bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phylogenetic and Genetic Analysis of Feline Immunodeficiency Virus
gag
,
pol
, and
env
Genes from Domestic Cats Undergoing Nucleoside Reverse Transcriptase Inhibitor Treatment or Treatment-Naïve Cats in Rio de Janeiro, Brazil
Authors: Martins Angelica N. , Medeiros Sheila O. , Simonetti Jose P. , Schatzmayr Hermann G. , Tanuri Amílcar , Brindeiro Rodrigo M. 
Published: June 2008

ABSTRACT

Feline immunodeficiency virus (FIV) is the
Lentivirus
responsible for an immunodeficiency-like disease in domestic cats (
Felis catus
). FIV is divided into five phylogenetic subtypes (A, B, C, D, and E), based on genetic diversity. Knowledge of the geographical distribution of subtypes is relevant for understanding different disease progressions and for vaccine development. In this study, viral sequences of 26 infected cats from Rio de Janeiro, 8 undergoing treatment with zidovudine (AZT) for at least 5 years, were successfully amplified from blood specimens.
gag
capsid (CA),
pol
reverse transcriptase (RT), and
env
gp120 (V3-V4) regions were analyzed to determine subtypes and to evaluate potential mutations related to antiretroviral drug resistance among treated cats. Subtyping based on phylogenetic analysis was performed by the neighbor-joining and maximum likelihood methods. All of the sequences clustered with subtype B in the three regions, exhibiting low genetic variability. Additionally, we found evidence that the same virus is circulating in animals in close contact. The analysis of FIV RT sequences identified two new putative mutations related to drug resistance located in the RT “finger” domain, which has 60% identity to human immunodeficiency virus (HIV) sequence. Amino acid change K→R at codons 64 and 69 was found in 25% and 37.5% of the treated animals, respectively. These signatures were comparable to K65R and K70R thymidine-associated mutations found in the HIV-1 HXB2 counterpart. This finding strongly suggests a position correlation between the mutations found in FIV and the K65R and K70R substitutions from drug-resistant HIV-1 strains.
The Core Element of a CpG Island Protects Avian Sarcoma and Leukosis Virus-Derived Vectors from Transcriptional Silencing
Authors: Šenigl Filip , Plachý Jiří , Hejnar Jiří 
Published: June 2008

ABSTRACT
Unmethylated CpG islands are known to keep adjacent promoters transcriptionally active. In the CpG island adjacent to the adenosine phosphoribosyltransferase gene, the protection against transcriptional silencing can be attributed to the short CpG-rich core element containing Sp1 binding sites. We report here the insertion of this CpG island core element, IE, into the long terminal repeat of a retroviral vector derived from Rous sarcoma virus, which normally suffers from progressive transcriptional silencing in mammalian cells. IE insertion into a specific position between enhancer and promoter sequences led to efficient protection of the integrated vector from silencing and gradual CpG methylation in rodent and human cells. Individual cell clones with IE-modified reporter vectors display high levels of reporter expression for a sustained period and without substantial variegation in the cell culture. The presence of Sp1 binding sites is important for the protective effect of IE, but at least some part of the entire antisilencing capacity is maintained in IE with mutated Sp1 sites. We suggest that this strategy of antisilencing protection by the CpG island core element may prove generally useful in retroviral vectors.
The Large Polymerase Protein Is Associated with the Virulence of Newcastle Disease Virus
Authors: Rout Subrat N. , Samal Siba K. 
Published: June 2008

ABSTRACT
Naturally occurring Newcastle disease virus (NDV) strains vary greatly in virulence, ranging from no apparent infection to severe disease causing 100% mortality in chickens. The viral determinants of NDV virulence are not completely understood. Cleavage of the fusion protein is required for the initiation of infection, and it acts as a determinant of virulence. The attachment protein HN was found to play a minor role in virulence. In this study, we have evaluated the role of the internal proteins (N, P, and L) in NDV virulence by using a chimeric reverse-genetics approach. The N, P, and L genes were exchanged individually between an avirulent NDV strain, LaSota, and an intermediate virulent NDV strain, Beaudette C (BC), and the N and P genes were also exchanged together. The recovered chimeric viruses were evaluated for their pathogenicity in the natural host, chickens. Our results showed that the pathogenicities of N and P chimeric viruses were similar to those of their respective parental viruses, indicating that the N and P genes probably play minor roles in virulence. However, replacement of the L gene of BC with that of LaSota significantly increased the pathogenicity of the L-chimeric virus, suggesting that the L gene probably contributes to the virulence of NDV. The L-chimeric BC virus was found to replicate at a 100-fold-higher level than its parental virus in chicken brain, suggesting that the increase in pathogenicity may be due to the increased replication level of the chimeric virus. Our findings offer new insights into the pathogenesis of NDV infection.
The High Prevalence of Herpes Simplex Virus Type 1 DNA in Human Trigeminal Ganglia Is Not a Function of Age or Gender
Authors: Hill James M. , Ball Melvyn J. , Neumann Donna M. , Azcuy Ann M. , Bhattacharjee Partha S. , Bouhanik Saadallah , Clement Christian , Lukiw Walter J. , Foster Timothy P. , Kumar Manish , Kaufman Herbert E. , Thompson Hilary W. 
Published: June 2008

ABSTRACT

The purpose of this study was to determine the presence and copy numbers of herpes simplex virus type 1 (HSV-1) DNA in human trigeminal ganglia (TG) with respect to age, gender, and postmortem interval (PMI). Human TG (
n
= 174, obtained from the Oregon Brain Bank, with data on age, gender, and PMI) were analyzed for HSV-1 DNA copies (HSV-1 DNA polymerase gene) by using real-time PCR. We found that 89.1% (131/147) of subjects and 90.1% (155/174) of TG contained HSV-1 DNA. The copy numbers of HSV-1 DNA in the positives ranged from very high (>10
6
) to very low (5). These data confirm and strengthen our previous findings that subjects were positive for HSV-1 DNA in tears (46/50; 92%) and saliva (47/50; 94%). These TG data and tear and saliva data demonstrated considerable variability in copy numbers of HSV-1 DNA per subject. Statistical analysis showed no significant relationship between gender and copy number, age and copy number, or PMI and copy number for each pair of variables. A factorial analysis of gender, age, and PMI with respect to copy number also showed no statistical significance. This is the first study that provides statistical analysis that documents that the prevalence of HSV-1 DNA in the human TG is not a function of either gender or age.
Amino Acid 226 in the Hemagglutinin of H4N6 Influenza Virus Determines Binding Affinity for α2,6-Linked Sialic Acid and Infectivity Levels in Primary Swine and Human Respiratory Epithelial Cells
Authors: Bateman Allen C. , Busch Marc G. , Karasin Alexander I. , Bovin Nicolai , Olsen Christopher W. 
Published: June 2008

ABSTRACT
Avian lineage H4N6 influenza viruses previously isolated from pigs differ at hemagglutinin amino acids 226 and 228 from H4 subtype viruses isolated from birds. Using a parental H4N6 swine isolate and hemagglutinin mutant viruses (at residues 226 and/or 228), we determined that viruses which contain L226 had a higher affinity for sialic acid α2,6 galactose (SAα2,6Gal) and a higher infectivity level for primary swine and human respiratory epithelial cells, whereas viruses which contain Q226 had lower SAα2,6Gal affinity and lower infectivity levels for both types of cells. Using specific neuraminidases, we found that irrespective of their relative binding preferences, all of the influenza viruses examined utilized SAα2,6Gal to infect swine and human cells.
Mouse Hepatitis Virus Type 2 Enters Cells through a Clathrin-Mediated Endocytic Pathway Independent of Eps15
Authors: Pu Yinghui , Zhang Xuming 
Published: June 2008

ABSTRACT

It has recently been shown that cell entry of mouse hepatitis virus type 2 (MHV-2) is mediated through endocytosis (Z. Qiu et al., J. Virol.
80
:5768-5776, 2006). However, the molecular mechanism underlying MHV-2 entry is not known. Here we employed multiple chemical and molecular approaches to determine the molecular pathways for MHV-2 entry. Our results showed that MHV-2 gene expression and infectivity were significantly inhibited when cells were treated with chemical and physiologic blockers of the clathrin-mediated pathway, such as chlorpromazine and hypertonic sucrose medium. Furthermore, viral gene expression was significantly inhibited when cells were transfected with a small interfering RNA specific to the clathrin heavy chain. However, these treatments did not affect the infectivity and gene expression of MHV-A59, demonstrating the specificity of the inhibitions. In addition, overexpression of a dominant-negative mutant of caveolin 1 did not have any effect on MHV-2 infection, while it significantly blocked the caveolin-dependent uptake of cholera toxin subunit B. These results demonstrate that MHV-2 utilizes the clathrin- but not caveolin-mediated endocytic pathway for entry. Interestingly, when the cells transiently overexpressed a dominant-negative form (DIII) of Eps15, which is thought to be an essential component of the clathrin pathway, viral gene expression and infectivity were unaffected, although DIII expression blocked transferrin uptake and vesicular stomatitis virus infection, which are dependent on clathrin-mediated endocytosis. Thus, MHV-2 entry is mediated through clathrin-dependent but Eps15-independent endocytosis.
Novel Astroviruses in Insectivorous Bats
Authors: Chu D. K. W. , Poon L. L. M. , Guan Y. , Peiris J. S. M. 
Published: June 2008

ABSTRACT

Bats are increasingly recognized to harbor a wide range of viruses, and in most instances these viruses appear to establish long-term persistence in these animals. They are the reservoir of a number of human zoonotic diseases including Nipah, Ebola, and severe acute respiratory syndrome. We report the identification of novel groups of astroviruses in apparently healthy insectivorous bats found in Hong Kong, in particular, bats belonging to the genera
Miniopterus
and
Myotis
. Astroviruses are important causes of diarrhea in many animal species, including humans. Many of the bat astroviruses form distinct phylogenetic clusters in the genus
Mamastrovirus
within the family
Astroviridae
. Virus detection rates of 36% to 100% and 50% to 70% were found in
Miniopterus magnater
and
Miniopterus pusillus
bats, respectively, captured within a single bat habitat during four consecutive visits spanning 1 year. There was high genetic diversity of viruses in bats found within this single habitat. Some bat astroviruses may be phylogenetically related to human astroviruses, and further studies with a wider range of bat species in different geographic locations are warranted. These findings are likely to provide new insights into the ecology and evolution of astroviruses and reinforce the role of bats as a reservoir of viruses with potential to pose a zoonotic threat to human health.
Human Parvovirus B19 NS1 Protein Modulates Inflammatory Signaling by Activation of STAT3/PIAS3 in Human Endothelial Cells
Authors: Duechting Anja , Tschöpe Carsten , Kaiser Heike , Lamkemeyer Tobias , Tanaka Nobuyuki , Aberle Susanne , Lang Florian , Torresi Joseph , Kandolf Reinhard , Bock C.-Thomas 
Published: June 2008

ABSTRACTThe pathogenic mechanism by which parvovirus B19 may induce inflammatory cardiomyopathy (iCMP) is complex but is known to involve inflammatory processes, possibly including activation of JAK/STAT signaling. The nonstructural B19 protein NS1 acts as a transactivator triggering signaling cascades that eventually lead to activation of interleukin 6 (IL-6). We examined the impact of NS1 on modulation of STAT signaling in human endothelial cells (HMEC-1). The NS1 sequences were identified from B19 DNA isolated from the myocardia of patients with fatal iCMP. B19 infection as well as NS1 overexpression in HMEC-1 cells produced a significant upregulation in the phosphorylation of both tyrosine705and serine727STAT3 (P< 0.05). The increased STAT3 phosphorylation was accompanied by dimerization, nuclear translocation, and DNA binding of pSTAT3. In contrast, NS1 expression did not result in increased STAT1 activation. Notably, the expression levels of the negative regulators of STAT activation, SOCS1 and SOCS3, were not altered by NS1. However, the level of PIAS3 was upregulated in NS1-expressing HMEC-1 cells. Analysis of the transcriptional activation of target genes revealed that NS1-induced STAT3 signaling was associated with upregulation of genes involved in immune response (e.g., the IFNAR1 and IL-2 genes) and downregulation of genes associated with viral defense (e.g., the OAS1 and TYK2 genes). Our results demonstrate that B19 NS1 modulates the STAT/PIAS pathway. The NS1-induced upregulation of STAT3/PIAS3 in the absence of STAT1 phosphorylation and the lack of SOCS1/SOCS3 activation may contribute to the mechanisms by which B19 evades the immune response and establishes persistent infection in human endothelial cells. Thus, NS1 may play a critical role in the mechanism of viral pathogenesis in B19-associated iCMP.
A Novel Cellular Protein, VPEF, Facilitates Vaccinia Virus Penetration into HeLa Cells through Fluid Phase Endocytosis
Authors: Huang Cheng-Yen , Lu Tsai-Yi , Bair Chi-Horng , Chang Yuan-Shau , Jwo Jeng-Kuan , Chang Wen 
Published: June 2008

ABSTRACT
Vaccinia virus is a large DNA virus that infects many cell cultures in vitro and animal species in vivo. Although it has been used widely as a vaccine, its cell entry pathway remains unclear. In this study, we showed that vaccinia virus intracellular mature virions bound to the filopodia of HeLa cells and moved toward the cell body and entered the cell through an endocytic route that required a dynamin-mediated pathway but not a clathrin- or caveola-mediated pathway. Moreover, virus penetration required a novel cellular protein, vaccinia virus penetration factor (VPEF). VPEF was detected on cell surface lipid rafts and on vesicle-like structures in the cytoplasm. Both vaccinia virus and dextran transiently colocalized with VPEF, and, importantly, knockdown of VPEF expression blocked vaccinia virus penetration as well as intracellular transport of dextran, suggesting that VPEF mediates vaccinia virus entry through a fluid uptake endocytosis process in HeLa cells. Intracellular VPEF-containing vesicles did not colocalize with Rab5a or caveolin but partially colocalized with Rab11, supporting the idea that VPEF plays a role in vesicle trafficking and recycling in HeLa cells. In summary, this study characterized the mechanism by which vaccinia virus enters HeLa cells and identified a cellular factor, VPEF, that is exploited by vaccinia virus for cell entry through fluid phase endocytosis.
Liver-Specific MicroRNA miR-122 Enhances the Replication of Hepatitis C Virus in Nonhepatic Cells
Authors: Chang Jinhong , Guo Ju-Tao , Jiang Dong , Guo Haitao , Taylor John M. , Block Timothy M. 
Published: June 2008

ABSTRACT
The liver-specific microRNA miR-122 has been shown to be required for the replication of hepatitis C virus (HCV) in the hepatoma cell line Huh7. The aim of this study was to test if HCV replication can be modulated by exogenously expressed miR-122 in human embryonic kidney epithelial cells (HEK-293). Our results demonstrate that miR-122 enhances the colony formation efficiency of the HCV replicon and increases the steady-state level of HCV RNA in HEK-293 cells. Therefore, we conclude that although miR-122 is not absolutely required, it greatly enhances HCV replication in nonhepatic cells.
Cellular La Protein Shields Nonsegmented Negative-Strand RNA Viral Leader RNA from RIG-I and Enhances Virus Growth by Diverse Mechanisms
Authors: Bitko Vira , Musiyenko Alla , Bayfield Mark A. , Maraia Richard J. , Barik Sailen 
Published: June 2008

ABSTRACT
The La antigen (SS-B) associates with a wide variety of cellular and viral RNAs to affect gene expression in multiple systems. We show that La is the major cellular protein found to be associated with the abundant 44-nucleotide viral leader RNA (leRNA) early after infection with respiratory syncytial virus (RSV), a nonsegmented negative-strand RNA virus. Consistent with this, La redistributes from the nucleus to the cytoplasm in RSV-infected cells. Upon RNA interference knockdown of La, leRNA is redirected to associate with the RNA-binding protein RIG-I, a known activator of interferon (IFN) gene expression, and this is accompanied by the early induction of IFN mRNA. These results suggest that La shields leRNA from RIG-I, abrogating the early viral activation of type I IFN. We mapped the leRNA binding function to RNA recognition motif 1 of La and showed that while wild-type La greatly enhanced RSV growth, a La mutant defective in RSV leRNA binding also did not support RSV growth. Comparative studies of RSV and Sendai virus and the use of IFN-negative Vero cells indicated that La supports the growth of nonsegmented negative-strand RNA viruses by both IFN suppression and a potentially novel IFN-independent mechanism.
Enrichment of Early Fetal‐Liver Hemopoietic Stem Cellsof the Rat Using Monoclonal Antibodies Against theTransferrin Receptor, Thy‐1, and MRC‐Oχ82
Authors: Crook Kenneth , Hunt Simon V. 
Published: June 2008

Fetal livers from inbred rat fetuses at 14 days′ gestation were dispersed into a single‐cell
suspension by physical disruption and collagenase digestion. Pluripotent stem cells were
characterized and partially purified by a combination of monoclonal antibodies. These
included CD71 (anti‐transferrin receptor, MRC‐Oχ26, used for rosetting), Cdw90 (anti‐
Thy‐1, MRC‐Oχ7), and the newly described MRC‐Oχ82 (reacting with myeloid cells in
peritoneal exudate), employed in FACS sorting. Enrichment was monitored by long‐term
reconstitution of lethally irradiated congenic rats genetically distinguishable from the donor
by an allelomorphic variant of the CD45 cell‐surface antigen. At intervals from 3 months
to 1 year, lymph‐node cells and peritoneal exudate cells were biopsied for analysis by
two‐color flow cytometry‐one color to determine donor origin, the other to identify Th cell
(CD4+), Tc cell (CD8+), B cell (sIg+ or CD45RC+ ), neutrophil (Oχ82 + or Oχ43‐ ), and
macrophage (Oχ43+) compartments. The degree of chimaerism was taken as the read out
of stem‐cell activity. No significant differentials between lymph‐node and peritoneal
exudate chimaerisms were detected in any of the recipients; therefore, the enrichment
procedure revealed only pluripotent cells, not stem cells of restricted potency. All recovered
stem‐cell activity was in the Oχ26(CD71)‐negative, Oχ7(CDw90)‐positive, Oχ82‐positive
fraction. In the optimum case, an enrichment of very roughly 200‐fold in cell‐for‐cell
activity was obtained.Rat bone‐marrow colony‐forming units in the spleen (CFUs‐12) were found to lack the
surface antigens recognized by the monoclonal antibodies CD53 (MRC‐Oχ44), MRC‐Oχ39,
MRC‐Oχ59, and 144.2.15. These would provide a strategy for their enrichment by
depletion.
Role of Prolactin and Growth Hormone on Thymus Physiology
Authors: De Mello-Coelho Valéria , Savino Wilson , Postel-Vinay Marie-Catherine , Dardenne Mireille 
Published: June 2008

Intrathymic T‐cell differentiation is under the control of the thymic microenvironment, which acts on maturing thymocytes via membrane as well as soluble products. Increasing data show that this process can be modulated by classical hormones, as exemplified herein by prolactin (PRL) and growth hormone (GH), largely secreted by the pituitary gland.Both PRL and GH stimulate the secretion of thymulin, a thymic hormone produced by thymic epithelial cells. Conversely, low levels of circulating thymulin parallel hypopituitary states. Interestingly, the enhancing effects of GH on thymulin seem to be mediated by insulinlike growth factor (IGF‐1) since they can be abrogated with anti‐IGF‐1 or anti‐IGF‐l‐receptor antibodies. The influence of PRL and GH on the thymic epithelium is pleiotropic: PRL enhances in vivo the expression of high‐molecular‐weight cytokeratins and stimulates in vitro TEC proliferation, an effect that is shared by GH and IGF‐1.Differentiating T cells are also targets for the intrathymic action of PRL and GH. In vivo inoculation of a rat pituitary cell line into old rats results in restoration of the thymus, including differentiation of CD4-CD8- thymocytes into CD4+CD8+ cells. Furthermore, PRL may regulate the maintenance of thymocyte viability during the double‐positive stage of thymocyte differentiation.Injections of GH into aging mice increase total thymocyte numbers and the percentage of CD3‐bearing cells, as well as the Concanavalin‐A mitogenic response and IL‐6 production by thymocytes. Interestingly, similar findings are observed in animals treated with IGF‐1. Lastly, the thymic hypoplasia observed in dwarf mice can be reversed with GH treatment.In keeping with the data summarized earlier is the detection of receptors for PRL and GH on both thymocytes and thymic epithelial cells. Importantly, recent studies indicate that both cell types can produce PRL and GH intrathymically. Similarly, production of IGF‐1 and expression of a corresponding receptor has also been demonstrated.In conclusion, these data strongly indicate that the thymus is physiologically under control of pituitary hormones PRL and GH. In addition to the classical endocrine pathway, paracrine and
autocrine circuits are probably implicated in such control.
Prostacyclin induction by high-density lipoprotein (HDL) in vascular smooth muscle cells depends on sphingosine 1-phosphate receptors: Effect of simvastatin
Authors: González-Díez María , Rodríguez Cristina , Badimon Lina , Martínez-González José 
Published: June 2008

SummaryProstacyclin (PGI2) is an important regulator of vascular homeostasis. Our goal was to analyze the role of sphingosine 1-phosphate (S1P) and its receptors in the up-regulation of cyclooxygenase-2 (Cox-2) induced by HDL in human vascular smooth muscle cells (VSMC). S1P induces Cox-2 expression in a time-and dose-dependent manner at concentrations (0.02–1 µM) compatible with those present in physiological HDL levels. The effect was mimicked by dihydro-S1P (DhS1P), a S1P derivative that only acts through cell surface S1P receptors. Desensitiz-ation of S1P receptors with S1P (or DhS1P) abolished HDL-induced Cox-2 up-regulation and PGI2 release. Inhibition of S1P receptors by suramin (inhibitor of S1P3), JTE013 (inhibitor of S1P2) or VPC23019 (inhibitor of S1P1 and S1P3) reduced the up-regulation of Cox-2 induced by HDL and S1P. The combination of suramin and JTE013 increased the inhibitory effect compared to that observed in cells treated with each inhibitor alone. siRNA against S1P2 or S1P3 significantly reduced the ability of HDL and S1P to up-regulate Cox-2. Simvastatin induced over-expression of S1P3 and potentiated the induction of Cox-2 expression produced by HDL (or S1P). Finally, suramin, JTE013 and VPC23019 inhibited p38 MAPK and ERK1/2 signaling pathways activated by HDL (or S1P) and the downstream activation of CREB, a key transcription factor involved in Cox-2 transcriptional up-regulation. These results indicate that S1P receptors, in particular S1P2 and S1P3, are involved in the Cox-2-dependent effects of HDL on vascular cells. Strategies aimed to therapeutically modulate S1P or S1P receptors could be useful to improve cardiovascular protection.