bluuebunny/crossref_metadata_2025_split huggingface dataset:
The R33 G Protein-Coupled Receptor Gene of Rat Cytomegalovirus Plays an Essential Role in the Pathogenesis of Viral Infection
Authors: Beisser Patrick S. , Vink Cornelis , Van Dam Joanne G. , Grauls Gert , Vanherle Sabina J. V. , Bruggeman Cathrien A. 
Published: December 2019

ABSTRACTWe have identified a rat cytomegalovirus (RCMV) gene that encodes a G-protein-coupled receptor (GCR) homolog. This gene (R33) belongs to a family that includes the human cytomegalovirus UL33 gene. R33 was found to be transcribed during the late phase of RCMV infection in rat embryo fibroblasts. Unlike the mRNAs from all the other members of the UL33 family that have been studied to date, the R33 mRNA is not spliced. To study the function of the R33 gene, we constructed an RCMV strain in which the R33 open reading frame is disrupted. The mutant strain (RCMVΔR33) did not show differences in replication from wild-type RCMV upon infection of several rat cell types in vitro. However, marked differences were seen between the mutant and wild-type strain in the pathogenesis of infection in immunocompromised rats. First, the mutant strain induced a significantly lower mortality than the wild-type virus did. Second, in contrast to wild-type RCMV, the mutant strain did not efficiently replicate in the salivary gland epithelial cells of immunocompromised rats. Although viral DNA was detected in salivary glands of RCMVΔR33-infected rats up to 14 days postinfection, it could not be detected at later time points. This indicates that although the strain with R33 deleted is probably transported to the salivary glands in a similar fashion to that for wild-type virus, the mutant virus is not able to either enter or replicate in salivary gland epithelial cells. We conclude that the RCMV R33 gene plays a vital role in the pathogenesis of infection.
Immune Response to Recombinant Capsid Proteins of Adenovirus in Humans: Antifiber and Anti-Penton Base Antibodies Have a Synergistic Effect on Neutralizing Activity
Authors: Gahéry-Ségard Hanne , Farace Françoise , Godfrin Dominique , Gaston Jesintha , Lengagne Renée , Tursz Thomas , Boulanger Pierre , Guillet Jean-Gérard 
Published: December 2019

ABSTRACT
Replication-deficient adenovirus used in humans for gene therapy induces a strong immune response to the vector, resulting in transient recombinant protein expression and the blocking of gene transfer upon a second administration. Therefore, in this study we examined in detail the capsid-specific humoral immune response in sera of patients with lung cancer who had been given one dose of a replication-defective adenovirus. We analyzed the immune response to the three major components of the viral capsid, hexon (Hx), penton base (Pb), and fiber (Fi). A longitudinal study of the humoral response assayed on adenovirus particle-coated enzyme-linked immunosorbent assay plates showed that patients had preexisting immunity to adenovirus prior to the administration of adenovirus–β-gal. The level of the response increased in three patients after adenovirus administration and remained at a maximum after three months. One patient had a strong immune response to adenovirus prior to treatment, and this response was unaffected by adenovirus administration. Sera collected from the patients were assayed for recognition of each individual viral capsid protein to determine more precisely the molecular basis of the humoral immune response. Clear differences existed in the humoral response to the three major components of the viral capsid in serum from humans. Sequential appearance of these antibodies was observed: anti-Fi antibodies appeared first, followed by anti-Pb antibodies and then by anti-Hx antibodies. Moreover, anti-Fi antibodies preferentially recognized the native trimeric form of Fi protein, suggesting that they recognized conformational epitopes. Our results showed that sera with no neutralizing activity contained only anti-Fi antibodies. In contrast, neutralizing activity was only obtained with sera containing anti-Fi and anti-Pb antibodies. More importantly, we showed that anti-native Fi and anti-Pb antibodies had a synergistic effect on neutralization. The application of these conclusions to human gene therapy with recombinant adenovirus should lead to the development of strategies to overcome the formation of such neutralization antibodies, which have been shown to limit the efficacy of gene transfer in humans.
Human Immunodeficiency Virus (HIV) Envelope Binds to CXCR4 Independently of CD4, and Binding Can Be Enhanced by Interaction with Soluble CD4 or by HIV Envelope Deglycosylation
Authors: Bandres Juan C. , Wang Qing F. , O’Leary Jeanne , Baleaux Françoise , Amara Ali , Hoxie James A. , Zolla-Pazner Susan , Gorny Miroslaw K. 
Published: December 2019

ABSTRACT

Chemokine receptor CXCR4 (also known as LESTR and fusin) has been shown to function as a coreceptor for T-cell-tropic strains of human immunodeficiency virus type 1 (HIV-1). We have developed a binding assay to show that HIV envelope (Env) can interact with CXCR4 independently of CD4 but that this binding is markedly enhanced by the previous interaction of Env with soluble CD4. We also show that nonglycosylated HIV-1
SF-2
gp120 or sodium metaperiodate-treated oligomeric gp160 from HIV-1
451
bound much more readily to CXCR4 than their counterparts with intact carbohydrate residues did.
Identification of Determinants on a Dualtropic Human Immunodeficiency Virus Type 1 Envelope Glycoprotein That Confer Usage of CXCR4
Authors: Cho Michael W. , Lee Myung K. , Carney Michelle C. , Berson Joanne F. , Doms Robert W. , Martin Malcolm A. 
Published: December 2019

ABSTRACTThe chemokine receptors CCR5 and CXCR4, in combination with CD4, mediate cellular entry of macrophage-tropic (M-tropic) and T-cell-tropic strains of human immunodeficiency virus type 1 (HIV-1), respectively, while dualtropic viruses can use either receptor. We have constructed a panel of chimeric viruses and envelope glycoproteins in which various domains of the dualtropic HIV-1DH12gp160 were introduced into the genetic background of an M-tropic HIV-1 isolate, HIV-1AD8. These constructs were employed in cell fusion and virus infectivity assays using peripheral blood mononuclear cells, MT4 T cells, primary monocyte-derived macrophages, or HOS-CD4 cell lines, expressing various chemokine receptors, to assess the contributions of different gp120 subdomains in coreceptor usage and cellular tropism. As expected, the dualtropic HIV-1DH12gp120 utilized either CCR3, CCR5, or CXCR4, whereas HIV-1AD8gp120 was able to use only CCR3 or CCR5. We found that either the V1/V2 or the V3 region of HIV-1DH12gp120 individually conferred on HIV-1AD8the ability to use CXCR4, while the combination of both the V1/V2 and V3 regions increased the efficiency of CXCR4 use. In addition, while the V4 or the V5 region of HIV-1DH12gp120 failed to confer the capacity to utilize CXCR4 on HIV-1AD8, these regions were required in conjunction with regions V1 to V3 of HIV-1DH12gp120 for efficient utilization of CXCR4. Comparison of virus infectivity analyses with various cell types and cell fusion assays revealed assay-dependent discrepancies and indicated that events occurring at the cell surface during infection are complex and cannot always be predicted by any one assay.
Heterosexual Transmission of a Murine AIDS Virus
Authors: Okada Yoshiaki , Abe Eri , Komuro Katsutoshi , Mizuochi Toshiaki 
Published: December 2019

ABSTRACT
Heterosexual transmission of a murine leukemia virus mixture named LP-BM5 MuLV, which is known as the murine AIDS virus, was investigated. Our results indicated that the heterosexual transmission of LP-BM5 MuLV occurs in both directions with high frequency and that the frequencies of virus transmission in the cervix and penis are higher than those in other genital organs. The results suggested that infection by LP-BM5 MuLV via heterosexual transmission may initially take place at particular retrovirus-sensitive sites (cells) in the genital organs.
Inhibition of Hepatitis B Virus Replication during Adenovirus and Cytomegalovirus Infections in Transgenic Mice
Authors: Cavanaugh Victoria J. , Guidotti Luca G. , Chisari Francis V. 
Published: December 2019

ABSTRACTWe have previously demonstrated that hepatitis B virus (HBV) replication and gene expression are abolished in the livers of HBV transgenic mice by cytotoxic T lymphocytes (CTLs) and during lymphocytic choriomeningitis virus (LCMV) infection, stimuli that trigger the production of alpha/beta interferon, gamma interferon, and tumor necrosis factor alpha in the liver. We now report that hepatic HBV replication and gene expression are inhibited by the local induction of these cytokines during adenovirus- and murine cytomegalovirus (MCMV)-induced hepatitis. Further, we show that MCMV also blocks HBV replication and gene expression in the proximal convoluted tubules of the kidney by causing interstitial nephritis and inducing the same cytokines in the renal parenchyma. These results suggest that inflammatory cytokines probably contribute to viral clearance during acute viral hepatitis in humans, and they imply that induction of these cytokines in the liver and other infected tissues of chronically infected patients might have therapeutic value.
Immune Response to Mouse Mammary Tumor Virus in Mice Lacking the Alpha/Beta Interferon or the Gamma Interferon Receptor
Authors: Maillard Ivan , Launois Pascal , Xenarios Ioannis , Louis Jacques A. , Acha-Orbea Hans , Diggelmann Heidi 
Published: December 2019

ABSTRACTMouse mammary tumor virus (MMTV) is a retrovirus which induces a strong immune response and a dramatic increase in the number of infected cells through the expression of a superantigen (SAg). Many cytokines are likely to be involved in the interaction between MMTV and the immune system. In particular, alpha/beta interferon (IFN-α/β) and gamma interferon (IFN-γ) exert many antiviral and immunomodulatory activities and play a critical role in other viral infections. In this study, we have investigated the importance of interferons during MMTV infection by using mice with a disrupted IFN-α/β or IFN-γ receptor gene. We found that the SAg response to MMTV was not modified in IFN-α/βR0/0and IFN-γR0/0mice. This was true both for the early expansion of B and T cells induced by the SAg and for the deletion of SAg-reactive cells at later stages of the infection. In addition, no increase in the amount of proviral DNA was detected in tissues of IFN-α/βR0/0and IFN-γR0/0mice, suggesting that interferons are not essential antiviral defense mechanisms during MMTV infection. In contrast, IFN-γR0/0mice had increased amounts of IL-4 mRNA and an altered usage of immunoglobulin isotypes with a reduced frequency of IgG2a- and IgG3-producing cells. This was associated with lower titers of virus-specific antibodies in serum early after infection, although efficient titers were reached later.
Generation of a Mutant Infectious Bursal Disease Virus That Does Not Cause Bursal Lesions
Authors: Yao Kun , Goodwin Mark A. , Vakharia Vikram N. 
Published: December 2019

ABSTRACT
A reverse genetics system for birnavirus, based on synthetic transcripts of the infectious bursal disease virus (IBDV) genome, was recently developed (E. Mundt and V. N. Vakharia, Proc. Natl. Acad. Sci. USA 93:11131–11136, 1996). To study the function of the 17-kDa nonstructural (NS) protein in viral growth and pathogenesis, we constructed a cDNA clone of IBDV segment A in which the first and only initiation codon (ATG) of NS protein was mutated to a stop codon (TAG). Transfection of Vero cells with combined transcripts of either modified or unmodified segment A, and with segment B, generated viable IBDV progeny. When chicken embryo fibroblast cells infected with transfectant viruses were analyzed by immunofluorescence assays using NS-specific antiserum, the mutant virus did not yield a fluorescence signal, indicating a lack of NS protein expression. Furthermore, replication kinetics and cytotoxic effects of the mutant virus were compared with those of the parental attenuated vaccine strain of IBDV (D78) in vitro. The mutant virus grew to slightly lower titers than D78 virus and exhibited decreased cytotoxic and apoptotic effects in cell culture. To evaluate the characteristics of the recovered viruses in vivo, we inoculated 3-week-old chickens with D78 or mutant virus and analyzed their bursa for histopathological lesions. The recovered D78 virus caused microscopic lesions and atrophy of the bursa, while the mutant virus failed to induce any pathological lesions or clinical signs of disease. In both instances, the virus was recovered from the bursa, and the presence or absence of mutation in these viruses was confirmed by nucleotide sequence analysis of NS gene. Although the mutant virus exhibited a delay in replication in vivo, it induced levels of IBDV neutralizing antibodies that were similar to those of D78 virus. In addition, no reversion of mutation was detected in the mutant virus recovered from inoculated chickens. These results demonstrate that NS protein is dispensable for viral replication in vitro and in vivo and that it plays an important role in viral pathogenesis. Thus, generation of such NS protein-deficient virus will facilitate the study of immunosuppression and aid in the development of live-attenuated vaccines for IBDV.
Antirotavirus Immunoglobulin A Neutralizes Virus In Vitro after Transcytosis through Epithelial Cells and Protects Infant Mice from Diarrhea
Authors: Ruggeri Franco M. , Johansen Kari , Basile Gino , Kraehenbuhl Jean-Pierre , Svensson Lennart 
Published: December 2019

ABSTRACTRotaviruses are the major cause of severe diarrhea in infants and young children worldwide. Due to their restricted site of replication, i.e., mature enterocytes, local intestinal antibodies have been proposed to play a major role in protective immunity. Whether secretory immunoglobulin A (IgA) antibodies alone can provide protection against rotavirus diarrhea has not been fully established. To address this question, a library of IgA monoclonal antibodies (MAbs) previously developed against different proteins of rhesus rotavirus was used. A murine hybridoma “backpack tumor” model was established to examine if a single MAb secreted onto mucosal surfaces via the normal epithelial transport pathway was capable of protecting mice against diarrhea upon oral challenge with rotavirus. Of several IgA and IgG MAbs directed against VP8 and VP6 of rotavirus, only IgA VP8 MAbs (four of four) were found to protect newborn mice from diarrhea. An IgG MAb recognizing the same epitope as one of the IgA MAbs tested failed to protect mice from diarrhea. We also investigated if antibodies could be transcytosed in a biologically active form from the basolateral domain to the apical domain through filter-grown Madin-Darby canine kidney (MDCK) cells expressing the polymeric immunoglobulin receptor. Only IgA antibodies with VP8 specificity (four of four) neutralized apically administered virus. The results support the hypothesis that secretory IgA antibodies play a major role in preventing rotavirus diarrhea. Furthermore, the results show that the in vivo and in vitro methods described are useful tools for exploring the mechanisms of viral mucosal immunity.
RNase L Mediates the Antiviral Effect of Interferon through a Selective Reduction in Viral RNA during Encephalomyocarditis Virus Infection
Authors: Li Xiao-Ling , Blackford John A. , Hassel Bret A. 
Published: December 2019

ABSTRACT
The 2′,5′-oligoadenylate (2-5A) system is an RNA degradation pathway which plays an important role in the antipicornavirus effects of interferon (IFN). RNase L, the terminal component of the 2-5A system, is thought to mediate this antiviral activity through the degradation of viral RNA; however, the capacity of RNase L to selectively target viral RNA has not been carefully examined in intact cells. Therefore, the mechanism of RNase L-mediated antiviral activity was investigated following encephalomyocarditis virus (EMCV) infection of cell lines in which expression of transfected RNase L was induced or endogenous RNase L activity was inhibited. RNase L induction markedly enhanced the anti-EMCV activity of IFN via a reduction in EMCV RNA. Inhibition of endogenous RNase L activity inhibited this reduction in viral RNA. RNase L had no effect on IFN-mediated protection from vesicular stomatitis virus. RNase L induction reduced the rate of EMCV RNA synthesis, suggesting that RNase L may target viral RNAs involved in replication early in the virus life cycle. The RNase L-mediated reduction in viral RNA occurred in the absence of detectable effects on specific cellular mRNAs and without any global alteration in the cellular RNA profile. Extensive rRNA cleavage, indicative of high levels of 2-5A, was not observed in RNase L-induced, EMCV-infected cells; however, transfection of 2-5A into cells resulted in widespread degradation of cellular RNAs. These findings provide the first demonstration of the selective capacity of RNase L in intact cells and link this selective activity to cellular levels of 2-5A.
Plasma Membrane-Targeted Raf Kinase Activates NF-κB and Human Immunodeficiency Virus Type 1 Replication in T Lymphocytes
Authors: Flory Egbert , Weber Christoph K. , Chen Peifeng , Hoffmeyer Angelika , Jassoy Christian , Rapp Ulf R. 
Published: December 2019

ABSTRACTIncreasing evidence points to a role of the mitogenic Ras/Raf/MEK/ERK signaling cascade in regulation of human immunodeficiency virus type 1 (HIV-1) gene expression. Stimulation of elements of this pathway leads to transactivation of the HIV-1 promoter. In particular, the NF-κB motif in the HIV long terminal repeat (LTR) represents a Raf-responsive element in fibroblasts. Regulation of the Raf kinase in T cells differs from findings with a variety of cell lines that the catalytic domain of Raf (RafΔ26–303) shows no activity. In this study, we restored the activity of the kinase in T cells by fusing its catalytic domain to the CAAX motif (-Cx) of Ras, thus targeting the enzyme to the plasma membrane. Constitutive activity of Raf was demonstrated by phosphorylation of mitogen-activated protein kinase kinase (MEK) and endogenous mitogen-activated protein kinase 1/2 (ERK1/2) in A3.01 T cells transfected with RafΔ26–303-Cx. Membrane-targeted Raf also stimulates NF-κB, as judged by κB-dependent reporter assays and enhanced NF-κB p65 binding on band shift analysis. Moreover, we found that active Raf transactivates the HIVNL4-3LTR in A3.01 T lymphocytes and that dominant negative Raf (C4) blocked 12-O-tetradecanoylphorbol-13-acetate induced transactivation. When cotransfected with infectious HIVNL4-3DNA, membrane-targeted Raf induces viral replication up to 10-fold over basal levels, as determined by the release of newly synthesized p24gagprotein. Our study clearly demonstrates that the activity of the catalytic domain of Raf in A3.01 T cells is dependent on its cellular localization. The functional consequences of active Raf in T lymphocytes include not only NF-κB activation and transactivation of the HIVNL4-3LTR but also synthesis and release of HIV particles.
Deletion of a CD2-Like Gene,8-DR, from African Swine Fever Virus Affects Viral Infection in Domestic Swine
Authors: Borca M. V. , Carrillo C. , Zsak L. , Laegreid W. W. , Kutish G. F. , Neilan J. G. , Burrage T. G. , Rock D. L. 
Published: December 2019

ABSTRACTAn African swine fever virus (ASFV) gene with similarity to the T-lymphocyte surface antigen CD2 has been found in the pathogenic African isolate Malawi Lil-20/1 (open reading frame [ORF] 8-DR) and a cell culture-adapted European virus, BA71V (ORF EP402R) and has been shown to be responsible for the hemadsorption phenomenon observed for ASFV-infected cells. The structural and functional similarities of the ASFV gene product to CD2, a cellular protein involved in cell-cell adhesion and T-cell-mediated immune responses, suggested a possible role for this gene in tissue tropism and/or immune evasion in the swine host. In this study, we constructed an ASFV8-DRgene deletion mutant (Δ8-DR) and its revertant (8-DR.R) from the Malawi Lil-20/1 isolate to examine gene function in vivo. In vitro, Δ8-DR, 8-DR.R, and the parental virus exhibited indistinguishable growth characteristics on primary porcine macrophage cell cultures. In vivo,8-DRhad no obvious effect on viral virulence in domestic pigs; disease onset, disease course, and mortality were similar for the mutant Δ8-DR, its revertant 8-DR.R, and the parental virus. Altered viral infection was, however, observed for pigs infected with Δ8-DR. A delay in spread to and/or replication of Δ8-DR in the draining lymph node, a delay in generalization of infection, and a 100- to 1,000-fold reduction in virus titers in lymphoid tissue and bone marrow were observed. Onset of viremia for Δ8-DR-infected animals was significantly delayed (by 2 to 5 days), and mean viremia titers were reduced approximately 10,000-fold at 5 days postinfection and 30- to 100-fold at later times; moreover, unlike in 8-DR.R-infected animals, the viremia was no longer predominantly erythrocyte associated but rather was equally distributed among erythrocyte, leukocyte, and plasma fractions. Mitogen-dependent lymphocyte proliferation of swine peripheral blood mononuclear cells in vitro was reduced by 90 to 95% following infection with 8-DR.R but remained unaltered following infection with Δ8-DR, suggesting that8-DRhas immunosuppressive activity in vitro. Together, these results suggest an immunosuppressive role for8-DRin the swine host which facilitates early events in viral infection. This may be of most significance for ASFV infection of its highly adapted natural host, the warthog.
A Single Amino Acid Change in the Hemagglutinin Protein of Measles Virus Determines Its Ability To Bind CD46 and Reveals Another Receptor on Marmoset B Cells
Authors: Hsu Eric C. , Sarangi Farida , Iorio Caterina , Sidhu Mohinderjit S. , Udem Stephen A. , Dillehay Dirck L. , Xu Wenbo , Rota Paul A. , Bellini William J. , Richardson Christopher D. 
Published: December 2019

ABSTRACT
This paper provides evidence for a measles virus receptor other than CD46 on transformed marmoset and human B cells. We first showed that most tissues of marmosets are missing the SCR1 domain of CD46, which is essential for the binding of Edmonston measles virus, a laboratory strain that has been propagated in Vero monkey kidney cells. In spite of this deletion, the common marmoset was shown to be susceptible to infections by wild-type isolates of measles virus, although they did not support Edmonston measles virus production. As one would expect from these results, measles virus could not be propagated in owl monkey or marmoset kidney cell lines, but surprisingly, both a wild-type isolate (Montefiore 89) and the Edmonston laboratory strain of measles virus grew efficiently in B95-8 marmoset B cells. In addition, antibodies directed against CD46 had no effect on wild-type infections of marmoset B cells and only partially inhibited the replication of the Edmonston laboratory strain in the same cells. A direct binding assay with insect cells expressing the hemagglutinin (H) proteins of either the Edmonston or Montefiore 89 measles virus strains was used to probe the receptors on these B cells. Insect cells expressing Edmonston H but not the wild-type H bound to rodent cells with CD46 on their surface. On the other hand, both the Montefiore 89 H and Edmonston H proteins adhered to marmoset and human B cells. Most wild-type H proteins have asparagine residues at position 481 and can be converted to a CD46-binding phenotype by replacement of the residue with tyrosine. Similarly, the Edmonston H protein did not bind CD46 when its Tyr481 was converted to asparagine. However, this mutation did not affect the ability of Edmonston H to bind marmoset and human B cells. The preceding results provide evidence, through the use of a direct binding assay, that a second receptor for measles virus is present on primate B cells.