Transfection efficiency and cytotoxicity of cationic liposomes in salmonid cell lines of hepatocyte and macrophage origin

AbstractThe transfection efficiency of liposome-based DNA formulations was studied in different salmonid cell lines of hepatocyte and macrophage origin. Parallel assessment of cell viability was carried out to define the balance between transfection efficiency and toxicity. For all cell lines, transfection efficiency varied with the lipoplex charge ratio and the amount of DNA added to the liposomes. The hepatocyte-derived cell line was most readily transfected while lower transfection efficiency was observed for the macrophage cell lines. The cationic liposomes showed a dose-dependent toxicity and were found to be most toxic for cells of macrophage origin. This was in line with the observation that higher amounts of lipids were associated with the cells of macrophage origin than the hepatocytes. Complexing DNA with the liposomes reduced the toxicity for all three cell lines, most markedly, however, for macrophage cell lines. The differences in the transfection and toxicity patterns between the cell lines are probably caused by differences in membrane composition as well as differences in phagocytic activity and processing of the liposomes/lipoplexes

VER-155008 induced Hsp70 proteins expression in fish cell cultures while impeding replication of two RNA viruses

The final publication is available at Elsevier via https://doi.org/10.1016/j.antiviral.2019.01.001 © 2019. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/The heat-shock protein 70 (Hsp70) inhibitor, VER-155008 (VER), was explored as a potential antiviral agent for two RNA viruses important to fish aquaculture, viral hemorrhagic septicemia virus (VHSV) and infectious pancreatic necrosis virus (IPNV). Studies were done at a temperature of 14 °C, and with cell lines commonly used to propagate these viruses. These were respectively EPC from fathead minnow for VHSV and CHSE-214 from Chinook salmon embryo for IPNV. Additionally, both viruses were studied with the Atlantic salmon heart endothelial cell line ASHe. For both VHSV and IPNV, 25 μM VER impeded replication. This was evidenced by delays in the development of cytopathic effect (CPE) and the expression of viral proteins, N for VHSV and VP2 for IPNV, and by less production of viral RNA and of viral titre. As VER inhibits the activity of Hsp70 family members, these results suggest that VHSV and IPNV utilize one or more Hsp70s in their life cycles. Yet neither virus induced Hsp70. Surprisingly VER alone induced Hsp70, but whether this induction modulated VER's antiviral effects is unknown. Exploring this apparent paradox in the future should improve the usefulness of VER as an antiviral agent.Natural Science and Engineering Research Council, Grant 468298 - 14Elanco Canada Limite

CK-2 of rainbow trout (Oncorhynchus mykiss) has two differentially regulated alleles that encode a functional chemokine

The final publication is available at Elsevier via https://doi.org/10.1016/j.vetimm.2018.02.003. © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/Rainbow trout chemokine 2 (CK-2) is currently the only known CC chemokine to have a mucin stalk. Further analysis of the mucin stalk region revealed a second, related CC chemokine sequence, denoted here as CK-2.1. This second sequence was determined to be an allele of CK-2 following genomic PCR analysis on several outbred individuals. Furthermore, in both in vivo and in vitro trials, CK-2 and CK-2.1 were both present, but appeared to have differential tissue expression in both control and PHA stimulated samples. Upon the development of a polyclonal antibody to rCK-2, CK-2 was only observed in the brain, liver and head kidney of PHA stimulated rainbow trout tissues. In comparison, when using the rainbow trout monocyte/macrophage-like cell line, RTS-11, CK-2 protein was observed in both control and PHA stimulated conditions. When studying the function of CK-2, a chemotaxis assay revealed that both peripheral blood leukocytes and RTS-11 cells migrated towards rCK-2 significantly at all concentrations studied when compared to truncated β2m. Interestingly, this migration was lowest at both the highest concentration and the lowest concentrations of CK-2. Thus, teleostean chemokine receptors may become desensitized when overstimulated as has been observed in mammalian models. The observed chemotactic function was indeed due to rCK-2 as cell migration was inhibited through pre-treatment of both the cells and the polyclonal antibody with rCK-2. As has been observed thus far with all other chemokines, CK-2 does appear to function through binding to a G-coupled protein receptor as chemotaxis could be inhibited through pre-treatment with pertussis toxin. Overall, the results of this study indicate that CK-2 is a functional chemokine that is encoded by two differentially expressed alleles in rainbow trout, CK-2 and CK-2.1.Natural Sciences and Engineering Research Council || 21752

An evaluation of potential reference genes for stability of expression in two salmonid cell lines after infection with either Piscirickettsia salmonis or IPNV

<p>Abstract</p> <p>Background</p> <p>Due to the limited number of species specific antibodies against fish proteins, differential gene expression analyses are vital for the study of host immune responses. Quantitative real-time reverse transcription PCR (qRT-PCR) is one of the most powerful tools for this purpose. Nevertheless, the accuracy of the method will depend on the careful selection of genes whose expression are stable and can be used as internal controls for a particular experimental setting.</p> <p>Findings</p> <p>The expression stability of five commonly used housekeeping genes [beta-actin (<it>ACTB</it>), elongation factor 1-alpha (<it>EF1A</it>), ubiquitin (<it>UBQ</it>), glyceraldehyd-3-phosphate dehydrogenase (<it>GAPDH</it>) and tubulin alpha (<it>TUBA</it>)] were monitored in salmonid cell lines CHSE-214 and RTS11 after infection with two of the most fastidious fish pathogens, the facultative bacterium <it>Piscirickettsia salmonis </it>and the aquabirnavirus IPNV (Infectious Pancreatic Necrosis Virus). After geNorm analysis, <it>UBQ </it>and <it>EF1A </it>appeared as the most stable, although <it>EF1A </it>was slightly upregulated at late stages of <it>P. salmonis </it>infection in RTS11. <it>ACTB </it>instead, showed a good performance in each case, being always considered within the three most stable genes of the panel. In contrast, infection-dependent differential regulation of <it>GAPDH </it>and <it>TUBA </it>was also demonstrated.</p> <p>Conclusion</p> <p>Based on the data presented here with the cell culture models CHSE-214 and RTS11, we suggest the initial choice of <it>UBQ</it>, <it>ACTB </it>and <it>EF1A </it>as reference genes in qRT-PCR assays for studying the effect of <it>P. salmonis </it>and IPNV on the host immune response.</p

Structural and Kinetic Studies on the Potent Inhibition of Metallo-β-Lactamases by 6- Phosphonomethylpyridine-2-Carboxylates

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Biochemistry, copyright © American Chemical Society after peer review and technical editing by publisher. To access the final edited and published work see http://dx.doi.org/10.1021/acs.biochem.7b01299There are currently no clinically available inhibitors of metallo-β-lactamases (MBLs), enzymes which hydrolyze β-lactam antibiotics and confer resistance on Gram-negative bacteria. Here we present 6-phosphonomethylpyridine-2-carboxylates (PMPCs) as potent inhibitors of subclass B1 (IMP-1, VIM-2, NDM-1) and B3 (L1) MBLs. Inhibition followed a competitive, slow-binding model without an isomerization step (IC50 values 0.3 – 7.2 µM; Ki 0.03 – 1.5 µM). Minimum inhibitory concentration assays demonstrated potentiation of β-lactam (meropenem) activity against MBL-producing bacteria, including clinical isolates, at concentrations where eukaryotic cells remain viable. Crystal structures revealed unprecedented modes of inhibitor binding to B1 (IMP-1) and B3 (L1) MBLs. In IMP-1, binding does not replace the nucleophilic hydroxide and the PMPC carboxylate and pyridine nitrogen interact closely (2.3 and 2.7 Å, respectively) with the Zn2 ion of the binuclear metal site. The phosphonate group makes limited interactions, but is 2.6 Å from the nucleophilic hydroxide. Furthermore, the presence of a water molecule interacting with the PMPC phosphonate and pyridine N-C2 π-bond, as well as the nucleophilic hydroxide, suggests that the PMPC binds to the MBL active site as its hydrate. Binding is markedly different in L1, with the phosphonate displacing both Zn2, forming a monozinc enzyme, and the nucleophilic hydroxide, while also making multiple interactions with the protein main chain and Zn1. The carboxylate and pyridine nitrogen interact with Ser221/223, respectively (3 Å distance). The potency, low toxicity, cellular activity and amenability to further modification of PMPCs indicate these and similar phosphonate compounds can be further considered for future MBL inhibitor development.This work was supported by grants from the U.K. Medical Research Council and Canadian Institutes of Health Research (U.K.-Canada Team Grant G1100135 and FRN114046) to J.S. and G.I.D, Canadian Institutes of Health Research operating grant (FRN106531) to G.I.D., the National Institute of Allergy and Infectious Diseases of the U.S. National Institutes of Health to J.S. (R01AI100560) and the Engineering and Physical Sciences Research Council (EP/M027546/1) to M.B.A. and J.S..K.C. was in receipt of a postgraduate scholarship from SENESCYT, Ecuador

Tapasin's protein interactions in the rainbow trout peptide-loading complex

The final publication is available at Elsevier via http://dx.doi.org/10.1016/j.dci.2017.12.015 © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/Major histocompatibility complex (MHC) class I receptors play a key role in the immune system by presenting non-self peptides to T cell lymphocytes. In humans, the assembly of the MHC class I with a peptide is mediated by machinery in the endoplasmic reticulum referred as the peptide loading complex (PLC). Although, the identity of the PLC has been widely explored in humans, this complex has not been characterized in fish. Co-immunoprecipitation and mass spectrometry analysis revealed that the protein-protein interactions which exist in the human PLC are conserved in the monocyte/macrophage rainbow trout cell line (RTS11), in particular the interaction of tapasin with the transporter associated with antigen processing (TAP), MHC class I and ERp57. Importantly, a 20 kDa tapasin version that contains an intact C and N terminal domains was found to associate with ERp57 and form a 75 kDa heterodimer. These results suggest a possible novel alternative spliced version of tapasin may regulate the formation of the peptide-loading complex in teleosts.NSERC Discovery Grant number 217529-2008Canada Research Council Research Chair held by B

Development and validation of HERWIG 7 tunes from CMS underlying-event measurements

This paper presents new sets of parameters (“tunes”) for the underlying-event model of the HERWIG7 event generator. These parameters control the description of multiple-parton interactions (MPI) and colour reconnection in HERWIG7, and are obtained from a fit to minimum-bias data collected by the CMS experiment at s=0.9, 7, and 13Te. The tunes are based on the NNPDF 3.1 next-to-next-to-leading-order parton distribution function (PDF) set for the parton shower, and either a leading-order or next-to-next-to-leading-order PDF set for the simulation of MPI and the beam remnants. Predictions utilizing the tunes are produced for event shape observables in electron-positron collisions, and for minimum-bias, inclusive jet, top quark pair, and Z and W boson events in proton-proton collisions, and are compared with data. Each of the new tunes describes the data at a reasonable level, and the tunes using a leading-order PDF for the simulation of MPI provide the best description of the dat

Measurement of the top quark forward-backward production asymmetry and the anomalous chromoelectric and chromomagnetic moments in pp collisions at √s = 13 TeV

Abstract The parton-level top quark (t) forward-backward asymmetry and the anomalous chromoelectric (d̂ t) and chromomagnetic (μ̂ t) moments have been measured using LHC pp collisions at a center-of-mass energy of 13 TeV, collected in the CMS detector in a data sample corresponding to an integrated luminosity of 35.9 fb−1. The linearized variable AFB(1) is used to approximate the asymmetry. Candidate t t ¯ events decaying to a muon or electron and jets in final states with low and high Lorentz boosts are selected and reconstructed using a fit of the kinematic distributions of the decay products to those expected for t t ¯ final states. The values found for the parameters are AFB(1)=0.048−0.087+0.095(stat)−0.029+0.020(syst),μ̂t=−0.024−0.009+0.013(stat)−0.011+0.016(syst), and a limit is placed on the magnitude of | d̂ t| &lt; 0.03 at 95% confidence level. [Figure not available: see fulltext.

Search for new particles in events with energetic jets and large missing transverse momentum in proton-proton collisions at root s=13 TeV

A search is presented for new particles produced at the LHC in proton-proton collisions at root s = 13 TeV, using events with energetic jets and large missing transverse momentum. The analysis is based on a data sample corresponding to an integrated luminosity of 101 fb(-1), collected in 2017-2018 with the CMS detector. Machine learning techniques are used to define separate categories for events with narrow jets from initial-state radiation and events with large-radius jets consistent with a hadronic decay of a W or Z boson. A statistical combination is made with an earlier search based on a data sample of 36 fb(-1), collected in 2016. No significant excess of events is observed with respect to the standard model background expectation determined from control samples in data. The results are interpreted in terms of limits on the branching fraction of an invisible decay of the Higgs boson, as well as constraints on simplified models of dark matter, on first-generation scalar leptoquarks decaying to quarks and neutrinos, and on models with large extra dimensions. Several of the new limits, specifically for spin-1 dark matter mediators, pseudoscalar mediators, colored mediators, and leptoquarks, are the most restrictive to date.Peer reviewe