bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pathogenesis of Herpes Simplex Virus-Induced Ocular Immunoinflammatory Lesions in B-Cell-Deficient Mice
Authors: Deshpande Shilpa P. , Zheng Mei , Daheshia Massoud , Rouse Barry T. 
Published: July 2002

ABSTRACTThe role of B cells and humoral immunity in herpes simplex virus (HSV) ocular infections was studied in immunoglobulin μ chain gene-targeted B-cell-deficient mice (μK/O). At doses of virus well tolerated by immunocompetent mice, heightened susceptibility of μK/O mice to herpetic encephalitis as well as to herpetic stromal keratitis (HSK) was observed. An explanation was sought for the increased severity of HSK in the μK/O mice. First, the lack of antibody responses in μK/O mice resulted in longer viral persistence and dissemination to the corneal stroma, the site of inflammation. Prolonged virus expression in the corneal stroma was suggested to cause bystander activation of Th1-type CD4+T cells, further contributing to the severity of HSK lesion expression in μK/O mice. Second, μK/O mice generated minimal Th2 cytokine responses compared to wild-type mice. Such responses might serve to downregulate the severity of Th1-mediated HSK lesions.
A Block to Human Immunodeficiency Virus Type 1 Assembly in Murine Cells
Authors: Mariani Roberto , Rutter Gabriel , Harris Matthew E. , Hope Thomas J. , Kräusslich Hans-Georg , Landau Nathaniel R. 
Published: July 2002

ABSTRACT

Human immunodeficiency virus type 1 (HIV-1) does not replicate in murine cells. We investigated the basis of this block by infecting a murine NIH 3T3 reporter cell line that stably expressed human CD4, CCR5, and cyclin T1 and contained a transactivatable HIV-1 long terminal repeat (LTR)-green fluorescent protein (GFP) cassette. Although the virus entered efficiently, formed provirus, and was expressed at a level close to that in a highly permissive human cell line, the murine cells did not support M-tropic HIV-1 replication. To determine why the virus failed to replicate, the efficiency of each postentry step in the virus replication cycle was analyzed using vesicular stomatitis virus G pseudotypes. The murine cells supported reverse transcription and integration at levels comparable to those in the human osteosarcoma-derived cell line GHOST.R5, and human cyclin T1 restored provirus expression, consistent with earlier findings of others. The infected murine cells contained nearly as much virion protein as did the human cells but released less than 1/500 the amount of p24

gag

into the culture medium. A small amount of p24

gag

was released and was in the form of fully infectious virus. Electron microscopy suggested that aberrantly assembled virion protein had accumulated in cytoplasmic vesicular structures. Virions assembling at the cell membrane were observed but were rare. The entry of M-tropic JR.FL-pseudotyped reporter virus was moderately reduced in the murine cells, suggesting a minor reduction in coreceptor function. A small reduction in the abundance of full-length viral mRNA transcripts was also noted; however, the major block was at virion assembly. This could have been due to a failure of Gag to target to the cell membrane. This block must be overcome before a murine model for HIV-1 replication can be developed.
Structural Analysis of a Fiber-Pseudotyped Adenovirus with Ocular Tropism Suggests Differential Modes of Cell Receptor Interactions
Authors: Chiu Charles Y. , Wu Eugene , Brown Swati L. , Von Seggern Dan J. , Nemerow Glen R. , Stewart Phoebe L. 
Published: July 2002

ABSTRACT
Adenovirus (Ad) entry into cells is initiated by the binding of the fiber knob to a cell surface receptor. The coxsackie- and adenovirus receptor (CAR) functions as the attachment receptor for many, but not all, Ad serotypes. Ad type 37 (Ad37), a subgroup D virus that causes keratoconjunctivitis in humans, does not infect cells via CAR despite demonstrated binding of the Ad37 knob to CAR. We have pseudotyped a fiber deletion Ad5 vector with the Ad37 fiber (Ad37f), and this vector retains the ocular tropism of Ad37. Here we present a cryo-electron microscopy reconstruction of Ad37f that shows the entire Ad37 fiber, including the shaft and knob domains. We have previously proposed that Ad37 may not utilize CAR for cell entry because of the geometric constraints imposed by a rigid fiber (E. Wu, J. Fernandez, S. K. Fleck, D. Von Seggern, S. Huang, and G. R. Nemerow, Virology 279:78–89, 2001). Consistent with this hypothesis, our structural results show that the Ad37 fiber is straight and rigid. Modeling of the interaction between Ad37f and host cell receptors indicates that fiber flexibility or rigidity, as well as length, can affect receptor usage and cellular tropism.
Immunogenicity and Protective Efficacy of Recombinant Human T-Cell Leukemia/Lymphoma Virus Type 1 NYVAC and Naked DNA Vaccine Candidates in Squirrel Monkeys (Saimiri sciureus)
Authors: Kazanji Mirdad , Tartaglia James , Franchini Genoveffa , de Thoisy Benoit , Talarmin Antoine , Contamin Hugues , Gessain Antoine , de Thé Guy 
Published: July 2002

ABSTRACTWe assessed the immunogenicities and efficacies of two highly attenuated vaccinia virus-derived NYVAC vaccine candidates encoding the human T-cell leukemia/lymphoma virus type 1 (HTLV-1)envgene or both theenvandgaggenes in prime-boost pilot regimens in combination with naked DNA expressing the HTLV-1 envelope. Three inoculations of NYVAC HTLV-1envat 0, 1, and 3 months followed by a single inoculation of DNAenvat 9 months protected against intravenous challenge with HTLV-1-infected cells in one of three immunized squirrel monkeys. Furthermore, humoral and cell-mediated immune responses against HTLV-1 Env could be detected in this protected animal. However, priming the animal with a single dose ofenvDNA, followed by immunization with the NYVAC HTLV-1gagandenvvaccine at 6, 7, and 8 months, protected all three animals against challenge with HTLV-1-infected cells. With this protocol, antibodies against HTLV-1 Env and cell-mediated responses against Env and Gag could also be detected in the protected animals. Although the relative superiority of a DNA prime-NYVAC boost regimen over addition of the Gag component as an immunogen cannot be assessed directly, our findings nevertheless show that an HTLV-1 vaccine approach is feasible and deserves further study.
Both
Lymantria dispar
Nucleopolyhedrovirus
Enhancin
Genes Contribute to Viral Potency
Authors: Popham Holly J. R. , Bischoff David S. , Slavicek James M. 
Published: July 2002

ABSTRACT

Enhancins are a group of proteins first identified in granuloviruses (GV) that have the ability to enhance nuclear polyhedrosis virus potency. We had previously identified an
enhancin
gene (E1) in the
Lymantria dispar
multinucleocapsid nucleopolyhedrovirus (Ld
M
NPV) (D. S. Bischoff and J. M. Slavicek, J. Virol. 71:8133–8140, 1997). Inactivation of the
E1
gene product within the viral genome lowered viral potency by an average of 2.9-fold. A second
enhancin
gene (E2) was identified when the entire genome of Ld
M
NPV was sequenced (Kuzio et al., Virology 253:17–34, 1999). The E2 protein exhibits approximately 30% amino acid identity to the Ld
M
NPV E1 protein as well as the enhancins from
Trichoplusia ni
GV,
Pseudaletia unipuncta
GV,
Helicoverpa armigera
GV, and
Xestia c-nigrum
GV. Northern analysis of viral RNA indicated that the
E2
gene transcripts are expressed at late times postinfection from a consensus baculovirus late promoter. The effect of the enhancin proteins on viral potency was investigated through bioassay using two recombinant viruses, one with a deletion in the
E2
gene (E2del) and a second with deletion mutations in both
enhancin
genes (E1delE2del). The
enhancin
gene viral constructs were verified by Southern analysis and shown not to produce
enhancin
gene transcripts by Northern analysis. The E2del virus exhibited an average decrease in viral potency of 1.8-fold compared to wild-type virus. In the same bioassays, the recombinant virus E1cat, which does not produce an
E1
gene transcript, exhibited an average decrease in viral potency of 2.3-fold compared to control virus. The E1delE2del virus exhibited an average decrease in viral potency of 12-fold compared to wild-type virus. Collectively, these results suggest that both Ld
M
NPV
enhancin
genes contribute to viral potency, that each enhancin protein can partially compensate for the lack of the other protein, and that both enhancin genes are necessary for wild-type viral potency.
Adenovirus Protein V Induces Redistribution of Nucleolin and B23 from Nucleolus to Cytoplasm
Authors: Matthews David A. 
Published: July 2002

ABSTRACT
Adenovirus infection inhibits synthesis and processing of rRNA and redistributes nucleolar antigens. Adenovirus protein V associates with nucleoli in infected cells. This study delineates regions of protein V independently capable of nucleolar targeting. Also, evidence is presented that protein V has the unique property of relocating nucleolin and B23 to the cytoplasm when transiently expressed on its own in uninfected cells. Point mutation analysis indicates a role for the C terminus of protein V in the redirection of nucleolin and B23 to the cytoplasm. This is the first time an adenovirus protein has been shown to have a direct effect on nucleolar antigens in isolation from viral infection. Moreover, adenovirus protein V is the first protein demonstrated to be capable of redirecting nucleolin and B23 to the cytoplasm.
Central Role of Hemocytes in
Autographa californica M
Nucleopolyhedrovirus Pathogenesis in
Heliothis virescens
and
Helicoverpa zea
Authors: Trudeau Dominique , Washburn Jan O. , Volkman Loy E. 
Published: July 2002

ABSTRACT

Autographa californica M
nucleopolyhedrovirus (Ac
M
NPV) can infect and kill a wide range of larval lepidopteran hosts, but the dosage required to achieve mortal infection varies greatly. Using a reporter gene construct, we identified key differences between Ac
M
NPV pathogenesis in
Heliothis virescens
and
Helicoverpa zea
, a fully permissive and a semipermissive host, respectively. Even though there was more than a 1,000-fold difference in the susceptibilities of these two species to mortal infection, there was no significant difference in their susceptibilities to primary infections in the midgut or secondary infections in the tracheal epidermis. Foci of infection within the tracheal epidermis of
H. zea
, however, were melanized and encapsulated by 48 h after oral inoculation, a host response not observed in
H. virescens
. Further,
H. zea
hemocytes, unlike those of
H. virescens
, were highly resistant to Ac
M
NPV infection; reporter gene expression was observed only rarely even though virus was taken up readily, and nucleocapsids were transported to the nucleus. Collectively, these results demonstrated that hemocytes—by removing virus from the hemolymph instead of amplifying it and by participating in the encapsulation of infection foci—together with the host's melanization response, formed the basis of
H. zea
's resistance to fatal infection by Ac
M
NPV.
Functional Roles of Equine Infectious Anemia Virus Gag p9 in Viral Budding and Infection
Authors: Chen Chaoping , Li Feng , Montelaro Ronald C. 
Published: July 2002

ABSTRACT

Previous studies utilizing Gag polyprotein budding assays with transfected cells reveal that the equine infectious anemia virus (EIAV) Gag p9 protein provides a late assembly function mediated by a critical Y
23
P
24
D
25
L
26
motif (L-domain) to release viral particles from the plasma membrane. To elucidate further the role of EIAV p9 in virus assembly and replication, we have examined the replication properties of a defined series of p9 truncation and site-directed mutations in the context of a reference infectious molecular proviral clone, EIAV
uk
. Characterization of these p9 proviral mutants revealed new functional properties of p9 in EIAV replication, not previously elucidated by Gag polyprotein budding assays. The results of these studies demonstrated that only the N-terminal 31 amino acids of a total of 51 residues in the complete p9 protein were required to maintain replication competence in transfected equine cells; proviral mutants with p9 C-terminal truncations of 20 or fewer amino acids remained replication competent, while mutants with truncations of 21 or more residues were completely replication defective. The inability of the defective p9 proviral mutations to produce infectious virus could not be attributed to defects in Gag polyprotein expression or processing, in virion RT activity, or in virus budding. While proviral replication competence appeared to be associated with the presence of a K
30
K
31
motif and potential ubiquitination of the EIAV p9 protein, mutations of these lysine residues to methionines produced variant proviruses that replicated as well as the parental EIAV
uk
in transfected ED cells. Thus, these observations reveal for the first time that EIAV p9 is not absolutely required for virus budding in the context of proviral gene expression, suggesting that other EIAV proteins can at least in part mediate late budding functions previously associated with the p9 protein. In addition, the data define a function for EIAV p9 in the infectivity of virus particles, indicating a previously unrecognized role for this Gag protein in EIAV replication.
Alternative Mechanisms of Respiratory Syncytial Virus Clearance in Perforin Knockout Mice Lead to Enhanced Disease
Authors: Aung Sandra , Rutigliano John A. , Graham Barney S. 
Published: July 2002

ABSTRACTVirus-specific cytotoxic T lymphocytes are key effectors for the clearance of virus-infected cells and are required for the normal clearance of respiratory syncytial virus (RSV) in mice. Although perforin/granzyme-mediated lysis of infected cells is thought to be the major molecular mechanism used by CD8+cytotoxic T lymphocytes for elimination of virus, its role in RSV has not been reported. Here, we show that viral clearance in perforin knockout (PKO) mice is slightly delayed but that both PKO and wild-type mice clear virus by day 10, suggesting an alternative mechanism of RSV clearance. Effector T cells from the lungs of both groups of mice were shown to lyse Fas (CD95)-overexpressing target cells in greater numbers than target cells expressing low levels of Fas, suggesting that Fas ligand (CD95L)-mediated target cell lysis was occurring in vivo. This cell lysis was associated with a delay in RSV-induced disease in PKO mice compared to the time of disease onset for wild-type controls, which correlated with increased and prolonged production of gamma interferon and tumor necrosis factor alpha levels in PKO mice. We conclude that while perforin is not necessary for the clearance of primary RSV infection, the use of alternative CTL target cell killing mechanisms is less efficient and can lead to enhanced disease.
African Swine Fever Virus Infection of Porcine Aortic Endothelial Cells Leads to Inhibition of Inflammatory Responses, Activation of the Thrombotic State, and Apoptosis
Authors: Vallée Isabelle , Tait Stephen W. G. , Powell Penelope P. 
Published: July 2002

ABSTRACTAfrican swine fever (ASF) is an asymptomatic infection of warthogs and bushpigs, which has become an emergent disease of domestic pigs, characterized by hemorrhage, lymphopenia, and disseminated intravascular coagulation. It is caused by a large icosohedral double-stranded DNA virus, African swine fever virus (ASFV), with infection of macrophages well characterized in vitro and in vivo. This study shows that virulent isolates of ASFV also infect primary cultures of porcine aortic endothelial cells and bushpig endothelial cells (BPECs) in vitro. Kinetics of early and late gene expression, viral factory formation, replication, and secretion were similar in endothelial cells and macrophages. However, ASFV-infected endothelial cells died by apoptosis, detected morphologically by terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling and nuclear condensation and biochemically by poly(ADP-ribose) polymerase (PARP) cleavage at 4 h postinfection (hpi). Immediate-early proinflammatory responses were inhibited, characterized by a lack of E-selectin surface expression and interleukin 6 (IL-6) and IL-8 mRNA synthesis. Moreover, ASFV actively downregulated interferon-induced major histocompatibility complex class I surface expression, a strategy by which viruses evade the immune system. Significantly, Western blot analysis showed that the 65-kDa subunit of the transcription factor NF-κB, a central regulator of the early response to viral infection, decreased by 8 hpi and disappeared by 18 hpi. Both disappearance of NF-κB p65 and cleavage of PARP were reversed by the caspase inhibitor z-VAD-fmk. Interestingly, surface expression and mRNA transcription of tissue factor, an important initiator of the coagulation cascade, increased 4 h after ASFV infection. These data suggest a central role for vascular endothelial cells in the hemorrhagic pathogenesis of the disease. Since BPECs infected with ASFV also undergo apoptosis, resistance of the natural host must involve complex pathological factors other than viral tropism.
Molecular Determinants of Peptide Binding to Two Common Rhesus Macaque Major Histocompatibility Complex Class II Molecules
Authors: Dzuris John L. , Sidney John , Horton Helen , Correa Rose , Carter Donald , Chesnut Robert W. , Watkins David I. , Sette Alessandro 
Published: July 2002

ABSTRACTMajor histocompatibility complex class II molecules encoded by two common rhesus macaque alleles Mamu-DRB1*0406 and Mamu-DRB*w201 have been purified, and quantitative binding assays have been established. The structural requirements for peptide binding to each molecule were characterized by testing panels of single-substitution analogs of the two previously defined epitopes HIV Env242 (Mamu-DRB1*0406 restricted) and HIV Env482 (Mamu-DRB*w201 restricted). Anchor positions of both macaque DR molecules were spaced following a position 1 (P1), P4, P6, P7, and P9 pattern. The specific binding motif associated with each molecule was distinct, but largely overlapping, and was based on crucial roles of aromatic and/or hydrophobic residues at P1, P6, and P9. Based on these results, a tentative Mamu class II DR supermotif was defined. This pattern is remarkably similar to a previously defined human HLA-DR supermotif. Similarities in binding motifs between human HLA and macaque Mamu-DR molecules were further illustrated by testing a panel of more than 60 different single-substitution analogs of the HLA-DR-restricted HA 307–319 epitope for binding to Mamu-DRB*w201 and HLA-DRB1*0101. The Mamu-DRB1*0406 and -DRB*w201 binding capacity of a set of 311 overlapping peptides spanning the entire simian immunodeficiency virus (SIV) genome was also evaluated. Ten peptides capable of binding both molecules were identified, together with 19 DRB1*0406 and 43 DRB*w201 selective binders. The Mamu-DR supermotif was found to be present in about 75% of the good binders and in 50% of peptides binding with intermediate affinity but only in approximately 25% of the peptides which did not bind either Mamu class II molecule. Finally, using flow cytometric detection of antigen-induced intracellular gamma interferon, we identify a new CD4+T-lymphocyte epitope encoded within the Rev protein of SIV.
Functional Interactions of Human Immunodeficiency Virus Type 1 Integrase with Human and Yeast HSP60
Authors: Parissi Vincent , Calmels Christina , De Soultrait Vaea Richard , Caumont Anne , Fournier Michel , Chaignepain Stéphane , Litvak Simon 
Published: July 2002

ABSTRACT

Integration of human immunodeficiency virus type 1 (HIV-1) proviral DNA in the nuclear genome is catalyzed by the retroviral integrase (IN). In addition to IN, viral and cellular proteins associated in the high-molecular-weight preintegration complex have been suggested to be involved in this process. In an attempt to define host factors interacting with IN, we used an in vitro system to identify cellular proteins in interaction with HIV-1 IN. The yeast
Saccharomyces cerevisiae
was chosen since (i) its complete sequence has been established and the primary structure of all the putative proteins from this eucaryote has been deduced, (ii) there is a significant degree of homology between human and yeast proteins, and (iii) we have previously shown that the expression of HIV-1 IN in yeast induces a lethal phenotype. Strong evidences suggest that this lethality is linked to IN activity in infected human cells where integration requires the cleavage of genomic DNA. Using IN-affinity chromatography we identified four yeast proteins interacting with HIV-1 IN, including the yeast chaperonin yHSP60, which is the counterpart of human hHSP60. Yeast lethality induced by HIV-1 IN was abolished when a mutated HSP60 was coexpressed, therefore suggesting that both proteins interact in vivo. Besides interacting with HIV-1 IN, the hHSP60 was able to stimulate the in vitro processing and joining activities of IN and protected this enzyme from thermal denaturation. In addition, the functional human HSP60-HSP10 complex in the presence of ATP was able to recognize the HIV-1 IN as a substrate.
Amino Acids Responsible for the Absolute Sialidase Activity of the Influenza A Virus Neuraminidase: Relationship to Growth in the Duck Intestine
Authors: Kobasa Darwyn , Wells Krisna , Kawaoka Yoshihiro 
Published: July 2002

ABSTRACT

The 1957 human pandemic strain of influenza A virus contained an avian virus hemagglutinin (HA) and neuraminidase (NA), both of which acquired specificity for the human receptor,
N
-acetylneuraminic acid linked to galactose of cellular glycoconjugates via an α2-6 bond (NeuAcα2-6Gal). Although the NA retained considerable specificity for NeuAcα2-3Gal, its original substrate in ducks, it lost the ability to support viral growth in the duck intestine, suggesting a growth-restrictive change other than a shift in substrate specificity. To test this possibility, we generated a panel of reassortant viruses that expressed the NA genes of human H2N2 viruses isolated from 1957 to 1968 with all other genes from the avian virus A/duck/Hong Kong/278/78 (H9N2). Only the NA of A/Singapore/1/57 supported efficient viral growth in the intestines of orally inoculated ducks. The growth-supporting capacity of the NA correlated with a high level of enzymatic activity, comparable to that found to be associated with avian virus NAs. The specific activities of the A/Ann Arbor/6/60 and A/England/12/62 NAs, which showed greatly restricted abilities to support viral growth in ducks, were only 8 and 5%, respectively, of the NA specific activity for A/Singapore/1/57. Using chimeric constructs based on A/Singapore/1/57 and A/England/12/62 NAs, we localized the determinants of high specific NA activity to a region containing six amino acid substitutions in A/England/12/62: Ser331→Arg, Asp339→Asn, Asn367→Ser, Ser370→Leu, Asn400→Ser, and Pro431→Glu. Five of these six residues (excluding Asn400) were required and sufficient for the full specific activity of the A/Singapore/1/57 NA. Thus, in addition to a change in substrate specificity, a reduction in high specific activity may be required for the adaptation of avian virus NAs to growth in humans. This change is likely needed to maintain an optimal balance between NA activity and the lower affinity shown by human virus HAs for their cellular receptor.