bluuebunny/crossref_metadata_2025_split huggingface dataset:
Individual Contributions of Mutant Protease and Reverse Transcriptase to Viral Infectivity, Replication, and Protein Maturation of Antiretroviral Drug-Resistant Human Immunodeficiency Virus Type 1
Authors: Bleiber Gabriela , Munoz Miguel , Ciuffi Angela , Meylan Pascal , Telenti Amalio 
Published: July 2002

ABSTRACT
Human immunodeficiency virus type 1 (HIV-1) variants resistant to protease (PR) and reverse transcriptase (RT) inhibitors may display impaired infectivity and replication capacity. The individual contributions of mutated HIV-1 PR and RT to infectivity, replication, RT activity, and protein maturation (herein referred to as “fitness”) in recombinant viruses were investigated by separately cloning PR, RT, and PR-RT cassettes from drug-resistant mutant viral isolates into the wild-type NL4-3 background. Both mutant PR and RT contributed to measurable deficits in fitness of viral constructs. In peripheral blood mononuclear cells, replication rates (means ± standard deviations) of RT recombinants were 72.5% ± 27.3% and replication rates of PR recombinants were 60.5% ± 33.6% of the rates of NL4-3. PR mutant deficits were enhanced in CEM T cells, with relative replication rates of PR recombinants decreasing to 15.8% ± 23.5% of NL4-3 replication rates. Cloning of the cognate RT improved fitness of some PR mutant clones. For a multidrug-resistant virus transmitted through sexual contact, RT constructs displayed a marked infectivity and replication deficit and diminished packaging of Pol proteins (RT content in virions diminished by 56.3% ± 10.7%, and integrase content diminished by 23.3% ± 18.4%), a novel mechanism for a decreased-fitness phenotype. Despite the identified impairment of recombinant clones, fitness of two of the three drug-resistant isolates was comparable to that of wild-type, susceptible viruses, suggestive of extensive compensation by genomic regions away from PR and RT. Only limited reversion of mutated positions to wild-type amino acids was observed for the native isolates over 100 viral replication cycles in the absence of drug selective pressure. These data underscore the complex relationship between PR and RT adaptive changes and viral evolution in antiretroviral drug-resistant HIV-1.
Cervicovaginal Lamina Propria Lymphocytes: Phenotypic Characterization and Their Importance in Cytotoxic T-Lymphocyte Responses to Simian Immunodeficiency Virus SIVmac251
Authors: Stevceva Liljana , Kelsall Brian , Nacsa Janos , Moniuszko Marcin , Hel Zdeněk , Tryniszewska Elzbieta , Franchini Genoveffa 
Published: July 2002

ABSTRACTMost human immunodeficiency virus (HIV) type 1 infections occur by the mucosal route. Thus, it is important to assess the immune responses to HIV in the vaginal, cervical, and rectal compartments. Here we quantitated the virus-specific CD8+T-cell response and characterized the phenotype of lymphocytes in the genital tracts of naive macaques, macaques acutely or chronically infected with simian immunodeficiency virus SIVmac251, and macaques chronically infected with chimeric simian/human immunodeficiency virus SHIVKU2.Vaginal biopsy samples or samples obtained at the time of euthanasia were used in this analysis. The percentage of Gag-specific, tetramer-positive T cells was as high as 13 to 14% of the CD3+CD8+T-cell population in the vaginal and cervical laminae propriae of both SIVmac251and SHIVKU2chronically infected macaques. In most cases, the frequency of this response in the cervicovaginal compartment far exceeded the frequency in the blood or the draining iliac lymph node. Vaginal laminae propriae of naive macaques contained 55 to 65% CD3+CD8+cells and 28 to 34% CD3+CD4+cells, while the majority of intraepithelial cells were CD8+T cells (75 to 85%). For the same cells, the surface expression of CD62L was low whereas that of αEβ7 was high. No difference in the expression of CD45RA on CD8+T cells was observed in the chronic stage of SIVmac251infection. Although no decrease in the percentage of CD4+cells in the genital tract was observed within the first 12 days of infection, by 6 weeks from SIVmac251infection and thereafter the percentage of CD4+T cells was decreased in the laminae propriae of the vagina and cervix. Expression of CD45RA did not differ in naive and acutely SIVmac251infected macaques. Information on the quality and quantity of local immune responses may help in the design of vaccine strategies aimed at containing viral replication at the site of viral encounter.
Transduction of Interphase Cells by Avian Sarcoma Virus
Authors: Katz Richard A. , Greger James G. , Darby Kristen , Boimel Pamela , Rall Glenn F. , Skalka Anna Marie 
Published: July 2002

ABSTRACT

It has been generally believed that oncoretroviruses are dependent on mitosis for efficient nuclear entry of viral DNA. We previously identified a nuclear localization signal in the integrase protein of an oncoretrovirus, avian sarcoma virus (ASV), suggesting an active import mechanism for the integrase-DNA complex (G. Kukolj, R. A. Katz, and A. M. Skalka, Gene 223:157-163, 1998). Here, we have evaluated the requirement for mitosis in nuclear import and integration of ASV DNA. Using a modified ASV encoding a murine leukemia virus amphotropic
env
gene and a green fluorescent protein (GFP) reporter gene, DNA nuclear import was measured in cell cycle-arrested avian (DF-1) as well as human (HeLa) and mouse cells. The results showed efficient accumulation of nuclear forms of ASV DNA in γ-irradiation-arrested cells. Efficient transduction of a GFP reporter gene was also observed after infection of cells that were arrested with γ-irradiation, mitomycin C, nocodazole, or aphidicolin, confirming that nuclear import and integration of ASV DNA can occur in the absence of mitosis. By monitoring GFP expression in individual cells, we also obtained evidence for nuclear import of viral DNA during interphase in cycling cells. Lastly, we observed that ASV can transduce postmitotic mouse neurons. These results support an active nuclear import mechanism for the oncoretrovirus ASV and suggest that this mechanism can operate in both nondividing and dividing cells.
Pre- and Postexposure Prophylaxis of Ebola Virus Infection in an Animal Model by Passive Transfer of a Neutralizing Human Antibody
Authors: Parren Paul W. H. I. , Geisbert Tom W. , Maruyama Toshiaki , Jahrling Peter B. , Burton Dennis R. 
Published: July 2002

ABSTRACT
A neutralizing human monoclonal antibody, KZ52, protects guinea pigs from lethal Ebola Zaire virus challenge. Administration before or up to 1 h after challenge resulted in dose-dependent protection by the antibody. Interestingly, some antibody-treated animals survived despite developing high-level viremia, suggesting that the mechanism of protection by KZ52 may extend beyond reduction of viremia by virus neutralization. KZ52 is a promising candidate for immunoprophylaxis of Ebola virus infection.
Identification of Immunodominant Neutralizing Epitopes on the Hemagglutinin Protein of Rinderpest Virus
Authors: Sugiyama Makoto , Ito Naoto , Minamoto Nobuyuki , Tanaka Seiichi 
Published: July 2002

ABSTRACT
The immunodominant epitopes on the hemagglutinin protein of rinderpest virus (RPV-H) were determined by analyzing selected monoclonal antibody (MAb)-resistant mutants and estimating the level of antibody against each epitope in five RPV-infected rabbits with the competitive enzyme-linked immunosorbent assay (c-ELISA). Six neutralizing epitopes were identified, at residues 474 (epitope A), 243 (B), 548 to 551 (D), 587 to 592 (E), 310 to 313 (G), and 383 to 387 (H), from the data on the amino acid substitutions of hemagglutinin protein of MAb-resistant mutants and the reactivities of MAbs against RPV-H to the other morbilliviruses. The epitopes identified in this study are all positioned on the loop of the propeller-like structure in a hypothetical three-dimensional model of RPV-H (J. P. M. Langedijk et al., J. Virol. 71:6155-6167, 1997). Polyclonal sera obtained from five rabbits infected experimentally with RPV were examined by c-ELISA using a biotinylated MAb against each epitope as a competitor. Although these rabbit sera hardly blocked binding of each MAb to epitopes A and B, they moderately blocked binding of each MAb to epitopes G and D and strongly blocked binding of each MAb to epitopes E and H. These results suggest that epitopes at residues 383 to 387 and 587 to 592 may be immunodominant in humoral immunity to RPV infection.
Decreased Frequency of the
HLA-DRB1*11
Allele in Patients with Chronic Hepatitis C Virus Infection
Authors: Yenigün Ayla , Durupinar Belma 
Published: July 2002

ABSTRACT

A genetically determined resistance or susceptibility to chronic hepatitis C virus (HCV) infection may make an important contribution to the course of liver disease and may be linked to the human major histocompatibility complex (MHC). The aim of this study was to investigate the HLA class II genotype profile in chronic hepatitis C and to determine the HLA-hepatitis C association. The experimental population was composed of 49 unrelated chronic HCV patients (31 females, 18 males; mean age, 54.4 ± 1.7 years; range, 34 to 73 years). The control population consisted of 43 ethnically matched healthy donors.
HLA-DR
and -DQ alleles were studied for patients and controls by a PCR-sequence-specific-primer low-resolution method. Anti-HCV was investigated with enzyme-linked immunosorbent assay II, and HCV RNA was investigated with reverse transcriptase nested PCR. The HLA class II allele,
DRB1*11
, was found at reduced frequency in 49 patients with chronic hepatitis C (anti-HCV and HCV RNA positive) compared to that for controls (22.4 versus 51.0%;
P
< 0.01, odds ratio = 0.3, confidence interval = 0.1 to 0.7). No further HLA associations with chronic HCV infection were observed, and there was no correlation between the stage of disease and HLA.
DRB1*11
was also found at reduced frequency in all HCV antibody-positive patients compared to controls (corrected
P
= not significant).
DRB1*11
was associated with chronic HCV infection, and it is possible that
HLA-DRB1*11
may have a protective feature in chronic HCV infection. In addition,
DRB1*11
was associated with protection from HCV infection. These findings suggest that host HLA class II genotype is an important factor determining the outcome of infection with HCV.
Interferon-Regulated Pathways That Control Hepatitis B Virus Replication in Transgenic Mice
Authors: Guidotti Luca G. , Morris Amber , Mendez Heike , Koch Rick , Silverman Robert H. , Williams Bryan R. G. , Chisari Francis V. 
Published: July 2002

ABSTRACTWe previously showed that the intrahepatic induction of cytokines such as alpha/beta interferon (IFN-α/β) and gamma interferon (IFN-γ) inhibits hepatitis B virus (HBV) replication noncytopathically in the livers of transgenic mice. The intracellular pathway(s) responsible for this effect is still poorly understood. To identify interferon (IFN)-inducible intracellular genes that could play a role in our system, we crossed HBV transgenic mice with mice deficient in IFN regulatory factor 1 (IRF-1), the double-stranded RNA-activated protein kinase (PKR), or RNase L (RNase L) (IRF-1−/−, PKR−/−, or RNase L−/−mice, respectively), three well-characterized IFN-inducible genes that mediate antiviral activity. We showed that unmanipulated IRF-1−/−or PKR−/−transgenic mice replicate HBV in the liver at slightly higher levels than the respective controls, suggesting that both IRF-1 and PKR individually appear to mediate signals that modulate HBV replication under basal conditions. These same animals were responsive to the antiviral effects of the IFN-α/β inducer poly(I-C) or recombinant murine IFN-γ, suggesting that under these conditions, either the IRF-1 or the PKR genes can mediate the antiviral activity of the IFNs or other IFN-inducible genes mediate the antiviral effects. Finally, RNase L−/−transgenic mice were undistinguishable from controls under basal conditions and after poly(I-C) or IFN-γ administration, suggesting that RNase L does not modulate HBV replication in this model.
Mouse Model for the Equilibration Interaction between the Host Immune System and Human T-Cell Leukemia Virus Type 1 Gene Expression
Authors: Furuta Rika A. , Sugiura Kikuya , Kawakita Shigenari , Inada Takefumi , Ikehara Susumu , Matsuda Tadashi , Fujisawa Jun-ichi 
Published: July 2002

ABSTRACT
To study the involvement of immune responses against Tax of human T-cell leukemia virus type 1 (HTLV-1) in the growth of and gene suppression in Tax-expressing tumor cells in vivo, we established a model system involving C57BL/6J mice and a syngeneic lymphoma cell line, EL4. When mice were immunized by DNA-based immunization with Tax expression plasmids, solid tumor formation upon subcutaneous inoculation of EL4 cells expressing green fluorescent protein-fused Tax (Gax) under the control of the HTLV-1 enhancer was strongly inhibited, and in vitro analysis showed that DNA immunization elicited cytotoxic T-lymphocyte (CTL) responses but not production of antibodies to Tax protein. Since EL4/Gax cells inoculated into DNA-immunized mice were not completely eradicated but were maintained as small solid tumors for a long period, there appeared to be a certain equilibrium between CTL activity and the growth of Gax-expressing cells. With such a balance, expression of the Gax gene in EL4/Gax cells was strongly suppressed. These results suggested that gene expression under the control of the HTLV-1 long terminal repeat and Tax is silenced in vivo, resulting in an equilibrium between viral expression and the host immune system. Such a balance would represent a status of persistent infection by HTLV-1 in virus-infected individuals during the latency period.
Physical Association of the K3 Protein of Gamma-2 Herpesvirus 68 with Major Histocompatibility Complex Class I Molecules with Impaired Peptide and β2-Microglobulin Assembly
Authors: Yu Y. Y. Lawrence , Harris Michael R. , Lybarger Lonnie , Kimpler Lisa A. , Myers Nancy B. , Virgin IV Herbert W. , Hansen Ted H. 
Published: July 2002

ABSTRACTTo persist in the presence of an active immune system, viruses encode proteins that decrease expression of major histocompatibility complex class I molecules by using a variety of mechanisms. For example, murine gamma-2 herpesvirus 68 expresses the K3 protein, which causes the rapid turnover of nascent class I molecules. In this report we show that certain mouse class I alleles are more susceptible than others to K3-mediated down regulation. Prior to their rapid degradation, class I molecules in K3-expressing cells exhibit impaired assembly with β2-microglobulin. Furthermore, K3 is detected predominantly in association with class I molecules lacking assembly with high-affinity peptides, including class I molecules associated with the peptide loading complex TAP/tapasin/calreticulin. The detection of K3 with class I assembly intermediates raises the possibility that molecular chaperones involved in class I assembly are involved in K3-mediated class I regulation.
Infectious and Whole Inactivated Simian Immunodeficiency Viruses Interact Similarly with Primate Dendritic Cells (DCs): Differential Intracellular Fate of Virions in Mature and Immature DCs
Authors: Frank I. , Piatak M. , Stoessel H. , Romani N. , Bonnyay D. , Lifson J.D. , Pope M. 
Published: July 2002

ABSTRACTAs potential targets for human immunodeficiency virus type 1 and simian immunodeficiency virus (HIV-1 and SIV), dendritic cells (DCs) likely play a significant role in the onset and spread of infection as well as in the induction of antiviral immunity. Using the SIV-macaque system to study the very early events in DC-virus interactions, we compared chemically inactivated SIV having conformationally and functionally intact envelope glycoproteins (2,2′-dithiodipyridine [AT-2] SIV) to infectious and heat-treated SIV. Both human and macaque DCs interact similarly with SIV without detectable effects on DC viability, phenotype, or endocytic function. As assessed by measuring cell-associated viral RNA, considerable amounts of virus are captured by the DCs and this is reduced when the virus is heat treated or derived from a strain that expresses low levels of envelope glycoprotein. Immunostaining for SIV proteins and electron microscopy indicated that few intact virus particles are retained at the periphery of the endocytically active, immature DCs. This contrasts with a perinuclear localization of numerous virions in large vesicular compartments deeper within mature DCs (in which macropinocytosis is down-regulated). Both immature and mature DCs are capable of clathrin-coated pit-mediated uptake of SIV, supporting the notion that the receptor-mediated uptake of virus can occur readily in mature DCs. While large numbers of whole viruses were preferentially found in mature DCs, both immature and mature DCs contained similar amounts of viral RNA, suggesting that different uptake/virus entry mechanisms are active in immature and mature DCs. These findings have significant implications for cell-to-cell transmission of HIV-1 and SIV and support the use of AT-2 SIV, an authentic but noninfectious form of virus, as a useful tool for studies of processing and presentation of AT-2 SIV antigens by DCs.
Lack of both Fas Ligand and Perforin Protects from Flavivirus-Mediated Encephalitis in Mice
Authors: Licon Luna Rosa M. , Lee Eva , Müllbacher Arno , Blanden Robert V. , Langman Rod , Lobigs Mario 
Published: July 2002

ABSTRACTThe mechanism by which encephalitic flaviviruses enter the brain to inflict a life-threatening encephalomyelitis in a small percentage of infected individuals is obscure. We investigated this issue in a mouse model for flavivirus encephalitis in which the virus was administered to 6-week-old animals by the intravenous route, analogous to the portal of entry in natural infections, using a virus dose in the range experienced following the bite of an infectious mosquito. In this model, infection with 0.1 to 105PFU of virus gave mortality in ∼50% of animals despite low or undetectable virus growth in extraneural tissues. We show that the cytolytic effector functions play a crucial role in invasion of the encephalitic flavivirus into the brain. Mice deficient in either the granule exocytosis- or Fas-mediated pathway of cytotoxicity showed delayed and reduced mortality. Mice deficient in both cytotoxic effector functions were resistant to a low-dose peripheral infection with the neurotropic virus.
Adenovirus Binding to the Coxsackievirus and Adenovirus Receptor or Integrins Is Not Required To Elicit Brain Inflammation but Is Necessary To Transduce Specific Neural Cell Types
Authors: Thomas Clare E. , Edwards Penny , Wickham Thomas J. , Castro Maria G. , Lowenstein Pedro R. 
Published: July 2002

ABSTRACT
Intracranial administration of adenovirus vectors elicits rapid, capsid-mediated dose-dependent brain inflammation. The mechanisms through which adenovirus capsids trigger inflammation in the brain remain unknown. We determined whether adenovirus interaction with the primary and secondary cell surface receptors for infection (CAR and αv integrins) was necessary to trigger acute adenovirus-mediated brain inflammation, and, furthermore, whether capsid mutations that abrogated CAR and integrin binding altered vector tropism in the brain. Vectors ablated for CAR binding, but retaining integrin binding function, transduced equivalent areas of brain compared to vectors with wild-type capsids; however, vector tropsim was dramatically altered. Vectors with wild-type capsids predominantly transduced oligodendrocytes, whereas mutation of the fiber protein to ablate CAR binding resulted in a loss of oligodendrocyte transduction and a consequent redirection of transduction to neurons and other types of glial cells. Combined mutations of fiber and penton base that ablate both CAR and integrin binding almost abolished brain transduction. Thus, doubly-ablated capsids engineered to express new ligands should allow complete vector retargeting in the central nervous system. Although transduction by the doubly-ablated vectors was reduced by greater than 95%, inflammation was not reduced compared to wild-type vectors, demonstrating that brain inflammation occurs independently of adenovirus binding and infection of cells via CAR and integrin receptors.
Relation of anterior pelvic tilt during running to clinical and kinematic measures of hip extension
Authors: Schache Anthony G , Blanch Peter D , Murphy Anna T 
Published: July 2002

Background—Limited hip extension flexibility due to tight hip flexor musculature or anterior hip capsular and ligamentous structures is a possible cause of increased anterior tilt of the pelvis during running. However, to date, research exploring this relation, as well as the kinematic relation between anterior tilt of the pelvis and peak hip extension range of motion during running, is not available.Objective—To assess the relation of anterior pelvic tilt during running to peak hip extension range of motion measured during running and hip extension flexibility measured clinically.Methods—Hip extension flexibility was assessed using the Thomas test, and the three dimensional kinematic motion of the pelvis and hips were recorded using a VICON motion analysis system with 14 elite athletes running on a treadmill at 20 km/h.Results—Anterior pelvic tilt displayed a significant (p<0.01) correlation with peak hip extension range of motion during running. Anterior pelvic tilt tended to be increased in runners who displayed reduced absolute peak hip extension range of motion during terminal stance. No significant correlation was shown for hip extension flexibility with either anterior pelvic tilt or peak hip extension range of motion during running.Conclusions—The outcomes of this study indicate that anterior pelvic tilt and hip extension are coordinated movements during running. Static hip extension flexibility measured using the modified Thomas test does not appear to be reflective of these dynamic movements.
Effect of ethylene vinyl acetate (EVA) closed cell foam on transmitted forces in mouthguard material
Authors: Westerman B , Stringfellow P M , Eccleston J A , Harbrow D J 
Published: July 2002

Objectives:To compare transmitted forces through ethylene vinyl acetate (EVA) mouthguard material and the same EVA material with gas inclusions in the form of a closed cell foam.Method:EVA mouthguard materials with and without foam gas inclusions and 4 mm thick were impacted with a constant force from an impact pendulum. Various porosity levels in the foam materials were produced by 1%, 5%, and 10% by weight foaming agent. The forces transmitted through the EVA after energy absorption by the test materials were measured with a force sensor and compared.Results:Only minor non-significant differences in transmitted forces through the EVA with and without foam were shown.Conclusions:The inclusion of gas in the form of a closed cell foam in 4 mm thick EVA mouthguard materials did not improve the impact performance of the EVA mouthguard material.