bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cellular Entry of Hantaviruses Which Cause Hemorrhagic Fever with Renal Syndrome Is Mediated by β3Integrins
Authors: Gavrilovskaya Irina N. , Brown Eric J. , Ginsberg Mark H. , Mackow Erich R. 
Published: December 2019

ABSTRACTHantaviruses replicate primarily in the vascular endothelium and cause two human diseases, hemorrhagic fever with renal syndrome (HFRS) and hantavirus pulmonary syndrome (HPS). In this report, we demonstrate that the cellular entry of HFRS-associated hantaviruses is facilitated by specific integrins expressed on platelets, endothelial cells, and macrophages. Infection of human umbilical vein endothelial cells and Vero E6 cells by the HFRS-causing hantaviruses Hantaan (HTN), Seoul (SEO), and Puumala (PUU) is inhibited by antibodies to αvβ3integrins and by the integrin ligand vitronectin. The cellular entry of HTN, SEO, and PUU viruses, but not the nonpathogenic Prospect Hill (PH) hantavirus (i.e., a virus with no associated human disease), was also mediated by introducting recombinant αIIbβ3or αvβ3integrins into β3-integrin-deficient CHO cells. In addition, PH infectivity was not inhibited by αvβ3-specific sera or vitronectin but was blocked by α5β1-specific sera and the integrin ligand fibronectin. RGD tripeptides, which are required for many integrin-ligand interactions, are absent from all hantavirus G1 and G2 surface glycoproteins, and GRGDSP peptides did not inhibit hantavirus infectivity. Further, a mouse-human hybrid β3integrin-specific Fab fragment, c7E3 (ReoPro), also inhibited the infectivity of HTN, SEO, and PUU as well as HPS-associated hantaviruses, Sin Nombre (SN) and New York-1 (NY-1). These findings indicate that pathogenic HPS- and HFRS-causing hantaviruses enter cells via β3integrins, which are present on the surfaces of platelets, endothelial cells, and macrophages. Since β3integrins regulate vascular permeability and platelet function, these findings also correlate β3integrin usage with common elements of hantavirus pathogenesis.
Frequent Detection of Escape from Cytotoxic T-Lymphocyte Recognition in Perinatal Human Immunodeficiency Virus (HIV) Type 1 Transmission: the Ariel Project for the Prevention of Transmission of HIV from Mother to Infant
Authors: Wilson Cara C. , Brown R. Clark , Korber Bette T. , Wilkes Barbara M. , Ruhl Debbie J. , Sakamoto Doreen , Kunstman Kevin , Luzuriaga Katherine , Hanson I. Celine , Widmayer Susan M. , Wiznia Andrew , Clapp Sheila , Ammann Arthur J. , Koup Richard A. , Wolinsky Steven M. , Walker Bruce D. ,   The Ariel Project Investigators
Published: December 2019

ABSTRACTHost immunologic factors, including human immunodeficiency virus (HIV)-specific cytotoxic T lymphocytes (CTL), are thought to contribute to the control of HIV type 1 (HIV-1) replication and thus delay disease progression in infected individuals. Host immunologic factors are also likely to influence perinatal transmission of HIV-1 from infected mother to infant. In this study, the potential role of CTL in modulating HIV-1 transmission from mother to infant was examined in 11 HIV-1-infected mothers, 3 of whom transmitted virus to their offspring. Frequencies of HIV-1-specific human leukocyte antigen class I-restricted CTL responses and viral epitope amino acid sequence variation were determined in the mothers and their infected infants. Maternal HIV-1-specific CTL clones were derived from each of the HIV-1-infected pregnant women. Amino acid substitutions within the targeted CTL epitopes were more frequently identified in transmitting mothers than in nontransmitting mothers, and immune escape from CTL recognition was detected in all three transmitting mothers but in only one of eight nontransmitting mothers. The majority of viral sequences obtained from the HIV-1-infected infant blood samples were susceptible to maternal CTL. These findings demonstrate that epitope amino acid sequence variation and escape from CTL recognition occur more frequently in mothers that transmit HIV-1 to their infants than in those who do not. However, the transmitted virus can be a CTL susceptible form, suggesting inadequate in vivo immune control.
Immunotyping of Human Immunodeficiency Virus Type 1 (HIV): an Approach to Immunologic Classification of HIV
Authors: Zolla-Pazner Susan , Gorny Miroslaw K. , Nyambi Phillipe N. , VanCott Thomas C. , Nádas Arthur 
Published: December 2019

ABSTRACTBecause immunologic classification of human immunodeficiency virus type 1 (HIV) might be more relevant than genotypic classification for designing polyvalent vaccines, studies were undertaken to determine whether immunologically defined groups of HIV (“immunotypes”) could be identified. For these experiments, the V3 region of the 120-kDa envelope glycoprotein (gp120) was chosen for study. Although antibodies (Abs) to V3 may not play a major protective role in preventing HIV infection, identification of a limited number of immunologically defined structures in this extremely variable region would set a precedent supporting the hypothesis that, despite its diversity, the HIV family, like the V3 region, might be divisible into immunotypes. Consequently, the immunochemical reactivities of 1,176 combinations of human anti-V3 monoclonal Abs (MAbs) and V3 peptides, derived from viruses of several clades, were studied. Extensive cross-clade reactivity was observed. The patterns of reactivities of 21 MAbs with 50 peptides from clades A through H were then analyzed by a multivariate statistical technique. To test the validity of the mathematical approach, a cluster analysis of the 21 MAbs was performed. Five groups were identified, and these MAb clusters corresponded to classifications of these same MAbs based on the epitopes which they recognize. The concordance between the MAb clusters identified by mathematical analysis and by their specificities supports the validity of the mathematical approach. Therefore, the same mathematical technique was used to identify clusters within the 50 peptides. Seven groups of peptides, each containing peptides from more than one clade, were defined. Inspection of the amino acid sequences of the peptides in each of the mathematically defined peptide clusters revealed unique “signature sequences” that suggest structural motifs characteristic of each V3-based immunotype. The results suggest that cluster analysis of immunologic data can define immunotypes of HIV. These immunotypes are distinct from genotypic classifications. The methods described pave the way for identification of immunotypes defined by immunochemical and neutralization data generated with anti-HIV Env MAbs and intact, viable HIV virions.
Design of 5′ Untranslated Sequences in Retroviral Vectors Developed for Medical Use
Authors: Hildinger Markus , Abel Kristin L. , Ostertag Wolfram , Baum Christopher 
Published: December 2019

ABSTRACT

Utilizing genetic modules of simple retroviruses, we have developed a novel generation of gene transfer vectors with improved therapeutic potential. In the 5′ untranslated “leader” sequences, all AUG codons which may aberrantly initiate translation and all viral coding sequences were removed. Thus, the probability of expressing unwanted peptides and the potential for homologous recombination with retroviral genes were largely reduced, and the cloning capacity was increased. The transgene was inserted to replace the viral
gag
sequences, and a new minimal splice acceptor was introduced, resulting in increased expression with all genes tested (those coding for human multidrug resistance 1 and enhanced green fluorescent protein, as well as the
lacZ
gene). These vectors may represent attractive tools for human gene therapy, because they increase the efficiency of transgene expression and may also increase safety in medical applications.
Live-Cell Analysis of a Green Fluorescent Protein-Tagged Herpes Simplex Virus Infection
Authors: Elliott Gillian , O’Hare Peter 
Published: December 2019

ABSTRACT
Many stages of the herpes simplex virus maturation pathway have not yet been defined. In particular, little is known about the assembly of the virion tegument compartment and its subsequent incorporation into maturing virus particles. Here we describe the construction of a herpes simplex virus type 1 (HSV-1) recombinant in which we have replaced the gene encoding a major tegument protein, VP22, with a gene expressing a green fluorescent protein (GFP)-VP22 fusion protein (GFP-22). We show that this virus has growth properties identical to those of the parental virus and that newly synthesized GFP-22 is detectable in live cells as early as 3 h postinfection. Moreover, we show that GFP-22 is incorporated into the HSV-1 virion as efficiently as VP22, resulting in particles which are visible by fluorescence microscopy. Consequently, we have used time lapse confocal microscopy to monitor GFP-22 in live-cell infection, and we present time lapse animations of GFP-22 localization throughout the virus life cycle. These animations demonstrate that GFP-22 is present in a diffuse cytoplasmic location when it is initially expressed but evolves into particulate material which travels through an exclusively cytoplasmic pathway to the cell periphery. In this way, we have for the first time visualized the trafficking of a herpesvirus structural component within live, infected cells.
Packaging Cell Lines for Simian Foamy Virus Type 1 Vectors
Authors: Wu Min , Mergia Ayalew 
Published: December 2019

ABSTRACT
Foamy viruses are nonpathogenic retroviruses that offer several unique opportunities for gene transfer in various cell types from different species. We have previously demonstrated the utility of simian foamy virus type 1 (SFV-1) as a vector system by transient expression assay (M. Wu et al., J. Virol. 72:3451–3454, 1998). In this report, we describe the first stable packaging cell lines for foamy virus vectors based on SFV-1. We developed two packaging cell lines in which the helper DNA is placed under the control of either a constitutive cytomegalovirus (CMV) immediate-early gene or inducible tetracycline promoter for expression. Although the constitutive packaging expressing cell line had a higher copy number of packaging DNA, the inducible packaging cell line produced four times more vector particles. This result suggested that the structural gene products in the constitutively expressing packaging cell line were expressed at a level that is not toxic to the cells, and thus vector production was reduced. The SFV-1 vector in the presence of vesicular stomatitis virus envelope protein G (VSV-G) produced an insignificant level of transduction, indicating that foamy viruses could not be pseudotyped with VSV-G to generate high-titer vectors. The availability of stable packaging cell lines represents a step toward the use of an SFV-1 vector delivery system that will allow scaled-up production of vector stocks for gene therapy.
Incomplete Regulation of NF-κB by IκBα during Respiratory Syncytial Virus Infection in A549 Cells
Authors: Fiedler Michael A. , Wernke-Dollries Kara 
Published: December 2019

ABSTRACTRespiratory syncytial virus (RSV) infection of airway epithelial cells results in persistent NF-κB activation and NF-κB-mediated interleukin-8 production. Previous studies in airway epithelial cells demonstrated that tumor necrosis factor alpha (TNF-α)-induced NF-κB activation is transient due to regulation by IκBα. However, during RSV infection, IκBα has only a partial inhibitory effect on NF-κB activation. Studies presented here demonstrate that neither increased IκBα production which occurs as a result of RSV-induced NF-κB activation nor inhibition of proteasome-mediated IκBα degradation results in a reversal of RSV-induced NF-κB activation. Thus, while manipulation of IκBα results in reversal of TNF-α-induced NF-κB activation, manipulation of IκBα does not result in a reversal of RSV-induced NF-κB activation.
Gastrointestinal Epithelium Is an Early Extrathymic Site for Increased Prevalence of CD34+Progenitor Cells in Contrast to the Thymus during Primary Simian Immunodeficiency Virus Infection
Authors: Mattapallil Joseph J. , Smit-McBride Zeljka , Dandekar Satya 
Published: December 2019

ABSTRACTThe objective of this study was to determine the effects of primary simian immunodeficiency virus (SIV) infection on the prevalence and phenotype of progenitor cells present in the gastrointestinal epithelia of SIV-infected rhesus macaques, a primate model for human immunodeficiency virus pathogenesis. The gastrointestinal epithelium was residence to progenitor cells expressing CD34 antigen, a subset of which also coexpressed Thy-1 and c-kitreceptors, suggesting that the CD34+population in the intestine comprised a subpopulation of primitive precursors. Following experimental SIVmac251 infection, an early increase in the proportions of CD34+Thy-1+and CD34+c-kit+progenitor cells was observed in the gastrointestinal epithelium. In contrast, the proportion of CD34+cells in the thymus declined during primary SIV infection, which was characterized by a decrease in the frequency of CD34+Thy-1+progenitor cells. A severe depletion in the frequency of CD4-committed CD34+progenitors was observed in the gastrointestinal epithelium 2 weeks after SIV infection which persisted even 4 weeks after infection. A coincident increase in the frequency of CD8- committed CD34+progenitor cells was observed during primary SIV infection. These results indicate that in contrast to the primary lymphoid organs such as the thymus, the gastrointestinal epithelium may be an early extrathymic site for the increased prevalence of both primitive and committed CD34+progenitor cells. The gastrointestinal epithelium may potentially play an important role in maintaining T-cell homeostasis in the intestinal mucosa during primary SIV infection.
The Hemagglutinin-Esterase of Mouse Hepatitis Virus Strain S Is a Sialate-4-
O
-Acetylesterase
Authors: Regl Gerhard , Kaser Alexandra , Iwersen Matthias , Schmid Hiltrud , Kohla Guido , Strobl Birgit , Vilas Ulrike , Schauer Roland , Vlasak Reinhard 
Published: December 2019

ABSTRACT

By comparative analysis of the hemagglutinin-esterase (HE) protein of mouse hepatitis virus strain S (MHV-S) and the HE protein of influenza C virus, we found major differences in substrate specificities. In striking contrast to the influenza C virus enzyme, the MHV-S esterase was unable to release acetate from bovine submandibulary gland mucin. Furthermore, MHV-S could not remove influenza C virus receptors from erythrocytes. Analysis with free sialic acid derivatives revealed that the MHV-S HE protein specifically de-O-acetylates 5-
N
-acetyl-4-
O
-acetyl sialic acid (Neu4,5Ac
2
) but not 5-
N
-acetyl-9-
O
-acetyl sialic acid (Neu5,9Ac
2
), which is the major substrate for esterases of influenza C virus and bovine coronaviruses. In addition, the MHV-S esterase converted glycosidically bound Neu4,5Ac
2
of guinea pig serum glycoproteins to Neu5Ac. By expression of the MHV esterase with recombinant vaccinia virus and incubation with guinea pig serum, we demonstrated that the viral HE possesses sialate-4-
O
-acetylesterase activity. In addition to observed enzymatic activity, MHV-S exhibited affinity to guinea pig and horse serum glycoproteins. Binding required sialate-4-
O
-acetyl groups and was abolished by chemical de-O-acetylation. Since Neu4,5Ac
2
has not been identified in mice, the nature of potential substrates and/or secondary receptors for MHV-S in the natural host remains to be determined. The esterase of MHV-S is the first example of a viral enzyme with high specificity and affinity toward 4-O-acetylated sialic acids.
Implication of Interfering Antibody Formation and Apoptosis as Two Different Mechanisms Leading to Variable Duration of Adenovirus-Mediated Transgene Expression in Immune-Competent Mice
Authors: Schowalter David B. , Himeda Charis L. , Winther Brian L. , Wilson Christopher B. , Kay Mark A. 
Published: December 2019

ABSTRACTThis study explores the genetic and immunologic factors involved in the differences in duration of transgene expression following in vivo transduction with recombinant adenoviruses. Different strains of mice (C3H/HeJ [C3H], C57BL/6J [B6], BALB/cJ [Balb/c], C.B10-H2b/LiMcdJ [Balb.B], CB6F1/J [(Balb/c × B6)F1], B6C3F1/J [(B6 × C3H)F1], and BALB/cj SCID) received 5 × 109PFU of the first-generation adenovirus, which expresses human α1-antitrypsin (Ad/RSVhAAT). While all strains studied showed similar patterns of anti-adenovirus antibody formation, only Balb/c and C3H mice developed significant levels of anti-hAAT antibodies by 8 weeks posttransduction. In addition, while all strains had quantitatively comparable amounts of adenovirus genomes and hAAT mRNA transcripts in the liver 9 days posttransduction, only Balb/c mice had undetectable adenovirus vector genomes and hAAT mRNA in the liver 40 days posttransduction. Terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling staining of liver sections from control and Ad/RSVhAAT-infected mice 5, 9, and 40 days posttransduction suggested that apoptosis was involved in the rapid elimination of transduced hepatocytes in Balb/c mice. Persistent expression of hAAT protein observed in BALB/cj SCID mice suggests that antigen-dependent immunity was essential for this apoptotic process in transduced Balb/c hepatocytes. In contrast to Balb/c mice, the loss of expression in C3H mice did not correlate with the loss of vector genomes or hAAT mRNA. Instead, the anti-hAAT antibodies in C3H but not Balb/c mice were found to interfere with detection of hAAT in the serum. In Balb.B and B6 mice, vector genome, hAAT mRNA transcripts, and hAAT protein levels persisted for at least 40 days posttransduction. This persistence correlated with poor anti-hAAT antibody formation and minimal hepatocyte toxicity. The expression of hAAT in (Balb/c × B6)F1pups was found to be intermediate between the duration observed in the parental strains, while in (C3H × B6)F1pups hAAT expression was similar to that seen in the B6 parents, which together support polygenic control of the immune responses in these mice. In summary, these findings suggest that there are three different profiles and at least two defined immune system-mediated mechanisms resulting in the loss of hAAT expression in mice and that different strains differ in the capacity to utilize these mechanisms.
Epithelial Cell Adhesion to Extracellular Matrix Proteins Induces Tyrosine Phosphorylation of the Epstein-Barr Virus Latent Membrane Protein 2: a Role for C-Terminal Src Kinase
Authors: Scholle Frank , Longnecker Richard , Raab-Traub Nancy 
Published: December 2019

ABSTRACT
The Epstein-Barr virus (EBV) latent membrane protein 2 (LMP2) is expressed in latently EBV-infected B cells, where it forms patches in the plasma membrane and interferes with B-cell receptor signal transduction through dominant-negative effects on protein kinases. LMP2 transcripts are detected in nasopharyngeal carcinoma, an epithelial-cell malignancy. In this study the function of LMP2A in epithelial cells was investigated. LMP2A was found to coprecipitate with protein kinase activities and to become phosphorylated in in vitro kinase assays. Analysis of LMP2A deletion mutants demonstrated that tyrosines implicated in interacting with Src family kinase SH2 domains and the SH2 domain of Csk, as well as the LMP2A immunoreceptor tyrosine-based activation motif, are important for its phosphorylation in epithelial cells. LMP2A tyrosine phosphorylation was triggered by cell adhesion to extracellular-matrix (ECM) proteins. Src family kinases, whose involvement in cell-ECM signaling and LMP2A phosphorylation in B lymphocytes has been well established, were found not to be responsible for LMP2A phosphorylation in epithelial cells. Instead, coexpression of Csk, a negative Src regulator, and LMP2A led to an increase in LMP2A phosphorylation both in nonadherent cells and upon cell adhesion. Csk also phosphorylated LMP2A in vitro. These results suggest that LMP2A has a different role in epithelial cells, where it interacts with cell adhesion-initiated signaling pathways. Although tyrosine phosphorylation of LMP2A occurs in both cell types, different protein kinases seem to be used: Src family kinases in B lymphocytes and Csk in epithelial cells.
Definition of the Stage of Host Cell Genetic Restriction of Replication of Human Immunodeficiency Virus Type 1 in Monocytes and Monocyte-Derived Macrophages by Using Twins
Authors: Naif Hassan M. , Li Shan , Alali Mohammed , Chang Joon , Mayne Carol , Sullivan John , Cunningham Anthony L. 
Published: December 2019

ABSTRACTUsing identical (ID) twins, we have previously demonstrated that host cell genes exert a significant impact on productive human immunodeficiency virus (HIV) infection of monocytes and macrophages (J. Chang et al., J. Virol. 70:7792–7803, 1996). Therefore, the stage in the replication cycle at which these host genetic influences act was investigated in a study using 8 pairs of ID twins and 10 pairs of sex- and age-matched unrelated donors (URDs). In the first phase of the study, blood monocytes and monocyte-derived macrophages (MDM) of ID twins and URDs were infected with 15 HIV type 1 strains. Four well-characterized primary isolates and HIV-BaL were then examined in more detail. The host cell genetic effect in MDM was exerted predominantly prior to complete reverse transcription, as the HIV DNA level and p24 antigen levels were concordant (r= 0.91,P= 0.0001) and similar between the pairs of ID twin pairs (r= 0.96,P= 0.0001) but discordant between URD pairs (r= 0.11,P= 0.3) in both phases of the study. To further examine genetic influence on viral entry, we examined the proportion of CCR5 membrane expression on MDM. As expected, there was wide variability in proportion of MDM expressing CCR5 among URDs (r= 0.58,P= 0.2); however, this variability was significantly reduced between ID twin pairs (r= 0.81,P= 0.01). Differences in viral entry did not necessarily correlate with CCR5 expression, and only very low levels of CCR5 expression restricted HIV entry and production. In summary, the host cell genetic effect on HIV replication in macrophages appears to be exerted predominantly pre-reverse transcription. Although CCR5 was necessary for infection, other unidentified host genes are likely to limit productive infection.
Sequences between the Enhancer and Promoter in the Long Terminal Repeat Affect Murine Leukemia Virus Pathogenicity and Replication in the Thymus
Authors: Yoshimura Fayth K. , Wang Tao , Cankovic Milena 
Published: December 2019

ABSTRACTWe previously showed that the 93-bp region between the enhancer and promoter (named DEN for downstream of enhancer) of the long terminal repeat (LTR) of the MCF13 murine leukemia virus is an important determinant of the ability of this virus to induce thymic lymphoma. In this study we observed that DEN plays a role in the regulation of virus replication in the thymus during the preleukemic period. A NF-κB site in the DEN region partially contributes to the effect of DEN on both lymphomagenicity and virus replication. To further study the effects of DEN and the NF-κB site on viral pathogenicity during the preleukemic period, we examined replication of wild-type and mutant viruses with a deletion of the NF-κB site or the entire DEN region in the thymus. Thymic lymphocytes which were infected with wild-type and mutant viruses were predominantly the CD3−CD4+CD8+and CD3+CD4+CD8+cells. The increase in infection by wild-type virus and both mutant viruses of these two subpopulations during the preleukemic period ranged from 9- to 84-fold, depending upon the time point and virus. The major difference between the wild-type and both mutant viruses was the lower rate and lower level of mutant virus replication in these thymic subpopulations. Significant differences in replication between wild-type and both mutant viruses were seen in the CD3−CD4+CD8+and CD3−CD4−CD8−subpopulations, suggesting that these thymic cell types are important targets for viral transformation.