bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pattern Recognition Receptor MDA5 Modulates CD8
+
T Cell-Dependent Clearance of West Nile Virus from the Central Nervous System
Authors: Lazear Helen M. , Pinto Amelia K. , Ramos Hilario J. , Vick Sarah C. , Shrestha Bimmi , Suthar Mehul S. , Gale Michael , Diamond Michael S. 
Published: August 2013

ABSTRACT

Many viruses induce type I interferon responses by activating cytoplasmic RNA sensors, including the RIG-I-like receptors (RLRs). Although two members of the RLR family, RIG-I and MDA5, have been implicated in host control of virus infection, the relative role of each RLR in restricting pathogenesis
in vivo
remains unclear. Recent studies have demonstrated that MAVS, the adaptor central to RLR signaling, is required to trigger innate immune defenses and program adaptive immune responses, which together restrict West Nile virus (WNV) infection
in vivo
. In this study, we examined the specific contribution of MDA5 in controlling WNV in animals.
MDA5
−/−
mice exhibited enhanced susceptibility, as characterized by reduced survival and elevated viral burden in the central nervous system (CNS) at late times after infection, even though small effects on systemic type I interferon response or viral replication were observed in peripheral tissues. Intracranial inoculation studies and infection experiments with primary neurons
ex vivo
revealed that an absence of MDA5 did not impact viral infection in neurons directly. Rather, subtle defects were observed in CNS-specific CD8
+
T cells in
MDA5
−/−
mice. Adoptive transfer into recipient
MDA5
+/+
mice established that a non-cell-autonomous deficiency of MDA5 was associated with functional defects in CD8
+
T cells, which resulted in a failure to clear WNV efficiently from CNS tissues. Our studies suggest that MDA5 in the immune priming environment shapes optimal CD8
+
T cell activation and subsequent clearance of WNV from the CNS.
Nuclear Relocalization of Polyadenylate Binding Protein during Rift Valley Fever Virus Infection Involves Expression of the NSs Gene
Authors: Copeland Anna Maria , Altamura Louis A. , Van Deusen Nicole M. , Schmaljohn Connie S. 
Published: August 2013

ABSTRACT

Rift Valley fever virus (RVFV), an ambisense member of the family
Bunyaviridae
, genus
Phlebovirus
, is the causative agent of Rift Valley fever, an important zoonotic infection in Africa and the Middle East. Phlebovirus proteins are translated from virally transcribed mRNAs that, like host mRNA, are capped but, unlike host mRNAs, are not polyadenylated. Here, we investigated the role of PABP1 during RVFV infection of HeLa cells. Immunofluorescence studies of infected cells demonstrated a gross relocalization of PABP1 to the nucleus late in infection. Immunofluorescence microscopy studies of nuclear proteins revealed costaining between PABP1 and markers of nuclear speckles. PABP1 relocalization was sharply decreased in cells infected with a strain of RVFV lacking the gene encoding the RVFV nonstructural protein S (NSs). To determine whether PABP1 was required for RVFV infection, we measured the production of nucleocapsid protein (N) in cells transfected with small interfering RNAs (siRNAs) targeting PABP1. We found that the overall percentage of RVFV N-positive cells was not changed by siRNA treatment, indicating that PABP1 was not required for RVFV infection. However, when we analyzed populations of cells producing high versus low levels of PABP1, we found that the percentage of RVFV N-positive cells was decreased in cell populations producing physiologic levels of PABP1 and increased in cells with reduced levels of PABP1. Together, these results suggest that production of the NSs protein during RVFV infection leads to sequestration of PABP1 in the nuclear speckles, creating a state within the cell that favors viral protein production.
A Specific Population of Abnormal Prion Protein Aggregates Is Preferentially Taken Up by Cells and Disaggregated in a Strain-Dependent Manner
Authors: Choi Young Pyo , Priola Suzette A. 
Published: August 2013

ABSTRACTPrion diseases are characterized by the conversion of the soluble protease-sensitive host-encoded prion protein (PrPC) into its aggregated, protease-resistant, and infectious isoform (PrPSc). One of the earliest events occurring in cells following exposure to an exogenous source of prions is the cellular uptake of PrPSc. It is unclear how the biochemical properties of PrPScinfluence its uptake, although aggregate size is thought to be important. Here we show that for two different strains of mouse prions, one that infects cells (22L) and one that does not (87V), a fraction of PrPScassociated with distinct sedimentation properties is preferentially taken up by the cells. However, while the fraction of PrPScand the kinetics of uptake were similar for both strains, PrPScderived from the 87V strain was disaggregated more rapidly than that derived from 22L. The increased rate of PrPScdisaggregation did not correlate with either the conformational or aggregate stability of 87V PrPSc, both of which were greater than those of 22L PrPSc. Our data suggest that the kinetics of disaggregation of PrPScfollowing cellular uptake is independent of PrPScstability but may be dependent upon some component of the PrPScaggregate other than PrP. Rapid disaggregation of 87V PrPScby the cell may contribute, at least in part, to the inability of 87V to infect cellsin vitro.
Generation of Rhesus Macaque-Tropic HIV-1 Clones That Are Resistant to Major Anti-HIV-1 Restriction Factors
Authors: Nomaguchi Masako , Yokoyama Masaru , Kono Ken , Nakayama Emi E. , Shioda Tatsuo , Doi Naoya , Fujiwara Sachi , Saito Akatsuki , Akari Hirofumi , Miyakawa Kei , Ryo Akihide , Ode Hirotaka , Iwatani Yasumasa , Miura Tomoyuki , Igarashi Tatsuhiko , Sato Hironori , Adachi Akio 
Published: August 2013

ABSTRACT

Human immunodeficiency virus type 1 (HIV-1) replication in macaque cells is restricted mainly by antiviral cellular APOBEC3, TRIM5α/TRIM5CypA, and tetherin proteins. For basic and clinical HIV-1/AIDS studies, efforts to construct macaque-tropic HIV-1 (HIV-1mt) have been made by us and others. Although rhesus macaques are commonly and successfully used as infection models, no HIV-1 derivatives suitable for
in vivo
rhesus research are available to date. In this study, to obtain novel HIV-1mt clones that are resistant to major restriction factors, we altered Gag and Vpu of our best HIV-1mt clone described previously. First, by sequence- and structure-guided mutagenesis, three amino acid residues in Gag-capsid (CA) (M94L/R98S/G114Q) were found to be responsible for viral growth enhancement in a macaque cell line. Results of
in vitro
TRIM5α susceptibility testing of HIV-1mt carrying these substitutions correlated well with the increased viral replication potential in macaque peripheral blood mononuclear cells (PBMCs) with different
TRIM5
alleles, suggesting that the three amino acids in HIV-1mt CA are involved in the interaction with TRIM5α. Second, we replaced the transmembrane domain of Vpu of this clone with the corresponding region of simian immunodeficiency virus SIVgsn166 Vpu. The resultant clone, MN4/LSDQgtu, was able to antagonize macaque but not human tetherin, and its Vpu effectively functioned during viral replication in a macaque cell line. Notably, MN4/LSDQgtu grew comparably to SIVmac239 and much better than any of our other HIV-1mt clones in rhesus macaque PBMCs. In sum, MN4/LSDQgtu is the first HIV-1 derivative that exhibits resistance to the major restriction factors in rhesus macaque cells.
Human Cytomegalovirus UL76 Elicits Novel Aggresome Formation via Interaction with S5a of the Ubiquitin Proteasome System
Authors: Lin Shin-Rung , Jiang Meei Jyh , Wang Hung-Hsueh , Hu Cheng-Hui , Hsu Ming-Shan , Hsi Edward , Duh Chang-Yih , Wang Shang-Kwei 
Published: August 2013

ABSTRACT

HCMV UL76 is a member of a conserved
Herpesviridae
protein family (Herpes_UL24) that is involved in viral production, latency, and reactivation. UL76 presents as globular aggresomes in the nuclei of transiently transfected cells. Bioinformatic analyses predict that UL76 has a propensity for aggregation and targets cellular proteins implicated in protein folding and ubiquitin-proteasome systems (UPS). Furthermore, fluorescence recovery after photobleaching experiments suggests that UL76 reduces protein mobility in the aggresome, which indicates that UL76 elicits the aggregation of misfolded proteins. Moreover, in the absence of other viral proteins, UL76 interacts with S5a, which is a major receptor of polyubiquitinated proteins for UPS proteolysis via its conserved region and the von Willebrand factor type A (VWA) domain of S5a. We demonstrate that UL76 sequesters polyubiquitinated proteins and S5a to nuclear aggresomes in biological proximity. After knockdown of endogenous S5a by RNA interference techniques, the UL76 level was only minimally affected in transiently expressing cells. However, a significant reduction in the number of cells containing UL76 nuclear aggresomes was observed, which suggests that S5a may play a key role in aggresome formation. Moreover, we show that UL76 interacts with S5a in the late phase of viral infection and that knockdown of S5a hinders the development of both the replication compartment and the aggresome. In this study, we demonstrate that UL76 induces a novel nuclear aggresome, likely by subverting S5a of the UPS. Given that UL76 belongs to a conserved family, this underlying mechanism may be shared by all members of the
Herpesviridae
.
Structure of the NS1 Protein N-Terminal Origin Recognition/Nickase Domain from the Emerging Human Bocavirus
Authors: Tewary Sunil Kumar , Zhao Haiyan , Shen Weiran , Qiu Jianming , Tang Liang 
Published: August 2013

ABSTRACT
Human bocavirus is a newly identified, globally prevalent, parvovirus that is associated with respiratory infection in infants and young children. Parvoviruses encode a large nonstructural protein 1 (NS1) that is essential for replication of the viral single-stranded DNA genome and DNA packaging and may play versatile roles in virus-host interactions. Here, we report the structure of the human bocavirus NS1 N-terminal domain, the first for any autonomous parvovirus. The structure shows an overall fold that is canonical to the histidine-hydrophobic-histidine superfamily of nucleases, which integrates two distinct DNA-binding sites: (i) a positively charged region mediated by a surface hairpin (residues 190 to 198) that is responsible for recognition of the viral origin of replication of the double-stranded DNA nature and (ii) the nickase active site that binds to the single-stranded DNA substrate for site-specific cleavage. The structure reveals an acidic-residue-rich subdomain that is present in bocavirus NS1 proteins but not in the NS1 orthologs in erythrovirus or dependovirus, which may mediate bocavirus-specific interaction with DNA or potential host factors. These results provide insights into recognition of the origin of replication and nicking of DNA during bocavirus genome replication. Mapping of variable amino acid residues of NS1s from four human bocavirus species onto the structure shows a scattered pattern, but the origin recognition site and the nuclease active site are invariable, suggesting potential targets for antivirals against this clade of highly diverse human viruses.
Transmissible Gastroenteritis Coronavirus Genome Packaging Signal Is Located at the 5′ End of the Genome and Promotes Viral RNA Incorporation into Virions in a Replication-Independent Process
Authors: Morales Lucia , Mateos-Gomez Pedro A. , Capiscol Carmen , del Palacio Lorena , Enjuanes Luis , Sola Isabel 
Published: August 2013

ABSTRACT

Preferential RNA packaging in coronaviruses involves the recognition of viral genomic RNA, a crucial process for viral particle morphogenesis mediated by RNA-specific sequences, known as packaging signals. An essential packaging signal component of transmissible gastroenteritis coronavirus (TGEV) has been further delimited to the first 598 nucleotides (nt) from the 5′ end of its RNA genome, by using recombinant viruses transcribing subgenomic mRNA that included potential packaging signals. The integrity of the entire sequence domain was necessary because deletion of any of the five structural motifs defined within this region abrogated specific packaging of this viral RNA. One of these RNA motifs was the stem-loop SL5, a highly conserved motif in coronaviruses located at nucleotide positions 106 to 136. Partial deletion or point mutations within this motif also abrogated packaging. Using TGEV-derived defective minigenomes replicated in
trans
by a helper virus, we have shown that TGEV RNA packaging is a replication-independent process. Furthermore, the last 494 nt of the genomic 3′ end were not essential for packaging, although this region increased packaging efficiency. TGEV RNA sequences identified as necessary for viral genome packaging were not sufficient to direct packaging of a heterologous sequence derived from the green fluorescent protein gene. These results indicated that TGEV genome packaging is a complex process involving many factors in addition to the identified RNA packaging signal. The identification of well-defined RNA motifs within the TGEV RNA genome that are essential for packaging will be useful for designing packaging-deficient biosafe coronavirus-derived vectors and providing new targets for antiviral therapies.
A Stabilized Headless Measles Virus Attachment Protein Stalk Efficiently Triggers Membrane Fusion
Authors: Brindley Melinda A. , Suter Rolf , Schestak Isabel , Kiss Gabriella , Wright Elizabeth R. , Plemper Richard K. 
Published: August 2013

ABSTRACT
Paramyxovirus attachment and fusion (F) envelope glycoprotein complexes mediate membrane fusion required for viral entry. The measles virus (MeV) attachment (H) protein stalk domain is thought to directly engage F for fusion promotion. However, past attempts to generate truncated, fusion-triggering-competent H-stem constructs remained fruitless. In this study, we addressed the problem by testing the hypothesis that truncated MeV H stalks may require stabilizing oligomerization tags to maintain intracellular transport competence and F-triggering activity. We engineered H-stems of different lengths with added 4-helix bundle tetramerization domains and demonstrate restored cell surface expression, efficient interaction with F, and fusion promotion activity of these constructs. The stability of the 4-helix bundle tags and the relative orientations of the helical wheels of H-stems and oligomerization tags govern the kinetics of fusion promotion, revealing a balance between H stalk conformational stability and F-triggering activity. Recombinant MeV particles expressing a bioactive H-stem construct in the place of full-length H are viable, albeit severely growth impaired. Overall, we demonstrate that the MeV H stalk represents the effector domain for MeV F triggering. Fusion promotion appears linked to the conformational flexibility of the stalk, which must be tightly regulated in viral particles to ensure efficient virus entry. While the pathways toward assembly of functional fusion complexes may differ among diverse members of the paramyxovirus family, central elements of the triggering machinery emerge as highly conserved.
The Role of Interleukin-6 in the Expression of PD-1 and PDL-1 on Central Nervous System Cells following Infection with Theiler's Murine Encephalomyelitis Virus
Authors: Jin Young-Hee , Hou Wanqiu , Kang Hyun Seok , Koh Chang-Sung , Kim Byung S. 
Published: August 2013

ABSTRACTInfection with Theiler's murine encephalomyelitis virus (TMEV) in the central nervous system (CNS) of susceptible mice results in an immune-mediated demyelinating disease which is considered a relevant viral model of human multiple sclerosis. We previously demonstrated that the expression of positive costimulatory molecules (CD40, CD80, and CD86) is higher on the microglia of TMEV-resistant C57BL/6 (B6) mice than the microglia of TMEV-susceptible SJL/J (SJL) mice. In this study, we analyzed the expression levels of the negative costimulatory molecules PD-1 and PDL-1 in the CNS of TMEV-infected SJL mice and B6 mice. Our results indicated that TMEV infection induces the expression of both PD-1 and PDL-1 on microglia and macrophages in the CNS but not in the periphery. The expression of PD-1 only on CNS-infiltrating macrophages and not on resident microglia was considerably higher (>4-fold) in TMEV-infected SJL mice than TMEV-infected B6 mice. We further demonstrated that interleukn-6 (IL-6) is necessary to induce the maximal expression of PDL-1 but not PD-1 after TMEV infection using IL-6-deficient mice and IL-6-transgenic mice in conjunction with recombinant IL-6. In addition, cells from type I interferon (IFN) receptor knockout mice failed to upregulate PD-1 and PDL-1 expression after TMEV infectionin vitro, indicating that type I IFN signaling is associated with the upregulation. However, other IFN signaling may also participate in the upregulation. Taken together, these results strongly suggest that the expression of PD-1 and PDL-1 in the CNS is primarily upregulated following TMEV infection via type I IFN signaling and the maximal expression of PDL-1 additionally requires IL-6 signaling.
Nontraditional Localization and Retention Signals Localize Human Cytomegalovirus pUL34 to the Nucleus
Authors: Biegalke Bonita J. 
Published: August 2013

ABSTRACT
The human cytomegalovirus (HCMV) UL34 proteins localize to the nucleus. We identified a 204-amino-acid region, amino acids 40 to 244, as required for nuclear retention. A highly conserved 12-amino-acid section, amino acids 198 to 210, was required for nuclear localization. Although the nuclear localization and retention signals of pUL34 overlap the domain required for DNA-binding activity, the two regions are separable by point mutations. Our results presented here identify the first example of an HCMV protein with separable nuclear localization and retention signals.
Evidence in managing traumatic anterior shoulder instability: a scoping review
Authors: Monk A Paul , Garfjeld Roberts Patrick , Logishetty Kartik , Price Andrew J , Kulkarni Rohit , Rangan Amar , Rees Jonathan L 
Published: August 2013

BackgroundTraumatic anterior shoulder instability (TASI) accounts for 95% of glenohumeral dislocations and is associated with soft tissue and bony pathoanatomies. Non-operative treatments include slings, bracing and physiotherapy. Operative treatment is common, including bony and soft-tissue reconstructions performed through open or arthroscopic approaches. There is management variation in patient pathways for TASI including when to refer and when to operate.MethodsA scoping review of systematic reviews, randomised controlled trials, comparing operative with non-operative treatments and different operative treatments were the methods followed. Search was conducted for online bibliographic databases and reference lists of relevant articles from 2002 to 2012. Systematic reviews were appraised using AMSTAR (assessment of multiple systematic reviews) criteria. Controlled trials were appraised using the CONSORT (consolidation of standards of reporting trials) tool.ResultsAnalysis of the reviews did not offer strong evidence for a best treatment option for TASI. No studies directly compare open, arthroscopic and structured rehabilitation programmes. Evaluation of arthroscopic studies and comparison to open procedures was difficult, as many of the arthroscopic techniques included are no longer used. Recurrence rate was generally considered the best measure of operative success, but was poorly documented throughout all studies. There was conflicting evidence on the optimal timing of intervention and no consensus on any scoring system or outcome measure.ConclusionsThere is no agreement about which validated outcome tool should be used for assessing shoulder instability in patients. There is limited evidence regarding the comparative effectiveness of surgical and non-surgical treatment of TASI, including a lack of evidence regarding the optimal timing of such treatments. There is a need for a well-structured randomised control trial to assess the efficacy of surgical and non-surgical interventions for this common type of shoulder instability.
Maximal step-up height as a simple and relevant health indicator: a study of leg muscle strength and the associations to age, anthropometric variables, aerobic fitness and physical function
Authors: Nyberg Lillemor A , Hellénius Mai-Lis , Wändell Per , Kowalski Jan , Sundberg Carl Johan 
Published: August 2013

BackgroundLow muscle strength is related to an increased risk for several chronic diseases. Increased muscle strength improves daily function and quality of life.ObjectiveTo measure maximal step-up height, an assessment of leg strength and function, and its association to age, anthropometric variables, maximal oxygen uptake (VO2-max) and self-reported physical function before and after a physical activity programme.MethodsFemale patients (n=178, 22–83 years) with musculoskeletal disorders, metabolic risk factors and other chronic diseases were recruited from primary care. Maximal step-up height (standardised step-up without a kick-off with the floor foot), anthropometric variables, VO2-max and self-reported physical function (Short Form 36 (SF-36)) were assessed before and after a 3-month group training intervention programme. Associations between maximal step-up height and other variables were examined using univariate and multivariate methods.ResultsAt baseline and after intervention, maximal step-up height was negatively correlated to age, waist circumference and body weight and positively correlated to VO2-max, self-reported physical function and height. Furthermore, maximal step-up height correlated to training intensity at follow-up. Variations in changes in maximal step-up height were significantly explained by changes in waist circumference and physical function, regardless of age and changes in VO2-max. Maximal step-up height below 24 cm discriminated patients with self-reported severe limitation in physical function.ConclusionsMaximal step-up height, assessed simply with a standardised step-up test, may function as a relevant indicator of health since it correlated negatively to the metabolic risk factors, waist circumference, body weight and age, and positively to VO2-max and physical function.