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algk is a tpr-containing protein and the periplasmic component of a novel exopolysaccharide secretin.the opportunistic pathogen pseudomonas aeruginosa causes chronic biofilm infections in cystic fibrosis patients. during colonization of the lung, p. aeruginosa converts to a mucoid phenotype characterized by overproduction of the exopolysaccharide alginate. here we show that algk, a protein essential for production of high molecular weight alginate, is an outer membrane lipoprotein that contributes to the correct localization of the porin alge. our 2.5 a structure shows algk is composed of 9.5 t ...201020159471
the early stage of bacterial genome-reductive evolution in the host.the equine-associated obligate pathogen burkholderia mallei was developed by reductive evolution involving a substantial portion of the genome from burkholderia pseudomallei, a free-living opportunistic pathogen. with its short history of divergence (approximately 3.5 myr), b. mallei provides an excellent resource to study the early steps in bacterial genome reductive evolution in the host. by examining 20 genomes of b. mallei and b. pseudomallei, we found that stepwise massive expansion of is ( ...201020523904
epidemiology and clinical presentations of the four human coronaviruses 229e, hku1, nl63, and oc43 detected over 3 years using a novel multiplex real-time pcr method.four human coronaviruses (hcov-229e, hcov-hku1, hcov-nl63, and hcov-oc43) are associated with a range of respiratory outcomes, including bronchiolitis and pneumonia. their epidemiologies and clinical characteristics are poorly described and are often reliant on case reports. to address these problems, we conducted a large-scale comprehensive screening for all four coronaviruses by analysis of 11,661 diagnostic respiratory samples collected in edinburgh, united kingdom, over 3 years between july ...201020554810
phosphoglucomutase of yersinia pestis is required for autoaggregation and polymyxin b resistance.yersinia pestis, the causative agent of plague, autoaggregates within a few minutes of cessation of shaking when grown at 28 degrees c. to identify the autoaggregation factor of y. pestis, we performed mariner-based transposon mutagenesis. autoaggregation-defective mutants from three different pools were identified, each with a transposon insertion at a different position within the gene encoding phosphoglucomutase (pgma; y1258). targeted deletion of pgma in y. pestis kim5 also resulted in loss ...201020028810
phosphoglucomutase of yersinia pestis is required for autoaggregation and polymyxin b resistance.yersinia pestis, the causative agent of plague, autoaggregates within a few minutes of cessation of shaking when grown at 28 degrees c. to identify the autoaggregation factor of y. pestis, we performed mariner-based transposon mutagenesis. autoaggregation-defective mutants from three different pools were identified, each with a transposon insertion at a different position within the gene encoding phosphoglucomutase (pgma; y1258). targeted deletion of pgma in y. pestis kim5 also resulted in loss ...201020028810
structural determinants of substrate recognition in the had superfamily member d-glycero-d-manno-heptose-1,7-bisphosphate phosphatase (gmhb) .the haloalkanoic acid dehalogenase (had) enzyme superfamily is the largest family of phosphohydrolases. in had members, the structural elements that provide the binding interactions that support substrate specificity are separated from those that orchestrate catalysis. for most had phosphatases, a cap domain functions in substrate recognition. however, for the had phosphatases that lack a cap domain, an alternate strategy for substrate selection must be operative. one such had phosphatase, gmhb ...201020050614
neutrophil gelatinase-associated lipocalin expresses antimicrobial activity by interfering with l-norepinephrine-mediated bacterial iron acquisition.l-norepinephrine (ne) is a neuroendocrine catecholamine that supports bacterial growth by mobilizing iron from a primary source such as holotransferrin to increase its bioavailability for cellular uptake. iron complexes of ne resemble those of bacterial siderophores that are scavenged by human neutrophil gelatinase-associated lipocalin (ngal) as part of the innate immune defense. here, we show that ngal binds iron-complexed ne, indicating physiological relevance for both bacterial and human iron ...201020086155
swarming motility, secretion of type 3 effectors and biofilm formation phenotypes exhibited within a large cohort of pseudomonas aeruginosa clinical isolates.pseudomonas aeruginosa is an opportunistic gram-negative pathogen capable of acutely infecting or persistently colonizing susceptible hosts. p. aeruginosa colonizes surfaces in vitro by either biofilm formation or swarming motility. the choice of behaviour is influenced by the physical properties of the surface and specific nutrient availability, and subject to regulatory networks that also govern type 2 and type 3 protein secretion. biofilm formation by clinical isolates has been well-studied. ...201020093376
a computational genomics pipeline for prokaryotic sequencing projects.motivation: new sequencing technologies have accelerated research on prokaryotic genomes and have made genome sequencing operations outside major genome sequencing centers routine. however, no off-the-shelf solution exists for the combined assembly, gene prediction, genome annotation and data presentation necessary to interpret sequencing data. the resulting requirement to invest significant resources into custom informatics support for genome sequencing projects remains a major impediment to th ...201020519285
influenza virus coinfection with bordetella bronchiseptica enhances bacterial colonization and host responses exacerbating pulmonary lesions.influenza virus (flu) infection and secondary complications are a leading cause of morbidity and mortality worldwide. the increasing number of annual flu cases, coupled with the recent flu pandemic, has amplified concerns about the impact of flu on human and animal health. similar to humans, flu is problematic in pigs, not only as a primary pathogen but as an agent in polymicrobial pneumonia. bordetella species play a role in mixed infections and often colonize the respiratory tract without over ...201020558274
burkdiff: a real-time pcr allelic discrimination assay for burkholderia pseudomallei and b. mallei.a real-time pcr assay, burkdiff, was designed to target a unique conserved region in the b. pseudomallei and b. mallei genomes containing a snp that differentiates the two species. sensitivity and specificity were assessed by screening burkdiff across 469 isolates of b. pseudomallei, 49 isolates of b. mallei, and 390 isolates of clinically relevant non-target species. concordance of results with traditional speciation methods and no cross-reactivity to non-target species show burkdiff is a robus ...201021103048
physiological and evolutionary studies of nap systems in shewanella piezotolerans wp3.most of the shewanella species contain two periplasmic nitrate reductases (nap-α and nap-β), which is a unique feature of this genus. in the present study, the physiological function and evolutionary relationship of the two nap systems were studied in the deep-sea bacterium shewanella piezotolerans wp3. both of the wp3 nap gene clusters: nap-α (napd1a1b1c) and nap-β (napd2a2b2) were shown to be involved in nitrate respiration. phylogenetic analyses suggest that nap-β originated earlier than nap- ...201021124486
physiological and evolutionary studies of nap systems in shewanella piezotolerans wp3.most of the shewanella species contain two periplasmic nitrate reductases (nap-α and nap-β), which is a unique feature of this genus. in the present study, the physiological function and evolutionary relationship of the two nap systems were studied in the deep-sea bacterium shewanella piezotolerans wp3. both of the wp3 nap gene clusters: nap-α (napd1a1b1c) and nap-β (napd2a2b2) were shown to be involved in nitrate respiration. phylogenetic analyses suggest that nap-β originated earlier than nap- ...201021124486
species-specific and inhibitor-dependent conformations of lpxc: implications for antibiotic design.lpxc is an essential enzyme in the lipid a biosynthetic pathway in gram-negative bacteria. several promising antimicrobial lead compounds targeting lpxc have been reported, though they typically display a large variation in potency against different gram-negative pathogens. we report that inhibitors with a diacetylene scaffold effectively overcome the resistance caused by sequence variation in the lpxc substrate-binding passage. compound binding is captured in complex with representative lpxc or ...201021167751
species-specific and inhibitor-dependent conformations of lpxc: implications for antibiotic design.lpxc is an essential enzyme in the lipid a biosynthetic pathway in gram-negative bacteria. several promising antimicrobial lead compounds targeting lpxc have been reported, though they typically display a large variation in potency against different gram-negative pathogens. we report that inhibitors with a diacetylene scaffold effectively overcome the resistance caused by sequence variation in the lpxc substrate-binding passage. compound binding is captured in complex with representative lpxc or ...201021167751
the multifunctional pe_pgrs11 protein from mycobacterium tuberculosis plays a role in regulating resistance to oxidative stress.mycobacterium tuberculosis utilizes unique strategies to survive amid the hostile environment of infected host cells. infection-specific expression of a unique mycobacterial cell surface antigen that could modulate key signaling cascades can act as a key survival strategy in curtailing host effector responses like oxidative stress. we demonstrate here that hypothetical pe_pgrs11 orf encodes a functional phosphoglycerate mutase. the transcriptional analysis revealed that pe_pgrs11 is a hypoxia-re ...201020558725
alternative method of oral dosing for rats.oral administration of drugs to laboratory rodents typically is achieved by using the gavage technique. although highly effective, this method occasionally can cause esophageal injury as well as restraint-associated distress, particularly with repeated use. the aim of this study was to assess an alternative oral dosing method that could reduce the distress and morbidity associated with standard gavage techniques. the palatability and pharmacokinetic profile of 2 medicines approved for the treatm ...201020587166
antigenic variation among bordetella: bordetella bronchiseptica strain mo149 expresses a novel o chain that is poorly immunogenic.the o chain polysaccharide (o ps) of bordetella bronchiseptica and bordetella parapertussis lipopolysaccharide is a homopolymer of 2,3-diacetamido-2,3-dideoxygalacturonic acid (galnac3naca) in which some of the sugars are present as uronamides. the terminal residue contains several unusual modifications. to date, two types of modification have been characterized, and a survey of numerous strains demonstrated that each contained one of these two modification types. host antibody responses against ...201020592026
the bps polysaccharide of bordetella pertussis promotes colonization and biofilm formation in the nose by functioning as an adhesin.many respiratory pathogens establish persistent infection or a carrier state in the human nasopharynx without overt disease symptoms but the presence of these in the lungs usually results in disease. although the anatomy and microenvironments between nasopharynx and lungs are different, a virulence factor with an organ-specific function in the colonization of the nasopharynx is unknown. in contrast to the severity of pertussis and mortality in non-vaccinated young children, bordetella pertussis ...201020633227
control of biofilm formation and colonization in vibrio fischeri: a role for partner switching?bacteria employ a variety of mechanisms to promote and control colonization of their respective hosts, including restricting the expression of genes necessary for colonization to distinct situations (i.e. encounter with a prospective host). in the symbiosis between the marine bacterium vibrio fischeri and its host squid, euprymna scolopes, colonization proceeds via a transient biofilm formed by the bacterium. the production of this bacterial biofilm depends on a complex regulatory network that c ...201021966901
on the interaction of clostridium perfringens enterotoxin with claudins.clostridium perfringens causes one of the most common foodborne illnesses, which is largely mediated by the clostridium perfringens enterotoxin (cpe). the toxin consists of two functional domains. the n-terminal region mediates the cytotoxic effect through pore formation in the plasma membrane of the mammalian host cell. the c-terminal region (ccpe) binds to the second extracellular loop of a subset of claudins. claudin-3 and claudin-4 have been shown to be receptors for cpe with very high affin ...201022069641
abc transporters involved in export of cell surface glycoconjugates.complex glycoconjugates play critical roles in the biology of microorganisms. despite the remarkable diversity in glycan structures and the bacteria that produce them, conserved themes are evident in the biosynthesis-export pathways. one of the primary pathways involves representatives of the atp-binding cassette (abc) transporter superfamily. these proteins are responsible for the export of a wide variety of cell surface oligo- and polysaccharides in both gram-positive and gram-negative bacteri ...201020805402
[immunogenicity and protective efficacy of pertactin recombinants against bordetella bronchiseptica challenge].in this study we showed the immunogenicity and protective efficacy of five pertactin recombinants against bordetella bronchiseptica (bb) challenge.201021090265
does m. tuberculosis genomic diversity explain disease diversity?the outcome of tuberculosis infection and disease is highly variable. this variation has been attributed primarily to host and environmental factors, but better understanding of the global genomic diversity in the m. tuberculosis complex (mtbc) suggests that bacterial factors could also be involved. review of nearly 100 published reports shows that mtbc strains differ in their virulence and immunogenicity in experimental models, but whether this phenotypic variation plays a role in human disease ...201021076640
enantioselective protonation.enantioselective protonation is a common process in biosynthetic sequences. the decarboxylase and esterase enzymes that effect this valuable transformation are able to control both the steric environment around the proton acceptor (typically an enolate) and the proton donor (typically a thiol). recently, several chemical methods to achieve enantioselective protonation have been developed by exploiting various means of enantiocontrol in different mechanisms. these laboratory transformations have ...200920428461
dissecting the bacterial type vi secretion system by a genome wide in silico analysis: what can be learned from available microbial genomic resources?the availability of hundreds of bacterial genomes allowed a comparative genomic study of the type vi secretion system (t6ss), recently discovered as being involved in pathogenesis. by combining comparative and phylogenetic approaches using more than 500 prokaryotic genomes, we characterized the global t6ss genetic structure in terms of conservation, evolution and genomic organization.200919284603
gram-negative bacterial sensors for eukaryotic signal molecules.ample evidence exists showing that eukaryotic signal molecules synthesized and released by the host can activate the virulence of opportunistic pathogens. the sensitivity of prokaryotes to host signal molecules requires the presence of bacterial sensors. these prokaryotic sensors, or receptors, have a double function: stereospecific recognition in a complex environment and transduction of the message in order to initiate bacterial physiological modifications. as messengers are generally unable t ...200922399982
assessing the quality of whole genome alignments in bacteria.comparing genomes is an essential preliminary step to solve many problems in biology. matching long similar segments between two genomes is a precondition for their evolutionary, genetic, and genome rearrangement analyses. though various comparison methods have been developed in recent years, a quantitative assessment of their performance is lacking. here, we describe two families of assessment measures whose purpose is to evaluate bacteria-oriented comparison tools. the first measure is based o ...200920049164
effect of a novel nop receptor agonist (sch 225288) on guinea pig irritant-evoked, feline mechanically induced and canine infectious tracheobronchitis cough.previous studies have demonstrated that nociceptin/orphanin fq (n/ofq), the endogenous peptide ligand for the g-protein-coupled nop receptor, inhibits cough in experimental models. sch 225288 is a nonpeptide, orally active nop agonist that may provide the foundation for the development of novel treatments for cough.200919696521
refining timed pregnancies in two strains of genetically engineered mice.in order to efficiently generate genetically engineered mouse (gem) fetuses or neonates of a specified age range, researchers must develop strain-specific strategies, including reliable early pregnancy detection. the authors evaluated pregnancy indices (pregnancy rate, plug rate, pregnant plugged rate, first litter size and body weight) in two gem breeding colonies: homozygous soluble epoxide hydrolase knockout (sehko) mice (n=164 females) and l7-tau-green fluorescent protein (gfp) transgenic mi ...200919701181
novel calicivirus identified in rabbits, michigan, usa.we report a disease outbreak in a michigan rabbitry of a rabbit calicivirus distinct from the foreign animal disease agent, rabbit hemorrhagic disease virus (rhdv). the novel virus has been designated michigan rabbit calicivirus (mrcv). caliciviruses of the lagovirus genus other than rhdv have not been described in us rabbit populations. the case-fatality rate was 32.5% (65/200). clinical signs included hemorrhage and sudden death, with hepatic necrosis. analysis of viral rna sequence from >95% ...200919961675
norepinephrine represses the expression of toxa and the siderophore genes in pseudomonas aeruginosa.among the different extracellular virulence factors produced by pseudomonas aeruginosa are exotoxin a (eta) and the pyoverdine and pyochelin siderophores. production of eta and the siderophores requires the function of the iron-starvation sigma factor pvds, the transcriptional activator rega, and the arac-activator pchr. iron represses the production of eta and the siderophores by repressing the expression of pvds, rega, and pchr. pvds regulates the expression of the eta gene, toxa, rega, and th ...200919686346
bordetella bronchiseptica peritonitis -- beware of the dog! 200919910569
bordetella pertussis infection or vaccination substantially protects mice against b. bronchiseptica infection.although b. bronchiseptica efficiently infects a wide range of mammalian hosts and efficiently spreads among them, it is rarely observed in humans. in contrast to the many other hosts of b. bronchiseptica, humans are host to the apparently specialized pathogen b. pertussis, the great majority having immunity due to vaccination, infection or both. here we explore whether immunity to b. pertussis protects against b. bronchiseptica infection. in a murine model, either infection or vaccination with ...200919707559
molecular, antigenic, and functional characteristics of ferric enterobactin receptor cfra in campylobacter jejuni.the ferric enterobactin receptor cfra not only is responsible for high-affinity iron acquisition in campylobacter jejuni but also is essential for c. jejuni colonization in animal intestines. in this study, we determined the feasibility of targeting the iron-regulated outer membrane protein cfra for immune protection against campylobacter colonization. alignment of complete cfra sequences from 15 campylobacter isolates showed that the levels of amino acid identity for cfra range from 89% to 98%. ...200919737895
vibriobactin antibodies: a vaccine strategy.a new target strategy in the development of bacterial vaccines, the induction of antibodies to microbial outer membrane ferrisiderophore complexes, is explored. a vibriobactin (vib) analogue, with a thiol tether, 1-(2,3-dihydroxybenzoyl)-5,9-bis[[(4s,5r)-2-(2,3-dihydroxyphenyl)-4,5-dihydro-5-methyl-4-oxazolyl]carbonyl]-14-(3-mercaptopropanoyl)-1,5,9,14-tetraazatetradecane, was synthesized and linked to ovalbumin (ova) and bovine serum albumin (bsa). the antigenicity of the vib microbial iron che ...200919492834
clinical and laboratory evidence for neisseria meningitidis biofilms.neisseria meningitidis is the etiologic agent of meningococcal meningitis. carriage of the organism is approximately 10% while active disease occurs at a rate of 1:100,000. recent publications demonstrate that n. meningitidis has the ability to form biofilms on glass, plastic or cultured human bronchial epithelial cells. microcolony-like structures are also observed in histological sections from patients with active meningococcal disease. this review investigates the possible role of meningococc ...200919492966
active and passive immunizations with bordetella colonization factor a protect mice against respiratory challenge with bordetella bronchiseptica.bordetella colonization factor a (bcfa) is an outer membrane immunogenic protein, which is critical for efficient colonization of the murine respiratory tract. these properties of bcfa prompted us to examine its utility in inducing a protective immune response against bordetella bronchiseptica in a mouse model of intranasal infection. mice vaccinated with bcfa demonstrated reduced pathology in the lungs and harbored lower bacterial burdens in the respiratory tract. immunization with bcfa led to ...200919064638
safety and efficacy of neonatal vaccination.newborns have an immature immune system that renders them at high risk for infection while simultaneously reducing responses to most vaccines, thereby posing challenges in protecting this vulnerable population. nevertheless, certain vaccines, such as bcg and hepatitis b vaccine, do demonstrate safety and some efficacy at birth, providing proof of principal that certain antigen-adjuvant combinations are able to elicit protective neonatal responses. moreover, birth is a major point of healthcare c ...200919089811
microwave-assisted sample preparation for rapid and sensitive analysis of h. pylori lipid a applicable to a single colony.the lipid a of gram-negative bacteria plays a major role in the pathogenesis of bacterial infections. lipid a diversity is observed both in the number and length of fatty-acid side chains and in the presence of terminal phosphate residues and associated modifications. in this report, we describe a new sample preparation method based on microwave-assisted enzymatic digestion and detergent-free mild hydrolysis, in conjunction with a maldi-time-of-flight (tof)/tof analysis, to determine the structu ...200919401599
isolation of bordetella avium and novel bordetella strain from patients with respiratory disease.bordetella avium is thought to be strictly an avian pathogen. however, 16s rrna gene sequencing identified 2 isolates from 2 humans with respiratory disease as b. avium and a novel b. avium-like strain. thus, b. avium and b. avium-like organisms are rare opportunistic human pathogens.200919116056
oxa-143, a novel carbapenem-hydrolyzing class d beta-lactamase in acinetobacter baumannii.a carbapenem-resistant acinetobacter baumannii strain was isolated in brazil in 2004 in which no known carbapenemase gene was detected by pcr. cloning experiments, followed by expression in escherichia coli, gave an e. coli recombinant strain expressing a novel carbapenem-hydrolyzing class d beta-lactamase (chdl). oxa-143 showed 88% amino acid sequence identity with oxa-40, 63% identity with oxa-23, and 52% identity with oxa-58. it hydrolyzed penicillins, oxacillin, meropenem, and imipenem but n ...200919770279
annotating enzymes of uncertain function: the deacylation of d-amino acids by members of the amidohydrolase superfamily.the catalytic activities of three members of the amidohydrolase superfamily were discovered using amino acid substrate libraries. bb3285 from bordetella bronchiseptica, gox1177 from gluconobacter oxidans, and sco4986 from streptomyces coelicolor are currently annotated as d-aminoacylases or n-acetyl-d-glutamate deacetylases. these three enzymes are 22-34% identical to one another in amino acid sequence. substrate libraries containing nearly all combinations of n-formyl-d-xaa, n-acetyl-d-xaa, n-s ...200919518059
evidence for horizontal gene transfer of two antigenically distinct o antigens in bordetella bronchiseptica.host immunity is a major driving force of antigenic diversity, resulting in pathogens that can evade immunity induced by closely related strains. here we show that two bordetella bronchiseptica strains, rb50 and 1289, express two antigenically distinct o-antigen serotypes (o1 and o2, respectively). when 18 additional b. bronchiseptica strains were serotyped, all were found to express either the o1 or o2 serotype. comparative genomic hybridization and pcr screening showed that the expression of e ...200919528223
transcriptional and post-transcriptional regulation of the gmar antirepressor governs temperature-dependent control of flagellar motility in listeria monocytogenes.flagellar motility in listeria monocytogenes (lm) is restricted to temperatures below 37 degrees c due to the opposing activities of the mogr transcriptional repressor and the gmar antirepressor. previous studies have suggested that both the degu response regulator and mogr regulate expression of gmar. in this report, we further define the role of degu for gmar production and flagellar motility. we demonstrate that deletion of the receiver domain of degu has no effect on flagellar motility in lm ...200919796338
respiratory disease associated with bordetella bronchiseptica in a hoffmann's two-toed sloth (choloepus hoffmanni).a 2-yr-old female captive-born hoffmann's two-toed sloth (choloepus hoffmanni) presented with respiratory disease. a severe inspiratory dyspnea with nasal congestion was observed with open-mouthed breathing and bilateral mucopurulent nasal exudate. despite initial treatment with broad-spectrum antimicrobial therapy and anti-inflammatory and supportive care, the dyspnea persisted. the animal was anesthetized for bronchoscopy to obtain a deep tracheal sample. based on culture of bordetella bronchi ...200919569489
septic arthritis due to roseomonas gilardii in an immunocompetent adolescent.the genus roseomonas comprises groups of slow-growing, gram-negative coccobacilli, which only infrequently cause infection in humans. when identified, they are associated with immunocompromised adults, often causing bacteraemia. due to their rarity, members of this genus can be overlooked or misidentified using automated laboratory identification systems. we report on an immunocompetent adolescent patient who developed septic arthritis due to roseomonas gilardii following surgery for a sports in ...200919574413
tonb-dependent transporters and their occurrence in cyanobacteria.different iron transport systems evolved in gram-negative bacteria during evolution. most of the transport systems depend on outer membrane localized tonb-dependent transporters (tbdts), a periplasma-facing tonb protein and a plasma membrane localized machinery (exbbd). so far, iron chelators (siderophores), oligosaccharides and polypeptides have been identified as substrates of tbdts. for iron transport, three uptake systems are defined: the lactoferrin/transferrin binding proteins, the porphyr ...200919821963
insertion sequence content reflects genome plasticity in strains of the root nodule actinobacterium frankia.genome analysis of three frankia sp. strains has revealed a high number of transposable elements in two of the strains. twelve out of the 20 major families of bacterial insertion sequence (is) elements are represented in the 148 annotated transposases of frankia strain hfpcci3 (cci3) comprising 3% of its total coding sequences (cds). ean1pec (ean) has 183 transposase orfs from 13 is families comprising 2.2% of its cds. strain acn14a (acn) differs significantly from the other strains with only 33 ...200919821988
th17 cells at the crossroads of innate and adaptive immunity against infectious diseases at the mucosa.t helper type 17 (th17) cells are a distinct lineage of t cells that produce the effector molecules il-17, il-17f, il-21, and il-22. although the role of th17 cells in autoimmunity is well documented, there is growing evidence that the th17 lineage and other interleukin (il)-17-producing cells are critical for host defense against bacterial, fungal, and viral infections at mucosal surfaces. here we summarize recent progress in our understanding of the function of il-17-producing cells as a bridg ...200919587639
role of the type iii secretion system in a hypervirulent lineage of bordetella bronchiseptica.despite the fact that closely related bacteria can cause different levels of disease, the genetic changes that cause some isolates to be more pathogenic than others are generally not well understood. we use a combination of approaches to determine which factors contribute to the increased virulence of a bordetella bronchiseptica lineage. a strain isolated from a host with b. bronchiseptica-induced disease, strain 1289, was 60-fold more virulent in mice than one isolated from an asymptomatically ...200919596779
surface protein ef3314 contributes to virulence properties of enterococcus faecalis.identification of putative new virulence factors as additional targets for therapeutic approaches alternative to antibiotic treatment of multi-resistant enterococcal infections.200919856273
the physiologic responses of dutch belted rabbits infected with inhalational anthrax.bacillus anthracis, the causative agent of anthrax, is a category a priority pathogen that causes extensive damage in humans. for this reason, b. anthracis has been the focus of numerous studies using various animal models. in this study, we explored physiologic parameters in dutch belted rabbits with inhalation anthrax to characterize the disease progression in this model. to this end, we infected dutch belted rabbits with 100 ld(50) b. anthracis ames spores by nasal instillation and continuous ...200919619416
in vitro antibacterial activity of acyl-lysyl oligomers against helicobacter pylori.the gastric pathogen helicobacter pylori has developed resistance to virtually all current antibiotics; thus, there is a pressing need to develop new anti-h. pylori therapies. the goal of this work was to evaluate the antibacterial effect of oligo-acyl-lysyl (oak) antimicrobial peptidomimetics to determine if they might represent alternatives to conventional antibiotic treatment of h. pylori infection. a total of five oak sequences were screened for growth-inhibitory and/or bactericidal effects ...200919620333
microarray and functional analysis of growth phase-dependent gene regulation in bordetella bronchiseptica.growth phase-dependent gene regulation has recently been demonstrated to occur in bordetella pertussis, with many transcripts, including known virulence factors, significantly decreasing during the transition from logarithmic to stationary-phase growth. given that b. pertussis is thought to have derived from a bordetella bronchiseptica-like ancestor, we hypothesized that growth phase-dependent gene regulation would also occur in b. bronchiseptica. microarray analysis revealed and quantitative re ...200919667046
cxcr2-dependent mucosal neutrophil influx protects against colitis-associated diarrhea caused by an attaching/effacing lesion-forming bacterial pathogen.enteropathogenic escherichia coli (epec) is a major cause of diarrheal disease in young children, yet symptoms and duration are highly variable for unknown reasons. citrobacter rodentium, a murine model pathogen that shares important functional features with epec, colonizes mice in colon and cecum and causes inflammation, but typically little or no diarrhea. we conducted genome-wide microarray studies to define mechanisms of host defense and disease in c. rodentium infection. a significant fract ...200919675161
role of cold shock proteins in growth of listeria monocytogenes under cold and osmotic stress conditions.the gram-positive bacterium listeria monocytogenes is a food-borne pathogen of both public health and food safety significance. it possesses three small, highly homologous protein members of the cold shock protein (csp) family. we used gene expression analysis and a set of mutants with single, double, and triple deletions of the csp genes to evaluate the roles of cspa, cspb, and cspd in the cold and osmotic (nacl) stress adaptation responses of l. monocytogenes. all three csps are dispensable fo ...200919151183
the piglet as a model for b cell and immune system development.the ability to identify factors responsible for disease in all species depends on the ability to separate those factors which are environmental from those that are intrinsic. this is particularly important for studies on the development of the adaptive immune response of neonates. studies on laboratory rodents or primates have been ambiguous because neither the effect of environmental nor maternal factors on the newborn can be controlled in mammals that: (i) transmit potential maternal immunoreg ...200919056129
constitutive and regulated expression vectors to construct polyphosphate deficient bacteria.inorganic polyphosphate (polyp), a polymer of tens or hundreds of phosphate residues linked by atp-like bonds, is found in all organisms and performs a wide variety of functions. polyp is synthesized in bacterial cells by the actions of polyphosphate kinases (ppk1 and ppk2) and degraded by an exopolyphosphatase (ppx). bacterial cells with polyp deficiencies are impaired in many structural and important cellular functions such as motility, quorum sensing, biofilm formation and virulence. knockout ...200919323822
genomic evidence for the evolution of streptococcus equi: host restriction, increased virulence, and genetic exchange with human pathogens.the continued evolution of bacterial pathogens has major implications for both human and animal disease, but the exchange of genetic material between host-restricted pathogens is rarely considered. streptococcus equi subspecies equi (s. equi) is a host-restricted pathogen of horses that has evolved from the zoonotic pathogen streptococcus equi subspecies zooepidemicus (s. zooepidemicus). these pathogens share approximately 80% genome sequence identity with the important human pathogen streptococ ...200919325880
genomic analysis of the adenylate cyclase-hemolysin c-terminal region of bordetella pertussis, bordetella parapertussis and bordetella bronchiseptica.adenylate cyclase-hemolysin plays an important role in the virulence of bordetella pertussis, bordetella parapertussis and bordetella bronchiseptica species. its c-terminal region carries protective epitopes and receptor binding site for human cells. genomic analyses of this region indicate no polymorphism in b. pertussis and b. parapertussis regions, but substantial variability in b. bronchiseptica that might be linked to the various niches of this species.200919379809
the effect of the nonionic block copolymer pluronic p85 on gene expression in mouse muscle and antigen-presenting cells.dna vaccines can be greatly improved by polymer agents that simultaneously increase transgene expression and activate immunity. we describe here pluronic p85 (p85), a triblock copolymer of ethylene oxide (eo) and propylene oxide (po) eo(26)-po(40)-eo(26). using a mouse model we demonstrate that co-administration of a bacterial plasmid dna with p85 in a skeletal muscle greatly increases gene expression in the injection site and distant organs, especially the draining lymph nodes and spleen. the r ...200919064283
immunodominance in mouse and human cd4+ t-cell responses specific for the bordetella pertussis virulence factor p.69 pertactin.p.69 pertactin (p.69 prn), an adhesion molecule from the causative agent of pertussis, bordetella pertussis, is present in cellular and most acellular vaccines that are currently used worldwide. although both humoral immunity and cellular immunity directed against p.69 prn have been implicated in protective immune mechanisms, the identities of cd4(+) t-cell epitopes on the p.69 prn protein remain unknown. here, a single i-a(d)-restricted b. pertussis conserved cd4(+) t-cell epitope at the n term ...200919015250
antibody-mediated immunity to the obligate intracellular bacterial pathogen coxiella burnetii is fc receptor- and complement-independent.the obligate intracellular bacterial pathogen coxiella burnetii causes the zoonosis q fever. the intracellular niche of c. burnetii has led to the assumption that cell-mediated immunity is the most important immune component for protection against this pathogen. however, passive immunization with immune serum can protect naïve animals from challenge with virulent c. burnetii, indicating a role for antibody (ab) in protection. the mechanism of this ab-mediated protection is unknown. therefore, we ...200919426498
bordetella bronchiseptica aroa mutant as a live vaccine vehicle for heterologous porcine circovirus type 2 major capsid protein expression.porcine circovirus type 2 (pcv2) infections cause important respiratory diseases in the pig industry and are associated with many bacterial, mycoplasmal, and viral complications. in this study, a heterologous pcv2 major capsid protein (mcp) was expressed in the bordetella bronchiseptica aroa mutant strain (bbs-mcp) and used as a live vaccine vehicle. mice and pigs were immunized with live bbs-mcp via the intranasal route. the antibodies against mcp were induced successfully in the serum as deter ...200919428194
pseudogene accumulation in the evolutionary histories of salmonella enterica serovars paratyphi a and typhi.of the > 2000 serovars of salmonella enterica subspecies i, most cause self-limiting gastrointestinal disease in a wide range of mammalian hosts. however, s. enterica serovars typhi and paratyphi a are restricted to the human host and cause the similar systemic diseases typhoid and paratyphoid fever. genome sequence similarity between paratyphi a and typhi has been attributed to convergent evolution via relatively recent recombination of a quarter of their genomes. the accumulation of pseudogene ...200919159446
genomic and genetic analyses of diversity and plant interactions of pseudomonas fluorescens.pseudomonas fluorescens are common soil bacteria that can improve plant health through nutrient cycling, pathogen antagonism and induction of plant defenses. the genome sequences of strains sbw25 and pf0-1 were determined and compared to each other and with p. fluorescens pf-5. a functional genomic in vivo expression technology (ivet) screen provided insight into genes used by p. fluorescens in its natural environment and an improved understanding of the ecological significance of diversity with ...200919432983
bordetella bsp22 forms a filamentous type iii secretion system tip complex and is immunoprotective in vitro and in vivo.type iii secretion system (t3ss) tip complexes serve as adaptors that bridge the t3ss needle and the pore-forming translocation apparatus. in this report we demonstrate that bsp22, the most abundantly secreted substrate of the bordetella t3ss, self-polymerizes to form the bordetella bronchiseptica tip complex. bsp22 is required for both t3ss-mediated cytotoxicity against eukaryotic cells and haemoglobin release from erythrocytes. bacterial two-hybrid analysis and protein pull-down assays demonst ...200919040642
temporal signaling and differential expression of bordetella iron transport systems: the role of ferrimones and positive regulators.the bacterial respiratory pathogens bordetella pertussis and bordetella bronchiseptica employ multiple alternative iron acquisition pathways to adapt to changes in the mammalian host environment during infection. the alcaligin, enterobactin, and heme utilization pathways are differentially expressed in response to the cognate iron source availability by a mechanism involving substrate-inducible positive regulators. as inducers, the iron sources function as chemical signals termed ferrimones. fer ...200919130264
isolation, antimicrobial resistance, and virulence genes of pasteurella multocida strains from swine in china.a total of 233 isolates of pasteurella multocida were obtained from 2,912 cases of clinical respiratory disease in pigs in china, giving an isolation rate of 8.0%. serogroup a p. multocida isolates were isolated from 92 cases (39.5%), and serogroup d isolates were isolated from 128 cases (54.9%); 12 isolates (5.2%) were untypeable. p. multocida was the fourth most frequent pathogenic bacterium recovered from the respiratory tract, after streptococcus suis, haemophilus parasuis, and escherichia c ...200919158260
inefficient toll-like receptor-4 stimulation enables bordetella parapertussis to avoid host immunity.the recognition of bacterial lipopolysaccharide (lps) by host toll-like receptor (tlr)4 is a crucial step in developing protective immunity against several gram negative bacterial pathogens. bordetella bronchiseptica and b. pertussis stimulate robust tlr4 responses that are required to control the infection, but a close relative, b. parapertussis, poorly stimulates this receptor, and tlr4 deficiency does not affect its course of infection. this led us to hypothesize that inefficient tlr4 stimula ...200919169359
virulence factor secretion and translocation by bordetella species.here we review the bordetella virulence secretome with an emphasis on factors that translocate into target cells. recent advances in understanding the functions of adenylate cyclase toxin, a type 1 secretion system (t1ss) substrate, and pertussis toxin, a type iv secretion system (t4ss) substrate, are briefly described and a compilation of additional secretion systems and secreted factors is provided. particular attention is devoted to the bsc type iii secretion system (t3ss) and controversies s ...200919186097
relapsing peritonitis caused by bordetella bronchiseptica in continuous ambulatory peritoneal dialysis patient: a case report.bordetella (b) bronchiseptica is a common veterinary pathogen, but has rarely been implicated in human infections. most patients with b. bronchiseptica infections are compromised clinically such as in patients with a malignancy, aids, malnutrition, or chronic renal failure. we experienced a case of relapsing peritonitis caused by b. bronchiseptica associated with continuous ambulatory peritoneal dialysis (capd). a 56-yr-old male, treated with capd due to end stage renal disease (esrd), was admit ...200919194556
natural-host animal models indicate functional interchangeability between the filamentous haemagglutinins of bordetella pertussis and bordetella bronchiseptica and reveal a role for the mature c-terminal domain, but not the rgd motif, during infection.bacteria of the bordetella genus cause respiratory tract infections. both broad host range (e.g. bordetella bronchiseptica) and human-adapted (e.g. bordetella pertussis) strains produce a surface-exposed and secreted protein called filamentous haemagglutinin (fha) that functions in adherence and immunomodulation. previous studies using b. pertussis and cultured mammalian cells identified several fha domains with potential roles in host cell interactions, including an arg-gly-asp (rgd) triplet th ...200919220744
evolution of acute infections and the invasion-persistence trade-off.we seek to understand the conditions favoring the evolution of acute, highly transmissible infections. most work on the life-history evolution of pathogens has focused on the transmission-virulence trade-off. here we focus on a distinct trade-off that operates, even among avirulent pathogens, between a pathogen's speed of invasion and its ability to persist in a finite host population. other authors have shown how this invasion-persistence trade-off can lead to intermediate pathogen attack rates ...200919231966
contribution of bordetella bronchiseptica filamentous hemagglutinin and pertactin to respiratory disease in swine.bordetella bronchiseptica is pervasive in swine populations and plays multiple roles in respiratory disease. most studies addressing virulence factors of b. bronchiseptica are based on isolates derived from hosts other than pigs. two well-studied virulence factors implicated in the adhesion process are filamentous hemagglutinin (fha) and pertactin (prn). we hypothesized that both fha and prn would serve critical roles in the adhesion process and be necessary for colonization of the swine respira ...200919237531
euthanasia of neonatal rats with carbon dioxide.exposure to co(2) is a common method used to euthanize rodents in biomedical research and rodent production. the purpose of this study was to determine the length of co(2) exposure required to euthanize neonatal rats (0 to 10 d old). multiple groups of rats were exposed to 100% co(2) for 5 to 60 min. after co(2) exposure, rats were placed in room air for 20 min to allow for possible recovery. no difference was found in comparing 1 inbred strain and 1 outbred stock of rats. time to death varied i ...200919245746
anthrax edema toxin induces maturation of dendritic cells and enhances chemotaxis towards macrophage inflammatory protein 3beta.bacillus anthracis secretes two bipartite toxins, edema toxin (et) and lethal toxin (lt), which impair immune responses and contribute directly to the pathology associated with the disease anthrax. edema factor, the catalytic subunit of et, is an adenylate cyclase that impairs host defenses by raising cellular cyclic amp (camp) levels. synthetic camp analogues and compounds that raise intracellular camp levels lead to phenotypic and functional changes in dendritic cells (dcs). here, we demonstra ...200919273556
characterization of wbpb, wbpe, and wbpd and reconstitution of a pathway for the biosynthesis of udp-2,3-diacetamido-2,3-dideoxy-d-mannuronic acid in pseudomonas aeruginosa.the lipopolysaccharide of pseudomonas aeruginosa pao1 contains an unusual sugar, 2,3-diacetamido-2,3-dideoxy-d-mannuronic acid (d-mannac3naca). wbpb, wbpe, and wbpd are thought to encode oxidase, transaminase, and n-acetyltransferase enzymes. to characterize their functions, recombinant proteins were overexpressed and purified from heterologous hosts. activities of his(6)-wbpb and his(6)-wbpe were detected only when both proteins were combined in the same reaction. using a direct maldi-tof mass ...200919282284
the complete genome and proteome of laribacter hongkongensis reveal potential mechanisms for adaptations to different temperatures and habitats.laribacter hongkongensis is a newly discovered gram-negative bacillus of the neisseriaceae family associated with freshwater fish-borne gastroenteritis and traveler's diarrhea. the complete genome sequence of l. hongkongensis hlhk9, recovered from an immunocompetent patient with severe gastroenteritis, consists of a 3,169-kb chromosome with g+c content of 62.35%. genome analysis reveals different mechanisms potentially important for its adaptation to diverse habitats of human and freshwater fish ...200919283063
genomic island excisions in bordetella petrii.among the members of the genus bordetella b. petrii is unique, since it is the only species isolated from the environment, while the pathogenic bordetellae are obligately associated with host organisms. another feature distinguishing b. petrii from the other sequenced bordetellae is the presence of a large number of mobile genetic elements including several large genomic regions with typical characteristics of genomic islands collectively known as integrative and conjugative elements (ices). the ...200919615092
role of hrpa in biofilm formation of neisseria meningitidis and regulation of the hrpbas transcripts.two-partner secretion systems of gram-negative organisms are utilized in adherence, invasion, and biofilm formation. the hrpab proteins of neisseria meningitidis are members of a two-partner secretion system, and hrpa is established as being important to adherence and intracellular escape. this study set out to determine the expression pattern of members of the hrpbas putative operon and to find a functional role for the hrpa protein. the upregulation of these genes was found in situations of an ...200919289515
identification of a novel lipopolysaccharide core biosynthesis gene cluster in bordetella pertussis, and influence of core structure and lipid a glucosamine substitution on endotoxic activity.lipopolysaccharide (lps), also known as endotoxin, is one of the main constituents of the gram-negative bacterial outer membrane. whereas the lipid a portion of lps is generally considered the main determinant for endotoxic activity, the oligosaccharide moiety plays an important role in immune evasion and the interaction with professional antigen-presenting cells. here we describe a novel four-gene cluster involved in the biosynthesis of the bordetella pertussis core oligosaccharide. by insertio ...200919364841
expression levels of immune markers in actinobacillus pleuropneumoniae infected pigs and their relation to breed and clinical symptoms.in pigs little is known about the role of innate immune defence in bacterial infections of the respiratory tract, despite their major role in pig production. in the present study we characterized and compared in vitro and in vivo activation of immune markers of different pig breeds 7 days before, and 4 and 21 days after an experimental aerosol infection with actinobacillus (a.) pleuropneumoniae.200919383119
the pgaabcd locus of acinetobacter baumannii encodes the production of poly-beta-1-6-n-acetylglucosamine, which is critical for biofilm formation.we found that acinetobacter baumannii contains a pgaabcd locus that encodes proteins that synthesize cell-associated poly-beta-(1-6)-n-acetylglucosamine (pnag). both a mutant with an in-frame deletion of the pga locus (s1deltapga) and a transcomplemented strain (s1deltapga-c) of a. baumannii were constructed, and the pnag production by these strains was compared using an immunoblot assay. deleting the pga locus resulted in an a. baumannii strain without pnag, and transcomplementation of the s1de ...200919633088
rapid real-time pcr assays for detection of klebsiella pneumoniae with the rmpa or maga genes associated with the hypermucoviscosity phenotype: screening of nonhuman primates.the relationship of mucoviscosity-associated (maga) and/or regulator of mucoid phenotype (rmpa) genes to the klebsiella pneumoniae hypermucoviscosity (hmv) phenotype has been reported. we previously demonstrated that rmpa+ k. pneumoniae can cause serious disease in african green monkeys and isolated rmpa+ and maga+ hmv k. pneumoniae from other species of non-human primates. to rapidly screen african green monkeys/non-human primates for these infections, we developed three real-time pcr assays. t ...200919644019
successful management of rabbit anesthesia through the use of nasotracheal intubation.although nasotracheal intubation in the rabbit has been briefly described, scientific assessment of the procedure has not been reported. in this report we describe nasotracheal intubation performed in 38 male new zealand white rabbits (3.0 to 5.5 kg) used for a vascular patch study. the rabbits were placed under general anesthesia twice, with 2 mo between the initial and final intubations. rabbits were intubated by the oral or nasotracheal route and compared. previous literature dismissed nasotr ...200919383213
klebsiella pneumoniae triggers a cytotoxic effect on airway epithelial cells.klebsiella pneumoniae is a capsulated gram negative bacterial pathogen and a frequent cause of nosocomial infections. despite its clinical relevance, little is known about the features of the interaction between k. pneumoniae and lung epithelial cells on a cellular level, neither about the role of capsule polysaccharide, one of its best characterised virulence factors, in this interaction.200919650888
ralstonia pickettii-induced ataxia in immunodeficient mice.we report here the characterization of an asymmetric ataxia syndrome (head tilt and circling, with death in the most severe cases) demonstrated by profoundly immunodeficient mice housed at the institut curie spf facility. the immune system of the affected mice had been genetically modified so that they were deficient in both b and t cells. extensive bacteriologic, parasitic, serologic, and histopathologic analysis of the affected animals and their healthy controls led us to identify ralstonia pi ...200919389312
sequence-based prediction of type iii secreted proteins.the type iii secretion system (ttss) is a key mechanism for host cell interaction used by a variety of bacterial pathogens and symbionts of plants and animals including humans. the ttss represents a molecular syringe with which the bacteria deliver effector proteins directly into the host cell cytosol. despite the importance of the ttss for bacterial pathogenesis, recognition and targeting of type iii secreted proteins has up until now been poorly understood. several hypotheses are discussed, in ...200919390696
purification of legiobactin and importance of this siderophore in lung infection by legionella pneumophila.when cultured in a low-iron medium, legionella pneumophila secretes a siderophore (legiobactin) that is both reactive in the chrome azurol s (cas) assay and capable of stimulating the growth of iron-starved legionellae. using anion-exchange high-pressure liquid chromatography (hplc), we purified legiobactin from culture supernatants of a virulent strain of l. pneumophila. in the process, we detected the ferrated form of legiobactin as well as other cas-reactive substances. purified legiobactin h ...200919398549
emergence of quinolone-resistant bordetella pertussis in japan.six bordetella pertussis strains isolated from children in japan from 2004 to 2006 showed high-level resistance to nalidixic acid (nal; mic, >256 microg/ml) and decreased susceptibilities to fluoroquinolones. all of the nal-resistant strains had the same d87g mutation in gyra.200919414571
making the cut: central roles of intramembrane proteolysis in pathogenic microorganisms.proteolysis in cellular membranes to liberate effector domains from their transmembrane anchors is a well-studied regulatory mechanism in animal biology and disease. by contrast, the function of intramembrane proteases in unicellular organisms has received little attention. recent progress has now established that intramembrane proteases execute pivotal roles in a range of pathogens, from regulating mycobacterium tuberculosis envelope composition, cholera toxin production, bacterial adherence an ...200919421188
efflux-mediated drug resistance in bacteria: an update.drug efflux pumps play a key role in drug resistance and also serve other functions in bacteria. there has been a growing list of multidrug and drug-specific efflux pumps characterized from bacteria of human, animal, plant and environmental origins. these pumps are mostly encoded on the chromosome, although they can also be plasmid-encoded. a previous article in this journal provided a comprehensive review regarding efflux-mediated drug resistance in bacteria. in the past 5 years, significant pr ...200919678712
molecular determinants of the interaction between clostridium perfringens enterotoxin fragments and claudin-3.clostridium perfringens enterotoxin (cpe) binds to the extracellular loop 2 of a subset of claudins, e.g. claudin-3. here, the molecular mechanism of the cpe-claudin interaction was analyzed. using peptide arrays, recombinant cpe-(116-319) bound to loop 2 peptides of mouse claudin-3, -6, -7, -9, and -14 but not of 1, 2, 4, 5, 8, 10-13, 15, 16, 18-20, and 22. substitution peptide mapping identified the central motif (148)npl(150)vp, supposed to represent a turn region in the loop 2, as essential ...200919429681
new yeast recombineering tools for bacteria.recombineering with saccharomyces cerevisiae is a powerful methodology that can be used to clone multiple unmarked pieces of dna to generate complex constructs with high efficiency. here, we introduce two new tools that utilize the native recombination enzymes of s. cerevisiae to facilitate the manipulation of dna. first, yeast recombineering was used to make directed nested deletions in a bacteria-yeast shuttle plasmid using only one or two single stranded oligomers, thus obviating the need for ...200919477196
comparative genomic characterization of francisella tularensis strains belonging to low and high virulence subspecies.tularemia is a geographically widespread, severely debilitating, and occasionally lethal disease in humans. it is caused by infection by a gram-negative bacterium, francisella tularensis. in order to better understand its potency as an etiological agent as well as its potential as a biological weapon, we have completed draft assemblies and report the first complete genomic characterization of five strains belonging to the following different francisella subspecies (subsp.): the f. tularensis sub ...200919478886
porcine abortion outbreak associated with toxoplasma gondii in jeju island, korea.this report deals with the acute onset of an abortion outbreak and high sow mortality in one pig herd consisted of 1,200 pigs and 120 sows on jeju island, korea. affected pregnant sows showed clinical signs, including high fever, gradual anorexia, vomiting, depression, recumbency, prostration, abortion, and a few deaths. four dead sows, five aborted fetuses from the same litter, and 17 sera collected from sows infected or normal were submitted to the pathology division of the national veterinary ...200919461210
comparison of side effects between buprenorphine and meloxicam used postoperatively in dutch belted rabbits (oryctolagus cuniculus).one of the challenges facing veterinarians and investigators who use rabbits (oryctolagus cuniculus) as a surgical model in biomedical research is choosing an appropriate and efficacious postoperative analgesic without systemic complications and side effects. the objective of this study was to evaluate the gastrointestinal side effects associated with the postoperative use of buprenorphine in dutch belted rabbits. we also evaluated the analgesic meloxicam as an alternative to opioid administrati ...200919476717
[characterization of attenuated salmonella c500 strain with a delta asd mutant and use as an asd+ balanced-lethal host-vector system].salmonella enterica serovar choleraesuis strain c500 is a live, attenuated vaccine that has been used in china for over 40 years to prevent piglet paratyphoid. the objective of this study was to evaluate the potential of attenuated salmonella enterica serovar choleraesuis c500 strain with a delta asd mutant as an effective live vaccine vector by the asd+ balanced-lethal host-vector system. here, we compared the characteristics of s. enterica serovar choleraesuis delta asdc500 strain with the par ...200919441223
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