bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Genetic Bottleneck in Vertical Transmission of Subtype C HIV-1 Is Not Driven by Selection of Especially Neutralization-Resistant Virus from the Maternal Viral Population
Authors: Russell Elizabeth S. , Kwiek Jesse J. , Keys Jessica , Barton Kirston , Mwapasa Victor , Montefiori David C. , Meshnick Steven R. , Swanstrom Ronald 
Published: May 2011

ABSTRACT

Subtype C human immunodeficiency virus type 1 (HIV-1C) continues to cause the majority of new cases of mother-to-child transmission (MTCT), and yet there are limited data on HIV-1C transmission. We amplified
env
from plasma RNA for 19 HIV-1C MTCT pairs, 10 transmitting
in utero
(IU) and 9 transmitting intrapartum (IP). There was a strong genetic bottleneck between all mother-infant pairs, with a majority of transmission events involving the transmission of a single virus.
env
genes of viruses transmitted to infants IP, but not IU, encoded Env proteins that were shorter and had fewer putative N-linked glycosylation sites in the V1-V5 region than matched maternal sequences. Viruses pseudotyped with
env
clones representative of each maternal and infant population were tested for neutralization sensitivity. The 50% inhibitory concentration of autologous serum was similar against both transmitted (infant) and nontransmitted (maternal) viruses in a paired analysis. Mother and infant Env proteins were also similar in sensitivity to soluble CD4, to a panel of monoclonal antibodies, and to heterologous HIV-1C sera. In addition, there was no difference in the breadth or potency of neutralizing antibodies between sera from 50 nontransmitting and 23 IU and 23 IP transmitting HIV-1C-infected women against four Env proteins from heterologous viruses. Thus, while a strong genetic bottleneck was detected during MCTC, with viruses of shorter and fewer glycosylation sites in
env
present in IP transmission, our data do not support this bottleneck being driven by selective resistance to antibodies.
Ex Vivo
Bioluminescence Detection of Alcelaphine Herpesvirus 1 Infection during Malignant Catarrhal Fever
Authors: Dewals Benjamin , Myster Françoise , Palmeira Leonor , Gillet Laurent , Ackermann Mathias , Vanderplasschen Alain 
Published: May 2011

ABSTRACT

Alcelaphine herpesvirus 1
(AlHV-1), carried by wildebeest asymptomatically, causes malignant catarrhal fever (WD-MCF) when cross-species transmitted to a variety of susceptible species of the
Artiodactyla
order. Experimentally, WD-MCF can be reproduced in rabbits. WD-MCF is described as a combination of lymphoproliferation and degenerative lesions in virtually all organs and is caused by unknown mechanisms. Recently, we demonstrated that WD-MCF is associated with the proliferation of CD8
+
cells supporting a latent type of infection in lymphoid tissues. Here, we investigated the macroscopic distribution of AlHV-1 infection using
ex vivo
bioluminescence imaging in rabbit to determine whether it correlates with the distribution of lesions in lymphoid and nonlymphoid organs. To reach that goal, a recombinant AlHV-1 strain was produced by insertion of a luciferase expression cassette (
luc
) in an intergenic region.
In vitro
, the reconstituted AlHV-1
luc

+

strain replicated comparably to the parental strain, and luciferase activity was detected by bioluminescence imaging.
In vivo
, rabbits infected with the AlHV-1
luc

+

strain developed WD-MCF comparably to rabbits infected with the parental wild-type strain, with hyperthermia and increases of both CD8
+
T cell frequencies and viral genomic charge over time in peripheral blood mononuclear cells and in lymph nodes at time of euthanasia. Bioluminescent imaging revealed that AlHV-1 infection could be detected
ex vivo
in lymphoid organs but also in lung, liver, and kidney during WD-MCF, demonstrating that AlHV-1 infection is prevalent in tissue lesions. Finally, we show that the infiltrating mononuclear leukocytes in nonlymphoid organs are mainly CD8
+
T cells and that latency is predominant during WD-MCF.
The Internal Kaposi's Sarcoma-Associated Herpesvirus LANA Regions Exert a Critical Role on Episome Persistence
Authors: De León Vázquez Erika , Kaye Kenneth M. 
Published: May 2011

ABSTRACT
Kaposi's sarcoma-associated herpesvirus (KSHV) latency-associated nuclear antigen (LANA) is a 1,162-amino-acid protein that acts on viral terminal repeat (TR) DNA to mediate KSHV episome persistence. The two essential components of episome persistence are DNA replication prior to cell division and episome segregation to daughter nuclei. These functions are located within N- and C-terminal regions of LANA. N- and C-terminal regions of LANA are sufficient for TR DNA replication. In addition, N- and C-terminal regions of LANA tether episomes to mitotic chromosomes to segregate episomes to progeny cell nuclei. To generate a tethering mechanism, N-terminal LANA binds histones H2A/H2B to attach to mitotic chromosomes, and C-terminal LANA binds TR DNA and also associates with mitotic chromosomes. Here, we test the importance of the internal LANA sequence for episome persistence. We generated LANA mutants that contain N- and C-terminal regions of LANA but have most of the internal sequence deleted. As expected, the LANA mutants bound mitotic chromosomes in a wild-type pattern and also bound TR DNA as assayed by electrophoretic mobility shift assays (EMSA). The mutants mediated TR DNA replication, although with reduced efficiency compared with LANA. Despite the ability to replicate DNA and exert the chromosome and DNA binding functions necessary for segregating episomes to daughter nuclei, the mutants were highly deficient for the ability to mediate both short- and long-term episome persistence. These data indicate that internal LANA sequence exerts a critical effect on its ability to maintain episomes, possibly through effects on TR DNA replication.
Cyclophilin A Interacts with Domain II of Hepatitis C Virus NS5A and Stimulates RNA Binding in an Isomerase-Dependent Manner
Authors: Foster Toshana L. , Gallay Philippe , Stonehouse Nicola J. , Harris Mark 
Published: May 2011

ABSTRACTNS5A plays a critical, yet poorly defined, role in hepatitis C virus genome replication. The protein consists of three domains, each of which is able to bind independently to the 3′ untranslated region (UTR) of the viral positive strand genomic RNA. The peptidyl-prolyl isomerase cyclophilin A (CypA) binds to domain II, catalyzingcis-transisomerization. CypA inhibitors such as cyclosporine (CsA) have been shown to inhibit hepatitis C virus (HCV) replication. We show here that CypA stimulated domain II RNA binding activity, and this stimulation was abrogated by CsA. An isomerase mutant of CypA (H126Q) failed to bind to domain II and did not stimulate RNA binding. Finally, we demonstrate that the RNA binding of two domain II mutants, the D316E and D316E/Y317N mutants, previously shown to exhibit CypA independence for RNA replication, was unaffected by CypA. This study provides an insight into the molecular mechanism of CypA activity during HCV replication and further validates the use of CypA inhibitors in HCV therapy.
The Virulence of 1997 H5N1 Influenza Viruses in the Mouse Model Is Increased by Correcting a Defect in Their NS1 Proteins
Authors: Spesock April , Malur Meghana , Hossain M. Jaber , Chen Li-Mei , Njaa Bradley L. , Davis Charles T. , Lipatov Aleksandr S. , York Ian A. , Krug Robert M. , Donis Ruben O. 
Published: May 2011

ABSTRACT
The NS1 protein of human influenza A viruses binds the 30-kDa subunit of the cleavage and polyadenylation specificity factor (CPSF30), a protein required for 3′ end processing of cellular pre-mRNAs, thereby inhibiting production of beta interferon (IFN-β) mRNA. The NS1 proteins of pathogenic 1997 H5N1 viruses contain the CPSF30-binding site but lack the consensus amino acids at positions 103 and 106, F and M, respectively, that are required for the stabilization of CPSF30 binding, resulting in nonoptimal CPSF30 binding in infected cells. Here we have demonstrated that strengthening CPSF30 binding, by changing positions 103 and 106 in the 1997 H5N1 NS1 protein to the consensus amino acids, results in a remarkable 300-fold increase in the lethality of the virus in mice. Unexpectedly, this increase in virulence is not associated with increased lung pathology but rather is characterized by faster systemic spread of the virus, particularly to the brain, where increased replication and severe pathology occur. This increased spread is associated with increased cytokine and chemokine levels in extrapulmonary tissues. We conclude that strengthening CPSF30 binding by the NS1 protein of 1997 H5N1 viruses enhances virulence in mice by increasing the systemic spread of the virus from the lungs, particularly to the brain.
Extensive Geographical Mixing of 2009 Human H1N1 Influenza A Virus in a Single University Community
Authors: Holmes Edward C. , Ghedin Elodie , Halpin Rebecca A. , Stockwell Timothy B. , Zhang Xing-Quan , Fleming Regina , Davey Richard , Benson Constance A. , Mehta Sanjay , Taplitz Randy , Liu Yu-Tseung , Brouwer Kimberly C. , Wentworth David E. , Lin Xudong ,   the INSIGHT FLU002 Study Group, Schooley Robert T. 
Published: May 2011

ABSTRACT
Despite growing interest in the molecular epidemiology of influenza virus, the pattern of viral spread within individual communities remains poorly understood. To determine the phylogeography of influenza virus in a single population, we examined the spatial diffusion of H1N1/09 influenza A virus within the student body of the University of California, San Diego (UCSD), sampling for a 1-month period between October and November 2009. Despite the highly focused nature of our study, an analysis of complete viral genome sequences revealed between 24 and 33 independent introductions of H1N1/09 into the UCSD community, comprising much of the global genetic diversity in this virus. These data were also characterized by a relatively low level of on-campus transmission as well as extensive spatial mixing, such that there was little geographical clustering by either student residence or city ZIP code. Most notably, students experiencing illness on the same day and residing in the same dorm possessed phylogenetically distinct lineages. H1N1/09 influenza A virus is therefore characterized by a remarkable spatial fluidity, which is likely to impede community-based methods for its control, including class cancellations, quarantine, and chemoprophylaxis.
Clinical Outcome of Henipavirus Infection in Hamsters Is Determined by the Route and Dose of Infection
Authors: Rockx Barry , Brining Douglas , Kramer Joshua , Callison Julie , Ebihara Hideki , Mansfield Keith , Feldmann Heinz 
Published: May 2011

ABSTRACT
Nipah virus (NiV) and Hendra virus (HeV) are emerging zoonotic viruses and the causative agents of severe respiratory disease and encephalitis in humans. Little is known about the mechanisms that govern the development of respiratory and neurological disease. Using a hamster model of lethal NiV and HeV infection, we describe the role of the route and dose of infection on the clinical outcome and determine virus tropism and host responses following infection. Infection of hamster with a high dose of NiV or HeV resulted in acute respiratory distress. NiV initially replicated in the upper respiratory tract epithelium, whereas HeV initiated infection primarily in the interstitium. In contrast, infection with a low dose of NiV or HeV resulted in the development of neurological signs and more systemic spread of the virus through involvement of the endothelium. The development of neurological signs coincided with disruption of the blood-brain barrier (BBB) and expression of tumor necrosis alpha (TNF-α) and interleukin 1 β (IL-1β). In addition, interferon-inducible protein 10 (IP-10) was identified as playing an important role in NiV and HeV pathogenesis. These studies reveal novel information on the development and progression of NiV and HeV clinical disease, provide a mechanism for the differences in transmission observed between NiV and HeV outbreaks, and identify specific cytokines and chemokines that serve as important targets for treatment.
A Tyr Residue in the Reverse Transcriptase Domain Can Mimic the Protein-Priming Tyr Residue in the Terminal Protein Domain of a Hepadnavirus P Protein
Authors: Beck Jürgen , Nassal Michael 
Published: May 2011

ABSTRACTHepadnaviruses are the only known viruses that replicate by protein-primed reverse transcription. Beyond the conserved reverse transcriptase (RT) and RNase H domains, their polymerases (P proteins) carry a unique terminal protein (TP) domain that provides a specific Tyr residue, Tyr96 in duck hepatitis B virus (DHBV), to which the first nucleotide of minus-strand DNA is autocatalytically attached and extended by three more nucleotides.In vitroreconstitution of this priming reaction with DHBV P protein and cellular chaperones had revealed strict requirements for the Dε RNA stem-loop as a template and for catalytic activity of the RT domain plus RNA-binding competence of the TP domain. Chaperone dependence can be obviated by using a truncated P protein (miniP). Here, we found that miniP with a tobacco etch virus (TEV) protease cleavage site between TP and RT (miniPTEV) displayed authentic priming activity when supplied with α-32P-labeled deoxynucleoside triphosphates; however, protease cleavage revealed, surprisingly, that the RT domain was also labeled. RT labeling had identical requirements as priming at Tyr96 and originated from dNMP transfer to a unique Tyr residue identified as Tyr561 in the presumed RT primer grip motif. Mutating Tyr561 did not affect Tyr96 primingin vitroand only modestly reduced replication competence of an intact DHBV genome; hence, deoxynucleotidylated Tyr561 is not an obligate intermediate in TP priming. However, as a first alternative substrate for the exquisitely complex protein-priming reaction, dNMP transfer to Tyr561 is a novel tool to further clarify the mechanism of hepadnaviral replication initiation and suggests that specific priming inhibitors can be found.
Cryptic Protein Priming Sites in Two Different Domains of Duck Hepatitis B Virus Reverse Transcriptase for Initiating DNA Synthesis
In Vitro
Authors: Boregowda Rajeev K. , Lin Li , Zhu Qin , Tian Fang , Hu Jianming 
Published: May 2011

ABSTRACT

Initiation of reverse transcription in hepadnaviruses is accomplished by a unique protein-priming mechanism whereby a specific Y residue in the terminal protein (TP) domain of the viral reverse transcriptase (RT) acts as a primer to initiate DNA synthesis, which is carried out by the RT domain of the same protein. When separate TP and RT domains from the duck hepatitis B virus (DHBV) RT protein were tested in a
trans
-complementation assay
in vitro
, the RT domain could also serve, unexpectedly, as a protein primer for DNA synthesis, as could a TP mutant lacking the authentic primer Y (Y96) residue. Priming at these other, so-called cryptic, priming sites in both the RT and TP domains shared the same requirements as those at Y96. A mini RT protein with both the TP and RT domains linked in
cis
, as well as the full-length RT protein, could also initiate DNA synthesis using cryptic priming sites. The cryptic priming site(s) in TP was found to be S/T, while those in the RT domain were Y and S/T. As with the authentic TP Y96 priming site, the cryptic priming sites in the TP and RT domains could support DNA polymerization subsequent to the initial covalent linkage of the first nucleotide to the priming amino acid residue. These results provide new insights into the complex mechanisms of protein priming in hepadnaviruses, including the selection of the primer residue and the interactions between the TP and RT domains that is essential for protein priming.
Virally Expressed Interleukin-10 Ameliorates Acute Encephalomyelitis and Chronic Demyelination in Coronavirus-Infected Mice
Authors: Trandem Kathryn , Jin Qiushuang , Weiss Kayla A. , James Britnie R. , Zhao Jingxian , Perlman Stanley 
Published: May 2011

ABSTRACTThe absence of interleukin-10 (IL-10), a potent anti-inflammatory cytokine results in increased immune-mediated demyelination in mice infected with a neurotropic coronavirus (recombinant J2.2-V-1 [rJ2.2]). Here, we examined the therapeutic effects of increased levels of IL-10 at early times after infection by engineering a recombinant J2.2 virus to produce IL-10. We demonstrate that viral expression of IL-10, which occurs during the peak of virus replication and at the site of disease, enhanced survival and diminished morbidity in rJ2.2-infected wild-type B6 and IL-10−/−mice. The protective effects of increased IL-10 levels were associated with reductions in microglial activation, inflammatory cell infiltration into the brain, and proinflammatory cytokine and chemokine production. Additionally, IL-10 increased both the frequency and number of Foxp3+regulatory CD4 T cells in the infected central nervous system. Most strikingly, the ameliorating effects of IL-10 produced during the first 5 days after infection were long acting, resulting in decreased demyelination during the resolution phase of the infection. Collectively, these results suggest that the pathogenic processes that result in demyelination are initiated early during infection and that they can be diminished by exogenous IL-10 delivered soon after disease onset. IL-10 functions by dampening the innate or very early T cell immune response. Further, they suggest that early treatment with IL-10 may be useful adjunct therapy in some types of viral encephalitis.
Nipah Virus Uses Leukocytes for Efficient Dissemination within a Host
Authors: Mathieu Cyrille , Pohl Christine , Szecsi Judit , Trajkovic-Bodennec Selena , Devergnas Séverine , Raoul Hervé , Cosset François-Loïc , Gerlier Denis , Wild T. Fabian , Horvat Branka 
Published: May 2011

ABSTRACT

Nipah virus (NiV) is a recently emerged zoonotic paramyxovirus whose natural reservoirs are several species of
Pteropus
fruit bats. NiV provokes a widespread vasculitis often associated with severe encephalitis, with up to 75% mortality in humans. We have analyzed the pathogenesis of NiV infection, using human leukocyte cultures and the hamster animal model, which closely reproduces human NiV infection. We report that human lymphocytes and monocytes are not permissive for NiV and a low level of virus replication is detected only in dendritic cells. Interestingly, despite the absence of infection, lymphocytes could efficiently bind NiV and transfer infection to endothelial and Vero cells. This lymphocyte-mediated transinfection was inhibited after proteolytic digestion and neutralization by NiV-specific antibodies, suggesting that cells could transfer infectious virus to other permissive cells without the requirement for NiV internalization. In NiV-infected hamsters, leukocytes captured and carried NiV after intraperitoneal infection without themselves being productively infected. Such NiV-loaded mononuclear leukocytes transfer lethal NiV infection into naïve animals, demonstrating efficient virus transinfection
in vivo
. Altogether, these results reveal a remarkable capacity of NiV to hijack leukocytes as vehicles to transinfect host cells and spread the virus throughout the organism. This mode of virus transmission represents a rapid and potent method of NiV dissemination, which may contribute to its high pathogenicity.
Virion Structure of Baboon Reovirus, a Fusogenic Orthoreovirus That Lacks an Adhesion Fiber
Authors: Yan Xiaodong , Parent Kristin N. , Goodman Russell P. , Tang Jinghua , Shou Jingyun , Nibert Max L. , Duncan Roy , Baker Timothy S. 
Published: May 2011

ABSTRACT
Baboon reovirus (BRV) is a member of the fusogenic subgroup of orthoreoviruses. Unlike most other members of its genus, BRV lacks S-segment coding sequences for the outer fiber protein that binds to cell surface receptors. It shares this lack with aquareoviruses, which constitute a related genus and are also fusogenic. We used electron cryomicroscopy and three-dimensional image reconstruction to determine the BRV virion structure at 9.0-Å resolution. The results show that BRV lacks a protruding fiber at its icosahedral 5-fold axes or elsewhere. The results also show that BRV is like nonfusogenic mammalian and fusogenic avian orthoreoviruses in having 150 copies of the core clamp protein, not 120 as in aquareoviruses. On the other hand, there are no hub-and-spoke complexes attributable to the outer shell protein in the P2 and P3 solvent channels of BRV, which makes BRV like fusogenic avian orthoreoviruses and aquareoviruses but unlike nonfusogenic mammalian orthoreoviruses. The outermost “flap” domains of the BRV core turret protein appear capable of conformational variability within the virion, a trait previously unseen among other ortho- and aquareoviruses. New cDNA sequence determinations for the BRV L1 and M2 genome segments, encoding the core turret and outer shell proteins, were helpful for interpreting the structural features of those proteins. Based on these findings, we conclude that the evolution of ortho- and aquareoviruses has included a series of discrete gains or losses of particular components, several of which cross taxonomic boundaries. Gain or loss of adhesion fibers is one of several common themes in double-stranded RNA virus evolution.
Immune Mediators of Rotavirus Antigenemia Clearance in Mice
Authors: Marcelin Glendie , Miller Amber D. , Blutt Sarah E. , Conner Margaret E. 
Published: May 2011

ABSTRACTThe immunological mediators that clear rotavirus antigenemia or viremia remain undefined. Immunodeficient mice and antibody transfer were used to test whether lymphocytes or rotavirus-specific serum antibodies are essential for resolving antigenemia. Clearance of antigenemia required lymphocytes, but neither T nor B lymphocytes were absolutely required. Transfer of convalescent-phase or nonneutralizing rotavirus-specific serum antibodies to the systemic compartment of severe-combined-immunodeficient (SCID) mice temporarily suppressed the onset or level of chronic rotavirus antigenemia. Our findings provide the first report demonstrating that clearance of rotavirus antigenemia and possibly viremia are mediated by multiple effector lymphocyte subsets and serum antibodies.