bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enhanced skeletal muscle regrowth and remodelling in massaged and contralateral non‐massaged hindlimb
Authors: Miller Benjamin F. , Hamilton Karyn L. , Majeed Zana R. , Abshire Sarah M. , Confides Amy L. , Hayek Amanda M. , Hunt Emily R. , Shipman Patrick , Peelor Frederick F. , Butterfield Timothy A. , Dupont‐Versteegden Esther E. 
Published: November 2017

Key points
Muscle fibre cross sectional area is enhanced with massage in the form of cyclic compressive loading during regrowth after atrophy.
Massage enhances protein synthesis of the myofibrillar and cytosolic, but not the mitochondrial fraction, in muscle during regrowth.
Focal adhesion kinase activation and satellite cell number are elevated in muscles undergoing massage during regrowth.
Muscle fibre cross sectional area and protein synthesis of the myofibrillar fraction, but not DNA synthesis, are elevated in muscle of the contralateral non‐massaged limb.
Massage in the form of cyclic compressive loading is a potential anabolic intervention during muscle regrowth after atrophy.
AbstractMassage, in the form of cyclic compressive loading (CCL), is associated with multiple health benefits, but its potential anabolic effect on atrophied muscle has not been investigated. We hypothesized that the mechanical activity associated with CCL induces an anabolic effect in skeletal muscle undergoing regrowth after a period of atrophy. Fischer–Brown Norway rats at 10 months of age were hindlimb unloaded for a period of 2 weeks. The rats were then allowed reambulation with CCL applied at a 4.5 N load at 0.5 Hz frequency for 30 min every other day for four bouts during a regrowth period of 8 days. Muscle fibre cross sectional area was enhanced by 18% with massage during regrowth compared to reloading alone, and this was accompanied by elevated myofibrillar and cytosolic protein as well as DNA synthesis. Focal adhesion kinase phosphorylation indicated that CCL increased mechanical stimulation, while a higher number of Pax7+ cells likely explains the elevated DNA synthesis. Surprisingly, the contralateral non‐massaged limb exhibited a comparable 17% higher muscle fibre size compared to reloading alone, and myofibrillar protein synthesis, but not DNA synthesis, was also elevated. We conclude that massage in the form of CCL induces an anabolic response in muscles regrowing after an atrophy‐inducing event. We suggest that massage can be used as an intervention to aid in the regrowth of muscle lost during immobilization.
Systemic IL-6 and Myoglobin Response to Three Different Resistance Exercise Intensities in Older Men
Authors: Cornish Stephen M. , Chase Jeremie E. , Bugera Eric M. , Giesbrecht Gordon G. 
Published: November 2017

The purpose of this research was to identify if three different intensities of resistance exercise would acutely and differentially effect the systemic release of interleukin-6 (IL-6) and myoglobin in older men (≥65 years). A total of 11 older men performed isovolume resistance exercise on six different apparatuses at three different intensities (144 reps at 60%, 120 reps at 72%, and 108 reps at 80% of 1-repetition maximum), with the intensity order randomly allocated, to determine the systemic release of IL-6 and myoglobin in the blood. Blood samples were collected at six time points, including preexercise, immediately postexercise, and 3, 6, 24, and 48 hr postexercise. There were no differences between intensity levels; therefore, data for all conditions were pooled. IL-6 did not show any change from baseline values throughout all time points (p > .05), whereas myoglobin was elevated at 3, 6, and 24 hr postexercise and returned to baseline after 48 hr (p < .05).
A 3.0-Angstrom Resolution Cryo-Electron Microscopy Structure and Antigenic Sites of Coxsackievirus A6-Like Particles
Authors: Chen Jinhuan , Zhang Chao , Zhou Yu , Zhang Xiang , Shen Chaoyun , Ye Xiaohua , Jiang Wen , Huang Zhong , Cong Yao 
Published: November 2017

ABSTRACT

Coxsackievirus A6 (CVA6) has recently emerged as one of the predominant causative agents of hand, foot, and mouth disease (HFMD). The structure of the CVA6 mature viral particle has not been solved thus far. Our previous work shows that recombinant virus-like particles (VLPs) of CVA6 represent a promising CVA6 vaccine candidate. Here, we report the first cryo-electron microscopy (cryo-EM) structure of the CVA6 VLP at 3.0-Å resolution. The CVA6 VLP exhibits the characteristic features of enteroviruses but presents an open channel at the 2-fold axis and an empty, collapsed VP1 pocket, which is broadly similar to the structures of the enterovirus 71 (EV71) VLP and coxsackievirus A16 (CVA16) 135S expanded particle, indicating that the CVA6 VLP is in an expanded conformation. Structural comparisons reveal that two common salt bridges within protomers are maintained in the CVA6 VLP and other viruses of the
Enterovirus
genus, implying that these salt bridges may play a critical role in enteroviral protomer assembly. However, there are apparent structural differences among the CVA6 VLP, EV71 VLP, and CVA16 135S particle in the surface-exposed loops and C termini of subunit proteins, which are often antigenic sites for enteroviruses. By immunological assays, we identified two CVA6-specific linear B-cell epitopes (designated P42 and P59) located at the GH loop and the C-terminal region of VP1, respectively, in agreement with the structure-based prediction of antigenic sites. Our findings elucidate the structural basis and important antigenic sites of the CVA6 VLP as a strong vaccine candidate and also provide insight into enteroviral protomer assembly.

IMPORTANCE
Coxsackievirus A6 (CVA6) is becoming one of the major pathogens causing hand, foot, and mouth disease (HFMD), leading to significant morbidity and mortality in children and adults. However, no vaccine is currently available to prevent CVA6 infection. Our previous work shows that recombinant virus-like particles (VLPs) of CVA6 are a promising CVA6 vaccine candidate. Here, we present a 3.0-Å structure of the CVA6 VLP determined by cryo-electron microscopy. The overall architecture of the CVA6 VLP is similar to those of the expanded structures of enterovirus 71 (EV71) and coxsackievirus A16 (CVA16), but careful structural comparisons reveal significant differences in the surface-exposed loops and C termini of each capsid protein of these particles. In addition, we identified two CVA6-specific linear B-cell epitopes and mapped them to the GH loop and the C-terminal region of VP1, respectively. Collectively, our findings provide a structural basis and important antigenic information for CVA6 VLP vaccine development.
VP1 and VP3 Are Required and Sufficient for Translation Initiation of Uncapped Infectious Bursal Disease Virus Genomic Double-Stranded RNA
Authors: Ye Chengjin , Wang Yu , Zhang Enli , Han Xinpeng , Yu Zhaoli , Liu Hebin 
Published: November 2017

ABSTRACT

Infectious bursal disease virus (IBDV) is a bisegmented double-strand RNA (dsRNA) virus of the
Birnaviridae
family. While IBDV genomic dsRNA lacks a 5′ cap, the means by which the uncapped IBDV genomic RNA is translated effectively is unknown. In this study, we describe a cap-independent pathway of translation initiation of IBDV uncapped RNA that relies on VP1 and VP3. We show that neither purified IBDV genomic dsRNA nor the uncapped viral plus-sense RNA transcripts were directly translated and rescued into infectious viruses in host cells. This defect in translation of the uncapped IBDV genomic dsRNA was rescued by
trans
-supplementation of the viral proteins VP1 and VP3 which was dependent on both the intact polymerase activity of VP1 and the dsRNA binding activity of VP3. Deletion analysis showed that both 5′ and 3′ untranslated regions (UTRs) of IBDV dsRNA were essential for VP1/VP3-dependent translation initiation. Significantly, VP1 and VP3 could also mediate the recovery of infectious IBDV from the authentic minus-sense strand of IBDV dsRNA. Moreover, downregulation or inhibition of the cap-binding protein eIF4E did not decrease but, rather, enhanced the VP1/VP3-mediated translation of the uncapped IBDV RNA. Collectively, our findings for the first time reveal that VP1 and VP3 compensate for the deficiency of the 5′ cap and replace eIF4E to confer upon the uncapped IBDV RNA the ability to be translated and rescued into infectious viruses.

IMPORTANCE
A key point of control for virus replication is viral translation initiation. The current study shows that the uncapped IBDV RNA cannot be translated into viral proteins directly by host translation machinery and is thus noninfectious. Our results constitute the first direct experimental evidence that VP1 and VP3 are required and sufficient to initiate translation of uncapped IBDV genomic RNA by acting as a substitute for cap and replacing the cap-binding protein eIF4E. Significantly, VP1/VP3 mediate the recovery of infectious IBDV not only from the plus-sense strand but also from the minus-sense strand of the IBDV dsRNA. These findings provide not only new insights into the molecular mechanisms of the life cycle of IBDV but also a new tool for an alternative strategy for the recovery of IBDV from both the plus- and the minus-sense strands of the viral genomic dsRNA.
Characterization of Recombinant Flaviviridae Viruses Possessing a Small Reporter Tag
Authors: Tamura Tomokazu , Fukuhara Takasuke , Uchida Takuro , Ono Chikako , Mori Hiroyuki , Sato Asuka , Fauzyah Yuzy , Okamoto Toru , Kurosu Takeshi , Setoh Yin Xiang , Imamura Michio , Tautz Norbert , Sakoda Yoshihiro , Khromykh Alexander A. , Chayama Kazuaki , Matsuura Yoshiharu 
Published: November 2017

ABSTRACT

The family
Flaviviridae
consists of four genera,
Flavivirus
,
Pestivirus
,
Pegivirus
, and
Hepacivirus
, and comprises important pathogens of human and animals. Although the construction of recombinant viruses carrying reporter genes encoding fluorescent and bioluminescent proteins has been reported, the stable insertion of foreign genes into viral genomes retaining infectivity remains difficult. Here, we applied the 11-amino-acid subunit derived from NanoLuc luciferase to the engineering of the
Flaviviridae
viruses and then examined the biological characteristics of the viruses. We successfully generated recombinant viruses carrying the split-luciferase gene, including dengue virus, Japanese encephalitis virus, hepatitis C virus (HCV), and bovine viral diarrhea virus. The stability of the viruses was confirmed by five rounds of serial passages in the respective susceptible cell lines. The propagation of the recombinant luciferase viruses in each cell line was comparable to that of the parental viruses. By using a purified counterpart luciferase protein, this split-luciferase assay can be applicable in various cell lines, even when it is difficult to transduce the counterpart gene. The efficacy of antiviral reagents against the recombinant viruses could be monitored by the reduction of luciferase expression, which was correlated with that of viral RNA, and the recombinant HCV was also useful to examine viral dynamics
in vivo
. Taken together, our findings indicate that the recombinant
Flaviviridae
viruses possessing the split NanoLuc luciferase gene generated here provide powerful tools to understand viral life cycle and pathogenesis and a robust platform to develop novel antivirals against
Flaviviridae
viruses.

IMPORTANCE
The construction of reporter viruses possessing a stable transgene capable of expressing specific signals is crucial to investigations of viral life cycle and pathogenesis and the development of antivirals. However, it is difficult to maintain the stability of a large foreign gene, such as those for fluorescence and bioluminescence, after insertion into a viral genome. Here, we successfully generated recombinant
Flaviviridae
viruses carrying the 11-amino-acid subunit derived from NanoLuc luciferase and demonstrated that these viruses are applicable to
in vitro
and
in vivo
experiments, suggesting that these recombinant
Flaviviridae
viruses are powerful tools for increasing our understanding of viral life cycle and pathogenesis and that these recombinant viruses will provide a robust platform to develop antivirals against
Flaviviridae
viruses.
Inducible MicroRNA-3570 Feedback Inhibits the RIG-I-Dependent Innate Immune Response to Rhabdovirus in Teleost Fish by Targeting MAVS/IPS-1
Authors: Xu Tianjun , Chu Qing , Cui Junxia , Bi Dekun 
Published: November 2017

ABSTRACT
Effectively recognizing invading viruses and subsequently inducing innate antiviral immunity are essential for host antiviral defense. Although these processes are closely regulated by the host to maintain immune balance, viruses have evolved the ability to downregulate or upregulate these processes for their survival. MicroRNAs (miRNAs) are a family of small noncoding RNAs that play vital roles in modulating host immune response. Accumulating evidence demonstrates that host miRNAs as mediators are involved in regulating viral replication and host antiviral immunity in mammals. However, the underlying regulatory mechanisms in fish species are still poorly understood. Here, we found that rhabdovirus infection significantly upregulated host miR-3570 expression in miiuy croaker macrophages. Induced miR-3570 negatively modulated RNA virus-triggered type I interferon (IFN) and antiviral gene production, thus facilitating viral replication. Furthermore, miR-3570 was found to target and posttranscriptionally downregulate mitochondrial antiviral signaling protein (MAVS), which functions as a platform for innate antiviral signal transduction. Moreover, we demonstrated that miR-3570 suppressed the expression of MAVS, thereby inhibiting MAVS-mediated NF-κB and IRF3 signaling. The collective results demonstrated a novel regulation mechanism of MAVS-mediated immunity during RNA viral infection by miRNA.

IMPORTANCE
RNA viral infection could upregulate host miR-3570 expression in miiuy croaker macrophages. Induced miR-3570 negatively modulates RNA virus-triggered type I IFN and antiviral gene production, thus facilitating viral replication. Remarkably, miR-3570 could target and inhibit MAVS expression, which thus modulates MAVS-mediated NF-κB and IRF3 signaling. The collective results of this study suggest a novel regulation mechanism of MAVS-mediated immunity during RNA viral infection by miR-3570. Thus, a novel mechanism for virus evasion in fish is proposed.
Glycan Shield and Fusion Activation of a Deltacoronavirus Spike Glycoprotein Fine-Tuned for Enteric Infections
Authors: Xiong Xiaoli , Tortorici M. Alejandra , Snijder Joost , Yoshioka Craig , Walls Alexandra C. , Li Wentao , McGuire Andrew T. , Rey Félix A. , Bosch Berend-Jan , Veesler David 
Published: November 2017

ABSTRACT

Coronaviruses recently emerged as major human pathogens causing outbreaks of severe acute respiratory syndrome and Middle East respiratory syndrome. They utilize the spike (S) glycoprotein anchored in the viral envelope to mediate host attachment and fusion of the viral and cellular membranes to initiate infection. The S protein is a major determinant of the zoonotic potential of coronaviruses and is also the main target of the host humoral immune response. We report here the 3.5-Å-resolution cryo-electron microscopy structure of the S glycoprotein trimer from the pathogenic porcine deltacoronavirus (PDCoV), which belongs to the recently identified
Deltacoronavirus
genus. Structural and glycoproteomics data indicate that the glycans of PDCoV S are topologically conserved compared with the human respiratory coronavirus NL63 S, resulting in similar surface areas being shielded from neutralizing antibodies and implying that both viruses are under comparable immune pressure in their respective hosts. The structure further reveals a shortened S
2
′ activation loop, containing a reduced number of basic amino acids, which participates in rendering the spike largely protease resistant. This property distinguishes PDCoV S from recently characterized betacoronavirus S proteins and suggests that the S protein of enterotropic PDCoV has evolved to tolerate the protease-rich environment of the small intestine and to fine-tune its fusion activation to avoid premature triggering and reduction of infectivity.

IMPORTANCE
Coronaviruses use transmembrane S glycoprotein trimers to promote host attachment and fusion of the viral and cellular membranes. We determined a near-atomic-resolution cryo-electron microscopy structure of the S ectodomain trimer from the pathogenic PDCoV, which is responsible for diarrhea in piglets and has had devastating consequences for the swine industry worldwide. Structural and glycoproteomics data reveal that PDCoV S is decorated with 78 N-linked glycans obstructing the protein surface to limit accessibility to neutralizing antibodies in a way reminiscent of what has recently been described for a human respiratory coronavirus. PDCoV S is largely protease resistant, which distinguishes it from most other characterized coronavirus S glycoproteins and suggests that enteric coronaviruses have evolved to fine-tune fusion activation in the protease-rich environment of the small intestine of infected hosts.
Synergy between Active Efflux and Outer Membrane Diffusion Defines Rules of Antibiotic Permeation into Gram-Negative Bacteria
Authors: Krishnamoorthy Ganesh , Leus Inga V. , Weeks Jon W. , Wolloscheck David , Rybenkov Valentin V. , Zgurskaya Helen I. 
Published: November 2017

ABSTRACT

Gram-negative bacteria are notoriously resistant to antibiotics, but the extent of the resistance varies broadly between species. We report that in significant human pathogens
Acinetobacter baumannii
,
Pseudomonas aeruginosa
, and
Burkholderia
spp., the differences in antibiotic resistance are largely defined by their penetration into the cell. For all tested antibiotics, the intracellular penetration was determined by a synergistic relationship between active efflux and the permeability barrier. We found that the outer membrane (OM) and efflux pumps select compounds on the basis of distinct properties and together universally protect bacteria from structurally diverse antibiotics. On the basis of their interactions with the permeability barriers, antibiotics can be divided into four clusters that occupy defined physicochemical spaces. Our results suggest that rules of intracellular penetration are intrinsic to these clusters. The identified specificities in the permeability barriers should help in the designing of successful therapeutic strategies against antibiotic-resistant pathogens.

IMPORTANCE
Multidrug-resistant strains of Gram-negative pathogens rapidly spread in clinics. Significant efforts worldwide are currently directed to finding the rules of permeation of antibiotics across two membrane envelopes of these bacteria. This study created the tools for analysis of and identified the major differences in antibacterial activities that distinguish the permeability barriers of
P. aeruginosa
,
A. baumannii
,
Burkholderia thailandensis
, and
B. cepacia
. We conclude that synergy between active efflux and the outer membrane barrier universally protects Gram-negative bacteria from antibiotics. We also found that the diversity of antibiotics affected by active efflux and outer membrane barriers is broader than previously thought and that antibiotics cluster according to specific biological determinants such as the requirement of specific porins in the OM, targeting of the OM, or specific recognition by efflux pumps. No universal rules of antibiotic permeation into Gram-negative bacteria apparently exist. Our results suggest that antibiotic clusters are defined by specific rules of permeation and that further studies could lead to their discovery.
The Metallophore Staphylopine Enables
Staphylococcus aureus
To Compete with the Host for Zinc and Overcome Nutritional Immunity
Authors: Grim Kyle P. , San Francisco Brian , Radin Jana N. , Brazel Erin B. , Kelliher Jessica L. , Párraga Solórzano Paola K. , Kim Philip C. , McDevitt Christopher A. , Kehl-Fie Thomas E. 
Published: November 2017

ABSTRACT

During infection, the host sequesters essential nutrients, such as zinc, to combat invading microbes. Despite the ability of the immune effector protein calprotectin to bind zinc with subpicomolar affinity,
Staphylococcus aureus
is able to successfully compete with the host for zinc. However, the zinc importers expressed by
S. aureus
remain unknown. Our investigations have revealed that
S. aureus
possesses two importers, AdcABC and CntABCDF, which are induced in response to zinc limitation. While AdcABC is similar to known zinc importers in other bacteria, CntABCDF has not previously been associated with zinc acquisition. Concurrent loss of the two systems severely impairs the ability of
S. aureus
to obtain zinc and grow in zinc-limited environments. Further investigations revealed that the Cnt system is responsible for the ability of
S. aureus
to compete with calprotectin for zinc in culture and contributes to acquisition of zinc during infection. The
cnt
locus also enables
S. aureus
to produce the broad-spectrum metallophore staphylopine. Similarly to the Cnt transporter, loss of staphylopine severely impairs the ability of
S. aureus
to resist host-imposed zinc starvation, both in culture and during infection. Further investigations revealed that together staphylopine and the Cnt importer function analogously to siderophore-based iron acquisition systems in order to facilitate zinc acquisition by
S. aureus
. Analogous systems are found in a broad range of Gram-positive and Gram-negative bacterial pathogens, suggesting that this new type of zinc importer broadly contributes to the ability of bacteria to cause infection.

IMPORTANCE
A critical host defense against infection is the restriction of zinc availability. Despite the subpicomolar affinity of the immune effector calprotectin for zinc,
Staphylococcus aureus
can successfully compete for this essential metal. Here, we describe two zinc importers, AdcABC and CntABCDF, possessed by
S. aureus
, the latter of which has not previously been associated with zinc acquisition. The ability of
S. aureus
to compete with the host for zinc is dependent on CntABCDF and the metallophore staphylopine, both in culture and during infection. These results expand the mechanisms utilized by bacteria to obtain zinc, beyond Adc-like systems, and demonstrate that pathogens utilize strategies similar to siderophore-based iron acquisition to obtain other essential metals during infection. The staphylopine synthesis machinery is present in a diverse collection of bacteria, suggesting that this new family of zinc importers broadly contributes to the ability of numerous pathogens to cause infection.