bluuebunny/crossref_metadata_2025 huggingface dataset:
Two Distinct Gamma-2 Herpesviruses in African Green Monkeys: a Second Gamma-2 Herpesvirus Lineage among Old World Primates?
Authors: Greensill Julie , Sheldon Julie A. , Renwick Neil M. , Beer Brigitte E. , Norley Steve , Goudsmit Jaap , Schulz Thomas F.
Published: July 2002

Primate gamma-2 herpesviruses (rhadinoviruses) have so far been found in humans (Kaposi's sarcoma-associated herpesvirus [KSHV], also called human herpesvirus 8), macaques (
Macaca
spp.) (rhesus rhadinovirus [RRV] and retroperitoneal fibromatosis herpesvirus [RFHV]), squirrel monkeys (
Saimiri sciureus
) (herpesvirus saimiri), and spider monkeys (
Ateles
spp.) (herpesvirus ateles). Using serological screening and degenerate consensus primer PCR for the viral DNA polymerase gene, we have detected sequences from two distinct gamma-2 herpesviruses, termed
Chlorocebus
rhadinovirus 1 (ChRV1) and ChRV2, in African green monkeys. ChRV1 is more closely related to KSHV and RFHV, whereas ChRV2 is closest to RRV. Our findings suggest the existence of two distinct rhadinovirus lineages, represented by the KSHV/RFHV/ChRV1 group and the RRV/ChRV2 group, respectively, in at least two Old World monkey species. Antibodies to members of the RRV/ChRV2 lineage may cross-react in an immunofluorescence assay for early and late KSHV antigens.
Virus-Induced Abrogation of Transplantation Tolerance Induced by Donor-Specific Transfusion and Anti-CD154 Antibody
Authors: Welsh Raymond M. , Markees Thomas G. , Woda Bruce A. , Daniels Keith A. , Brehm Michael A. , Mordes John P. , Greiner Dale L. , Rossini Aldo A.
Published: July 2002

Treatment with a 2-week course of anti-CD154 antibody and a single transfusion of donor leukocytes (a donor-specific transfusion or DST) permits skin allografts to survive for >100 days in thymectomized mice. As clinical trials of this methodology in humans are contemplated, concern has been expressed that viral infection of graft recipients may disrupt tolerance to the allograft. We report that acute infection with lymphocytic choriomeningitis virus (LCMV) induced allograft rejection in mice treated with DST and anti-CD154 antibody if inoculated shortly after transplantation. Isografts resisted LCMV-induced rejection, and the interferon-inducing agent polyinosinic:polycytidylic acid did not induce allograft rejection, suggesting that the effect of LCMV is not simply a consequence of nonspecific inflammation. Administration of anti-CD8 antibody to engrafted mice delayed LCMV-induced allograft rejection. Pichinde virus also induced acute allograft rejection, but murine cytomegalovirus and vaccinia virus (VV) did not. Injection of LCMV ∼50 days after tolerance induction and transplantation had minimal effect on subsequent allograft survival. Treatment with DST and anti-CD154 antibody did not interfere with clearance of LCMV, but a normally nonlethal high dose of VV during tolerance induction and transplantation killed graft recipients. We conclude that DST and anti-CD154 antibody induce a tolerant state that can be broken shortly after transplantation by certain viral infections. Clinical application of transplantation tolerance protocols may require patient isolation to facilitate the procedure and to protect recipients.
A Novel Mechanism of Resistance to Mouse Mammary Tumor Virus Infection
Authors: Golovkina Tatyana V.
Published: July 2002

Exogenous mouse mammary tumor virus (MMTV) is carried from the gut of suckling pups to the mammary glands by lymphocytes and induces mammary gland tumors. MMTV-induced tumor incidence in inbred mice of different strains ranges from 0 to as high as 100%. For example, mice of the C3H/HeN strain are highly susceptible, whereas mice of the I/LnJ strain are highly resistant. Of the different factors that together determine the susceptibility of mice to development of MMTV-induced mammary tumors, genetic elements play a major role, although very few genes that determine a susceptibility-resistance phenotype have been identified so far. Our data indicate that MMTV fails to infect mammary glands in I/LnJ mice foster nursed on viremic C3H/HeN females, even though the I/LnJ mammary tissue is not refractory to MMTV infection. Lymphocytes from fostered I/LnJ mice contained integrated MMTV proviruses and shed virus but failed to establish infection in the mammary glands of susceptible syngeneic (I × C3H.JK)F1females. Based on the susceptible-resistant phenotype distribution in N2females, both MMTV mammary gland infection and mammary gland tumor development in I/LnJ mice are controlled by a single locus.
Chimeric Dengue Type 2 (Vaccine Strain PDK-53)/Dengue Type 1 Virus as a Potential Candidate Dengue Type 1 Virus Vaccine
Authors: Huang Claire Y.-H. , Butrapet Siritorn , Pierro Dennis J. , Chang Gwong-Jen J. , Hunt Ann R. , Bhamarapravati Natth , Gubler Duane J. , Kinney Richard M.
Published: July 2002

We constructed chimeric dengue type 2/type 1 (DEN-2/DEN-1) viruses containing the nonstructural genes of DEN-2 16681 virus or its vaccine derivative, strain PDK-53, and the structural genes (encoding capsid protein, premembrane protein, and envelope glycoprotein) of DEN-1 16007 virus or its vaccine derivative, strain PDK-13. We previously reported that attenuation markers of DEN-2 PDK-53 virus were encoded by genetic loci located outside the structural gene region of the PDK-53 virus genome. Chimeric viruses containing the nonstructural genes of DEN-2 PDK-53 virus and the structural genes of the parental DEN-1 16007 virus retained the attenuation markers of small plaque size and temperature sensitivity in LLC-MK2cells, less efficient replication in C6/36 cells, and attenuation for mice. These chimeric viruses elicited higher mouse neutralizing antibody titers against DEN-1 virus than did the candidate DEN-1 PDK-13 vaccine virus or chimeric DEN-2/DEN-1 viruses containing the structural genes of the PDK-13 virus. Mutations in the envelope protein of DEN-1 PDK-13 virus affected in vitro phenotype and immunogenicity in mice. The current PDK-13 vaccine is the least efficient of the four Mahidol candidate DEN virus vaccines in human trials. The chimeric DEN-2/DEN-1 virus might be a potential DEN-1 virus vaccine candidate. This study indicated that the infectious clones derived from the candidate DEN-2 PDK-53 vaccine are promising attenuated vectors for development of chimeric flavivirus vaccines.
The Primary Sequence of Rhesus Monkey Rhadinovirus Isolate 26-95: Sequence Similarities to Kaposi's Sarcoma-Associated Herpesvirus and Rhesus Monkey Rhadinovirus Isolate 17577
Authors: Alexander Louis , Denekamp Lynn , Knapp Amanda , Auerbach Marcy R. , Damania Blossom , Desrosiers Ronald C.
Published: July 2002

The primary sequence of the long unique region L-DNA (L for low GC) of rhesus monkey rhadinovirus (RRV) isolate 26-95 was determined. The L-DNA consists of 130,733 bp that contain 84 open reading frames (ORFs). The overall organization of the RRV26-95 genome was found to be very similar to that of human Kaposi sarcoma-associated herpesvirus (KSHV). BLAST search analysis revealed that in almost all cases RRV26-95 coding sequences have a greater degree of similarity to corresponding KSHV sequences than to other herpesviruses. All of the ORFs present in KSHV have at least one homologue in RRV26-95 except K3 and K5 (bovine herpesvirus-4 immediate-early protein homologues), K7 (nut-1), and K12 (Kaposin). RRV26-95 contains one MIP-1 and eight interferon regulatory factor (vIRF) homologues compared to three MIP-1 and four vIRF homologues in KSHV. All homologues are correspondingly located in KSHV and RRV with the exception of dihydrofolate reductase (DHFR). DHFR is correspondingly located near the left end of the genome in RRV26-95 and herpesvirus saimiri (HVS), but in KSHV the DHFR gene is displaced 16,069 nucleotides in a rightward direction in the genome. DHFR is also unusual in that the RRV26-95 DHFR more closely resembles HVS DHFR (74% similarity) than KSHV DHFR (55% similarity). Of the 84 ORFs in RRV26-95, 83 contain sequences similar to the recently determined sequences of the independent RRV isolate 17577. RRV26-95 and RRV17577 sequences differ in that ORF 67.5 sequences contained in RRV26-95 were not found in RRV17577. In addition, ORF 4 is significantly shorter in RRV26-95 than was reported for RRV17577 (395 versus 645 amino acids). Only four of the corresponding ORFs between RRV26-95 and RRV17577 exhibited less than 95% sequence identity: glycoproteins H and L, uracil DNA glucosidase, and a tegument protein (ORF 67). Both RRV26-95 and RRV17577 have unique ORFs between positions 21444 to 21752 and 110910 to 114899 in a rightward direction and from positions 116524 to 111082 in a leftward direction that are not found in KSHV. Our analysis indicates that RRV26-95 and RRV17577 are clearly independent isolates of the same virus species and that both are closely related in structural organization and overall sequence to KSHV. The availability of detailed sequence information, the ability to grow RRV lytically in cell culture, and the ability to infect monkeys experimentally with RRV will facilitate the construction of mutant strains of virus for evaluating the contribution of individual genes to biological properties.
Changes in Human Immunodeficiency Virus Type 1 Populations after Treatment Interruption in Patients Failing Antiretroviral Therapy
Authors: Hance Allan J. , Lemiale Virginie , Izopet Jacques , Lecossier Denise , Joly Véronique , Massip Patrice , Mammano Fabrizio , Descamps Diane , Brun-Vézinet Françoise , Clavel François
Published: July 2002

Mutations in human immunodeficiency virus type 1 (HIV-1) reverse transcriptase and protease that confer resistance to antiretroviral agents are usually accompanied by a reduction in the viral replicative capacity under drug-free conditions. Consequently, when antiretroviral treatment is interrupted in HIV-1-infected patients harboring drug-resistant virus, resistant quasi-species appear to be most often replaced within several weeks by wild-type virus. Using a real-time PCR-based technique for the selective quantification of resistant viral sequences in plasma, we have studied the kinetics of the switch from mutant to wild-type virus and evaluated the extent to which minority populations of resistant viruses not detected by genotyping persist in these individuals. Among 12 patients with viruses expressing the V82A or L90M resistance mutation who had undergone a 3-month interruption of therapy and for whom conventional genotyping had revealed an apparent total reconversion to wild-type virus, minority populations expressing these mutations, representing 0.1 to 21% of total virus, were still detectable in 9 cases. Kinetic studies demonstrated that viruses expressing resistance mutations could be detected for >5 months after the discontinuation of treatment in some patients. Most of the minority resistant genomes detected more than 3 months after the interruption of therapy carried only part of the mutations present in the resistant viruses prior to treatment interruption and appeared to result from the emergence of existing strains selected at earlier stages in the development of drug resistance. Thus, following the interruption of treatment, viral populations containing resistance mutations can persist for several months after the time when conventional genotyping techniques detect only wild-type virus. These populations include viral strains with only some of the resistance mutations initially present, strains that presumably express better fitness under drug-free conditions.
Identification of Envelope Determinants of Feline Leukemia Virus Subgroup B That Permit Infection and Gene Transfer to Cells Expressing Human Pit1 or Pit2
Authors: Sugai James , Eiden Maribeth , Anderson Maria M. , Van Hoeven Neal , Meiering Christopher D. , Overbaugh Julie
Published: July 2002

The retroviral vector systems that are in common use for gene therapy are designed to infect cells expressing either of two widely expressed phosphate transporter proteins, Pit1 or Pit2. Subgroup B feline leukemia viruses (FeLV-Bs) use the gibbon ape leukemia virus receptor, Pit1, as a receptor for entry. Our previous studies showed that some chimeric envelope proteins encoding portions of FeLV-B could also enter cells by using a related receptor protein, Pit2, which serves as the amphotropic murine leukemia virus receptor (S. Boomer, M. Eiden, C. C. Burns, and J. Overbaugh, J. Virol. 71:8116–8123, 1997). Here we show that an arginine at position 73 within variable region A (VRA) of the FeLV-B envelope surface unit (SU) is necessary for viral entry into cells via the human Pit2 receptor. However, C-terminal SU sequences have a dominant effect in determining human Pit2 entry, even though this portion of the protein is outside known receptor binding domains. This suggests that a combination of specific VRA sequences and C-terminal sequences may influence interactions between FeLV-B SU and the human Pit2 receptor. Binding studies suggest that the C-terminal sequences may affect a postbinding step in viral entry via the Pit2 receptor, although in all cases, binding of FeLV-B SU to human Pit2 was weak. In contrast, neither the arginine 73 nor specific C-terminal sequences are required for efficient binding or infection with Pit1. Taken together, these data suggest that different residues in SU may interact with these two receptors. The specific FeLV-Bs described here, which can enter cells using either human Pit receptor, may be useful as envelope pseudotypes for viruses used in gene therapy.
Human Parvovirus B19 Induces Cell Cycle Arrest at G
2
Phase with Accumulation of Mitotic Cyclins
Authors: Morita Eiji , Tada Kotaro , Chisaka Hiroshi , Asao Hironobu , Sato Hiroyuki , Yaegashi Nobuo , Sugamura Kazuo
Published: July 2002

Human parvovirus B19 infects specifically erythroid progenitor cells, which causes transient aplastic crises and hemolytic anemias. Here, we demonstrate that erythroblastoid UT7/Epo cells infected with B19 virus fall into growth arrest with 4N DNA, indicating G
2
/M arrest. These B19 virus-infected cells displayed accumulation of cyclin A, cyclin B1, and phosphorylated cdc2 and were accompanied by an up-regulation in the kinase activity of the cdc2-cyclin B1 complex, similar to that in cells treated with the mitotic inhibitor. However, degradation of nuclear lamina and phosphorylation of histone H3 and H1 were not seen in B19 virus-infected cells, indicating that the infected cells do not enter the M phase. Accumulation of cyclin B1 was persistently localized in the cytoplasm, but not in the nucleus, suggesting that B19 virus infection of erythroid cells raises suppression of nuclear import of cyclin B1, resulting in cell cycle arrest at the G
2
phase. The B19 virus-induced G
2
/M arrest may be the critical event in the damage of erythroid progenitor cells seen in patients with B19 virus infection.
Retroviral Integration at the
Epi1
Locus Cooperates with
Nf1
Gene Loss in the Progression to Acute Myeloid Leukemia
Authors: Blaydes Susan M. , Kogan Scott C. , Truong Bao-Tran H. , Gilbert Debra J. , Jenkins Nancy A. , Copeland Neal G. , Largaespada David A. , Brannan Camilynn I.
Published: July 2002

Juvenile myelomonocytic leukemia (JMML) is a disease that occurs in young children and is associated with a high mortality rate. In most patients, JMML has a progressive course leading to death by virtue of infection, bleeding, or progression to acute myeloid leukemia (AML). As it is known that children with neurofibromatosis type 1 syndrome have a markedly increased risk of developing JMML, we have previously developed a mouse model of JMML through reconstitution of lethally irradiated mice with hematopoietic stem cells homozygous for a loss-of-function mutation in the
Nf1
gene (D. L. Largaespada, C. I. Brannan, N. A. Jenkins, and N. G. Copeland, Nat. Genet. 12:137–143, 1996). In the course of these experiments, we found that all these genetically identical reconstituted mice developed a JMML-like disorder, but only a subset went on to develop more acute disease. This result strongly suggests that additional genetic lesions are responsible for disease progression to AML. Here, we describe the production of a unique tumor panel, created using the BXH-2 genetic background, for identification of these additional genetic lesions. Using this tumor panel, we have identified a locus,
Epi1
, which maps 30 to 40 kb downstream of the
Myb
gene and appears to be the most common site of somatic viral integration in BXH-2 mice. Our findings suggest that proviral integrations at
Epi1
cooperate with loss of
Nf1
to cause AML.
Chemical Mutagenesis of Dengue Virus Type 4 Yields Mutant Viruses Which Are Temperature Sensitive in Vero Cells or Human Liver Cells and Attenuated in Mice
Authors: Blaney Joseph E. , Johnson Daniel H. , Firestone Cai-Yen , Hanson Christopher T. , Murphy Brian R. , Whitehead Stephen S.
Published: July 2002

A recombinant live attenuated dengue virus type 4 (DEN4) vaccine candidate, 2AΔ30, was found previously to be generally well tolerated in humans, but a rash and an elevation of liver enzymes in the serum occurred in some vaccinees. 2AΔ30, a non-temperature-sensitive (non-ts) virus, contains a 30-nucleotide deletion (Δ30) in the 3′ untranslated region (UTR) of the viral genome. In the present study, chemical mutagenesis of DEN4 was utilized to generate attenuating mutations which may be useful in further attenuation of the 2AΔ30 candidate vaccine. Wild-type DEN4 2A virus was grown in Vero cells in the presence of 5-fluorouracil, and a panel of 1,248 clones were isolated. Twentytsmutant viruses were identified that weretsin both simian Vero and human liver HuH-7 cells (n= 13) or only in HuH-7 cells (n= 7). Each of the 20tsmutant viruses possessed an attenuation phenotype, as indicated by restricted replication in the brains of 7-day-old mice. The complete nucleotide sequence of the 20tsmutant viruses identified nucleotide substitutions in structural and nonstructural genes as well as in the 5′ and 3′ UTRs, with more than one change occurring, in general, per mutant virus. Atsmutation in the NS3 protein (nucleotide position 4995) was introduced into a recombinant DEN4 virus possessing the Δ30 deletion, thereby creating rDEN4Δ30-4995, a recombinant virus which istsand more attenuated than rDEN4Δ30 virus in the brains of mice. We are assembling a menu of attenuating mutations that should be useful in generating satisfactorily attenuated recombinant dengue vaccine viruses and in increasing our understanding of the pathogenesis of dengue virus.
A Commonly Recognized Simian Immunodeficiency Virus Nef Epitope Presented to Cytotoxic T Lymphocytes of Indian-Origin Rhesus Monkeys by the Prevalent Major Histocompatibility Complex Class I Allele Mamu-A*02
Authors: Robinson Suzanne , Charini William A. , Newberg Michael H. , Kuroda Marcelo J. , Lord Carol I. , Letvin Norman L.
Published: July 2002

The ability to monitor vaccine-elicited CD8+cytotoxic T-lymphocyte (CTL) responses in simian immunodeficiency virus (SIV)- and simian-human immunodeficiency virus (SHIV)-infected rhesus monkeys has been limited by our knowledge of viral epitopes predictably presented to those lymphocytes by common rhesus monkey MHC class I alleles. We now define an SIV and SHIV Nef CTL epitope (YTSGPGIRY) that is presented to CD8+T lymphocytes by the common rhesus monkey MHC class I molecule Mamu-A*02. All seven infectedMamu-A*02+monkeys evaluated demonstrated this response, and peptide-stimulated interferon gamma Elispot assays indicated that the response represents a large proportion of the entire CD8+T-lymphocyte SIV- or SHIV-specific immune response of these animals. Knowledge of this epitope and MHC class I allele substantially increases the number of available rhesus monkeys that can be used for testing prototype HIV vaccines in this important animal model.
Identification of a Hepatic Factor Capable of Supporting Hepatitis C Virus Replication in a Nonpermissive Cell Line
Authors: Yeh Chau-Ting , Lai Hsin-Yu , Chen Tse-Ching , Chu Chia-Ming , Liaw Yun-Fan
Published: July 2002

Although hepatitis C virus E2 protein can bind to human cells by interacting with a putative viral receptor, CD81, the interaction alone is not sufficient to establish permissiveness for hepatitis C virus infection. Using an Epstein-Barr virus-based extrachromosomal replication system, we have screened through a human liver cDNA library and successfully identified a cDNA capable of supporting hepatitis C virus replication in an otherwise nonpermissive cell line. This cDNA encodes a protein exhibiting homology to a group of proteins derived from various evolutionarily distant species, including
Oryza sativa
submergence-induced protein 2A. The mRNAs encoding this factor are heterogeneous at the 5′ ends and are ubiquitously expressed in multiple tissues, albeit in a very small amount. The longest mRNA contains an in-frame and upstream initiation codon and codes for a larger protein. This 5′-extended form of mRNA was detected in hepatocellular carcinoma, but not in normal liver tissue. Immunofluorescence analysis demonstrated that the hepatic factor was distributed evenly in cells, but occasionally formed aggregations in the peri- or intranuclear areas. In summary, we have identified a hepatic factor capable of supporting hepatitis C virus replication in an otherwise nonpermissive cell line. This factor belongs to a previously uncharacterized protein family. The physiological function of this protein awaits further study.
Role of Matrix and Fusion Proteins in Budding of Sendai Virus
Authors: Takimoto Toru , Murti K. Gopal , Bousse Tatiana , Scroggs Ruth Ann , Portner Allen
Published: July 2002

Paramyxoviruses are assembled at the surface of infected cells, where virions are formed by the process of budding. We investigated the roles of three Sendai virus (SV) membrane proteins in the production of virus-like particles. Expression of matrix (M) proteins from cDNA induced the budding and release of virus-like particles that contained M, as was previously observed with human parainfluenza virus type 1 (hPIV1). Expression of SV fusion (F) glycoprotein from cDNA caused the release of virus-like particles bearing surface F, although their release was less efficient than that of particles bearing M protein. Cells that expressed only hemagglutinin-neuraminidase (HN) released no HN-containing vesicles. Coexpression of M and F proteins enhanced the release of F protein by a factor greater than 4. The virus-like particles containing F and M were found in different density gradient fractions of the media of cells that coexpressed M and F, a finding that suggests that the two proteins formed separate vesicles and did not interact directly. Vesicles released by M or F proteins also contained cellular actin; therefore, actin may be involved in the budding process induced by viral M or F proteins. Deletion of C-terminal residues of M protein, which has a sequence similar to that of an actin-binding domain, significantly reduced release of the particles into medium. Site-directed mutagenesis of the cytoplasmic tail of F revealed two regions that affect the efficiency of budding: one domain comprising five consecutive amino acids conserved in SV and hPIV1 and one domain that is similar to the actin-binding domain required for budding induced by M protein. Our results indicate that both M and F proteins are able to drive the budding of SV and propose the possible role of actin in the budding process.
NF-κBcis-Acting Motifs of the Human Immunodeficiency Virus (HIV) Long Terminal Repeat Regulate HIV Transcription in Human Macrophages
Authors: Asin Susana , Bren Gary D. , Carmona Eva M. , Solan Nancie J. , Paya Carlos V.
Published: July 2002

The role of NF-κB in the reactivation of human immunodeficiency virus (HIV) from latency in CD4 T lymphocytes is well documented. However, its role in driving HIV transcription in human macrophages, which contain a constitutive nuclear pool of NF-κB, is less well understood. In this study we have investigated the role that the constitutive pool of NF-κB and the NF-κBcis-acting motifs of the HIV long terminal repeat (LTR) play in regulating HIV transcription in human monocytic cells and primary macrophages. Inhibition of the constitutive nuclear pool of NF-κB (RelA and RelB) in the promonocytic U937 cell line using dominant-negative IκBα significantly decreases HIV replication. Moreover, it is demonstrated that in the differentiated monocytic cell line THP1, which contains a constitutive nuclear pool of NF-κB (RelB),an HIV provirus containing mutations of the κBcis-acting sites in the LTR is transcriptionally impaired. Reduction of the constitutive pool of NF-κB in human macrophages by an adenovirus vector expressing a dominant-negative IκBα also reduces HIV transcription. Lastly, mutation of the NF-κBcis-acting sites in the LTR of an R5 HIV provirus completely abrogates the first cycle of HIV transcription. These studies indicate that thecis-acting NF-κB motifs of the HIV LTR are critical in initiating HIV transcription in human macrophages and suggest that the constitutive nuclear pool of NF-κB is important in regulating HIV transcription in these cells.
Proteinase-Polymerase Precursor as the Active Form of Feline Calicivirus RNA-Dependent RNA Polymerase
Authors: Wei Lai , Huhn Jason S. , Mory Aaron , Pathak Harsh B. , Sosnovtsev Stanislav V. , Green Kim Y. , Cameron Craig E.
Published: July 2002

The objective of this study was to identify the active form of the feline calicivirus (FCV) RNA-dependent RNA polymerase (RdRP). Multiple active forms of the FCV RdRP were identified. The most active enzyme was the full-length proteinase-polymerase (Pro-Pol) precursor protein, corresponding to amino acids 1072 to 1763 of the FCV polyprotein encoded by open reading frame 1 of the genome. Deletion of 163 amino acids from the amino terminus of Pro-Pol (the Val-1235 amino terminus) caused a threefold reduction in polymerase activity. Deletion of an additional one (the Thr-1236 amino terminus) or two (the Ala-1237 amino terminus) amino acids produced derivatives that were 7- and 175-fold, respectively, less active than Pro-Pol. FCV proteinase-dependent processing of Pro-Pol in the interdomain region preceding Val-1235 was not observed in the presence of a catalytically active proteinase; however, processing within the polymerase domain was observed. Inactivation of proteinase activity by changing the catalytic cysteine-1193 to glycine permitted the production and purification of intact Pro-Pol. Biochemical analysis of Pro-Pol showed that this enzyme has properties expected of a replicative polymerase, suggesting that Pro-Pol is an active form of the FCV RdRP.
Increased Neutralization Sensitivity of CD4-Independent Human Immunodeficiency Virus Variants
Authors: Kolchinsky Peter , Kiprilov Enko , Sodroski Joseph
Published: July 2002

Naturally occurring human immunodeficiency virus (HIV-1) variants require the presence of CD4 and specific chemokine receptors to enter a cell. In the laboratory, HIV-1 variants that are capable of bypassing CD4 and utilizing only the CCR5 chemokine receptor for virus entry have been generated. Here we report that these CD4-independent viruses are significantly more sensitive to neutralization by soluble CD4 and a variety of antibodies. The same amino acid changes in the HIV-1 gp120 envelope glycoprotein determined CD4 independence and neutralization sensitivity. The CD4-independent envelope glycoproteins exhibited higher affinity for antibodies against CD4-induced gp120 epitopes but not other neutralizing ligands. The CD4-independent envelope glycoproteins did not exhibit increased lability relative to the wild-type envelope glycoproteins. The utilization of two receptors apparently allows HIV-1 to maintain a more neutralization-resistant state prior to engaging CD4 on the target cell, explaining the rarity of CD4 independence in wild-type HIV-1.
Y2, the Smallest of the Sendai Virus C Proteins, Is Fully Capable of both Counteracting the Antiviral Action of Interferons and Inhibiting Viral RNA Synthesis
Authors: Kato Atsushi , Ohnishi Yukano , Kohase Masayoshi , Saito Sakura , Tashiro Masato , Nagai Yoshiyuki
Published: July 2002

An open reading frame (ORF) overlapping the amino-terminal portion of the Sendai virus (SeV)
P
ORF in the +1 frame produces a nested set of carboxy-coterminal proteins, C′, C, Y1, and Y2, which are referred to collectively as the C proteins. The C proteins are extremely versatile triple-role players; they counteract the antiviral action of interferons (IFNs), inhibit viral RNA synthesis, and are involved in virus assembly. In this study, we established HeLa cell lines stably expressing the C, Y1, and Y2 proteins individually and examined the capacities of these cells to circumvent the antiviral action of alpha/beta IFN (IFN-α/β) and IFN-γ and to inhibit viral transcription. The assay protocols included monitoring of IFN-α/β-mediated signaling by interferon-stimulated response element-driven reporter gene expression and of the antiviral state induced by IFN-α/β and IFN-γ and measurement of reporter gene expression from an SeV minigenome, as well as quantification of SeV primary transcripts. When necessary, the activities measured were carefully normalized to the expression levels of the respective C proteins in cells. The data obtained clearly indicate that the smallest protein, Y2, was as active as the C and Y1 proteins in both counteracting the antiviral action of IFNs and inhibiting viral transcription. The data further show that intracellular transexpression of either C, Y1, or Y2 rendered HeLa cells moderately or only poorly permissive for not only wild-type SeV but also 4C(−) SeV, which expressed none of the four C proteins. On the basis of these findings, the roles of SeV C proteins in the natural life cycle are discussed.
Sites and Determinants of Early Cleavages in the Proteolytic Processing Pathway of Reovirus Surface Protein σ3
Authors: Jané-Valbuena Judit , Breun Laura A. , Schiff Leslie A. , Nibert Max L.
Published: July 2002

Entry of mammalian reovirus virions into target cells requires proteolytic processing of surface protein σ3. In the virion, σ3 mostly covers the membrane-penetration protein μ1, appearing to keep it in an inactive form and to prevent it from interacting with the cellular membrane until the proper time in infection. The molecular mechanism by which σ3 maintains μ1 in this inactive state and the structural changes that accompany σ3 processing and μ1 activation, however, are not well understood. In this study we characterized the early steps in σ3 processing and determined their effects on μ1 function and particle infectivity. We identified two regions of high protease sensitivity, “hypersensitive” regions located at residues 208 to 214 and 238 to 244, within which all proteases tested selectively cleaved σ3 as an early step in processing. Further processing of σ3 was required for infection, consistent with the fact that the fragments resulting from these early cleavages remained bound to the particles. Reovirus type 1 Lang (T1L), type 3 Dearing (T3D), and T1L × T3D reassortant virions differed in the sites of early σ3 cleavage, with T1L σ3 being cleaved mainly at residues 238 to 244 and T3D σ3 being cleaved mainly at residues 208 to 214. These virions also differed in the rates at which the early cleavages occurred, with cleavage of T1L σ3 occurring faster than cleavage of T3D σ3. Analyses using chimeric and site-directed mutants of recombinant σ3 identified carboxy-proximal residues 344, 347, and 353 as the primary determinants of these strain differences. The spatial relationships between these more carboxy-proximal residues and the hypersensitive regions were discerned from the σ3 crystal structure. The results indicate that proteolytic processing of σ3 during reovirus disassembly is a multistep pathway with a number of molecular determinants.
Cation-Independent Mannose 6-Phosphate Receptor Blocks Apoptosis Induced by Herpes Simplex Virus 1 Mutants Lacking Glycoprotein D and Is Likely the Target of Antiapoptotic Activity of the Glycoprotein
Authors: Zhou Guoying , Roizman Bernard
Published: July 2002

Herpes simplex virus 1 mutants lacking the gene encoding glycoprotein D (gD) and the gD normally present in the envelope of the virus (gD−/−stocks) or mutants lacking the gD gene but containingtrans-induced gD in their envelopes (gD−/+) cause apoptosis in human SK-N-SH cells. The gD−/−virions are taken up by endocytosis and are degraded, whereas gD−/+viruses replicate but produce gD−/−virus. Apoptosis is blocked by delivery of the gD gene intrans. Studies designed to test several hypotheses concerning the role of gD in apoptosis revealed the following. (i) gD−/−and gD−/+stocks induce fragmentation of cellular DNA in SK-N-SH, HEp-2, HeLa, and Vero cell lines. (ii) Chloroquine blocks apoptosis induced by gD−/−stocks but not by gD−/+stocks. The drug also rescues gD−/−from degradation. (iii) Cells transduced with cation-independent mannose 6-phosphate receptor (CI-MPR) block apoptosis induced by either gD−/−or gD−/+virus. (iv) Expression of sequences antisense to the cloned CI-MPR gene induced apoptosis by themselves. Wild-type virus but not gD−/−or gD−/+stocks of mutant virus blocked apoptosis induced by the expression of CI-MPR antisense sequences. These results exclude the possibility that to block apoptosis, gD must interact with its HveA receptor, a member of the tumor necrosis factor alpha receptor family. Instead, the data suggest that gD blocks the influx of lysosomal enzymes into the endosomal compartment by binding to CI-MPR. This conclusion is consistent with published reports that phosphorylated gD interacts with CI-MPR.
The Genome of Swinepox Virus
Authors: Afonso C. L. , Tulman E. R. , Lu Z. , Zsak L. , Osorio F. A. , Balinsky C. , Kutish G. F. , Rock D. L.
Published: July 2002

Swinepox virus
(SWPV), the sole member of the
Suipoxvirus
genus of the
Poxviridae
, is the etiologic agent of a worldwide disease specific for swine. Here we report the genomic sequence of SWPV. The 146-kbp SWPV genome consists of a central coding region bounded by identical 3.7-kbp inverted terminal repeats and contains 150 putative genes. Comparison of SWPV with chordopoxviruses reveals 146 conserved genes encoding proteins involved in basic replicative functions, viral virulence, host range, and immune evasion. Notably, these include genes with similarity to genes for gamma interferon (IFN-γ) receptor, IFN resistance protein, interleukin-18 binding protein, IFN-α/β binding protein, extracellular enveloped virus host range protein, dUTPase, hydroxysteroid dehydrogenase, superoxide dismutase, serpin, herpesvirus major histocompatibility complex inhibitor, ectromelia virus macrophage host range protein, myxoma virus M011L, variola virus B22R, four ankyrin repeat proteins, three kelch-like proteins, five vaccinia virus (VV) A52R-like family proteins, and two G protein-coupled receptors. The most conserved genomic region is centrally located and corresponds to the VV region located between genes F9L and A38L. Within the terminal 13 kbp, colinearity is disrupted and multiple poxvirus gene homologues are absent or share a lower percentage of amino acid identity. Most of these differences involve genes and gene families with likely functions involving viral virulence and host range. Three open reading frames (SPV018, SPV019. and SPV020) are unique for SWPV. Phylogenetic analysis, genome organization, and amino acid identity indicate that SWPV is most closely related to the capripoxvirus lumpy skin disease virus, followed by the yatapoxvirus yaba-like disease virus and the leporipoxviruses. The gene complement of SWPV better defines
Suipoxvirus
within the
Chordopoxvirinae
subfamily and provides a basis for future genetic comparisons.
Endoplasmic Reticulum-Golgi Intermediate Compartment Membranes and Vimentin Filaments Participate in Vaccinia Virus Assembly
Authors: Risco Cristina , Rodríguez Juan R. , López-Iglesias Carmen , Carrascosa José L. , Esteban Mariano , Rodríguez Dolores
Published: July 2002

Vaccinia virus (VV) has a complex morphogenetic pathway whose first steps are poorly characterized. We have studied the early phase of VV assembly, when viral factories and spherical immature viruses (IVs) form in the cytoplasm of the infected cell. After freeze-substitution numerous cellular elements are detected around assembling viruses: membranes, ribosomes, microtubules, filaments, and unidentified structures. A double membrane is clearly resolved in the VV envelope for the first time, and freeze fracture reveals groups of tubules interacting laterally on the surface of the viroplasm foci. These data strongly support the hypothesis of a cellular tubulovesicular compartment, related to the endoplasmic reticulum-Golgi intermediate compartment (ERGIC), as the origin of the first VV envelope. Moreover, the cytoskeletal vimentin intermediate filaments are found around viral factories and inside the viroplasm foci, where vimentin and the VV core protein p39 colocalize in the areas where crescents protrude. Confocal microscopy showed that ERGIC elements and vimentin filaments concentrate in the viral factories. We propose that modified cellular ERGIC membranes and vimentin intermediate filaments act coordinately in the construction of viral factories and the first VV form through a unique mechanism of viral morphogenesis from cellular elements.
A Replication-Competent, Neutralization-Sensitive Variant of Simian Immunodeficiency Virus Lacking 100 Amino Acids of Envelope
Authors: Johnson Welkin E. , Morgan Jennifer , Reitter Julie , Puffer Bridget A. , Czajak Susan , Doms Robert W. , Desrosiers Ronald C.
Published: July 2002

Coding sequences for the first two variable loops of the gp120 envelope glycoprotein were removed from simian immunodeficiency virus (SIV) strain 239 (SIVmac239). This deletion encompassed 100 amino acids. The resulting virus replicated poorly after transfection into immortalized T-cell lines, with peak replication occurring only after 25 to 30 days. Limited passaging of SIVmac239ΔV1V2 in cultures gave rise to a variant which had significantly improved replication kinetics but which retained the original 100-amino-acid deletion in gp120. Cloning and sequencing revealed 11 changes in the envelope, including amino acid substitutions in both gp120 (5 substitutions) and gp41(6 substitutions). Four of the five changes in gp120 are predicted to lie within and around the putative coreceptor binding domain, a region which is believed to be covered by the V1 and V2 loops in the native envelope complex. Analysis of recombinant clones surprisingly revealed that the changes in gp41 were sufficient to overcome the replication deficiency created by deletion of the V1 and V2 loops from gp120. The SIVmac239ΔV1V2 envelope displayed a significant reduction in its ability to mediate cell-cell fusion, and the infectious titer of SIVmac239ΔV1V2 was approximately four- to eightfold lower than that of parental SIVmac239. Although SIVmac239 is strongly dependent on both CD4 and a coreceptor for entry, envelope protein lacking the V1 and V2 loops was able to mediate fusion with CD4
−
CCR5
+
cells at 60% the level observed with CD4
+
CCR5
+
cells. Plasma from SIVmac239-infected monkeys was at least 100 to 1,000 times more effective at neutralizing SIVmac239ΔV1V2 than SIVmac239. These results demonstrate the dispensability of the V1-V2 sequences of SIVmac239 for viral replication, a role for V1 and V2 in shielding the coreceptor binding region of the envelope, and the extreme sensitivity of a SIV lacking these sequences to antibody-mediated neutralization.
Endocytosis of Adeno-Associated Virus Type 5 Leads to Accumulation of Virus Particles in the Golgi Compartment
Authors: Bantel-Schaal Ursula , Hub Birgit , Kartenbeck Juergen
Published: July 2002

Among the adeno-associated virus (AAV) serotypes which are discussed as vectors for gene therapy AAV type 5 (AAV5) represents a candidate with unique advantages. To further our knowledge on AAV5-specific characteristics, we studied the entry pathway of wild-type virus in HeLa cells in the absence of helper virus by immunofluorescence and electron microscopy and by Western blot analysis. We found virus binding at the apical cell surface, especially at microvilli and, with increasing incubation time, virus accumulation at cell-cell boundaries. The different binding kinetics suggest different binding properties at apical versus lateral plasma membranes. Endocytosis of viruses was predominantly by clathrin-coated vesicles from both membrane domains; however, particles were also detected in noncoated pits. AAV5 particles were mainly routed to the Golgi area, where they could be detected within cisternae of the trans-Golgi network and within vesicles associated with cisternae and with the dictyosomal stacks of the Golgi apparatus. These data suggest that AAV5 makes use of endocytic routes that have hitherto not been described as pathways for virus entry.
Ebola Virus Glycoproteins Induce Global Surface Protein Down-Modulation and Loss of Cell Adherence
Authors: Simmons Graham , Wool-Lewis Rouven J. , Baribaud Frédéric , Netter Robert C. , Bates Paul
Published: July 2002

The Ebola virus envelope glycoprotein (GP) derived from the pathogenic Zaire subtype mediates cell rounding and detachment from the extracellular matrix in 293T cells. In this study we provide evidence that GPs from the other pathogenic subtypes, Sudan and Côte d'Ivoire, as well as from Reston, a strain thought to be nonpathogenic in humans, also induced cell rounding, albeit at lower levels than Zaire GP. Sequential removal of regions of potential O-linked glycosylation at the C terminus of GP1 led to a step-wise reduction in cell detachment without obviously affecting GP function, suggesting that such modifications are involved in inducing the detachment phenotype. While causing cell rounding and detachment in 293T cells, Ebola virus GP did not cause an increase in cell death. Indeed, following transient expression of GP, cells were able to readhere and continue to divide. Also, the rounding effect was not limited to 293T cells. Replication-deficient adenovirus vectors expressing Ebola virus GP induced the loss of cell adhesion in a range of cell lines and primary cell types, including those with proposed relevance to Ebola virus infection in vivo, such as endothelial cells and macrophages. In both transfected 293T and adenovirus-infected Vero cells, a reduction in cell surface expression of adhesion molecules such as integrin β1 concurrent with the loss of cell adhesion was observed. A number of other cell surface molecules, however, including major histocompatibility complex class I and the epidermal growth factor receptor, were also down-modulated, suggesting a global mechanism for surface molecule down-regulation.
Capsid-Specific Cytotoxic T Lymphocytes Recognize Three Distinct H-2Db-Restricted Regions of the BeAn Strain of Theiler's Virus and Exhibit Different Cytokine Profiles
Authors: Lyman Michael A. , Lee Hee-Gu , Kang Bong Su , Kang Hee-Kap , Kim Byung S.
Published: July 2002

The role of virus-specific cytotoxic T lymphocytes (CTL) in Theiler's murine encephalomyelitis virus (TMEV)-induced demyelinating disease, a viral model for multiple sclerosis, is not yet clear. To investigate the specificity and function of CTL generated in response to TMEV infection, we generated a panel of overlapping 20-mer peptides encompassing the entire capsid and leader protein region of the BeAn strain of TMEV. Binding of these peptides to H-2Kband H-2Dbclass I molecules of resistant mice was assessed using RMA-S cells. Several peptides displayed significant binding to H-2Kb, H-2Db, or both. However, infiltrating cytotoxic T cells in the central nervous system of virus-infected mice preferentially lysed target cells pulsed with VP2111-130/121-140or VP2121-130, a previously defined CTL epitope shared by the DA strain of TMEV and other closely related cardioviruses. In addition, at a high effector-to-target cell ratio, two additional peptides (VP2161-180and VP3101-120) sensitized target cells for cytolysis by infiltrating T cells or splenic T cells from virus-infected mice. The minimal epitopes within these peptides were defined as VP2165-173and VP3110-120. Based on cytokine profiles, CTL specific for these subdominant epitopes are Tc2, in contrast to CTL for the immunodominant epitope, which are of the Tc1 type. Interestingly, CTL function towards both of these subdominant epitopes is restricted by the H-2D molecule, despite the fact that these epitopes bind both H-2K and H-2D molecules. This skewing toward an H-2Db-restricted response may confer resistance to TMEV-induced demyelinating disease, which is known to be associated with theH-2Dgenetic locus.
Radical Intermediates in Photochemical and Redox Initiated Decomposition of Thioazo Compounds(an EPR and Cyclovoltammetric Study)
Authors: Erentová Katarína , Adamčík Vladimír , Staško Andrej , Nuyken Oskar , Lang Arming , Leitner Michael B.
Published: July 2002

The cathodically and photochemically induced decomposition of thioazo compounds XC6H4-N2-S-C6H4CH3 and their polymers with X = NO2, COOH, and SO3H were investigated. The formation of carbon-centered XC6H4. and sulfur-centered .S-C6H4Y radicals was confirmed using spin-trap technique. These reactive radicals either abstract hydrogen from CH3CN solvent molecule forming .CH2CN radical or they recombine to cage products XC6H4-S-C6H4CH3 eliminating N2. The decomposition rate of the investigated thioazo compounds is characterized by a formal half-life time of 5 to 10 s.
Spin-Orbit Coupling in Biradicals. 3. Heavy Atom Effects in Carbenes
Authors: Havlas Zdeněk , Michl Josef
Published: July 2002

CASSCF(8,6)/cc-pVDZ calculations of electron spin-spin dipole interaction tensor in the lowest triplet state of CH2, CHF, CHCl, and CHBr, spin-orbit coupling of each of the three sublevels with the lowest singlet, and the triplet zero-field-splitting parameters are reported as a function of the valence angle, with bond lengths optimized for the triplet state at the B3LYP/cc-pVTZ level of approximation. Both the one- and the two-electron parts of the spin-orbit coupling Hamiltonian are used, and the contributions to spin-orbit coupling provided by each atom and orbital pair in Weinhold's natural hybrid orbital basis are evaluated separately. This provides intuitive insight into the origin of spin-orbit coupling in carbenes and especially, the heavy atom effect of the substituent.
Catalytic Activity of 4-Hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl in Homogeneous Electrooxidation of Hydroxylamine
Authors: Xia He , Li Hu Lin
Published: July 2002

4-Hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl (1) shows catalytic electroactivity in homogeneous oxidation of hydroxylamine on a glassy carbon electrode. Kinetic parameters of the electrode reaction were measured and an catalytic reaction mechanism for the electrooxidation was proposed. Possible application of electrocatalytic activity of 1 in determination hydroxylamine was also discussed.
Determination of the Accurate Values of the Rate Constant and Thermodynamic Parameters for the Rotation About the C(sp2)-C(aryl) Bond. 3-Substituted N,N,2,4,6-Pentamethylbenzamides
Authors: Přibylová Eva , Holík Miroslav
Published: July 2002

Three programs for the 1H NMR line shape analysis of systems with unequally populated sites have been tested in order to get highly accurate rate constants of the hindered rotation about a single bond using four published criteria. The programs differ in the number of optimized parameters. As test compounds, 3-(adamantan-1-carbonyl)-N,N,2,4,6-pentamethylbenzamide (1) and 3-(2-dimethylpropanoyl)-N,N,2,4,6-pentamethylbenzamide (2) were prepared. It was found that a supermodified simplex method with only six parameters optimized in one step gives the most accurate values of the rate constants. Consequently, the calculated thermodynamic parameters Ea, ∆H≠ and ∆S≠ lie in relatively narrow confidence intervals.