Recombinant Escherichia coli Cell Lysates as a Low-Cost Alternative for Vaccines Against Veterinary Clostridial Diseases.

This chapter describes a practical, industry-friendly, and efficient vaccine protocol based on the use of Escherichia coli cell fractions (inclusion bodies or cell lysate supernatant) containing the recombinant antigen. This approach was characterized and evaluated in laboratory and farm animals by the seroneutralization assay in mice, thereby showing to be an excellent alternative to induce a protective immune response against clostridial diseases.

Introducing a cost-effective method for purification of bioactive flagellin from several flagellated gram-negative bacteria.

The objective of this study was to introduce a simple and cheap method for purification of flagellin. So, flagellin proteins of Salmonella typhimurium (S. typhimurium), Escherichia coli (E. coli), Citrobacter freundii (C. freundii) and Salmonella typhi (S. typhi) were purified by a modified simple method. Bacterial cultures were precipitated by centrifugation. Precipitates were washed twice and flagellin proteins were detached by shaking vigorously (in PBS pH = 2), and then flagellin proteins were precipitated by ammonium sulfate saturation. Evaluation of purification efficiency and concentration were examined by SDS-PAGE and Bradford assay. Polyclonal antibodies were produced against S. typhimurium FliC and cross-reactivity of anti-S. typhimurium was assessed against other flagellins. Bioactivity of flagellins was evaluated by cell proliferation and IL-8 protein expression assay in HEK293 cells, and also, IL-6 and TNF-α genes expression in chicken cells. Results showed a single band for flagellin proteins of all bacteria on %10 SDS-PAGE, which concentration ranged from 150 to 400 µg/mL. All flagellin proteins increased cell proliferation, and IL-8 levels were increased after treatment by flagellins and levels of IL-6 and TNF-α were increased after treatment with S. typhimurium FliC. All flagellin proteins showed cross-reactivity with antibodies. Findings showed that application of our method, not only reduced time and cost, but also, the purified flagellin proteins had acceptable bioactivity.

Bioinformatics and Functional Assessment of Toxin-Antitoxin Systems in Staphylococcus aureus.

Staphylococcus aureus is a nosocomial pathogen that can cause chronic to persistent infections. Among different mediators of pathogenesis, toxin-antitoxin (TA) systems are emerging as the most prominent. These systems are frequently studied in Escherichia coli and Mycobacterial species but rarely explored in S. aureus. In the present study, we thoroughly analyzed the S. aureus genome and screened all possible TA systems using the Rasta bacteria and toxin-antitoxin database. We further searched E. coli and Mycobacterial TA homologs and selected 67 TA loci as putative TA systems in S. aureus. The host inhibition of growth (HigBA) TA family was predominantly detected in S. aureus. In addition, we detected seven pathogenicity islands in the S. aureus genome that are enriched with virulence genes and contain 26 out of 67 TA systems. We ectopically expressed multiple TA genes in E. coli and S. aureus that exhibited bacteriostatic and bactericidal effects on cell growth. The type I Fst toxin created holes in the cell wall while the TxpA toxin reduced cell size and induced cell wall septation. Besides, we identified a new TA system whose antitoxin functions as a transcriptional autoregulator while the toxin functions as an inhibitor of autoregulation. Altogether, this study provides a plethora of new as well as previously known TA systems that will revitalize the research on S. aureus TA systems.

Characterization of an Escherichia coli-derived human papillomavirus type 16 and 18 bivalent vaccine.

Human papillomavirus (HPV) types 16 and 18 account for approximately 70% of cervical cancer worldwide. Neutralizing HPV prophylactic vaccines offer significant benefit, as they block HPV infection and prevent subsequent disease. However, the three licensed HPV vaccines that cover these two genotypes were produced in eukaryotic cells, which is expensive, particularly for low-income countries where HPV is highest. Here, we report a new HPV16 and -18 bivalent candidate vaccine produced from Escherichia coli. We used two strategies of N-terminal truncation of HPV L1 proteins and soluble non-fusion expression to generate HPV16 and HPV18 L1-only virus-like particles (VLPs) in a scalable process. Through comprehensive characterization of the bivalent candidate vaccine, we confirm lot consistency in a pilot scale-up of 30L, 100L and 500L. Using cryo-EM 3D reconstruction, we found that HPV16 and -18VLPs present in a T=7 icosahedral arrangement, similar in shape and size to that of the native virions. This HPV16/18 bivalent vaccine shares comparable immunogenicity with the licensed vaccines. Overall, we show that the production of a HPV16/18 bivalent vaccine from an E. coli expression system is robust and scalable, with potentially good accessibility worldwide as a population-based immunization strategy.

Eficacia y seguridad de L-asparaginasa erwinia y L-asparaginasa E. Coli pegilada en el tratamiento de pacientes con leucemia linfoblástica aguda que presentam hipersensibilidad a L-asparaginasa E. coli nativa / Efficacy and safety of L-asparaginase erwinia and L-asparaginase E. coli pegylated in the treatment of patients with acute lymphoblastic leukemia who are hypersensitive to L-asparaginase E. coli native

INTRODUÇÃO: Antecedentes: El presente dictamen expone la evaluación de tecnología de la eficacia y seguridad del uso de L-asparaginasa Erwinia y L-asparaginasa E. coli pegilada para el tratamiento de pacientes con leucemia linfoblástica aguda que presentan hipersensibilidad a L-asparaginasa E. coli nativa. Aspectos Generales: La leucemia es el tipo de cáncer más común en niños, representando aproximadamente el 30% de todos los tipos de cáncer diagnosticados en niños; siendo la leucemia linfoblástica aguda (LLA) uno de los dos tipos de leucemias más comunes. Adicionalmente, alrededor del 60% de todos los casos de LLA ocurre en pacientes menores de 20 años. Así, LLA es un tipo de leucemia de alta importancia dentro de población joven. Tecnología Sanitaria de Interés: Las células neoplásicas en la leucemia linfoblástica aguda (LLA) no sintetizan las cantidades necesarias del aminoácido L-asparagina; por lo que requieren de funtes externas (i.e., L-asparagina extracelular). La L-asparaginasa, es una enzima que cataliza la conversión de L-asparagina más agua, en ácido aspártico y amoniaco, ocasionando que los niveles de L-asparagina extracelular disminuyan; y que por los tanto las células d ela LLA no cuenten con L-asparagina extracelular. Así, estas células neoplásicas se quedan sin fuentes de L-asparagina, y no pueden sintetizar proteínas de gran imporancia para su supervivencia, ocasionando su muerte. METODOLOGÍA: Estrategia de Búsqueda: Se realizó una búsqueda de la literatura a la eficacia y seguridad del uso de L-asparaginasa Erwinia y L-asparaginasa E. coli pegilada para el tratamiento de pacientes niños y adultos con leucemia linfoblástica aguda que presentan hipersensibilidad a L-asparaginasa E. coli nativa. Esta búsqueda se realizó utilizando los meta-buscadores: Translating Research into Practice (TRIPDATABASE) Y National Library of Medicine (Pubmed-Medline). RESULTADOS: Sinopsis de la Evidencia: Se realizó la búsqueda bibliográfica y de evidencia científica hasta marzo del 2017 para el sustento del uso de L-asparaginasa Erwinia en el tratamiento de leucemia linfoblástica aguda en pacientes niños y adultos que presentan hipersensibilidad a L-asparaginasa E. coli nativa. Se presente la evidencia disponible según el tipo de publicación priorizada en los criterios de inclusión (i.e., GP, ETS, RS y ECA fase III), siendo los ensayos de fase III o en su defecto ensayos controlados y aleatorizados la principal considerada. CONCLUSIONES: El presente dictamen evaluó la mejor evidencia disponible hasta marco 2017 en relación al uso de L-asparaginasa Erwinia y L-asparaginasa E. coli pegilada para el tratamiento de pacientes niños, adolescentes, y adultos con leucemia linfoblástica aguda, que presentan hipersensibilidad a L-asparaginasa E. coli nativa. El Instituto de Tecnologías Sanitarias-IETSI, aprueba el uso de L-asparaginasa Erwinia como parte del esquema quimioterápico utilizada para el tratamiento de pacientes niños, adolescentes, y adultos con leucemia linfoblástica aguda, que presentan hipersensibilidad grado 2 o más a L-asparaginasa E. coli nativa. La vigencia de este dictamen preliminar es de dos años a partir de la fecha de publicación. Asimismo, el Instituto de Tecnologías Sanitarias-IETSI, no aprueba el uso de L-asparaginasa E. coli pegilada en el tratamiento de pacientes niños, adolescentes, y adultos con leucemia linfoblástica aguda, que presentan hipersensiblidad grado 2 o más a L-asparaginasa E. coli nativa.

Influence of Escherichia coli chaperone DnaK on protein immunogenicity.

The production of anti-drug antibodies can impact significantly upon the safety and efficacy of biotherapeutics. It is known that various factors, including aggregation and the presence of process-related impurities, can modify and augment the immunogenic potential of proteins. The purpose of the investigations reported here was to characterize in mice the influence of aggregation and host cell protein impurities on the immunogenicity of a humanized single-chain antibody variable fragment (scFv), and mouse albumin. Host cell protein impurities within an scFv preparation purified from Escherichia coli displayed adjuvant-like activity for responses to the scFv in BALB/c strain mice. The 70 000 MW E. coli chaperone protein DnaK was identified as a key contaminant of scFv by mass spectrometric analysis. Preparations of scFv lacking detectable DnaK were spiked with recombinant E. coli DnaK to mimic the process-related impurity. Mice were immunized with monomeric and aggregated preparations, with and without 0·1% DnaK by mass. Aggregation alone enhanced IgM and IgG2a antibody responses, but had no significant effect on total IgG or IgG1 responses. The addition of DnaK further enhanced IgG and IgG2a antibody responses, but only in the presence of aggregated protein. DnaK was shown to be associated with the aggregated scFv by Western blot analysis. Experiments with mouse albumin showed an overall increase in immunogenicity with protein aggregation alone, and the presence of DnaK increased the vigour of the IgG2a antibody response further. Collectively these data reveal that DnaK has the potential to modify and enhance immunogenicity when associated with aggregated protein.

Longitudinal Assessment of Systemic and Genital Tract Inflammatory Markers and Endogenous Genital Tract E. coli Inhibitory Activity in HIV-Infected and Uninfected Women.

PROBLEM: Stability over time of systemic and mucosal immunity and their associations with bacterial vaginosis (BV) and HIV-specific parameters were assessed. METHOD OF STUDY: Immune mediators and HIV viral load in plasma and cervicovaginal lavage (CVL), E. coli inhibition, and Nugent score were measured at three semiannual visits among 94 participants in the Women's Interagency HIV Study. Mixed models identified the factors associated with immune mediators. RESULTS: There was higher E. coli inhibition and lower inflammation over time in the genital tract and systemically. BV was consistently associated with higher CVL inflammatory mediators and lower CVL E. coli inhibition. HIV-infected women with higher CD4 counts had lower systemic and genital inflammatory mediators, and genital HIV shedding was associated with higher CVL inflammatory mediators. Use of antiretroviral therapy (ART) was associated with lower plasma and CVL mediators, but higher E. coli inhibition. CONCLUSION: HIV and BV are linked to inflammation, and ART may be associated with improved vaginal health.

Partial budget analysis of prepartum antimicrobial therapy and Escherichia coli J5 vaccination of dairy heifers and their effect on milk production and milk quality parameters / Análise econômica da terapia antimicrobiana no pré-parto e da vacinação com Escherichia coli J5 em novilhas leiteiras e seu efeito sobre a produção e qualidade de leite

This study aimed to determine whether prepartum antimicrobial and/or Escherichia coli J5 vaccination in dairy heifers influence the milk production, milk quality, and estimate their economic benefit. Thus, 33 dairy heifers were enrolled in four groups using a split-splot design. Groups were: (G1) prepartum antimicrobial infusion and vaccination with an E. coli J5 bacterin, (G2) prepartum antimicrobial infusion, (G3) vaccination with an E. coli J5 bacterin, and (G4) control heifers. Composite milk samples for somatic cell count, total bacteria count and milk composition were collected 15 days after calving and every 15 days until the end of the experiment. Bacteriological analysis was carried out at the end of study. The milk production and the incidence of clinical cases of mastitis, as well as the costs associated with them were recorded. The results demonstrate a reduction on clinical mastitis rates by preventive strategies, which implicated in lower volume of discarded milk (0.99, 1.01, 1.04 and 3.98% for G1, G2, G3 and G4, respectively) and higher economic benefit. Thus, in well-managed dairy herds the prevention of heifer mastitis by vaccination or antimicrobial therapy can reduce the amount of antimicrobials needed to treat clinical mastitis cases and the days of discarded milk.

O presente estudo objetivou realizar uma análise econômica do tratamento antimicrobiano no pré-parto e/ou da vacinação com Escherihia coli J5 em novilhas leiteiras, e seu efeito sobre a produção e qualidade de leite. Portanto, utilizou-se o delineamento split-splot em esquema fatorial, no qual 33 novilhas da raça Holandesa foram divididas aleatoriamente em quatro grupos: (G1) antimicroianoterapia no pré-parto e vacinação com E. coli J5, (G2) antimicrobianoterapia no pré-parto, (G3) vacinação com E. coli J5 e (G4) controle. Amostras compostas de leite foram coletadas para contagem de células somáticas, contagem bacteriana total e composição do leite 15 dias após o parto, e a cada 15 dias até o término do experimento. A análise bacteriológica do leite foi realizada ao término do experimento. A produção de leite e a incidência dos casos clínicos de mastite, assim como, os custos associados à antimicrobianoterapia no pré-parto e/ou vacinação com E. coli J5 foram registrados. Os resultados demonstraram redução dos casos clínicos de mastite com a implementação das medidas preventivas resultando no menor volume de leite descartado (0,99, 1,01, 1,04 e 3,98% para os animais dos grupos G1, G2, G3 e G4, respectivemente) e maior benefício econômico. Desta forma, em rebanhos bem manejados, a implementação da antimicrobianoterapia no pré-parto e vacinação com E. coli J5 e novilhas pode reduzir a quantidade de antimicrobianos necessário para o tratamento de casos de mastite clínica durante a lactação, resultando em menor número de dias em que o leite é descartado.

The incidence and economic impact of the Escherichia coli peritonitis syndrome in Dutch poultry farming.

The incidence and economic impact of the Escherichia coli peritonitis syndrome (EPS), characterized by acute mortality, were estimated in chicken egg-producing farms in the Netherlands in 2013. The incidence was significantly higher (P < 0.05) in the meat-sector (35% affected farms) compared to the layer-sector (7% affected farms). In consumption egg-producing farms EPS occurred on 12% of the free range and organic farms, while it was found on 1% and 4% of the cage and barn farms, respectively. Data from four layer and two broiler breeder flocks with EPS were used to estimate the overall economic impact of the disease. Mean numbers of eggs lost were 10 and 11 per hen housed (phh), while mean slaughter weight loss was 0.2 and 0.5 kg phh in the four layer and two broiler breeder flocks, respectively. Total losses including costs of destruction of dead hens, compensated for reduced feed intake due to a smaller flock size, ranged from €0.28 phh (cage farms) to €9.75 phh (grandparent farms) in the layer-sector and from €1.87 phh (parent farms) to €10.73 phh (grandparent farms) in the meat-sector. Antibiotics against EPS were given often and repeatedly especially in the meat-sector. Including the costs of antibiotics, total losses were estimated at €0.4 million, €3.3 million and €3.7 million for the layer-sector, the meat-sector and poultry farming as a whole, respectively. Research focusing on the prevention and treatment of EPS is justified by its severe clinical and economic impact.

Dynamics of the systemic components of the chicken (Gallus gallus domesticus) immune system following activation by Escherichia coli; implications for the costs of immunity.

The immune response is thought to be costly and deters from growth and reproduction, but the magnitude and sources of these costs are unknown. Thus, we quantified the changes in mass of leukocytes (CD4(+) and CD8(+) T cells, Bu1(+) IgM(+) and Bu1(+) IgG(+) B cells, monocytes/macrophages, heterophils and thrombocytes) and protective plasma proteins in systemic (non-mucosal) components of adult chickens injected intravenously with dead Escherichia coli. During the first day after E. coli injection most types of blood leukocytes decreased and α-1-acid glycoprotein increased. Specific IgM, specific IgY, total IgM, Bu1(+) lymphocytes in the spleen and bone marrow and thymic CD8(+) lymphocytes increased at 5d post-injection. Quantitatively, the increases in the weight of cells and antibodies due to E. coli were dwarfed by the increase in the weight of the liver and acute phase proteins. Thus the acute phase response was markedly more costly than the subsequent adaptive response. The weight of the cells and proteins of the systemic immune system prior to challenge was 0.14% of body weight. Following E. coli injection, the additional weight of the immune components and the hypertrophy of the liver resulted in a 3.6-fold increase in weight which is equivalent to 18.5% of a large egg.

Engineering, conjugation, and immunogenicity assessment of Escherichia coli O121 O antigen for its potential use as a typhoid vaccine component.

State-of-the-art production technologies for conjugate vaccines are complex, multi-step processes. An alternative approach to produce glycoconjugates is based on the bacterial N-linked protein glycosylation system first described in Campylobacter jejuni. The C. jejuni N-glycosylation system has been successfully transferred into Escherichia coli, enabling in vivo production of customized recombinant glycoproteins. However, some antigenic bacterial cell surface polysaccharides, like the Vi antigen of Salmonella enterica serovar Typhi, have not been reported to be accessible to the bacterial oligosaccharyltransferase PglB, hence hamper development of novel conjugate vaccines against typhoid fever. In this report, Vi-like polysaccharide structures that can be transferred by PglB were evaluated as typhoid vaccine components. A polysaccharide fulfilling these requirements was found in Escherichia coli serovar O121. Inactivation of the E. coli O121 O antigen cluster encoded gene wbqG resulted in expression of O polysaccharides reactive with antibodies raised against the Vi antigen. The structure of the recombinantly expressed mutant O polysaccharide was elucidated using a novel HPLC and mass spectrometry based method for purified undecaprenyl pyrophosphate (Und-PP) linked glycans, and the presence of epitopes also found in the Vi antigen was confirmed. The mutant O antigen structure was transferred to acceptor proteins using the bacterial N-glycosylation system, and immunogenicity of the resulting conjugates was evaluated in mice. The conjugate-induced antibodies reacted in an enzyme-linked immunosorbent assay with E. coli O121 LPS. One animal developed a significant rise in serum immunoglobulin anti-Vi titer upon immunization.

Comparison of sensing strategies in SPR biosensor for rapid and sensitive enumeration of bacteria.

Rapid and sensitive detections of microorganisms are very important for biodefence, food safety, medical diagnosis and pharmaceutics. The present study aims to find out the most proper bioactive surface preparation method to develop rapid, sensitive and selective bacteria biosensor, based on surface plasmon resonance (SPR) spectroscopy. Escherichia coli (E. coli) was used as a model bacterium and four sensing strategies in SPR were tested. Three of these strategies are antibody immobilization methods that are non-specific adsorption, specific adsorption via the avidin-biotin interaction, and immobilization of antibodies via self-assembled monolayer formation. The fourth strategy is a novel method for bacteria enumeration based on the combination of the SPR spectroscopy and immunomagnetic separation with using gold-coated magnetic nanoparticles. According to results, the most efficient SPR method is the one based on gold-coated magnetic nanoparticles. This method allows to specifically separate E. coli from the environment and to quantify rapidly without any labeling procedure. The developed method has a linear range between 30 and 3.0 × 10(4)cfu/ml, and a detection limit of 3 cfu/ml. The selectivity of the method was examined with Enterobacter aerogenes and Enterobacter dissolvens, which did not produce any significant response. The usefulness of the method to detect E. coli in real water samples was also investigated, and the results were compared with the results from plate-counting method. There was no significant difference between the methods (p>0.05).

Assessment of immune response of the B subunit of Shiga toxin fused to AAF adhesin of enteroaggregative Escherichia coli.

Shiga toxin is a member of AB toxin family and is composed of an A subunit which mediated toxicity and a homopentameric protein responsible for toxin binding and internalization into target cells. Another group of diarrheagenic Escherichia coli, enteroaggregative E. coli (EAEC) is a group of E. coli with aggregative adherence to epithelial cells, which play an important role in its pathogenesis. In the present investigation, the immune response of recombinant hybrid peptide composed of B subunit of Shiga toxin (StxB) and Aggregative Adherence Fimbriae (AAF) of EAEC (B-AAF/I, B-AAF/II) that elicited protective response was further characterized. The assessment of IgG subclasses (IgG1 and IgG2a) and cytokine production by these peptides indicated that although the hybrid peptides could induce immune response, but two adhesins behave differently in this regard. Lymphocyte proliferation assay and IFN-γ production were highly significant for B-AAF/II. Overall, based on the data obtained from this study it seems that mixed population of Th1-Th2 type of immune responses were induced by these hybrid peptides, which probably lead to observed protective response. In the present study, it is shown that the two hybrid peptides i.e. B-AAF/I and B-AAF/II, could be a promising strategy to make more effective and powerful vaccine.

[Neutrophil extracellular traps: method of detection and assessment of bacterial trapping efficacy].

AIM: To develop express method for detection of neutrophil extracellular traps represented by extracellular strands of neutrophils' DNA. MATERIALS AND METHODS: Acridine orange staining was used for visualization of neutrophil exracellular traps, which allows to quickly reveal the forming structures and to quantify this phenomenon. RESULTS: Performed studies showed that after 30-min of in vitro interaction of Escherichia coli, Staphylococcus aureus, lactobacteria, bifidobacteria and latex particles with neutrophils, the latter produces extracellular net-like structures, which were well visualized after staining of fixed preparations with acridine orange. Such structures are able to trap latex particles and bacteria more efficiently than live cell. Additionally, representatives of normal flora (bifidobacteria) actively stimulate production of traps. CONCLUSION: Production of neutrophil extracellular traps could be one of the main and effective mechanisms in antimicrobial defense of mucosal surfaces.

Assessment of the ovine acute phase response and hepatic gene expression in response to Escherichia coli endotoxin.

Lipopolysaccharide (LPS), a bacterial membrane endotoxin, induces a systemic inflammatory response (IFR) through the activation of blood monocytes and hepatic kupffer cells. These cells secrete pro-inflammatory cytokines, which subsequently activate the hypothalamic-pituitary-adrenal axis (HPAA) to release cortisol, an anti-inflammatory hormone that regulates the IFR and subsequent immune response (IR). The intent of this study was to characterize the acute phase response in female sheep challenged systemically with a range of doses of Escherichia coli endotoxin. Yearling ewes were challenged with an i.v. bolus dose of LPS (0, 200, 400, 600 ng/kg BW) and the acute phase response assessed by measuring serum interleukin (IL)-6 and cortisol concentrations, and the febrile response over time. A follow-up liver biopsy study was performed to determine kinetic differences in the expression of eight candidate hepatic genes between LPS dose groups using real-time RT-PCR. The initial time trail did not follow a linear dose response relationship with respect to the febrile and HPAA response to LPS challenge. Serum IL-6 concentrations increased in the two highest treatment groups but did not correlate with the observed febrile and HPAA response. The expression of Toll-like receptor 4, CD14, IL-6, tumor necrosis factor-alpha, IL-1beta, macrophage migration inhibitory factor, 11-beta-hydroxysteroid dehydrogenase (HSD), and tachykinin precursor 1 hepatic genes was dependent on both the dose and the kinetics of the response to LPS.

Severity of E. coli mastitis is mainly determined by cow factors.

Intramammary infections of dairy cows with Gram-positive bacteria such as Staphylococcus aureus (major cause of mastitis) have received a lot of attention because of their major economic impact on the dairy farm through production losses induced by an increase in somatic cell count. Management strategies, including greater awareness for efficient milking and hygienic measures, have limited the spread of Gram-positive bacteria and resulted in a significant decrease of proportion of S. aureus isolates and subclinical mastitis worldwide. Other organisms such as coliform subspecies and Streptococcus uberis, both environmental bacteria that cause clinical mastitis, have received less attention. Escherichia coli causes inflammation of the mammary gland in dairy cows around parturition and during early lactation with striking local and sometimes severe systemic clinical symptoms. This disease affects many high producing cows in dairy herds and may cause several cases of death per year in the most severe cases. It is well known that bacterial, cow and environmental factors are interdependent and influence mastitis susceptibility. Many studies, executed during the last decade, indicate that the severity of E. coli mastitis is mainly determined by cow factors rather than by E. coli pathogenicity. During E. coli mastitis, the host defense status is a cardinal factor determining the outcome of the disease. Today, we know that the neutrophil is a key factor in the cows' defense against intramammary infection with E. coli. Effective elimination of the pathogen by neutrophils is important for the resolution of infection and the outcome of E. coli mastitis. This review is a compilation of some major findings over the last 15 years concerning mainly host factors that modulate and influence neutrophil function and the mammary inflammatory reaction. The individual chapters address: virulence factors of E. coli strains, how neutrophils kill E. coli, connection between endotoxins, tumor necrosis factor-alpha and nitric oxide, severity classification of E. coli mastitis, lifespan of neutrophils, host factors that influence severity, tissue damage and production loss.

Assessing the cost of mounting an immune response.

The evolution of parasite resistance has often been assumed to be governed by antagonistic selection pressures. Defense against pathogens, by mounting an immune response, confers evident benefits but may also incur costs, so that the optimal level of defense is expected to depend on the balance between benefits and costs. Although the benefits of immune surveillance are well known, estimates of costs are still equivocal. Here we studied the behavioral and physiological modifications associated with exposure to a nonreplicating antigen (lipopolysaccharide [LPS] of Escherichia coli) in a passerine species, the house sparrow (Passer domesticus). We further investigated whether the behavioral and physiological changes provoked by LPS induced measurable repercussions on life-history traits, such as the breeding effort and reproductive success. Finally, we tested whether the trade-off between immune activation and breeding effort was modulated by the workload required to feed the brood. Exposure to LPS reduced activity and increased body mass loss of captive individuals; similarly, LPS injection induced a dramatic drop in feeding rate and reproductive success of breeding females. However, this reduction depended on brood size, suggesting that the strength of the trade-off between immune activation and reproduction was affected by the workload required to feed the brood. Overall, this study stresses the magnitude of costs associated with mounting immune responses and the ecological and evolutionary consequences for natural populations.

Assessment in mice of the therapeutic potential of tailored, multivalent Shiga toxin carbohydrate ligands.

The therapeutic potential of 2 soluble multivalent receptor-based inhibitors of Shiga toxin (Stx) 1 and Stx2 was determined in mice. One of these, Starfish, protected mice when it was injected subcutaneously in admixture with a lethal dose of Stx1 but not Stx2. Starfish also reduced the distribution of (125)I-Stx1 but not (125)I-Stx2 to the murine kidney and brain. A modified version of Starfish, called "Daisy," in which the Stx alpha Gal(1,4)beta Gal(1,4)beta Glc receptors were installed on the core glucose structure via a modified tethering strategy, protected mice against both Stx1 and Stx2. Daisy also protected streptomycin-treated mice from Escherichia coli O91:H21 and did not interfere with the ability of the murine immune system to produce Stx-specific protective antibodies. These results extend the possibility of using soluble carbohydrate-based receptor inhibitors to prevent Stx-mediated complications arising from infections with enterohemorrhagic E. coli serotypes.

Field trial assessment of the efficacy of specific egg-yolk antibody product for control of postweaning E. coli diarrhea.

Postweaning diarrhea caused by Escherichia coli is a major cause of mortality and morbidity in many swine nurseries throughout North America. Commercial products containing chicken egg-yolk antibodies specific for the control of K88+ E. coli diarrhea have been used in an attempt to prevent disease losses. The present study evaluated the use of an egg-yolk antibody product incorporated into nursery feed on two farms where K88+ E. coli diarrhea was identified as a problem. There were no differences in the prevalence of diarrhea or mortality between treatment and control pigs at either farm under routine management conditions.

ADAR1 is involved in the development of microvascular lung injury.

Deamination of adenosine on pre-mRNA to inosine is a recently discovered process of posttranscription modification of pre-mRNA, termed A-to-I RNA editing, which results in the production of proteins not inherent in the genome. The present study aimed to identify a role for A-to-I RNA editing in the development of microvascular lung injury. To that end, the pulmonary expression and activity of the RNA editase ADAR1 were evaluated in a mouse model of endotoxin (15 mg/kg IP)-induced microvascular lung injury (n=5) as well as in cultured alveolar macrophages stimulated with endotoxin, live bacteria, or interferon. ADAR1 expression and activity were identified in sham lungs that were upregulated in lungs from endotoxin-treated mice (at 2 hours). Expression was localized to polymorphonuclear and monocytic cells. These events preceded the development of pulmonary edema and leukocyte accumulation in lung tissue and followed the local production of interferon-gamma, a known inducer of ADAR1 in other cell systems. ADAR1 was found to be upregulated in alveolar macrophages (MH-S cells) stimulated with endotoxin (1 to 100 microg/mL), live Escherichia coli (5x10(7) colony-forming units), or interferon-gamma (1000 U/mL). Taken together, these data suggest that ADAR1 may play a role in the pathogenesis of microvascular lung injury possibly through induction by interferon.