Modulation of Host Immunity by Human Respiratory Syncytial Virus Virulence Factors: A Synergic Inhibition of Both Innate and Adaptive Immunity

Indexación: Web of Science; Scopus.The Human Respiratory Syncytial Virus (hRSV) is a major cause of acute lower respiratory tract infections (ARTIs) and high rates of hospitalizations in children and in the elderly worldwide. Symptoms of hRSV infection include bronchiolitis and pneumonia. The lung pathology observed during hRSV infection is due in part to an exacerbated host immune response, characterized by immune cell infiltration to the lungs. HRSV is an enveloped virus, a member of the Pneumoviridae family, with a non-segmented genome and negative polarity-single RNA that contains 10 genes encoding for 11 proteins. These include the Fusion protein (F), the Glycoprotein (G), and the Small Hydrophobic (SH) protein, which are located on the virus surface. In addition, the Nucleoprotein (N), Phosphoprotein (P) large polymerase protein (L) part of the RNA-dependent RNA polymerase complex, the M2-1 protein as a transcription elongation factor, the M2-2 protein as a regulator of viral transcription and (M) protein all of which locate inside the virion. Apart from the structural proteins, the hRSV genome encodes for the non-structural 1 and 2 proteins (NS1 and NS2). HRSV has developed different strategies to evade the host immunity by means of the function of some of these proteins that work as virulence factors to improve the infection in the lung tissue. Also, hRSV NS-1 and NS-2 proteins have been shown to inhibit the activation of the type I interferon response. Furthermore, the hRSV nucleoprotein has been shown to inhibit the immunological synapsis between the dendritic cells and T cells during infection, resulting in an inefficient T cell activation. Here, we discuss the hRSV virulence factors and the host immunological features raised during infection with this virus.https://www.frontiersin.org/articles/10.3389/fcimb.2017.00367/ful

Exotic vertolike quark phenomenology in the minimal linear σ model

Extensions of the Standard Model that include vectorlike quarks commonly also include additional particles that may mediate new production or decay modes. Using the minimal linear σ model as an example, which reduces to the minimal SO (5)/SO (4) composite Higgs model in a specific limit, we consider the phenomenology of vectorlike quarks when a scalar singlet σ is present. This new particle may be produced in the decays T → tσ, B → bσ, where T and B are vectorlike quarks of charges 2/3 and −1/3, respectively, with the subsequent decay σ → W+W−, ZZ, hh. By scanning over the allowed parameter space we find that these decays may be dominant. In addition, we find that the presence of several new particles allows for single T production cross sections larger than those expected in minimal models. We discuss the observability of these new signatures in existing searchesThe authors acknowledge partial financial support by the Spanish MINECO through the Centro de excelencia Severo Ochoa Program under Grant No. SEV2016-0597. J. A. G., L. M. and J. A. A. S. acknowledge partial financial support by the Spanish “Agencia Estatal de Investigación” (AEI) and the EU “Fondo Europeo de Desarrollo Regional” (FEDER) through the Projects No. FPA2016-78645-P and No. FPA2016-78220-C3-1-P. L. M. acknowledges partial financial support by the Spanish MINECO through the “Ramón y Cajal” programme (RYC-2015-17173). J. M. N. acknowledges support from the Ramón y Cajal Fellowship Contract No. RYC-2017-22986 and from the Spanish Proyectos de I + D de Generación de Conocimiento via Grant No. PGC2018-096646-A-I00. L. M. and J. M. N. also acknowledge support from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie Grant agreements No. 690575 (RISE InvisiblesPlus) and No. 674896 (ITN ELUSIVES

Monte Carlo Hamiltonian - From Statistical Physics to Quantum Theory

Monte Carlo techniques have been widely employed in statistical physics as well as in quantum theory in the Lagrangian formulation. However, in some areas of application to quantum theories computational progress has been slow. Here we present a recently developed approach: the Monte Carlo Hamiltonian method, designed to overcome the difficulties of the conventional approach.Comment: StatPhys-Taiwan-1999, 6 pages, LaTeX using elsart.cl

NLO predictions for t-channel production of single top and fourth generation quarks at hadron colliders

We present updated NLO predictions for the electroweak t-channel production of heavy quarks at the Tevatron and at the LHC. We consider production of single top and fourth generation t' starting from both 2 to 2 and 2 to 3 Born processes. Predictions for tb' and t'b' cross sections at NLO are also given for the first time. A thorough study of the theoretical uncertainties coming from parton distribution functions, renormalisation and factorisation scale dependence and heavy quark masses is performed.Comment: 25 pages, 8 figure

Identifying top partners at LHC

We systematically study the possible signals at LHC of new vector-like quarks mainly coupled to the third generation. We consider heavy quarks T, B, X, Y of charges 2/3, -1/3, 5/3 and -4/3, respectively, in SU(2)_L isosinglets T_{L,R}, B_{L,R}, or isodoublets (T B)_{L,R}, (X T)_{L,R} or (B Y)_{L,R}. Analyses based on a fast detector simulation are presented for twelve different final states containing one, two, three or four charged leptons in several invariant mass regions, also considering various b quark multiplicities. It is shown that with the combination of the different channels the new quarks can be identified and their charged and neutral decays established. The comparison among final states also shows that the single lepton one offers the best discovery potential at LHC. For heavy quark masses of 500 GeV, the 5 sigma discovery luminosities range from 0.16 fb^-1 for a (X T)_{L,R} doublet to 1.9 fb^-1 for a B_{L,R} singlet.Comment: LaTeX 89 pages, 111 PS figures. Added one model to the analysis in all final states, plus one subsection and some references. Final version to appear in JHE

Search for anomalous top-gluon couplings at LHC revisited

Through top-quark pair productions at LHC, we study possible effects of nonstandard top-gluon couplings yielded by SU(3)xSU(2)xU(1) invariant dimension-6 effective operators. We calculate the total cross section and also some distributions for p p -> t tbar X as functions of two anomalous-coupling parameters, i.e., the chromoelectric and chromomagnetic moments of the top, which are constrained by the total cross section sigma(p pbar -> t tbar X) measured at Tevatron. We find that LHC might give us some chances to observe sizable effects induced by those new couplings.Comment: One comment and related two refs. added. Final version (to appear in Eur.Phys.J. C

Is Vtb=1 ?

The strongest constraint on Vtb presently comes from the 3 x 3 unitarity of the CKM matrix, which fixes Vtb to be very close to one. If the unitarity is relaxed, current information from top production at Tevatron still leaves open the possibility that Vtb is sizably smaller than one. In minimal extensions of the standard model with extra heavy quarks, the unitarity constraints are much weaker and the EW precision parameters entail the strongest bounds on Vtb. We discuss the experimental perspectives of discovering and identifying such new physics models at the Tevatron and the LHC, through a precise measurement of Vtb from the single top cross sections and by the study of processes where the extra heavy quarks are produced.Comment: 19 pages, 8 figure

Chromomagnetic Dipole Moment of the Top Quark Revisited

We study the complete one-loop contributions to the chromagnetic dipole moment $\Delta\kappa$ of the top quark in the Standard Model, two Higgs doublet models, topcolor assited technicolor models (TC2), 331 models and extended models with a single extra dimension. We find that the SM predicts $\Delta\kappa = - 0.056$ and that the predictions of the other models are also consitent with the constraints imposed on $\Delta\kappa$ by low-energy precision measurements.Comment: 20 pages, 5 figures, Updat

Model-independent extraction of ∣Vtq∣|V_{tq}| matrix elements from top-quark measurements at hadron colliders

Current methods to extract the quark-mixing matrix element $|V_{tb}|$ from single-top production measurements assume that $|V_{tb}|\gg |V_{td}|, |V_{ts}|$: top quarks decay into $b$ quarks with 100% branching fraction, s-channel single-top production is always accompanied by a $b$ quark and initial-state contributions from $d$ and $s$ quarks in the $t$-channel production of single top quarks are neglected. Triggered by a recent measurement of the ratio $R=\frac{|V_{tb}|^{2}}{|V_{td}|^{2}+|V_{ts}|^{2}+|V_{tb}|^{2}}=0.90 \pm 0.04$ performed by the D0 collaboration, we consider a $|V_{tb}|$ extraction method that takes into account non zero d- and s-quark contributions both in production and decay. We propose a strategy that allows to extract consistently and in a model-independent way the quark mixing matrix elements $|V_{td}|$, $|V_{ts}|$, and $|V_{tb}|$ from the measurement of $R$ and from single-top measured event yields. As an illustration, we apply our method to the Tevatron data using a CDF analysis of the measured single-top event yield with two jets in the final state one of which is identified as a $b$-quark jet. We constrain the $|V_{tq}|$ matrix elements within a four-generation scenario by combining the results with those obtained from direct measurements in flavor physics and determine the preferred range for the top-quark decay width within different scenarios.Comment: 36 pages, 17 figure