L-arginine supplementation abrogates hypoxia-induced virulence of Staphylococcus aureus in a murine diabetic pressure wound model

Diabetic foot ulcers (DFUs) are the most common complications of diabetes resulting from hyperglycemia leading to ischemic hypoxic tissue and nerve damage. Staphylococcus aureus is the most frequently isolated bacteria from DFUs and causes severe necrotic infections leading to amputations with a poor 5-year survival rate. However, very little is known about the mechanisms by which S. aureus dominantly colonizes and causes severe disease in DFUs. Herein, we utilized a pressure wound model in diabetic TALLYHO/JngJ mice to reproduce ischemic hypoxic tissue damage seen in DFUs and demonstrated that anaerobic fermentative growth of S. aureus significantly increased the virulence and the severity of disease by activating two-component regulatory systems leading to expression of virulence factors. Our in vitro studies showed that supplementation of nitrate as a terminal electron acceptor promotes anaerobic respiration and suppresses the expression of S. aureus virulence factors through inactivation of two-component regulatory systems, suggesting potential therapeutic benefits by promoting anaerobic nitrate respiration. Our in vivo studies revealed that dietary supplementation of L-arginine (L-Arg) significantly attenuated the severity of disease caused by S. aureus in the pressure wound model by providing nitrate. Collectively, these findings highlight the importance of anaerobic fermentative growth in S. aureus pathogenesis and the potential of dietary L-Arg supplementation as a therapeutic to prevent severe S. aureus infection in DFUs.IMPORTANCES. aureus is the most common cause of infection in DFUs, often resulting in lower-extremity amputation with a distressingly poor 5-year survival rate. Treatment for S. aureus infections has largely remained unchanged for decades and involves tissue debridement with antibiotic therapy. With high levels of conservative treatment failure, recurrence of ulcers, and antibiotic resistance, a new approach is necessary to prevent lower-extremity amputations. Nutritional aspects of DFU treatment have largely been overlooked as there has been contradictory clinical trial evidence, but very few in vitro and in vivo modelings of nutritional treatment studies have been performed. Here we demonstrate that dietary supplementation of L-Arg in a diabetic mouse model significantly reduced duration and severity of disease caused by S. aureus. These findings suggest that L-Arg supplementation could be useful as a potential preventive measure against severe S. aureus infections in DFUs.

Stimulation Strength Determined by Superantigen Dose Controls Subcellular Localization of FOXP3 Isoforms and Suppressive Function of CD4+CD25+FOXP3+ T Cells

Staphylococcal superantigens induce massive activation of T cells and inflammation, leading to toxic shock syndrome. Paradoxically, increasing evidence indicates that superantigens can also induce immunosuppression by promoting regulatory T cell (Treg) development. In this study, we demonstrate that stimulation strength plays a critical role in superantigen-mediated induction of immunosuppressive human CD4+CD25+FOXP3+ T cells. Suboptimal stimulation by a low dose (1 ng/ml) of staphylococcal enterotoxin C1 (SEC1) led to de novo generation of Treg-like CD4+CD25+FOXP3+ T cells with strong suppressive activity. In contrast, CD4+CD25+ T cells induced by optimal stimulation with high-dose SEC1 (1 µg/ml) were not immunosuppressive, despite high FOXP3 expression. Signal transduction pathway analysis revealed differential activation of the PI3K signaling pathway and expression of PTEN in optimal and suboptimal stimulation with SEC1. Additionally, we identified that FOXP3 isoforms in Treg-like cells from the suboptimal condition were located in the nucleus, whereas FOXP3 in nonsuppressive cells from the optimal condition localized in cytoplasm. Sequencing analysis of FOXP3 isoform transcripts identified five isoforms, including a FOXP3 isoform lacking partial exon 3. Overexpression of FOXP3 isoforms confirmed that both an exon 2-lacking isoform and a partial exon 3-lacking isoform confer suppressive activity. Furthermore, blockade of PI3K in optimal stimulation conditions led to induction of suppressive Treg-like cells with nuclear translocation of FOXP3, suggesting that PI3K signaling impairs induction of Tregs in a SEC1 dose-dependent manner. Taken together, these data demonstrate that the strength of activation signals determined by superantigen dose regulates subcellular localization of FOXP3 isoforms, which confers suppressive functionality.

Does swab type matter? Comparing methods for Mannheimia haemolytica recovery and upper respiratory microbiome characterization in feedlot cattle

Background

Bovine respiratory disease (BRD) is caused by interactions among host, environment, and pathogens. One standard method for antemortem pathogen identification in cattle with BRD is deep-guarded nasopharyngeal swabbing, which is challenging, costly, and waste generating. The objective was to compare the ability to recover Mannheimia haemolytica and compare microbial community structure using 29.5 inch (74.9 cm) deep-guarded nasopharyngeal swabs, 16 inch (40.6 cm) unguarded proctology swabs, or 6 inch (15.2 cm) unguarded nasal swabs when characterized using culture, real time-qPCR, and 16S rRNA gene sequencing. Samples for aerobic culture, qPCR, and 16S rRNA gene sequencing were collected from the upper respiratory tract of cattle 2 weeks after feedlot arrival.

Results

There was high concordance of culture and qPCR results for all swab types (results for 77% and 81% of sampled animals completely across all 3 swab types for culture and qPCR respectively). Microbial communities were highly similar among samples collected with different swab types, and differences identified relative to treatment for BRD were also similar. Positive qPCR results for M. haemolytica were highly concordant (81% agreed completely), but samples collected by deep-guarded swabbing had lower amounts of Mh DNA identified (Kruskal–Wallis analysis of variance on ranks, P < 0.05; Dunn-test for pairwise comparison with Benjamini–Hochberg correction, P < 0.05) and lower frequency of positive compared to nasal and proctology swabs (McNemar’s Chi-square test, P < 0.05).

Conclusions

Though differences existed among different types of swabs collected from individual cattle, nasal swabs and proctology swabs offer comparable results to deep-guarded nasopharyngeal swabs when identifying and characterizing M. haemolytica by culture, 16S rRNA gene sequencing, and qPCR.

Supplementary Information

The online version contains supplementary material available at 10.1186/s42523-022-00197-6.

Contribution of Puma to Inflammatory Resolution During Early Pneumococcal Pneumonia

Apoptosis of cells at the site of infection is a requirement for shutdown of inflammatory signaling, avoiding tissue damage, and preventing progression of sepsis. Puma^+/+ and Puma^-/- mice were challenged with TIGR4 strain pneumococcus and cytokines were quantitated from lungs and blood using a magnetic bead panel analysis. Puma^-/- mice exhibited higher lung and blood cytokine levels of several major inflammatory cytokines, including IL-6, G-CSF, RANTES, IL-12, IFN-ϒ, and IP-10. Puma^-/- mice were more susceptible to bacterial dissemination and exhibited more weight loss than their wild-type counterparts. RNA sequencing analysis of whole pulmonary tissue revealed Puma-dependent regulation of Nrxn2, Adam19, and Eln. Enrichment of gene ontology groups differentially expressed in Puma^-/- tissues were strongly correlated to IFN-β and -ϒ signaling. Here, we demonstrate for the first time the role of Puma in prohibition of the cytokine storm during bacterial pneumonia. These findings further suggest a role for targeting immunomodulation of IFN signaling during pulmonary inflammation. Additionally, our findings suggest previously undemonstrated roles for genes encoding regulatory and binding proteins during the early phase of the innate immune response of pneumococcal pneumonia.

Pneumococcal surface adhesion A protein (PsaA) interacts with human Annexin A2 on airway epithelial cells

Streptococcus pneumoniae (pneumococcus) is a normal colonizer of the human nasopharynx capable of causing serious invasive disease. Since colonization of the nasopharynx is a prerequisite for progression to invasive diseases, the development of future protein-based vaccines requires an understanding of the intimate interaction of bacterial adhesins with host receptors. In this study, we identified that pneumococcal surface adhesin A (PsaA), a highly conserved pneumococcal protein known to play an important role in colonization of pneumococcus, can interact with Annexin A2 (ANXA2) on Detroit 562 nasopharyngeal epithelial cells. Lentiviral expression of ANXA2 in HEK 293 T/17 cells, which normally express minimal ANXA2, significantly increased pneumococcal adhesion. Blocking of ANXA2 with recombinant PsaA negatively impacted pneumococcal adherence to ANXA2-transduced HEK cells. These results suggest that ANXA2 is an important host cellular receptor for pneumococcal colonization.

Responses to chemical cross-talk between the Mycobacterium ulcerans toxin, mycolactone, and Staphylococcus aureus

Buruli ulcer is a neglected tropical disease caused by the environmental pathogen, Mycobacterium ulcerans whose major virulence factor is mycolactone, a lipid cytotoxic molecule. Buruli ulcer has high morbidity, particularly in rural West Africa where the disease is endemic. Data have shown that infected lesions of Buruli ulcer patients can be colonized by quorum sensing bacteria such as Staphylococcus aureus, S. epidermidis, and Pseudomonas aeruginosa, but without typical pathology associated with those pathogens' colonization. M. ulcerans pathogenesis may not only be an individual act but may also be dependent on synergistic or antagonistic mechanisms within a polymicrobial network. Furthermore, co-colonization by these pathogens may promote delayed wound healing, especially after the initiation of antibiotic therapy. Hence, it is important to understand the interaction of M. ulcerans with other bacteria encountered during skin infection. We added mycolactone to S. aureus and incubated for 3, 6 and 24 h. At each timepoint, S. aureus growth and hemolytic activity was measured, and RNA was isolated to measure virulence gene expression through qPCR and RNASeq analyses. Results showed that mycolactone reduced S. aureus hemolytic activity, suppressed hla promoter activity, and attenuated virulence genes, but did not affect S. aureus growth. RNASeq data showed mycolactone greatly impacted S. aureus metabolism. These data are relevant and significant as mycolactone and S. aureus sensing and response at the transcriptional, translational and regulation levels will provide insight into biological mechanisms of interspecific interactions that may play a role in regulation of responses such as effects between M. ulcerans, mycolactone, and S. aureus virulence that will be useful for treatment and prevention.

Effect of a DNA-based immunostimulant on growth, performance, and expression of inflammatory and immune mediators in beef calves abruptly weaned and introduced to a complete ration

The effect of a DNA immunostimulant on inflammatory and immune responses, performance, and health in calves following abrupt weaning and introduction to a concentrate diet was tested. Sixty-four single source Angus crossbred steers were weaned on day 1 and assigned to receive a DNA immunostimulant (TRT) or saline (CON) on days 0, 2, 4, and 6. On day 0, steers received clostridial and respiratory vaccines and anthelmintic; they were then transported 2 h, allocated to pens (n = 8 per pen), and introduced to total mixed ration. Daily intake, ADG, and feed efficiency were measured. Serum haptoglobin, tumor necrosis factor-alpha (TNF-α), and interleukin-1 beta (IL-1β) were assayed by ELISA or AlphaLISA on days 0, 2, 4, 6, 14, and 28; serum-neutralizing antibodies (SNA) to bovine herpesvirus-1 and bovine viral diarrhea virus-1 (BVDV-1) were quantified on days 0, 28, 68, and 135. In a subset of cattle (n = 6 to 8 per treatment group), the percent macrophages and activated gamma delta (γδ) T cells in blood was determined by flow cytometry on days 2 and 6, and expression of mRNA for TNF-α, interferon-gamma (IFN-γ), IL-4, and IL-10 by stimulated blood mononuclear cells was assessed by real-time reverse transcriptase PCR on day 6. After 70 d, cattle were shipped 1,205 km to a feedlot and performance and health were followed. There was a significant effect of time on serum TNF-α, IL-1β, haptoglobin, and SNA (P < 0.001); the range in concentration among cattle on each day was large. The ratio of IFN-γ to IL-4 expression was significantly higher (P = 0.03) for TRT cattle, suggesting that treatment activated T-helper type 1 cells. There was a trend toward an improved feed conversion (P = 0.10) for TRT steers over the 70-d backgrounding period. There was no effect of treatment on feedlot performance or carcass merit (P > 0.10). During backgrounding, 1 TRT steer died of enterocolitis. In spite of backgrounding, cattle experienced an outbreak of bovine respiratory disease (BRD) in the feedlot and 1 of 31 TRT cattle and 5 of 32 CON cattle died of BRD. The immunostimulant modified some immune responses during backgrounding. Large variability in inflammatory responses during backgrounding indicated that events around weaning induce systemic inflammation that varies substantially among cattle.

Suboptimal stimulation with staphylococcal enterotoxin C1 induces immunosuppressive CD4+CD25+ regulatory T cells by differential expression of FOXP3 isoforms

Regulatory T cells (Tregs) play an important role in maintaining immune homeostasis and preventing excessive tissue damage upon immune activation. However, pathogens could exploit Tregs for their successful pathogenesis. We demonstrated that immunosuppressive CD4+CD25+FOXP3+ Tregs were induced by staphylococcal enterotoxin (SE) produced by an important human pathogen, Staphylococcus aureus. CD4+CD25+FOXP3+ T cells were induced from stimulation with SEC1 at a high (1 μg/ml) and low (1 ng/ml) concentrations that induced optimal stimulation and suboptimal stimulation, respectively. However, CD4+CD25+FOXP3+ T cells induced from suboptimal stimulation were functionally immunosuppressive, not from optimal stimulation. Immunosuppressive CD4+CD25+FOXP3+ T cells induced from suboptimal stimulation showed typical Treg surface markers such as CTLA-4, GITR, TNFR2, and CD45RO and produced immunomodulatory cytokines such as TGF-β and IL-10. However, suppression was mainly mediated by galectin-1 in a contact-dependent manner. We found that CD4+CD25+ Tregs from suboptimal stimulation highly express FOXP3 isoform lacking exon 2 (ΔE2) and partially lacking exon3 (ΔpE3) preferably localized to the nucleus, compared to those from optimal stimulation. Lentiviral transduction of FOXP3 isoforms (full length, ΔE2, ΔpE3) to Jurkat T cells did not result in immunosuppressive function. By contrast, when cultured in the media generated from suboptimal T cell stimulation, transduced Jurkat T cells became more immunosuppressive in an order of ΔE2 ΔpE3, and full length FOXP3. These results suggest that soluble factors generated from suboptimal T cell proliferation play an important role in induction of immunosuppressive Tregs.

Induction of Immunosuppressive CD8+CD25+FOXP3+ Regulatory T Cells by Suboptimal Stimulation with Staphylococcal Enterotoxin C1

Superantigens (SAgs) produced by Staphylococcus aureus at high concentrations induce proliferation of T cells bearing specific TCR Vβ sequences and massive cytokinemia that cause toxic shock syndrome. However, the biological relevance of SAgs produced at very low concentrations during asymptomatic colonization or chronic infections is not understood. In this study, we demonstrate that suboptimal stimulation of human PBMCs with a low concentration (1 ng/ml) of staphylococcal enterotoxin C1, at which half-maximal T cell proliferation was observed, induced CD8⁺CD25⁺ T cells expressing markers related to regulatory T cells (Tregs), such as IFN-γ, IL-10, TGF-β, FOXP3, CD28, CTLA4, TNFR2, CD45RO, and HLA-DR. Importantly, these CD8⁺CD25⁺ T cells suppressed responder cell proliferation mediated in contact-dependent and soluble factor-dependent manners, involving galectin-1 and granzymes, respectively. In contrast, optimal stimulation of human PBMCs with a high concentration (1 μg/ml) of staphylococcal enterotoxin C1, at which maximal T cell proliferation was observed, also induced similar expression of markers related to Tregs, including FOXP3 in CD8⁺CD25⁺ cells, but these T cells were not functionally immunosuppressive. We further demonstrated that SAg-induced TCR Vβ-restricted and MHC class II-restricted expansion of immunosuppressive CD8⁺CD25⁺ T cells is independent of CD4⁺ T cells. Our results suggest that the concentration of SAg strongly affects the functional characteristics of activated T cells, and low concentrations of SAg produced during asymptomatic colonization or chronic S. aureus infection induce immunosuppressive CD8⁺ Tregs, potentially promoting colonization, propagation, and invasion of S. aureus in the host.

The Staphylococcus aureus superantigen SElX is a bifunctional toxin that inhibits neutrophil function

Bacterial superantigens (SAgs) cause Vβ-dependent T-cell proliferation leading to immune dysregulation associated with the pathogenesis of life-threatening infections such as toxic shock syndrome, and necrotizing pneumonia. Previously, we demonstrated that staphylococcal enterotoxin-like toxin X (SElX) from Staphylococcus aureus is a classical superantigen that exhibits T-cell activation in a Vβ-specific manner, and contributes to the pathogenesis of necrotizing pneumonia. Here, we discovered that SElX can also bind to neutrophils from human and other mammalian species and disrupt IgG-mediated phagocytosis. Site-directed mutagenesis of the conserved sialic acid-binding motif of SElX abolished neutrophil binding and phagocytic killing, and revealed multiple glycosylated neutrophil receptors for SElX binding. Furthermore, the neutrophil binding-deficient mutant of SElX retained its capacity for T-cell activation demonstrating that SElX exhibits mechanistically independent activities on distinct cell populations associated with acquired and innate immunity, respectively. Finally, we demonstrated that the neutrophil-binding activity rather than superantigenicity is responsible for the SElX-dependent virulence observed in a necrotizing pneumonia rabbit model of infection. Taken together, we report the first example of a SAg, that can manipulate both the innate and adaptive arms of the human immune system during S. aureus pathogenesis.

Staphylococcus aureus is a bacterial pathogen responsible for an array of disease types in healthcare and community settings. One of the keys to the success of this pathogen is its ability to subvert the immune system of the host. Here we demonstrate that the superantigen (SAg) staphylococcal enterotoxin-like toxin X (SElX) contributes to immune evasion by inducing unregulated T-cell proliferation, and by inhibition of phagocytosis by neutrophils. We observed that the capacity to bind neutrophils appears to be central to the SElX-dependent toxicity observed in a necrotising pneumonia infection model in rabbits. We report the first example of a staphylococcal SAg with two independent immunomodulatory functions acting on distinct immune cell types.

Cannabidiol (CBD) induces functional Tregs in response to low-level T cell activation

Many effects of the non-psychoactive cannabinoid, cannabidiol (CBD), have been described in immune responses induced by strong immunological stimuli. It has also been shown that CBD enhances IL-2 production in response to low-level T cell stimulation. Since IL-2, in combination with TGF-β1, are critical for Treg induction, we hypothesized that CBD would induce CD4+CD25+FOXP3+ Tregs in response to low-level stimulation. Low-level T cell stimulation conditions were established based on minimal CD25 expression in CD4+ cells using suboptimal PMA/Io (4nM/0.05μM, S/o), ultrasuboptimal PMA/Io (1nM/0.0125μM, Us/o) or soluble anti-CD3/28 (400-800ng each, s3/28). CBD increased CD25+FOXP3+ cells from CD4+, CD4+CD25+, and CD4+CD25- T cells, as well as in CD4+ T cells derived from FOXP3-GFP mice. Most importantly, the Us/o+CBD-induced CD4+CD25+ Tregs robustly suppressed responder T cell proliferation, demonstrating that the mechanism by which CBD is immunosuppressive under low-level T cell stimulation involves induction of functional Tregs.

Genotypic and Phenotypic Characterization of Methicillin-Resistant Staphylococcus aureus Isolated from Bovine Mastitic Milk in Korea

Staphylococcus aureus is a major etiological pathogen for bovine mastitis, foodborne illness, and various clinical infections. Methicillin-resistant S. aureus (MRSA) has been isolated from bovine mastitic milk, and the presence of MRSA in milk is a major public health concern. We investigated the frequency of MRSA isolation from mastitic raw milk in Korea and characterized the patterns of antimicrobial resistance, virulence, and genotypes of the MRSA isolates. A total of 1,222 raw milk samples were collected from 47 dairy farms in Gyeonggi province from 2011 to 2012. Of these samples, 649 were considered mastitic milk based on somatic cell counts of more than 200,000 cells per ml, and 165 S. aureus isolates (from 25.4% of samples) were obtained from these samples. Of these isolates, 23 (13.9%) collected from five farms were confirmed as MRSA by detection of the mecA gene. Disk diffusion and MIC tests for antibiotic resistance revealed that all MRSA isolates were resistant to four or more antimicrobial agents. All MRSA isolates had staphylococcal enterotoxin genes, and two clusters of these genes were identified: seg-sei-sek-sem-sen-seo (20 isolates, 87%) and sed-seg-sei-sej-sem-sen-seo (3 isolates, 13%). Each MRSA-positive farm had only one spa-SCCmec type. Nine MRSA isolates (39.1%) with the t324-IVa genotype, which is related to community-acquired MRSA infection, were isolated from three dairy farms. Additional genotypes of t148-IVa and t002-II were detected and related to human MRSA strains. Most MRSA isolates had distinct pulsed-field gel electrophoresis subtypes, indicating they were not the same clones. Only two isolates collected from the same farm during different years had an identical electrophoresis type, indicating persistence of the clone at this farm. Taken together, these findings may indicate an increased virulence and risk of MRSA strains on dairy farms. Therefore, an efficient surveillance and control program is needed to prevent the transmission of MRSA from animals to humans.

Genotype and enterotoxigenicity of Staphylococcus epidermidis isolate from ready to eat meat products

We have previously shown that potentially pathogenic isolates of Staphylococcus epidermidis occur at high incidence in ready-to-eat food. Now, within 164 samples of ready-to-eat meat products we identified 32 S. epidermidis isolates. In 8 isolates we detected the genes encoding for staphylococcal enterotoxins, but in 7 S. epidermidis isolates these genes were not stable over passages. One isolate designated 4S was shown to stably harbour sec and sel genes. In the genome sequence of S. epidermidis 4S we identified 21,426-bp region flanked by direct-repeats, encompassing sec and sel genes, corresponding to the previously described composite staphylococcal pathogenicity island (SePI) in S. epidermidis FRI909. Alignment of S. epidermidis 4S and S. epidermidis FRI909 SePIs revealed 6 nucleotide mismatches located in 5 of the total of 29 ORFs. Genomic location of S. epidermidis 4S SePI was the same as in FRI909. S. epidermidis 4S is a single locus variant of ST561, being genetically different from FRI909. SECepi was secreted by S. epidermidis 4S to BHI broth ranging from 14 to almost 36μg/mL, to milk ranging from 6 to 9ng/mL, to beef meat juice from 2 to 3μg/mL and to pork meat juice from 1 to 2μg/mL after 24 and 48h of cultivation, respectively. We provide the first evidence that S. epidermidis occurring in food bears an element encoding an orthologue to Staphylococcus aureus SEC, and that SECepi can be produced in microbial broth, milk and meat juices. Regarding that only enterotoxins produced by S. aureus are officially tracked in food in EU, the ability to produce enterotoxin by S. epidermidis pose real risk for food safety.

Cannabidiol (CBD) induces functional CD4+ CD25+ FOXP3+ Tregs

We previously reported that cannabidiol (CBD), one of the Cannabis sativa-derived cannabinoid compounds and a potent immunosuppressive agent, increased CD25 and FOXP3 expression on CD4+ cells under “ultrasuboptimal” T cell stimulation (1 nM PMA/0.0125 μM Ionomycin, designated “Us/o”). We also observed that CBD increased IL-10 and il10 mRNA expression under Us/o stimulation. Thus, we tested the hypothesis that CBD-induced CD4+ CD25+ FOXP3+ cells are functional Tregs. First, we determined that the expression of CD25 and FOXP3 was induced on CD4-enriched cells in response to CBD (10 μM) plus Us/o activation as compared to CBD plus low level anti-CD3/28 stimulation (soluble anti-CD3 and anti-CD28 antibodies at 400 or 800 ng each) for 5 days. Second, we determined the functionality of the CBD-induced Tregs using a mixed lymphocyte response assay. For this study, splenocytes were treated with CBD (10 μM) plus Us/o activation for 5 days. CBD-induced CD4+ CD25+ and CD4+ CD25− cells were then purified and treated with mitomycin C (MMC). Fresh, naïve responder splenocytes were activated with anti-CD3/28-coated beads to induce proliferation of the responder cells, then mixed with the MMC-treated CD4+ CD25+ or CD4+ CD25− cells. CBD-induced CD4+ CD25+ cells, but not CBD-induced CD4+ CD25− cells, suppressed responder cell proliferation. Thus, CBD induced functional Tregs under conditions of low level activation, which is consistent with other studies demonstrating that CBD can induce Tregs under optimal stimulation conditions.

Mobilization of Genomic Islands of Staphylococcus aureus by Temperate Bacteriophage

The virulence of Staphylococcus aureus, in both human and animal hosts, is largely influenced by the acquisition of mobile genetic elements (MGEs). Most S. aureus strains carry a variety of MGEs, including three genomic islands (νSaα, νSaβ, νSaγ) that are diverse in virulence gene content but conserved within strain lineages. Although the mobilization of pathogenicity islands, phages and plasmids has been well studied, the mobilization of genomic islands is poorly understood. We previously demonstrated the mobilization of νSaβ by the adjacent temperate bacteriophage ϕSaBov from strain RF122. In this study, we demonstrate that ϕSaBov mediates the mobilization of νSaα and νSaγ, which are located remotely from ϕSaBov, mostly to recipient strains belonging to ST151. Phage DNA sequence analysis revealed that chromosomal DNA excision events from RF122 were highly specific to MGEs, suggesting sequence-specific DNA excision and packaging events rather than generalized transduction by a temperate phage. Disruption of the int gene in ϕSaBov did not affect phage DNA excision, packaging, and integration events. However, disruption of the terL gene completely abolished phage DNA packing events, suggesting that the primary function of temperate phage in the transfer of genomic islands is to allow for phage DNA packaging by TerL and that transducing phage particles are the actual vehicle for transfer. These results extend our understanding of the important role of bacteriophage in the horizontal transfer and evolution of genomic islands in S. aureus.

Optimization of Swine Breeding Programs Using Genomic Selection with ZPLAN

The objective of this study was to evaluate the present conventional selection program of a swine nucleus farm and compare it with a new selection strategy employing genomic enhanced breeding value (GEBV) as the selection criteria. The ZPLAN+ software was employed to calculate and compare the genetic gain, total cost, return and profit of each selection strategy. The first strategy reflected the current conventional breeding program, which was a progeny test system (CS). The second strategy was a selection scheme based strictly on genomic information (GS1). The third scenario was the same as GS1, but the selection by GEBV was further supplemented by the performance test (GS2). The last scenario was a mixture of genomic information and progeny tests (GS3). The results showed that the accuracy of the selection index of young boars of GS1 was 26% higher than that of CS. On the other hand, both GS2 and GS3 gave 31% higher accuracy than CS for young boars. The annual monetary genetic gain of GS1, GS2 and GS3 was 10%, 12%, and 11% higher, respectively, than that of CS. As expected, the discounted costs of genomic selection strategies were higher than those of CS. The costs of GS1, GS2 and GS3 were 35%, 73%, and 89% higher than those of CS, respectively, assuming a genotyping cost of $120. As a result, the discounted profit per animal of GS1 and GS2 was 8% and 2% higher, respectively, than that of CS while GS3 was 6% lower. Comparison among genomic breeding scenarios revealed that GS1 was more profitable than GS2 and GS3. The genomic selection schemes, especially GS1 and GS2, were clearly superior to the conventional scheme in terms of monetary genetic gain and profit.

Effect of preoperative autologous blood donation on patients undergoing bimaxillary orthognathic surgery: a retrospective analysis

The efficacy of preoperative autologous blood donation (PABD) was evaluated according to preoperative haemoglobin (Hb) values. The records of 295 patients who underwent bimaxillary orthognathic surgery between July 2007 and August 2008 were reviewed. The records for autologous blood donation, intraoperative transfusion, and related laboratory studies were also evaluated. The transfusion trigger used during this period was Hb < 10 g/dl. A total of 189 patients (64.1%) made a PABD and 106 patients (35.9%) did not. The incidence of allogeneic blood transfusion was significantly lower in the PABD group than in the no PABD group (15.9% vs. 29.2%, P = 0.007). This difference was greater in patients with a preoperative Hb < 14 g/dl (20.3% vs. 62.5%, P < 0.0001), and no difference was found in patients with Hb ≥ 14 g/dl (13.3% vs. 14.9%, P = 0.83). PABD reduced the incidence of allogeneic blood transfusion in patients undergoing bimaxillary orthognathic surgery, particularly in patients with a preoperative Hb < 14 g/dl. PABD could be used to reduce the frequency of intraoperative allogeneic blood transfusion in these patients.

Characterization and expression of monoclonal antibody-defined molecules on resting and activated bovine αβ, γδ T and NK cells

Monoclonal antibodies (mAbs) specific for leukocyte differentiation molecules (LDMs) were developed during the past few decades to expand reagents for research in ruminants, pigs, and horses. The specificity of some of the mAb-defined molecules was determined through participation in international workshops. Other molecules identified with mAbs during this time, and more recently with mAbs developed after the workshops, have remained partially characterized. Efforts are now underway to characterize the specificity of these mAbs. As reported here, flow cytometry (FC) was used to screen two sets of hybridomas to determine how many of the hybridomas produce mAbs that detect molecules with up-regulated expression on activated lymphocytes or NK cells. Thirty four hybridomas were identified. Comparison of the patterns of reactivity of the mAbs showed some of the mAbs formed clusters that recognize 5 different molecules. FC showed one cluster recognized CD25. Use of mass spectrometry showed 4 clusters recognized orthologues of CD26, CD50, gp96 and signaling lymphocytic activation molecule family member 9 (SLAMF9). Verification and documentation that CD26, CD50, and SLAMF9 were only up-regulated on activated cells was obtained with PBMC from calves vaccinated with a Mycobacterium avium paratuberculosis mutant, Map-relA. CD26 and CD50 were up-regulated on NK cells, CD4 and CD8 T cells and γδ T cells. SLAMF9 was only up-regulated on CD4, CD8, and γδ T cells. gp96 was detected on granulocytes, monocytes and activated NK cells. Detection was attributable to the binding of gp96 to its receptor CD91.

Effects of Palm Kernel Expellers on Productive Performance, Nutrient Digestibility, and White Blood Cells of Lactating Sows

This experiment was conducted to investigate the effects of palm kernel expellers on productive performance, nutrient digestibility, and changes in white blood cells (WBC) of lactating sows. A total of 14 sows (200±12 kg of average body weight [BW]; 2.5 of average parity) were used and moved from gestation room to farrowing room on d 109 of gestation. Sows were randomly assigned to 2 dietary treatments in a completely randomized design. The treatments were a diet based on corn and soybean meal (CON) and CON added with 20% of palm kernel expellers (PKE). Sows were fed the treatments for 28 days (weaning) after farrowing. Blood was collected from each sow and 4 randomly selected piglets from each sow before farrowing or on d 3, 7, or 14 of lactation. Sows were fed respective treatments containing 0.2% chromic oxide from d 15 to 21 of lactation. Fecal samples were collected daily for the last 3 days after the 4-d adjustment period. Measurements were performances and WBC changes of sows and litter, nutrient digestibility of sows, and daily diarrhea of litter. Sows fed PKE had greater average daily feed intake (7.38 vs 7.10 kg/d; p<0.05) and lost less BW (−6.85 vs −8.54 kg; p<0.05) and backfat depth (−0.42 vs −0.71 mm; p<0.05) than those fed CON. However, there were no differences on digestibility of dry matter, nitrogen, and energy and weaning to estrus interval of sows fed either CON or PKE. Piglets from sows fed PKE gained more BW (203 vs 181 g/d; p = 0.08) and had less frequency of diarrhea (6.80 vs 8.56%; p = 0.07) than those from sows fed CON. On the other hand, no difference was found on preweaning mortality of piglets from sows fed either CON or PKE. Sows fed PKE had lower number of WBC (9.57 vs 11.82 ×10³/μL; p = 0.09) before farrowing than those fed CON, but no difference on d 3 and 7. Similarly, piglets from sows fed PKE had also lower number of WBC (7.86 vs 9.80 ×10³/μL; p<0.05) on d 14 of lactation than those from sows fed CON, but no difference on d 3 and 7. In conclusion, addition of 20% palm kernel expellers to lactation diet based on corn and soybean meal had no negative effects on productive performance, nutrient digestibility, and WBC changes of lactating sows.

Estimation of Genetic Parameters for Pork Belly Components in Yorkshire Pigs

This study was conducted to estimate the genetic parameters for pork belly traits and muscles in Yorkshire pigs. Each pork belly was cut into nine parts perpendicular to the thoracic vertebrae (6th to 14th). Traits of belly muscles including the deep pectoral, latissimus dorsi, cutaneous trunci, rectus abdominis, external and internal abdominal oblique from 382 purebred pigs were recorded and analyzed using SAS Package (9.1) and Derivative-free restricted maximum likelihood methods. Heritability estimates for belly traits ranged from 0.27 to 0.49, while they were 0.12 to 0.66 for belly muscles. Moderate to high heritability estimates were noted in belly weight (0.33), belly length (0.28), and belly width (0.49). In belly muscles, the latissimus dorsi and deep pectoral, which are located only in the 6th to 9th vertebrae sections, were found to have heritability estimates ranging from 0.21 to 0.29 and 0.23 to 0.35, respectively. Strong heritability estimates were observed in the 7th to 13th sections of cutaneous trunci muscle ranging from 0.42 to 0.66. Genetic correlations of latissimus dorsi m. with belly length were positive (0.50), while cutaneous trunci m. with belly weight also revealed a positive relationship that ranged from 0.35 to 0.47. The estimated genetic parameters indicate that belly weight can be improved by genetic selection. Differences in the levels of heritability occurred among various parameters of Yorkshire pork belly, which should be considered when performing selection to improve pork belly quality. Moreover, these results can provide valuable information that can be used as the basis for further investigations to improve pork belly.

Estimation of Genetic Associations between Production and Meat Quality Traits in Duroc Pigs

Data collected from 690 purebred Duroc pigs from 2009 to 2012 were used to estimate the heritability, and genetic and phenotypic correlations between production and meat quality traits. Variance components were obtained through the restricted maximum likelihood procedure using Wombat and SAS version 9.0. Animals were raised under the same management in five different breeding farms. The average daily gain, loin muscle area (LMA), backfat thickness (BF), and lean percent (LP) were measured as production traits. Meat quality traits included pH, cooking loss, lightness (L*), redness (a*), yellowness (b*), marbling score (MS), moisture content (MC), water holding capacity (WHC), and shear force. The results showed that the heritability estimates for meat quality traits varied largely from 0.19 to 0.79. Production traits were moderate to highly heritable from 0.41 to 0.73. Genotypically, the BF was positively correlated (p<0.05) with MC (0.786), WHC (0.904), and pH (0.328) but negatively correlated with shear force (−0.533). The results of genetic correlations indicated that selection for less BF could decrease pH, moisture content, and WHC and increase the shear force of meat. Additionally, a significant positive correlation was recorded between average daily gain and WHC, which indicates pork from faster-growing animals has higher WHC. Furthermore, selection for larger LMA and LP could increase MS and lightness color of meat. The meat quality and production traits could be improved simultaneously if desired. Hence, to avoid further deterioration of pork characteristics, appropriate selection of traits should be considered.

Effects of Palm Kernel Expellers on Growth Performance, Nutrient Digestibility, and Blood Profiles of Weaned Pigs

This experiment was conducted to investigate the effects of palm kernel expellers on growth performance, nutrient digestibility, and blood profiles of weaned pigs. A total of 88 weaned pigs (6.94±0.76 kg body weight [BW]; 28 d old) were randomly allotted to 2 dietary treatments (4 pigs/pen; 11 replicates/treatment) in a randomized complete block design (sex as a block). The dietary treatments were a typical nursery diet based on corn and soybean meal (CON) and CON added with 20% of palm kernel expellers (PKE). Pigs were fed for 6 wk using a 3-phase feeding program with declining diet complexity and with phases of 1, 2, and 3 wk, respectively. Blood was collected from randomly selected 2 pigs in each pen before weaning and on d 7 after weaning. Pigs were fed respective dietary treatments containing 0.2% chromic oxide from d 29 to 35 after weaning. Fecal samples were collected from randomly selected 2 pigs in each pen daily for the last 3 days after the 4-d adjustment period. Measurements were growth performances, digestibility of dry matter, nitrogen and energy, white and red blood cell counts, packed cell volume, and incidence of diarrhea. The PKE increased average daily gain (ADG) (246 vs 215 g/d; p = 0.06) and average daily feed intake (ADFI) (470 vs 343 g/d; p<0.05) and decreased gain-to-feed ratio (G:F) (0.522 vs 0.628 g/g; p<0.05) during phase 2 compared with CON, but did not affect growth performance during phase 1 and 3. During overall experimental period, PKE increased ADG (383 vs 362 g/d; p = 0.05) and ADFI (549 vs 496 g/d; p<0.05) compared with CON, but did not affect G:F. However, no differences were found on digestibility of dry matter, nitrogen, and energy between CON and PKE. The PKE reduced frequency of diarrhea (15% vs 25%; p = 0.08) for the first 2 wk after weaning compared with CON. Similarly, PKE decreased white blood cells (8.19 vs 9.56×10(3)/μL; p = 0.07), red blood cells (2.92 vs 3.25×10(6)/μL; p = 0.09), and packed cell volume (11.1% vs 12.6%; p = 0.06) on d 7 after weaning compared with CON. In conclusion, addition of 20% palm kernel expellers to nursery diet based on corn and soybean meal had no negative effects on growth performance, nutrient digestibility, and blood profiles of weaned pigs.

Timing of reversal with respect to three nerve stimulator end-points from cisatracurium-induced neuromuscular block

After elective ear surgery with cisatracurium neuromuscular blockade, 48 adults were randomly assigned to receive neostigmine: (a) at appearance of the fourth twitch of a 'train-of-four'; (b) at loss of fade to train-of-four; or (c) at loss of fade to double-burst stimulation, all monitored using a TOF-Watch SX® on one arm. For each of these conditions, the recovery from train-of-four (TOF) ratio was measured in parallel objectively using a TOF-Watch SX placed on the contralateral arm. The median (IQR [range]) time from administration of reversal to a train-of-four ratio ≥ 0.9 was 11 (9-15.5 [2-28]) min, 8 (4-13.5 [1-25]) min and 7 (4-10 [2-15]) min in the three groups, respectively. This recovery time was significantly shorter when reversal was given at loss of fade to double-burst stimulation (c), than when given at the appearance of the fourth twitch (a), p = 0.046. However, the total time to extubation may be unaffected as it takes longer for fade to be lost after double-burst stimulation than for four twitches subjectively to appear.

Correlation among bioimpedance analysis, sonographic and circumferential measurement in assessment of breast cancer-related arm lymphedema

New approaches for assessment of lymphedema using ultrasonography (US) have been introduced recently and are reported to be reliable and simple. Ultrasonography provides detailed information about physical properties of the tissue in addition to volume and size. There have been only limited studies comparing bioimpedance analysis (BIA), US, and circumferential measurement (CM), which is considered a standard measurement. The aim of this study was to determine the relationship between US, BIA, and CM. Twenty-eight patients with lymphedema after breast cancer surgery underwent BIA, US, and CM. Impedance, which reflects the amount of extracellular fluid, was measured with 1 kHz frequency in affected and unaffected arms. Circumferences were measured at 10cm proximal and distal to the elbow and a truncated cone method used to calculate estimated volumes for upper arm and forearm. We found that interlimb forearm subcutis thickness differences measured by US were highly correlated with CM measurements and that interlimb upper arm subcutis thickness differences measured by US were moderately correlated with CM measurements and BIA ratios. However, the interlimb ratio of compressibility measured by US showed no or only weak correlation with impedance measurements and circumferential measurements. Our results also show that compressibility measured by US could not be predicted from BIA or CM measurements despite a high degree of concordance among subcutis thickness measured by US, CM, and BIA.

Proteome Analysis of Bovine Longissimus dorsi Muscle Associated with the Marbling Score

The breeding value of marbling score in skeletal muscle is an important factor for evaluating beef quality. In the present study, we investigated proteins associated with the breeding value of the marbling score for bovine sirloin to select potential biomarkers to improve meat quality through comparative proteomic analysis. Proteins isolated from muscle were separated by two-dimensional gel electrophoresis. After analyzing images of the stained gel, seven protein spots for the high marbling score group were identified corresponding to changes in expression that were at least two-fold compared to the low marbling score group. Four spots with increased intensities in the high marbling score group were identified as phosphoglycerate kinase 1, triosephophate isomerase, acidic ribosomal phosphoprotein PO, and capping protein (actin filament) Z-line alpha 2. Spots with decreased intensities in the high marbling score group compared to the low score group were identified as 14-3-3 epsilon, carbonic anhydrase II, and myosin light chain 1. Expression of myosin light chain 1 and carbonic anhydrase 2 was confirmed by Western blotting. Taken together, these data could help improve the economic performance of cattle and provide useful information about the underlying the function of bovine skeletal muscle.

Comparison and correlation analysis of different Swine breeds meat quality

This study was performed to determine the influence of pig breed and gender on the ultimate pH and physicochemical properties of pork. The correlations between pH and pork quality traits directly related to carcass grade, and consumer’s preference were also evaluated. The pH and meat grading scores for cold carcasses of 215 purebred pigs (Duroc, Landrace, and Yorkshire) from four different farms were obtained. Meat quality parameters of the pork loin were analyzed. Duroc and female animals were more affected compared to other breeds and male pigs. Duroc animals had the highest ultimate pH, carcass back fat thickness, marbling scores, yellowness, and fat content (p<0.05). Landrace pigs had the highest color lightness and cooking loss values (p<0.05). Among all trait parameters, marbling scores showed the highest significant differences when evaluating the impact of breed and gender on meat quality characteristics (p<0.001). Ultimate pH was positively correlated with carcass weight (0.20), back fat thickness (0.19), marbling score (0.17), and color score (0.16) while negatively correlated with cooking loss (−0.24) and shear force (−0.20). Therefore, pork samples with lower ultimate pH had lower cooking loss, higher lightness, and higher shear force values irrespective of breed.

Molecular cloning, sequence identification, and gene expression analysis of bovine ADCY2 gene

Adenylyl cyclase 2 (ADCY2), a class B member of adenylyl cyclases, is important in accelerating phosphor-acidification as well as glycogen synthesis and breakdown. Given its distinct role in flesh tenderization after butchering, we cloned and sequenced the ADCY2 gene from Yanbian cattle and assessed its expression in bovine tissues. A 2947 bp nucleotide sequence representing the full-length cDNA of bovine ADCY2 gene was obtained by 5' and 3' remote analysis computations for gene expression. Analyses of the putative protein sequence showed that ADCY2 had high homology among species, except with the non-mammal Oreochromis niloticus. Gene structural domain analyses in humans and rats indicated that the ADCY2 protein had no flaw; only the transmembrane domain was reduced and the CYCc structure domain was shortened. Assessment of ADCY2 expression in bovine tissues by real-time PCR showed that the highest expression was in the testes, followed by the longissimus dorsi, tensor fasciae latae, and latissimus dorsi. These data will serve as a foundation for further insight into the cattle ADCY2 gene.

Characterization of a potential Listeria monocytogenes virulence factor associated with attachment to fresh produce

A study to determine the attachment of L. monocytogenes serotype 4b strain F2365 on vegetables and fruits was conducted. In an initial study, we screened 32 genes encoding surface proteins and lipases of the strain to find highly expressed genes on lettuce leaves. The results showed that transcription levels of LMOf2365_0413, LMOf2365_0498, LMOf2365_0859, LMOf2365_2052, and LMOf2365_2812 were significantly upregulated on lettuce leaves. In silico analysis showed that LMOf2365_0859 contains a putative cellulose binding domain. Thus, we hypothesized that this gene may be involved in an attachment to vegetables, and named it lcp (gene encoding Listeria cellulose binding protein [LCP]). lcp mutant (Δlcp) and lcp complement (F2365::pMAD::cat::lcp) strains were generated by homologous recombination. The abilities of a wild-type (WT) strain, the Δlcp strain, and the complemented strain to attach to lettuce leaves were evaluated, which indicated that the attachment of the Δlcp strain to lettuce was significantly less than that of the WT and the complemented strains. Similar results were observed for baby spinach and cantaloupe. Fluorescence microscopy and field emission scanning microscopy analysis further supported these findings. The binding of L. monocytogenes to cellulose was determined using cellulose acetate-coated plates. The results showed that a binding ability of the Δlcp strain was significantly lower than that of the wild type. Combined, these results strongly suggest that LCP plays an important role in an attachment to vegetables and fruits.

Antinociceptive curcuminoid, KMS4034, effects on inflammatory and neuropathic pain likely via modulating TRPV1 in mice

BACKGROUND

Curcumin, the active ingredient of turmeric (Curcuma longa), has a wide range of beneficial effects including anti-inflammation and analgesia. However, poor bioavailability of curcumin hinders its clinical application. To overcome this limitation, we modified the structure of curcumin and synthesized new derivatives with favourable pharmacokinetic profiles. Recently, curcumin has been shown to have an antagonizing effect on transient receptor potential vanilloid type 1 (TRPV1) ion channels. We investigated the antinociceptive activity of KMS4034 which had the most favourable pharmacokinetics among the tested curcumin derivatives.

METHODS

To evaluate the mechanism of the antinociceptive effects of KMS4034, capsaicin (I(CAP))- and heat (I(heat))-induced currents in TRPV1 expressing HEK293 cells were observed after the application of KMS4034. Nociceptive behavioural measurement using the hot-plate test, formalin test, and chronic constriction injury (CCI) model were evaluated in mice. Also, calcitonin gene-related peptide (CGRP) was stained immunohistochemically in the L4/5 dorsal horns in mice with neuropathic pain.

RESULTS

I(CAP) (P<0.01) and I(heat) (P<0.05) of TRPV1 were significantly blocked by 10 μM KMS4034. Behaviourally, noticeable antinociceptive effects after 10 mg kg(-1) of KMS4034 treatment were observed in the first (P<0.05) and second phases (P<0.05) of the formalin and hot-plate tests. The mechanical threshold of CCI mice treated with 10 mg kg(-1) KMS4034 was significantly increased compared with control. Immunohistochemical CGRP expression was decreased in the lamina I-II of the lumbar dorsal horns in KMS4034-treated CCI mice compared with the control (P<0.05).

CONCLUSIONS

KMS4034 may be an effective analgesic for various pain conditions.

Enterotoxigenic potential of coagulase-negative staphylococci

Staphylococci are a worldwide cause of human and animal infections including life-threatening cases of bacteraemia, wound infections, pyogenic lesions, and mastitis. Enterotoxins produced by some staphylococcal species were recognized as causative agents of staphylococcal food poisoning (SFP), being also able to interrupt human and animal immune responses. Only enterotoxins produced by Staphylococcus aureus were as yet well characterized. Much less is known about enterotoxigenic potential of coagulase-negative species of genus Staphylococcus (CNS). The pathogenic role of CNS and their enterotoxigenicity in developing SFP has not been well established. Although it has been reported that enterotoxigenic CNS strains have been associated with human and animal infections and food poisoning, most of research lacked a deeper insight into structure of elements encoding CNS enterotoxins. Recent studies provided us with strong evidence for the presence and localization of enterotoxin-coding elements in CNS genomes and production of enterotoxins. Thus, the importance of pathogenic potential of CNS as a source of staphylococcal enterotoxins has been highlighted in human and animal infections as well as in food poisoning.

Expression of fat deposition and fat removal genes is associated with intramuscular fat content in longissimus dorsi muscle of Korean cattle steers

Intramuscular fat (IMF) in cattle is an important component of traits that influence meat quality. We measured carcass characteristics and gene expression in Korean steers to clarify the molecular mechanism(s) underlying IMF deposition in LM tissue by determining the correlation between IMF content and gene expression abundance and by developing models to predict IMF content using gene expression abundance. The deposition of IMF is determined by a balance between fat deposition and fat removal in the LM. We measured mRNA abundance of lipid metabolic genes including lipogenesis [acetyl CoA carboxylase (ACC), fatty acid synthase (FASN)], fatty lipid uptake [lipoprotein lipase (LPL), fatty acid translocase (CD36), fatty acid transport protein 1 (FATP1)], fatty acid esterification [glycerol-3-phosphate acyltransferase 1 (GPAT1), acylglycerol phosphate acyltransferase 1 (AGPAT1), diacylglycerol acyltransferase 1 (DGAT1), DGAT2], lipolysis [adipose triglyceride lipase (ATGL), hormone-sensitive lipase (HSL), monoglyceride lipase (MGL)], and fatty acid oxidation [carnitine palmitoyl transferase 1B, very long-chain acyl-CoA dehydrogenase (VLCAD), medium-chain acyl-CoA dehydrogenase (MCAD)] in the LM. The mRNA abundance of the GPAT1 gene showed the greatest correlation (r = 0.74; P < 0.001) with IMF content among 9 fat deposition genes. The gene expression abundance of other fat deposition genes including ACC, FASN, LPL, CD36, FATP1, AGPAT1, DGAT1, and DGAT2 also exhibited significant positive correlations (P < 0.05) with IMF content in the LM. Conversely, ATGL mRNA abundance showed the greatest negative correlation (r = -0.68; P < 0.001) with IMF content in the LM among 6 fat removal genes. The expression of other fat removal genes including MGL, VLCAD, and MCAD showed significant negative correlations (P < 0.05) with IMF content. Our findings show that the combined effects of increases in lipogenesis, fatty acid uptake, fatty acid esterification, and of decreases in lipolysis and fatty acid oxidation contribute to increasing IMF deposition in Korean steers. The multiple regression analysis revealed that the mRNA abundance of the GPAT1 gene in the LM was the first major variable predicting IMF content (54%) among 15 lipid metabolic genes. The second was mRNA abundance of ATGL (11%). In conclusion, these results suggest that GPAT1 and ATGL genes could be used as genetic markers to predict IMF deposition in the LM.

A novel core genome-encoded superantigen contributes to lethality of community-associated MRSA necrotizing pneumonia

Bacterial superantigens (SAg) stimulate T-cell hyper-activation resulting in immune modulation and severe systemic illnesses such as Staphylococcus aureus toxic shock syndrome. However, all known S. aureus SAgs are encoded by mobile genetic elements and are made by only a proportion of strains. Here, we report the discovery of a novel SAg staphylococcal enterotoxin-like toxin X (SElX) encoded in the core genome of 95% of phylogenetically diverse S. aureus strains from human and animal infections, including the epidemic community-associated methicillin-resistant S. aureus (CA-MRSA) USA300 clone. SElX has a unique predicted structure characterized by a truncated SAg B-domain, but exhibits the characteristic biological activities of a SAg including Vβ-specific T-cell mitogenicity, pyrogenicity and endotoxin enhancement. In addition, SElX is expressed by clinical isolates in vitro, and during human, bovine, and ovine infections, consistent with a broad role in S. aureus infections of multiple host species. Phylogenetic analysis suggests that the selx gene was acquired horizontally by a progenitor of the S. aureus species, followed by allelic diversification by point mutation and assortative recombination resulting in at least 17 different alleles among the major pathogenic clones. Of note, SElX variants made by human- or ruminant-specific S. aureus clones demonstrated overlapping but distinct Vβ activation profiles for human and bovine lymphocytes, indicating functional diversification of SElX in different host species. Importantly, SElX made by CA-MRSA USA300 contributed to lethality in a rabbit model of necrotizing pneumonia revealing a novel virulence determinant of CA-MRSA disease pathogenesis. Taken together, we report the discovery and characterization of a unique core genome-encoded superantigen, providing new insights into the evolution of pathogenic S. aureus and the molecular basis for severe infections caused by the CA-MRSA USA300 epidemic clone.

Staphylococcus aureus is a global pathogen, responsible for an array of different illnesses in humans and animals. In particular, community-associated methicillin-resistant S. aureus (CA-MRSA) strains of the pandemic USA300 clone have the capacity to cause lethal human necrotizing pneumonia, but the molecular basis for the enhanced virulence remains unclear. Bacterial superantigens (SAg) stimulate T-cell hyper-activation resulting in severe systemic illnesses such as toxic shock syndrome (TSS). However, all S. aureus SAgs identified to date are encoded by mobile genetic elements found only in a proportion of clinical isolates. Here, we report the discovery of a unique core genome-encoded SAg (SElX) which was acquired by an ancestor of the S. aureus species and which has undergone genetic and functional diversification in pathogenic clones infecting humans and animals. Importantly, we report that SElX made by pandemic USA300 contributes to lethality in a rabbit model of human necrotizing pneumonia revealing a novel virulence determinant of severe CA-MRSA infection.

Measurement of lymphedema using ultrasonography with the compression method

Lymphedema is swelling of soft tissues by accumulation of lymphatic fluid due to failure of the lymphatic drainage system. Although most measures for lymphedema focus on change of volume or size of the extremity, the physical properties of the tissue such as resistance to compression are also of clinical importance because they affect the quality of life of lymphedema patients. In this study, we aimed to compare the thickness and resistance to compression of the skin and subcutis between the affected and unaffected arms of patients with lymphedema by using ultrasonography together with the compression technique, and we also investigated the factors that have an influence on the results. Thirty-nine patients with post-mastectomy lymphedema participated in this study. All ultrasonographically-assessed thicknesses of skin and subcutaneous tissue in affected upper arms and forearms were significantly larger than the contralateral (p < 0.05) while all resistances to compression values were significantly lower (p < 0.05). These results suggest that measuring the resistance to compression and thickness using the compression method with ultrasonography may be a valuable tool for evaluating lymphedema after breast cancer surgery.

Evaluation of two mutants of Mycobacterium avium subsp. paratuberculosis as candidates for a live attenuated vaccine for Johne's disease

Control of Johne's disease, caused by Mycobacterium avium subsp. paratuberculosis, has been difficult because of a lack of an effective vaccine. To address this problem we used targeted gene disruption to develop candidate mutants with impaired capacity to survive ex vivo and in vivo to test as a vaccine. We selected relA and pknG, genes known to be important virulence factors in Mycobacterium tuberculosis and Mycobacterium bovis, for initial studies. Deletion mutants were made in a wild type Map (K10) and its recombinant strain expressing the green fluorescent protein (K10-GFP). Comparison of survival in an ex vivo assay revealed deletion of either gene attenuated survival in monocyte-derived macrophages compared to survival of wild-type K10. In contrast, study in calves revealed survival in vivo was mainly affected by deletion of relA. Bacteria were detected in tissues from wild-type and the pknG mutant infected calves by bacterial culture and PCR at three months post infection. No bacteria were detected in tissues from calves infected with the relA mutant (P<0.05). Flow cytometric analysis of the immune response to the wild-type K10-GFP and the mutant strains showed deletion of either gene did not affect their capacity to elicit a strong proliferative response to soluble antigen extract or live Map. Quantitative RT-PCR revealed genes encoding IFN-γ, IL-17, IL-22, T-bet, RORC, and granulysin were up-regulated in PBMC stimulated with live Map three months post infection compared to the response of PBMC pre-infection. A challenge study in kid goats showed deletion of pknG did not interfere with establishment of an infection. As in calves, deletion of relA attenuated survival in vivo. The mutant also elicited an immune response that limited colonization by challenge wild type Map. The findings show the relA mutant is a good candidate for development of a live attenuated vaccine for Johne's disease.

An Enterotoxin-Bearing Pathogenicity Island in Staphylococcus epidermidis

Cocolonization of human mucosal surfaces causes frequent encounters between various staphylococcal species, creating opportunities for the horizontal acquisition of mobile genetic elements. The majority of Staphylococcus aureus toxins and virulence factors are encoded on S. aureus pathogenicity islands (SaPIs). Horizontal movement of SaPIs between S. aureus strains plays a role in the evolution of virulent clinical isolates. Although there have been reports of the production of toxic shock syndrome toxin 1 (TSST-1), enterotoxin, and other superantigens by coagulase-negative staphylococci, no associated pathogenicity islands have been found in the genome of Staphylococcus epidermidis, a generally less virulent relative of S. aureus. We show here the first evidence of a composite S. epidermidis pathogenicity island (SePI), the product of multiple insertions in the genome of a clinical isolate. The taxonomic placement of S. epidermidis strain FRI909 was confirmed by a number of biochemical tests and multilocus sequence typing. The genome sequence of this strain was analyzed for other unique gene clusters and their locations. This pathogenicity island encodes and expresses staphylococcal enterotoxin C3 (SEC3) and staphylococcal enterotoxin-like toxin L (SElL), as confirmed by quantitative reverse transcription-PCR (qRT-PCR) and immunoblotting. We present here an initial characterization of this novel pathogenicity island, and we establish that it is stable, expresses enterotoxins, and is not obviously transmissible by phage transduction. We also describe the genome sequence, excision, replication, and packaging of a novel bacteriophage in S. epidermidis FRI909, as well as attempts to mobilize the SePI element by this phage.

Comparison of phenotypic and genotypic methods for the species identification of coagulase-negative staphylococcal isolates from bovine intramammary infections

Coagulase-negative staphylococci (CNS) are the most frequently isolated pathogens from cows with intramammary infection (IMI). Although API STAPH ID 20, a commercially available identification system, and PCR-restriction fragment length polymorphism (PCR-RFLP) of the gap gene (gap PCR-RFLP) have been successfully applied for the identification of CNS isolates from human specimens, their accuracy in the identification of veterinary isolates has not been fully established. In this study, we identified 263 CNS isolates from bovine IMI at species level by partial 16S rRNA gene sequence analysis as the definitive test. Species identification obtained using partial 16S rRNA gene sequence analysis was compared to results from the API STAPH ID 20 and gap PCR-RFLP analysis. Eleven different CNS species were identified by partial 16S rRNA gene sequence analysis. Only 76.0% (200/263) of the species identification results obtained by API STAPH ID 20 matched those obtained by partial 16S rRNA gene sequence analysis, whereas 97.0% (255/263) of the species identification results obtained by the gap PCR-RFLP analysis matched those obtained by partial 16S rRNA gene sequence analysis. The gap PCR-RFLP analysis could be a useful and reliable alternative method for the species identification of CNS isolates from bovine IMI and appears to be a more accurate method of species identification than the API STAPH ID 20 system.

Detection of classical and newly described staphylococcal superantigen genes in coagulase-negative staphylococci isolated from bovine intramammary infections

The coagulase-negative staphylococci (CNS) are the most prevalent mastitis pathogen group yet their virulence characteristics have not been well described. We investigated the presence of 19 classical and newly described staphylococcal superantigen (SAg) genes in CNS isolates from bovine intramammary infections (IMI). A total of 263 CNS representing 11 different Staphylococcus spp. were examined, and 31.2% (n=82) of CNS isolates had one or more SAg genes; there were 21 different SAg gene combinations. The most prevalent combination of SAg genes (seb, seln and selq; n=45) was found in S. chromogenes, S. xylosus, S. haemolyticus, S. sciuri subsp. carnaticus, S. simulans and S. succinus. The genes for SAgs appear to be widely distributed amongst CNS isolated from bovine IMI.

A quantitative real time PCR method to analyze T cell receptor Vbeta subgroup expansion by staphylococcal superantigens

Background

Staphylococcal enterotoxins (SEs), SE-like (SEl) toxins, and toxic shock syndrome toxin-1 (TSST-1), produced by Staphylococcus aureus, belong to the subgroup of microbial superantigens (SAgs). SAgs induce clonal proliferation of T cells bearing specific variable regions of the T cell receptor β chain (Vβ). Quantitative real time PCR (qRT-PCR) has become widely accepted for rapid and reproducible mRNA quantification. Although the quantification of Vβ subgroups using qRT-PCR has been reported, qRT-PCR using both primers annealing to selected Vβ nucleotide sequences and SYBR Green I reporter has not been applied to assess Vβ-dependent expansion of T cells by SAgs.

Methods

Human peripheral blood mononuclear cells were stimulated with various SAgs or a monoclonal antibody specific to human CD3. Highly specific expansion of Vβ subgroups was assessed by qRT-PCR using SYBR Green I reporter and primers corresponding to selected Vβ nucleotide sequences.

Results

qRT-PCR specificities were confirmed by sequencing amplified PCR products and melting curve analysis. To assess qRT-PCR efficiencies, standard curves were generated for each primer set. The average slope and R² of standard curves were -3.3764 ± 0.0245 and 0.99856 ± 0.000478, respectively, demonstrating that the qRT-PCR established in this study is highly efficient. With some exceptions, SAg Vβ specificities observed in this study were similar to those reported in previous studies.

Conclusions

The qRT-PCR method established in this study produced an accurate and reproducible assessment of Vβ-dependent expansion of human T cells by staphylococcal SAgs. This method could be a useful tool in the characterization T cell proliferation by newly discovered SAg and in the investigation of biological effects of SAgs linked to pathogenesis.

Superantigen-mediated differentiation of bovine monocytes into dendritic cells

Although many effects of staphylococcal superantigens (SAg) on T cells are well established, less is known about their effects on APC. In this study, bovine PBMC were stimulated with a low dose of staphylococcal enterotoxin C1 (SEC1). The phenotype of adherent cells (Ac) derived from bovine PBMC cultured with SEC1 [SEC1-stimulated Ac (sAc)] for 192 h was CD14(-), CD68(-), CD163(-), dendritic cell (DC)-specific ICAM-3-grabbing nonintegrin(+), MHC class II (MHC II)(high), CD11a(low), CD11b(high), CD11c(high), and CD1b(high), suggesting these cells were dendritic cells (DC). SEC1 also induced transcription of the CXCL1, -2, and -3 family, CXCL6, CCL2, and CCL5 genes in sAc, which increased rapidly but returned to basal levels by 48 h. In contrast, increased transcription of CCL3, CCL8, and CXCL12, responsible for mononuclear cell migration and chronic inflammation, was sustained. In vitro cell migration assays showed vigorous migration of granulocytes, followed by migration of mononuclear cells. The autologous MLR showed that sAc induced a dose-dependent proliferation of CD4(+) T cells and an even stronger proliferation of CD8(+) T cells. This effect was inhibited or reduced by pretreatment with mAb to CD11b, MHC II, or MHC II plus CD18. These results indicate that stimulation of bovine PBMC by SAg induces differentiation of monocytes into DC.

Measurement of soft tissue compliance with pressure using ultrasonography

Lymphedema is swelling, particularly in the subcutaneous tissues, due to accumulation of lymph. Previous imaging techniques have demonstrated associated structural changes and have been used for evaluating the status of soft tissues. However, the reliability of measurements using ultrasonography has not been evaluated and the ultrasonographic method has been unable to show changes in tissue softness. There is a need to determine if ultrasonography is a reliable technique to assess skin and subcutaneous thickness in the upper extremities with or without pressure and if the measure of compliance in soft tissue thickness is also reliable. Two examiners measured tissue thicknesses using ultrasonography and calculated the compliance with and without pressure on the forearm and upper arm, independently. The intra- and inter-rater cross-correlation coefficients of measuring soft tissue thickness were excellent (> 0.75) in the forearm (p < 0.05). In the upper arm, the reliabilities were fair-to-good. The intraclass correlation coefficients of pressure compliance in the forearm and upper arm were excellent and fair-to-good, respectively (p < 0.05). This study suggests that measurement of thickness of soft tissues using ultrasonography may be reliable and pressure compliance may reflect tissue softness in the upper extremity.

Development of monoclonal antibodies to detect bovine FOXP3 in PBMCs exposed to a staphylococcal superantigen

The role of regulatory T cells (Tregs) is well documented in immune homeostasis and protection against autoimmune disease. Forkhead box protein 3 (FOXP3) has been shown to be essential for the development and function of T(reg). Due to the lack of tools for FOXP3 detection in certain species, understanding the role of Treg in a variety of ruminant diseases has been hampered. In this study, we developed monoclonal antibodies (mAbs) against bovine FOXP3 using recombinant bovine FOXP3 lacking the forkhead domain as an immunogen. The specificity of the mAbs was confirmed by immunoblot and mass spectrometry. Expression of FOXP3 was induced in bovine PBMCs after 6 d of exposure to staphylococcal enterotoxin type C1 (SEC1) in vitro. Similar to findings in mice and humans, expression of FOXP3 was restricted to CD4+ CD25+ T cells. Transcriptional analysis of bovine TCR variable regions of the beta chain (boVbeta) showed that transcription of boVbeta sequences reactive with SEC1 increased for 6 d, and then boVbeta sequences non-reactive with SEC1 rapidly increased in the cultures. This indicates that induction of FOXP3+ CD4+ CD25+ Tregs by SEC1 is not Vbeta restricted. The FOXP3 mAbs developed in this study will be useful in the further investigation of the role of Treg in staphylococcal pathogenesis in bovine mastitis and other ruminant diseases.

Molecular variation in pigmentation genes contributing to coat colour in native Korean Hanwoo cattle

Pigmentation genes such as TYR (tyrosinase), TYRP1 (tyrosinase-related protein 1), DCT (previously TYRP2, or tyrosinase-related protein 2), ASIP (agouti) and MC1R (melanocortin receptor 1) play a major role in cattle coat colour. To understand the genotypic profile underlying coat colour in native Korean Hanwoo cattle and Angus black cattle, portions of the above-mentioned genes were amplified. Sequence analysis revealed variation in the TYRP1 (exon 5) and MC1R genes. Restriction enzyme analysis of these two genes could distinguish between different colours of Hanwoo cattle. Quantitative estimates of melanin and eumelanin in hair from three different-coloured Hanwoo phenotypes and Angus black showed significant differences at the breed and phenotypic levels. Finally, sequence variants in MC1R were associated with total melanin and eumelanin in breeds as well as in Hanwoo phenotypes.

Prevention of withdrawal movement associated with injection of rocuronium in children: comparison of remifentanil, alfentanil and fentanyl

BACKGROUND

We compared the efficacy of remifentanil, alfentanil and fentanyl in reducing withdrawal movement associated with the injection of rocuronium in children.

METHODS

In total, 164 ASA physical status I or II pediatric patients, aged 1-14 years, were randomly assigned to four treatment groups: group C received saline; group R, remifentanil 1 microg/kg; group A, alfentanil 10 micro/kg; and group F, fentanyl 2 microg/kg. Treatments were injected over 30 s, followed by thiopental 5 mg/kg. At 90 s after the start of the study drug injection, rocuronium 0.6 mg/kg was injected over 10 s. The patient's response to the injection of rocuronium was graded on a four-point scale in a double-blinded manner.

RESULTS

The incidence of withdrawal movement was 89.5% in group C, 70.3% in group F, 36.3% in group A and 7.2% in group R. The incidence of generalized movement (grade 4) was 86.9% in group C, 58.5% in group F, 15.9% in group A and 2.4% in group R.

CONCLUSION

Remifentanil, alfentanil and fentanyl all reduced the incidence of withdrawal movement when administered 90 s before the injection of rocuronium compared with saline. Remifentanil was the most effective, followed by alfentanil. Fentanyl was less effective but significantly different from the saline in reducing withdrawal movement in children.

Structure and biological activities of beta toxin from Staphylococcus aureus

Beta toxin is a neutral sphingomyelinase secreted by certain strains of Staphylococcus aureus. This virulence factor lyses erythrocytes in order to evade the host immune system as well as scavenge nutrients. The structure of beta toxin was determined at 2.4-A resolution using crystals that were merohedrally twinned. This structure is similar to that of the sphingomyelinases of Listeria ivanovii and Bacillus cereus. Beta toxin belongs to the DNase I folding superfamily; in addition to sphingomyelinases, the proteins most structurally related to beta toxin include human endonuclease HAP1, Escherichia coli endonuclease III, bovine pancreatic DNase I, and the endonuclease domain of TRAS1 from Bombyx mori. Our biological assays demonstrated for the first time that beta toxin kills proliferating human lymphocytes. Structure-directed active site mutations show that biological activities, including hemolysis and lymphotoxicity, are due to the sphingomyelinase activity of the enzyme.

Characterization of an Escherichia coli O157:H7 plasmid O157 deletion mutant and its survival and persistence in cattle

Escherichia coli O157:H7 causes hemorrhagic colitis and hemolytic-uremic syndrome in humans, and its major reservoir is healthy cattle. An F-like 92-kb plasmid, pO157, is found in most E. coli O157:H7 clinical isolates, and pO157 shares sequence similarities with plasmids present in other enterohemorrhagic E. coli serotypes. We compared wild-type (WT) E. coli O157:H7 and an isogenic DeltapO157 mutant for (i) growth rates and antibiotic susceptibilities, (ii) survival in environments with various acidity, salt, or heat conditions, (iii) protein expression, and (iv) survival and persistence in cattle following oral challenge. Growth, metabolic reactions, and antibiotic resistance of the DeltapO157 mutant were indistinguishable from those of its complement and the WT. However, in cell competition assays, the WT was more abundant than the DeltapO157 mutant. The DeltapO157 mutant was more resistant to acidic synthetic bovine gastric fluid and bile than the WT. In vivo, the DeltapO157 mutant survived passage through the bovine gastrointestinal tract better than the WT but, interestingly, did not colonize the bovine rectoanal junction mucosa as well as the WT. Many proteins were differentially expressed between the DeltapO157 mutant and the WT. Proteins from whole-cell lysates and membrane fractions of cell lysates were separated using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and two-dimensional gel electrophoresis. Ten differentially expressed approximately 50-kDa proteins were identified by quadrupole-time of flight mass spectrometry and sequence matching with the peptide fragment database. Most of these proteins, including tryptophanase and glutamate decarboxylase isozymes, were related to survival under salvage conditions, and expression was increased by the deletion of pO157. This suggested that the genes on pO157 regulate some chromosomal genes.

Unique features of bovine lymphocytes exposed to a staphylococcal enterotoxin

We previously demonstrated that stimulation of bovine peripheral blood mononuclear cells (PBMCs) with staphylococcal enterotoxin C (SEC), led to an inversion of the CD4⁺:CD8⁺ T cell ratio and generation of an atypical CD8⁺ T cell subpopulation expressing CD26. In the present study, we examined T cell apoptosis and proliferation profiles of PBMC subpopulations in cultures stimulated with SEC. Unlike when stimulated with concanavalin A, nucleic acid synthesis in bovine PBMC cultures stimulated with SEC was low during the first four days but increased greatly on day 5. In contrast, nucleic acid synthesis in human PBMC cultures stimulated with SEC increased continuously. To investigate the mechanism of delayed bovine T cell proliferation, various cell phenotypes were monitored. The inversion of the bovine CD4⁺:CD8⁺ T cell ratio in PBMC cultures stimulated by SEC was associated with higher proliferation and lower apoptosis of CD8⁺ T cells compared to CD4⁺ T cells. The mRNA levels for interleukin (IL)-4 and IL-13 were sustained over 4 days but IL-12 mRNA levels dropped to background on day 2. These data suggest that SEC induces a prolonged Th-2-biased microenvironment, and together with the inversion of the bovine CD4⁺:CD8⁺ T cell ratios in bovine PBMC cultures with SEC, may in part explain the inability of the mammary immune system to establish an effective response to Staphylococcus aureus infections.

Long-term staphylococcal enterotoxin C1 exposure induces soluble factor-mediated immunosuppression by bovine CD4+ and CD8+ T cells

Regulatory T cells (T(regs)) help control the development and maintenance of protective immunity and can lead to aberrant immune responses to some pathogens. Several lines of evidence suggest that T(regs) are induced by exposure to superantigens (SAgs) in vitro or in vivo. In this study, bovine peripheral blood mononuclear cells (PBMC) were exposed in vitro to a relatively low dose (5 ng/ml) of staphylococcal enterotoxin C1 (SEC1) for up to 10 days. Upon stimulation, CD4+ and CD8+ T cells initially proliferated at similar rates. Subsequently, from days 6 through 10, most CD4+ and CD8+ T cells proliferated regardless of Vbeta specificity, but the proliferation of CD8+ T cells occurred more vigorously. The transcription of CD25 and CD152 genes increased, whereas that of interleukin-2 (IL-2) decreased. gammadelta T cells appeared to be unresponsive. An increase in the transcription of IL-10 and transforming growth factor beta (TGF-beta) genes in SEC1-stimulated cultures was attributed to the CD4+ CD25+ T-cell subpopulation. The expression of Foxp3 mRNA also increased and was accompanied by the upregulation of CD152 and the downregulation of IL-2 transcription, suggesting that cells in this subpopulation are T(regs). Functionally, SEC1-stimulated CD4+ T cells suppressed the proliferation of naive PBMC in response to heat-killed-fixed Staphylococcus aureus. The suppression was partially mediated by IL-10 and TGF-beta, another characteristic of certain types of T(regs.) The CD8+ T-cell population also suppressed naive PBMC through another mechanism not mediated by IL-10 or TGF-beta. These results provide further insight into the potential mechanisms by which SAgs could contribute to evasion of the immune response, affecting the outcome of infection or colonization.