bluuebunny/crossref_metadata_2025_split huggingface dataset:
Matrix Protein and Another Viral Component Contribute to Induction of Apoptosis in Cells Infected with Vesicular Stomatitis Virus
Authors: Kopecky Sarah A. , Willingham Mark C. , Lyles Douglas S. 
Published: July 2002

ABSTRACT

The induction of apoptosis in host cells is a prominent cytopathic effect of vesicular stomatitis virus (VSV) infection. The viral matrix (M) protein is responsible for several important cytopathic effects, including the inhibition of host gene expression and the induction of cell rounding in VSV-infected cells. This raises the question of whether M protein is also involved in the induction of apoptosis. HeLa or BHK cells were transfected with M mRNA to determine whether M protein induces apoptosis when expressed in the absence of other viral components. Expression of M protein induced apoptotic morphological changes and activated caspase-3 in both cell types, indicating that M protein induces apoptosis in the absence of other viral components. An M protein containing a point mutation that renders it defective in the inhibition of host gene expression (M51R mutation) activated little, if any, caspase-3, while a deletion mutant lacking amino acids 4 to 21 that is defective in the virus assembly function but fully functional in the inhibition of host gene expression was as effective as wild-type (wt) M protein in activating caspase-3. To determine whether M protein influences the induction of apoptosis in the context of a virus infection, the M51R M protein mutation was incorporated onto a wt background by using a recombinant infectious cDNA clone (rM51R-M virus). The timing of the induction of apoptosis by rM51R-M virus was compared to that by the corresponding recombinant wt (rwt) virus and to that by
ts
O82 virus, the mutant virus in which the M51R mutation was originally identified. In HeLa cells, rwt virus induced apoptosis faster than did rM51R-M virus, demonstrating a role for M protein in the induction of apoptosis. In contrast to the results obtained with HeLa cells, rwt virus induced apoptosis more slowly than did rM51R-M virus in BHK cells. This indicates that a viral component other than M protein contributes to induction of apoptosis in BHK cells and that wt M protein acts to delay induction of apoptosis by the other viral component.
ts
O82 virus induced apoptosis more rapidly than did rM51R-M virus in both HeLa and BHK cells. These two viruses contain the same point mutation in their M proteins, suggesting that sequence differences in genes other than that for M protein affect their rates of induction of apoptosis.
Characterization of the Structural Gene Promoter of
Aedes aegypti
Densovirus
Authors: Ward Todd W. , Kimmick Michael W. , Afanasiev Boris N. , Carlson Jonathan O. 
Published: July 2002

ABSTRACT

Aedes aegypti
densonucleosis virus (AeDNV) has two promoters that have been shown to be active by reporter gene expression analysis (B. N. Afanasiev, Y. V. Koslov, J. O. Carlson, and B. J. Beaty, Exp. Parasitol. 79:322–339, 1994). Northern blot analysis of cells infected with AeDNV revealed two transcripts 1,200 and 3,500 nucleotides in length that are assumed to express the structural protein (VP) gene and nonstructural protein genes, respectively. Primer extension was used to map the transcriptional start site of the structural protein gene. Surprisingly, the structural protein gene transcript began at an initiator consensus sequence, CAGT, 60 nucleotides upstream from the map unit 61 TATAA sequence previously thought to define the promoter. Constructs with the β-galactosidase gene fused to the structural protein gene were used to determine elements necessary for promoter function. Deletion or mutation of the initiator sequence, CAGT, reduced protein expression by 93%, whereas mutation of the TATAA sequence at map unit 61 had little effect. An additional open reading frame was observed upstream of the structural protein gene that can express β-galactosidase at a low level (20% of that of VP fusions). Expression of the AeDNV structural protein gene was shown to be stimulated by the major nonstructural protein NS1 (Afanasiev et al., Exp. parasitol., 1994). To determine the sequences required for transactivation, expression of structural protein gene–β-galactosidase gene fusion constructs differing in AeDNV genome content was measured with and without NS1. The presence of NS1 led to an 8- to 10-fold increase in expression when either genomic end was present, compared to a 2-fold increase with a construct lacking the genomic ends. An even higher (37-fold) increase in expression occurred with both genomic ends present; however, this was in part due to template replication as shown by Southern blot analysis. These data indicate the location and importance of various elements necessary for efficient protein expression and transactivation from the structural protein gene promoter of AeDNV.
Murine Cytomegalovirus Open Reading Frame M27 Plays an Important Role in Growth and Virulence in Mice
Authors: Abenes Gerardo , Lee Manfred , Haghjoo Erik , Tong Tuong , Zhan Xiaoyan , Liu Fenyong 
Published: July 2002

ABSTRACT

Using a Tn
3
-based transposon mutagenesis approach, we have generated a pool of murine cytomegalovirus (MCMV) mutants. In this study, one of the mutants, RvM27, which contained the transposon sequence at open reading frame M27, was characterized both in tissue culture and in immunocompetent BALB/c mice and immunodeficient SCID mice. Our results suggest that the M27 carboxyl-terminal sequence is dispensable for viral replication in vitro. Compared to the wild-type strain and a rescued virus that restored the M27 region, RvM27 was attenuated in growth in both BALB/c and SCID mice that were intraperitoneally infected with the viruses. Specifically, the titers of RvM27 in the salivary glands, lungs, spleens, livers, and kidneys of the infected SCID mice at 21 days postinfection were 50- to 500-fold lower than those of the wild-type virus and the rescued virus. Moreover, the virulence of the mutant virus appeared to be attenuated, because no deaths occurred among SCID mice infected with RvM27 for up to 37 days postinfection, while all the animals infected with the wild-type and rescued viruses died within 27 days postinfection. Our observations provide the first direct evidence to suggest that a disruption of M27 expression results in reduced viral growth and attenuated viral virulence in vivo in infected animals. Moreover, these results suggest that M27 is a viral determinant required for optimal MCMV growth and virulence in vivo and provide insight into the functions of the M27 homologues found in other animal and human CMVs as well as in other betaherpesviruses.
Type B Leukemogenic Virus Has a T-Cell-Specific Enhancer That Binds AML-1
Authors: Mertz Jennifer A. , Mustafa Farah , Meyers Shari , Dudley Jaquelin P. 
Published: July 2002

ABSTRACTType B leukemogenic virus (TBLV) induces rapidly appearing T-cell tumors in mice. TBLV is highly related to mouse mammary tumor virus (MMTV) except that TBLV long terminal repeats (LTRs) have a deletion of negative regulatory elements and a triplication of sequences flanking the deletion. To determine if the LTR triplication represents a viral enhancer element, we inserted the triplication upstream and downstream in either orientation relative to the thymidine kinase promoter linked to the luciferase gene. These experiments showed that upregulation of reporter gene activity by the TBLV triplication was relatively orientation independent, consistent with the activity of eukaryotic enhancer elements. TBLV enhancer activity was observed in T-cell lines but not in fibroblasts, B cells, or mammary cells, suggesting that enhancer function is cell type dependent. To analyze the transcription factor binding sites that are important for TBLV enhancer function, we prepared substitution mutations in a reconstituted C3H MMTV LTR that recapitulates the deletion observed in the TBLV LTR. Transient transfections showed that a single mutation (556M) decreased TBLV enhancer activity at least 20-fold in two different T-cell lines. This mutation greatly diminished AML-1 (recently renamed RUNX1) binding in gel shift assays with a mutant oligonucleotide, whereas AML-1 binding to a wild-type TBLV oligomer was specific, as judged by competition and supershift experiments. The 556 mutation also reduced TBLV enhancer binding of two other protein complexes, called NF-A and NF-B, that did not appear to be related to c-Myb or Ets.AML-1overexpression in a mammary cell line enhanced expression from the TBLV LTR approximately 30-fold. These data suggest that binding of AML-1 to the TBLV enhancer, likely in combination with other factors, is necessary for optimal enhancer function.
Perinatal Transmission of Major, Minor, and Multiple Maternal Human Immunodeficiency Virus Type 1 Variants In Utero and Intrapartum
Authors: Dickover Ruth E. , Garratty Eileen M. , Plaeger Susan , Bryson Yvonne J. 
Published: July 2002

ABSTRACT

Previous studies have provided conflicting data on the presence of selective pressures in the transmission of a homogeneous maternal viral subpopulation to the infant. Therefore, the purpose of this study was to definitively characterize the human immunodeficiency virus type 1 (HIV-1) quasispecies transmitted in utero and intrapartum. HIV-1 envelope gene diversity from peripheral blood mononuclear cells and plasma was measured during gestation and at delivery in mothers who did and did not transmit HIV perinatally by using a DNA heteroduplex mobility assay. Children were defined as infected in utero or intrapartum based on the timing of the first detection of HIV. Untreated transmitting mothers (
n
= 19) had significantly lower HIV-1 quasispecies diversity at delivery than untreated nontransmittting mothers (
n
= 18) (median Shannon entropy, 0.711 [0.642 to 0.816] versus 0.853 [0.762 to 0.925],
P
= 0.005). Eight mothers transmitted a single major
env
variant to their infants in utero, and one mother transmitted a single major
env
variant intrapartum. Four mothers transmitted multiple HIV-1
env
variants to their infants in utero, and two mothers transmitted multiple
env
variants intrapartum. The remaining six intrapartum- and two in utero-infected infants had a homogeneous HIV-1
env
quasispecies which did not comigrate with their mothers' bands at their first positive time point. In conclusion, in utero transmitters were more likely to transmit single or multiple major maternal viral variants. In contrast, intrapartum transmitters were more likely to transmit minor HIV-1 variants. These data indicate that different selective pressures, depending on the timing of transmission, may be involved in determining the pattern of maternal HIV-1 variant transmission.
Effect on Polyomavirus T-Antigen Function of Mutations in a Conserved Leucine-Rich Segment of the DnaJ Domain
Authors: Li Hongyun , Söderbärg Karin , Houshmand Hamid , You Zhi-Yong , Magnusson Göran 
Published: July 2002

ABSTRACT
The N-terminal part of the mouse polyomavirus T antigens contains a highly conserved segment (-LLELLKL-), including amino acid residues 13 to 19. The sequence motif is predicted to form alpha helix I in the DnaJ domain of the T antigens. Four mutants with conservative substitutions of amino acid residues 13 and 14 were constructed. Of the four substitutions, L13M, L13I, L13V, and L14V, only L13V resulted in a phenotypic change. In transfected mouse cells, L13V large T antigen showed a more than 100-fold-reduced viral DNA synthesis. The viral replication could not be rescued by cotransfection of the cells with DNA expressing small t antigen or a large T antigen truncated at the C terminus that would compensate for a defect in host cell stimulation. In contrast to the effect on DNA replication, the L13V substitution in large T antigen did not prevent complex formation with Hsc70 and the Rb protein. Also, the activity of the protein in transactivation of transcription from the adenovirus E2 promoter was unimpaired, showing that the transcription factor E2F was released from pRb. The L13V substitution also caused a defect in small t antigen. However, this phenotypic change was due to protein instability. In contrast, middle T antigen with the L13V substitution remained stable and functional in cellular transformation. Together, the data show that the effect of the L13V substitution did not abrogate the Hsc70 interaction of the DnaJ domain. However, it is possible that the substitution of amino acid residue 13 affected specific DnaJ functions of large T antigen.
African Swine Fever Virus IAP Homologue Inhibits Caspase Activation and Promotes Cell Survival in Mammalian Cells
Authors: Nogal Marı́a L. , González de Buitrago Gonzalo , Rodrı́guez Clara , Cubelos Beatriz , Carrascosa Angel L. , Salas Marı́a L. , Revilla Yolanda 
Published: July 2002

ABSTRACT
African swine fever virus (ASFV) A224L is a member of the inhibitor of apoptosis protein (IAP) family. We have investigated the antiapoptotic function of the viral IAP both in stably transfected cells and in ASFV-infected cells. A224L was able to substantially inhibit caspase activity and cell death induced by treatment with tumor necrosis factor alpha and cycloheximide or staurosporine when overexpressed in Vero cells by gene transfection. We have also observed that ASFV infection induces caspase activation and apoptosis in Vero cells. Furthermore, using a deletion mutant of ASFV lacking the A224L gene, we have shown that the viral IAP modulates the proteolytic processing of the effector cell death protease caspase-3 and the apoptosis which are induced in the infected cells. Our findings indicate that A224L interacts with the proteolytic fragment of caspase-3 and inhibits the activity of this protease during ASFV infection. These observations could indicate a conserved mechanism of action for ASFV IAP and other IAP family members to suppress apoptosis.
Activation of NFAT-Dependent Gene Expression by Nef: Conservation among Divergent Nef Alleles, Dependence on SH3 Binding and Membrane Association, and Cooperation with Protein Kinase C-θ
Authors: Manninen Aki , Huotari Päivi , Hiipakka Marita , Renkema G. Herma , Saksela Kalle 
Published: July 2002

ABSTRACT
Here we show that the potential to regulate NFAT is a conserved property of different Nef alleles and that Nef residues involved in membrane targeting and SH3 binding are critical for this function. Cotransfection of an activated protein kinase C-θ (PKC-θ) with Nef implicated PKC-θ as a possible physiological cofactor of Nef in promoting NFAT-dependent gene expression and T-cell activation.
Membrane-Anchored Peptide Inhibits Human Immunodeficiency Virus Entry
Authors: Hildinger Markus , Dittmar Matthias T. , Schult-Dietrich Patricia , Fehse Boris , Schnierle Barbara S. , Thaler Sonja , Stiegler Gabriela , Welker Reinhold , von Laer Dorothee 
Published: July 2002

ABSTRACT
Peptides derived from the heptad repeats of human immunodeficiency virus (HIV) gp41 envelope glycoprotein, such as T20, can efficiently inhibit HIV type 1 (HIV-1) entry. In this study, replication of HIV-1 was inhibited more than 100-fold in a T-helper cell line transduced with a retrovirus vector expressing membrane-anchored T20 on the cell surface. Inhibition was independent of coreceptor usage.
Infection of the CD45RA+(Naive) Subset of Peripheral CD8+Lymphocytes by Human Immunodeficiency Virus Type 1 In Vivo
Authors: McBreen S. , Imlach S. , Shirafuji T. , Scott G. R. , Leen C. , Bell J. E. , Simmonds P. 
Published: July 2002

ABSTRACTTo investigate the mechanism and functional significance of infection of CD8+lymphocytes by human immunodeficiency virus type 1 (HIV-1) in vivo, we determined frequencies of infection, proviral conformation, and genetic relationships between HIV-1 variants infecting naive (CD45RA+) and memory (CD45RO+) peripheral blood CD4+and CD8+lymphocytes. Infection of CD3+CD8+CD45RA+cells was detected in 9 of 16 study subjects at frequencies ranging from 30 to 1,400 proviral copies/106cells, more frequently than CD3+CD8+lymphocytes expressing the RO isoform of CD45 (n= 2, 70 and 260 copies /106cells). In agreement with previous studies, there was no evidence for a similar preferential infection of CD4+naive lymphocytes. Proviral sequences in both CD4+and CD8+lymphocyte subsets were complete, as assessed by quantitation using primers from the long terminal repeat region spanning the tRNA primer binding site. In six of the seven study subjects investigated, variants infecting CD8+lymphocytes were partially or completely genetically distinct in the V3 region from those recovered from CD4+lymphocytes and showed a greater degree of compartmentalization than observed between naive and memory subsets of CD4+lymphocytes. In two study subjects, arginine substitutions at position 306, associated with use of the chemokine coreceptor CXCR4, were preferentially found in CD4 lymphocytes. These population differences may have originated through different times of infection rather than necessarily indicating a difference in their biological properties. The preferential distribution of HIV-1 in naive CD8+lymphocytes indeed suggests that infection occurred early in T-lymphocyte ontogeny, such as during maturation in the thymus. Destruction of cells destined to become CD8+lymphocytes may be a major factor in the decline in CD8+lymphocyte frequencies and function on disease progression and may contribute directly to the observed immunodeficiency in AIDS.
Two Antigenic Peptides from Genes
m123
and
m164
of Murine Cytomegalovirus Quantitatively Dominate CD8 T-Cell Memory in the
H-2

d

Haplotype
Authors: Holtappels Rafaela , Thomas Doris , Podlech Jürgen , Reddehase Matthias J. 
Published: July 2002

ABSTRACT

The importance of CD8 T cells for the control of cytomegalovirus (CMV) infection has raised interest in the identification of immunogenic viral proteins as candidates for vaccination and cytoimmunotherapy. The final aim is to determine the viral “immunome” for any major histocompatibility complex class I molecule by antigenicity screening of proteome-derived peptides. For human CMV, there is a limitation to this approach: the T cells used as responder cells for peptide screening are usually memory cells that have undergone in vivo selection. On this basis, pUL83 (pp65) and pUL123 (IE1 or pp68 to -72) were classified as immunodominant proteins. It is an open question whether this limited “memory immunome” really reflects the immunogenic potential of the human CMV proteome. Here we document an analogous focus of the memory repertoire on two proteins of murine CMV. Specifically, ca. 80% of all memory CD8 T cells in the spleen as well as in persisting pulmonary infiltrates were found to be specific for the known IE1 peptide
168
YPHFMPTNL
176
and for the peptide
257
AGPPRYSRI
265
, newly defined here, derived from open reading frame
m164
. Notably, CD8 T-cell lines of both specificities protected against acute infection upon adoptive transfer. In contrast, the natural immune response to acute infection in draining lymph nodes and in the lungs indicated a somewhat broader specificity repertoire. We conclude that the low number of antigenic peptides identified so far for CMVs reflects a focused memory repertoire, and we predict that more antigenic peptides will be disclosed by analysis of the acute immune response.
Activation of NF-κB by R5 and X4 Human Immunodeficiency Virus Type 1 Induces Macrophage Inflammatory Protein 1α and Tumor Necrosis Factor Alpha in Macrophages
Authors: Choe Wonkyu , Volsky David J. , Potash Mary Jane 
Published: July 2002

ABSTRACT
NF-κB is a transcriptional activator that often regulates inflammatory responses. We demonstrate that human immunodeficiency virus type 1 activates nuclear localization of NF-κB in macrophages in a manner dependent upon virus strain but independent of virus replication. Through the use of an inhibitor, NF-κB activation was found to be responsible for the cytokine and chemokine induction that we recently reported.
Sequencing of Porcine Enterovirus Groups II and III Reveals Unique Features of Both Virus Groups
Authors: Krumbholz Andi , Dauber Malte , Henke Andreas , Birch-Hirschfeld Eckhard , Knowles Nick J. , Stelzner Axel , Zell Roland 
Published: July 2002

ABSTRACT
The molecular classification of the porcine enterovirus (PEV) groups II and III was investigated. The sequence of the almost complete PEV-8 (group II) genome reveals that this virus has unique L and 2A gene regions. A reclassification of this group into a new picornavirus genus is suggested. PEV group III viruses are typical enteroviruses. They differ from other enteroviruses by a prolonged stem-loop D of the 5′-cloverleaf structure.
Detection of Viral DNA and Immune Responses to the Human Herpesvirus 6 101-Kilodalton Virion Protein in Patients with Multiple Sclerosis and in Controls
Authors: Tejada-Simon Maria V. , Zang Ying C. Q. , Hong Jian , Rivera Victor M. , Killian James M. , Zhang Jingwu Z. 
Published: July 2002

ABSTRACTHuman herpesvirus 6 (HHV-6), a latent lymphotropic and neurotropic virus, has been suspected as an etiologic agent in multiple sclerosis (MS). The study was undertaken to correlate virologic evidence for HHV-6 activity with the state of host immunity to HHV-6 in MS patients and control subjects. The study revealed that cell-free DNA of HHV-6 was detected more frequently in both serum and cerebrospinal fluid of MS patients than in those of control subjects. T cells recognizing the recombinant 101-kDa protein (101K) corresponding to the major immunoreactive region unique to HHV-6 occurred at significantly lower precursor frequency in MS patients than in control subjects. The resulting HHV-6-specific T-cell lines obtained from MS patients exhibited skewed cytokine profiles characterized by the inability to produce interleukin-4 (IL-4) and IL-10. The decreased T-cell responses to HHV-6 and the altered cytokine profile were consistent with significantly declined serum immunoglobulin G (IgG) titers for HHV-6 of MS patients compared to those of control subjects. In contrast, elevated serum IgM titers for HHV-6 were detected in the majority of MS patients, which may reflect frequent exposure of B cells to HHV-6. The findings suggest that the decreased immune responses to HHV-6 may be responsible for ineffective clearance of HHV-6 in MS patients.