF] plus PA) and edema toxin (edema factor [EF] plus PA) are essential for the establishment of the infection, as inactivation of these toxins results in attenuation of the pathogen. Since the toxins reach high toxemia levels at the bacteremic stages of the disease, the CDC's recommendations include combining antibiotic treatment with antitoxin (anti-PA) immunotherapy.

Efficacy of Single and Combined Antibiotic Treatments of Anthrax in Rabbits.

Respiratory anthrax is a fatal disease in the absence of early treatment with antibiotics. Rabbits are highly susceptible to infection with Bacillus anthracis spores by intranasal instillation, succumbing within 2 to 4 days postinfection. This study aims to test the efficiency of antibiotic therapy to treat systemic anthrax in this relevant animal model.

The central nervous system as target of Bacillus anthracis toxin independent virulence in rabbits and guinea pigs.

Infection of the central nervous system is considered a complication of Anthrax and was reported in humans and non-human primates. Previously we have reported that Bacillus anthracis possesses a toxin-independent virulent trait that, like the toxins, is regulated by the major virulence regulator, AtxA, in the presence of pXO2. This toxin-independent lethal trait is exhibited in rabbits and Guinea pigs following significant bacteremia and organ dissemination.

Digital cell quantification identifies global immune cell dynamics during influenza infection.

Hundreds of immune cell types work in coordination to maintain tissue homeostasis. Upon infection, dramatic changes occur with the localization, migration, and proliferation of the immune cells to first alert the body of the danger, confine it to limit spreading, and finally extinguish the threat and bring the tissue back to homeostasis. Since current technologies can follow the dynamics of only a limited number of cell types, we have yet to grasp the full complexity of global in vivo cell dynamics in normal developmental processes and disease.

Toxin-independent virulence of Bacillus anthracis in rabbits.

The accepted paradigm states that anthrax is both an invasive and toxinogenic disease and that the toxins play a major role in pathogenicity. In the guinea pig (GP) model we have previously shown that deletion of all three toxin components results in a relatively moderate attenuation in virulence, indicating that B. anthracis possesses an additional toxin-independent virulence mechanism.

Differential contribution of Bacillus anthracis toxins to pathogenicity in two animal models.

The virulence of Bacillus anthracis, the causative agent of anthrax, stems from its antiphagocytic capsule, encoded by pXO2, and the tripartite toxins encoded by pXO1. The accepted paradigm states that anthrax is both an invasive and toxinogenic disease and that the toxins play major roles in pathogenicity. We tested this assumption by a systematic study of mutants with combined deletions of the pag, lef, and cya genes, encoding protective antigen (PA), lethal factor (LF), and edema factor (EF), respectively.

The effect of deletion of the edema factor on Bacillus anthracis pathogenicity in guinea pigs and rabbits.

Bacillus anthracis secretes three major components, which assemble into two bipartite toxins: lethal toxin (LT), composed of lethal factor (LF) and protective antigen (PA) and edema toxin (ET), composed of edema factor (EF) and PA. EF is a potent calmodulin-dependent adenylate cyclase, which is internalized into the target cell following PA binding. Once inside the cell, EF elevates cAMP levels, interrupting intracellular signaling.

Lethal factor is not required for Bacillus anthracis virulence in guinea pigs and rabbits.

The major virulence factor of Bacillus anthracis is the tripartite anthrax toxin, comprising the protective antigen (PA), lethal factor (LF) and edema factor (EF). The LF of B. anthracis is a metalloprotease that has been shown to play an important role in pathogenicity.

Antibiotics cure anthrax in animal models.

Respiratory anthrax, in the absence of early antibiotic treatment, is a fatal disease. This study aimed to test the efficiency of antibiotic therapy in curing infected animals and those sick with anthrax. Postexposure prophylaxis (24 h postinfection [p.

Progress and novel strategies in vaccine development and treatment of anthrax.

The lethal anthrax disease is caused by spores of the gram-positive Bacillus anthracis, a member of the cereus group of bacilli. Although the disease is very rare in the Western world, development of anthrax countermeasures gains increasing attention due to the potential use of B. anthracis spores as a bio-terror weapon.

Involvement of TLR2 in innate response to Bacillus anthracis infection.

The involvement of TLR2 receptor in the innate response to infection with Bacillus anthracis was investigated. We studied the response to virulent or attenuated Vollum strains in either in vitro assays using macrophage cultures, or in an in vivo model comparing the sensitivity of Syrian hamster cells (expressing normal TLR2) to Chinese hamster cells (lacking functional TLR2) to infection by the various B. anthracis strains.

Protective antigen as a correlative marker for anthrax in animal models.

The most aggressive form of anthrax results from inhalation of airborne spores of Bacillus anthracis and usually progresses unnoticed in the early stages because of unspecific symptoms. The only reliable marker of anthrax is development of bacteremia, which increases with disease progress. Rapid diagnosis of anthrax is imperative for efficient treatment and cure.

Search for Bacillus anthracis potential vaccine candidates by a functional genomic-serologic screen.

Bacillus anthracis proteins that possess antigenic properties and are able to evoke an immune response were identified by a reductive genomic-serologic screen of a set of in silico-preselected open reading frames (ORFs). The screen included in vitro expression of the selected ORFs by coupled transcription and translation of linear PCR-generated DNA fragments, followed by immunoprecipitation with antisera from B. anthracis-infected animals.

Immunological correlates for protection against intranasal challenge of Bacillus anthracis spores conferred by a protective antigen-based vaccine in rabbits.

Correlates between immunological parameters and protection against Bacillus anthracis infection in animals vaccinated with protective antigen (PA)-based vaccines could provide surrogate markers to evaluate the putative protective efficiency of immunization in humans. In previous studies we demonstrated that neutralizing antibody levels serve as correlates for protection in guinea pigs (S. Reuveny et al.

The solute-binding component of a putative Mn(II) ABC transporter (MntA) is a novel Bacillus anthracis virulence determinant.

Here we describe the characterization of a lipoprotein previously proposed as a potential Bacillus anthracis virulence determinant and vaccine candidate. This protein, designated MntA, is the solute-binding component of a manganese ion ATP-binding cassette transporter. Coupled proteomic-serological screen of a fully virulent wild-type B.

Identification of strain specific markers in Bacillus anthracis by random amplification of polymorphic DNA.

Classification and differentiation of Bacillus anthracis isolates by genetic markers play an important role in anthrax research. We used a PCR based method--Random Amplification of Polymorphic DNA (RAPD)--to identify genetic markers in B. anthracis strains.

Genetic characterization and immunogenicity of coli surface antigen 4 from enterotoxigenic Escherichia coli when it is expressed in a Shigella live-vector strain.

The genes that encode the enterotoxigenic Escherichia coli (ETEC) CS4 fimbriae, csaA, -B, -C, -E, and -D', were isolated from strain E11881A. The csa operon encodes a 17-kDa major fimbrial subunit (CsaB), a 40-kDa tip-associated protein (CsaE), a 27-kDa chaperone-like protein (CsaA), a 97-kDa usher-like protein (CsaC), and a deleted regulatory protein (CsaD'). The predicted amino acid sequences of the CS4 proteins are highly homologous to structural and assembly proteins of other ETEC fimbriae, including CS1 and CS2, and to CFA/I in particular.

Immune responses elicited against multiple enterotoxigenic Escherichia coli fimbriae and mutant LT expressed in attenuated Shigella vaccine strains.

Shigella and enterotoxigenic Escherichia coli (ETEC) continue to be important causes of diarrheal disease in infants and young children in developing countries and are major etiologic agents of traveler's diarrhea. Since attenuated strains of Shigella have been developed as live oral vaccines against shigellosis, we have adapted these attenuated Shigella strains to serve as carriers of ETEC antigens, thereby constituting a hybrid vaccine. Since protective immunity against ETEC is largely directed against fimbrial antigens (of which there are multiple antigenic types), we have individually expressed four different ETEC fimbriae, including CFA/I, CS2, CS3, and CS4, using deltaguaBA attenuated Shigella vaccine strain CVD 1204 as a prototype live vector.

Postexposure prophylaxis against anthrax: evaluation of various treatment regimens in intranasally infected guinea pigs.

The efficiency of postexposure prophylaxis against Bacillus anthracis infection was tested in guinea pigs infected intranasally with either Vollum or strain ATCC 6605 spores (75 times the 50% lethal dose [LD(50)] and 87 times LD(50,) respectively). Starting 24 h postinfection, animals were treated three times per day for 14 days with ciprofloxacin, tetracycline, erythromycin, cefazolin, and trimethoprim-sulfamethoxazole (TMP-SMX). Administration of cefazolin and TMP-SMX failed to protect the animals, while ciprofloxacin, tetracycline, and erythromycin prevented death.

Efficiency of protection of guinea pigs against infection with Bacillus anthracis spores by passive immunization.

The efficacy of passive immunization as a postexposure prophylactic measure for treatment of guinea pigs intranasally infected with Bacillus anthracis spores was evaluated. Antisera directed either against the lethal toxin components (PA or LF) or against a toxinogenic strain (Sterne) were used for this evaluation. All antisera exhibited high enzyme-linked immunosorbent assay titers against the corresponding antigens, high titers of neutralization of cytotoxicity activity in an in vitro mouse macrophages cell line (J774A.