163 research outputs found
Identification and Characterization of the Host Protein DNAJC14 as a Broadly Active Flavivirus Replication Modulator
Viruses in the Flavivirus genus of the Flaviviridae family are arthropod-transmitted and contribute to staggering numbers of human infections and significant deaths annually across the globe. To identify cellular factors with antiviral activity against flaviviruses, we screened a cDNA library using an iterative approach. We identified a mammalian Hsp40 chaperone protein (DNAJC14) that when overexpressed was able to mediate protection from yellow fever virus (YFV)-induced cell death. Further studies revealed that DNAJC14 inhibits YFV at the step of viral RNA replication. Since replication of bovine viral diarrhea virus (BVDV), a member of the related Pestivirus genus, is also known to be modulated by DNAJC14, we tested the effect of this host factor on diverse Flaviviridae family members. Flaviviruses, including the pathogenic Asibi strain of YFV, Kunjin, and tick-borne Langat virus, as well as a Hepacivirus, hepatitis C virus (HCV), all were inhibited by overexpression of DNAJC14. Mutagenesis showed that both the J-domain and the C-terminal domain, which mediates self-interaction, are required for anti-YFV activity. We found that DNAJC14 does not block YFV nor HCV NS2-3 cleavage, and using non-inhibitory mutants demonstrate that DNAJC14 is recruited to YFV replication complexes. Immunofluorescence analysis demonstrated that endogenous DNAJC14 rearranges during infection and is found in replication complexes identified by dsRNA staining. Interestingly, silencing of endogenous DNAJC14 results in impaired YFV replication suggesting a requirement for DNAJC14 in YFV replication complex assembly. Finally, the antiviral activity of overexpressed DNAJC14 occurs in a time- and dose-dependent manner. DNAJC14 overexpression may disrupt the proper stoichiometry resulting in inhibition, which can be overcome upon restoration of the optimal ratios due to the accumulation of viral nonstructural proteins. Our findings, together with previously published work, suggest that the members of the Flaviviridae family have evolved in unique and important ways to interact with this host Hsp40 chaperone molecule
Observation of Two New Excited Îb0 States Decaying to Îb0 K-Ï+
Two narrow resonant states are observed in the Îb0K-Ï+ mass spectrum using a data sample of proton-proton collisions at a center-of-mass energy of 13 TeV, collected by the LHCb experiment and corresponding to an integrated luminosity of 6 fb-1. The minimal quark content of the Îb0K-Ï+ system indicates that these are excited Îb0 baryons. The masses of the Îb(6327)0 and Îb(6333)0 states are m[Îb(6327)0]=6327.28-0.21+0.23±0.12±0.24 and m[Îb(6333)0]=6332.69-0.18+0.17±0.03±0.22 MeV, respectively, with a mass splitting of Îm=5.41-0.27+0.26±0.12 MeV, where the uncertainties are statistical, systematic, and due to the Îb0 mass measurement. The measured natural widths of these states are consistent with zero, with upper limits of Î[Îb(6327)0]<2.20(2.56) and Î[Îb(6333)0]<1.60(1.92) MeV at a 90% (95%) credibility level. The significance of the two-peak hypothesis is larger than nine (five) Gaussian standard deviations compared to the no-peak (one-peak) hypothesis. The masses, widths, and resonant structure of the new states are in good agreement with the expectations for a doublet of 1D Îb0 resonances
Measurement of D s <sup>±</sup> production asymmetry in pp collisions at âs=7 and 8 TeV
The inclusive production asymmetry is measured in collisions
collected by the LHCb experiment at centre-of-mass energies of
and 8 TeV. Promptly produced mesons are used, which decay as
, with . The measurement is
performed in bins of transverse momentum, , and rapidity, ,
covering the range GeV and . No kinematic
dependence is observed. Evidence of nonzero production asymmetry is
found with a significance of 3.3 standard deviations.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2018-010.htm
Search for CP violation in Îb0âpKâ and Îb0âpÏâ decays
A search for CP violation in Îb0âpKâ and Îb0âpÏâ decays is presented using a sample of pp collisions collected with the LHCb detector and corresponding to an integrated luminosity of 3.0fbâ1. The CP -violating asymmetries are measured to be ACPpKâ=â0.020±0.013±0.019 and ACPpÏâ=â0.035±0.017±0.020, and their difference ACPpKââACPpÏâ=0.014±0.022±0.010, where the first uncertainties are statistical and the second systematic. These are the most precise measurements of such asymmetries to date
Precision measurement of violation in the penguin-mediated decay
A flavor-tagged time-dependent angular analysis of the decay
is performed using collision data collected
by the LHCb experiment at % at TeV, the center-of-mass energy of
13 TeV, corresponding to an integrated luminosity of 6 fb^{-1}. The
-violating phase and direct -violation parameter are measured
to be rad and
, respectively, assuming the same values
for all polarization states of the system. In these results, the
first uncertainties are statistical and the second systematic. These parameters
are also determined separately for each polarization state, showing no evidence
for polarization dependence. The results are combined with previous LHCb
measurements using collisions at center-of-mass energies of 7 and 8 TeV,
yielding rad and . This is the most precise study of time-dependent violation
in a penguin-dominated meson decay. The results are consistent with
symmetry and with the Standard Model predictions.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2023-001.html (LHCb
public pages
Measurement of the differential branching fraction
The branching fraction of the rare decay is measured for the first time, in the squared dimuon mass
intervals, , excluding the and regions. The data
sample analyzed was collected by the LHCb experiment at center-of-mass energies
of 7, 8, and 13 TeV, corresponding to a total integrated luminosity of $9\
\mathrm{fb}^{-1}q^{2}q^{2} >15.0\
\mathrm{GeV}^2/c^4$, where theoretical predictions have the smallest model
dependence, agrees with the predictions.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-050.html (LHCb
public pages
Search for dark photons produced in 13 TeV collisions
Searches are performed for both promptlike and long-lived dark photons,
A
0
, produced in proton-proton
collisions at a center-of-mass energy of 13 TeV, using
A
0
â
Ό
ĂŸ
Ό
â
decays and a data sample corresponding
to an integrated luminosity of
1
.
6
fb
â
1
collected with the LHCb detector. The promptlike
A
0
search covers
the mass range from near the dimuon threshold up to 70 GeV, while the long-lived
A
0
search is restricted to
the low-mass region
214
<m
Ă°
A
0
Ă
<
350
MeV. No evidence for a signal is found, and 90% confidence
level exclusion limits are placed on the
Îł
â
A
0
kinetic-mixing strength. The constraints placed on promptlike
dark photons are the most stringent to date for the mass range
10
.
6
<m
Ă°
A
0
Ă
<
70
GeV, and are
comparable to the best existing limits for
m
Ă°
A
0
Ă
<
0
.
5
GeV. The search for long-lived dark photons is the
first to achieve sensitivity using a displaced-vertex signature
Measurement of the CKM angle using with decays
A model-dependent amplitude analysis of the decay is performed using proton-proton collision data
corresponding to an integrated luminosity of 3.0fb, recorded at
and by the LHCb experiment. The CP violation observables
and , sensitive to the CKM angle , are measured to
be \begin{eqnarray*} x_- &=& -0.15 \pm 0.14 \pm 0.03 \pm 0.01, y_- &=& 0.25 \pm
0.15 \pm 0.06 \pm 0.01, x_+ &=& 0.05 \pm 0.24 \pm 0.04 \pm 0.01, y_+ &=&
-0.65^{+0.24}_{-0.23} \pm 0.08 \pm 0.01, \end{eqnarray*} where the first
uncertainties are statistical, the second systematic and the third arise from
the uncertainty on the amplitude model. These
are the most precise measurements of these observables. They correspond to
and , where is
the magnitude of the ratio of the suppressed and favoured decay amplitudes, in a mass region of around the
mass and for an absolute value of the cosine of the decay
angle larger than .Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2016-007.htm
Search for the and decays with the LHCb detector
A search is performed for the as yet unobserved baryonic and
decays with 3 of proton-proton collision data recorded by the LHCb
experiment. The decay is used as a
normalisation channel. No significant signal is observed for the decay. An upper limit is found on the
branching fraction of } at 90\% confidence level. Evidence is seen for
the presence of the decay at the level of
significance, with a branching fraction }.Comment: 22 pages, 6 figures. v2 is published version (very minor revisions
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