pinecone/core-2020-05-10-deduplication huggingface dataset:
Hantavirus Pulmonary Syndrome Outbreak in Argentina: Molecular Evidence for Person-to-Person Transmission of Andes Virus

AbstractAn increase of Hantavirus Pulmonary Syndrome (HPS) cases around a southwestern Argentina town and in persons living 1400 km away but in contact with those cases was detected during the spring of 1996. In order to evaluate person-to-person transmission we compared the homology of PCR-amplified viral sequences of 26 Argentine and Chilean cases. Sixteen of them were epidemiologically linked cases and had the same sequence (Epilink/96) in the S segment 3′ noncoding region and in the M segment partial G1 and G2 region (a total of 1075 nucleotides). Contrarily, two geographical and contemporary but nonepidemiologically related cases differed from Epilink/96 in the compared regions. No significant differences, such as glycosylation or hydrophilic pattern, were found between Epilink/96 and the other sequences. Nucleotide and deduced amino acid sequence homologies between samples from southern Argentina and Chile ranged from 90.9 to 100% and 96.4 to 100%, respectively. Phylogenetic analysis revealed that all the analyzed southwestern viruses belong to the Andes lineage. Although human infection principally occurs via inhalation of contaminated rodent excreta, our results with Andes virus show the first direct genetic evidence of person-to-person transmission of a hantavirus
Apoptotic Killing of CD4+T Lymphocytes in HIV-1-Infected PHA-Stimulated PBL Cultures Is Mediated by CD8+LAK Cells

AbstractIn vitroinfection of PHA-stimulated, normal CD4+human peripheral blood T lymphocytes (PBLs) with several HIV-1 isolates did not result in cytopathology, despite high levels of virus replication and the fact that some of these isolates were cytopathic in certain cell lines. In contrast, infection of unfractionated PBLs (containing CD8+as well as CD4+lymphocytes) with these isolates always resulted in death of the infected CD4+T lymphocytes. It has been well documented that PHA stimulation and culture of PBLs in medium containing IL-2 generates lymphokine-activated killer (LAK) cell activity which can destroy many transformed cells and virus-infected normal cells. When CD8+T lymphocytes from PHA-stimulated PBLs were added to HIV-1-infected purified CD4+T lymphocytes, significant lysis occurred. This cytotoxicity was not MHC class I-restricted, and depletion of CD8+T lymphocytes from unfractionated PBL cultures shortly after HIV infection largely abolished the killing of the infected CD4+T lymphocytes. These results demonstrated that CD8+LAK cells were killing the CD4+T lymphocytes in unfractionated PBL cultures infected with these noncytopathic HIV-1 strains. Care is thus warranted when studying HIV cytopathology in unfractionated PBL cultures. Morphological and DNA gel electrophoretic analyses of HIV-infected CD4+T lymphocytes being killed by CD8+LAK cells demonstrated that apoptosis was the predominant mechanism of LAK cell-mediated killing. In contrast, necrosis was the major mechanism involved in killing of purified CD4+T lymphocytes by HIV-1 strains which were directly cytopathic. These findings may explain some of the discrepancies in the literature concerning reports of either apoptotic or necrotic killing of cells by HIVin vitro.Moreover, these data strongly suggest that direct killing by replicating HIV-1in vivoshould reveal necrotic cells and immune effector cell killing should reveal apoptotic cells. Since the latter are much more frequently observedin vivo,perhaps immune effector-mediated depletion of CD4+T lymphocytes is more important as a pathogenic mechanism
Studies on the Movement of Cowpea Mosaic Virus Using the Jellyfish Green Fluorescent Protein

AbstractThe jellyfish green fluorescent protein (GFP) coding sequence was used to replace the coat protein (CP) genes in a full-length cDNA clone of CPMV RNA-2. Transcripts of this construct were replicated in the presence of RNA-1 in cowpea protoplasts, and GFP expression could be readily detected by fluorescent microscopy. It was not possible to infect cowpea plants with these transcripts, but combined with a mutant RNA-2, in which the 48-kDa movement protein (MP) gene has been deleted infection did occur. With this tripartite virus (CPMV-TRI) green fluorescent spots were visible under UV light on the inoculated leaf after 3 days and a few days later on the higher leaves. These results show that the polyproteins encoded by RNA-2 do not possess an essential function in the virus infection cycle and that there is, contrary to what we have found so far for the proteins encoded by RNA-1, no need for a tight regulation of the amounts of MP and CPs produced in a cell. Subsequently, the GFP gene was introduced between the MP and CP genes of RNA-2 utilizing artificial proteolytic processing sites for the viral proteinase. This CPMV-GFP was highly infectious on cowpea plants and the green fluorescent spots that developed on the inoculated leaves were larger and brighter than those produced by CPMV-TRI described above. When cowpea plants were inoculated with CPMV RNA-1 and RNA-2 mutants containing the GFP gene but lacking the CP or MP genes, only single fluorescent epidermal cells were detected between 2 and 6 days postinoculation. This experiment clearly shows that both the capsid proteins and the MP are absolutely required for cell-to-cell movement
SR Protein and snRNP Requirements for Assembly of the Rous Sarcoma Virus Negative Regulator of Splicing Complexin Vitro

AbstractRetroviruses use unspliced RNA as mRNA for expression of virion structural proteins and as genomic RNA; the full-length RNA often constitutes the majority of the viral RNA in an infected cell. Maintenance of this large pool of unspliced RNA is crucial since even a modest increase in splicing efficiency can lead to impaired replication. In Rous sarcoma virus, the negative regulator of splicing (NRS) was identified as aciselement that negatively impacts splicing of viral RNA. Components of the splicing apparatus appear to be involved in splicing inhibition since binding of a number of splicing factors (snRNPs and SR proteins) and assembly of a large complex (NRS-C) in nuclear extracts correlate with NRS-mediated splicing inhibition. In determining the requirements for NRS complex assembly, we show that NRS-C assembly can be reconstituted by addition of total SR proteins to an S100 extract that lacks these factors. Of the purified SR proteins tested, SF2/ASF was functional in NRS-C assembly, whereas SC35 and SRp40 were not. The participation of snRNPs in NRS-C assembly was addressed by selectively depleting individual snRNPs with oligonucleotides and RNase H or by sequestering critical snRNA domains with 2′-O-methyl RNA oligonucleotides. The results indicate that in addition to U11 snRNP, U1 snRNP and SR proteins, but not U2 snRNP, are involved in NRS-C assembly
An Equine Herpesvirus Type 1 Recombinant with a Deletion in the gE and gI Genes Is Avirulent in Young Horses

AbstractThe cell culture-adapted KyA strain of equine herpesvirus type 1 (EHV-1) has been found to be attenuated in young horses (Matsumuraet al.,1996,Vet. Microbiol.48, 353–365). The KyA strain lacks at least six genes in its genome, including those encoding glycoproteins gE and gI. To elucidate whether EHV-1 glycoproteins gE and gI play a role in viral virulence, we have constructed an EHV-1 recombinant that has the genes encoding both gE and gI deleted from its genome and its revertant. Growth properties of the deletion mutant virusin vitrowere compared with those of the parent and the revertant viruses. Plaque size of the mutant virus in fetal horse kidney (FHK) cells was significantly smaller than those of the parent and the revertant viruses. In one-step growth experiments, however, the yields of infectious virus from FHK cells infected with the deletion mutant, the parent, or the revertant virus were approximately the same. The results suggested that gE and/or gI of EHV-1 promoted cell-to-cell spread of the virus, but that these glycoproteins were not involved in the process of virus maturation and release or in virus attachment and penetration. Subsequently, the virulence of mutant and revertant viruses was examined in young horses. No clinical signs were observed in six horses, including three colostrum-deprived foals inoculated intranasally with the deletion mutant virus, whereas three colostrum-deprived foals inoculated intranasally with the revertant virus manifested clinical signs typical for EHV-1 respiratory infection (i.e., pyrexia, nasal discharge, and swelling of submandibular lymph nodes). The results obtained fromin vivostudies revealed that the EHV-1 mutant defective in both gE and gI genes was avirulent in young horses, suggesting that gE and/or gI of the EHV-1 have an important role in EHV-1 virulence. However, the EHV-1 mutant defective in both gE and gI genes induced only a partial protectivity in inoculated foals from manifestation of respiratory symptoms after challenge infection
Apoptosis Induced by a Postbinding Step of Vaccinia Virus Entry into Chinese Hamster Ovary Cells

AbstractUnlike most cell types examined, nonpermissive Chinese hamster ovary (CHO) cells readily underwent apoptosis upon infection with vaccinia virus (VV). Apoptosis was observed as early as 3 h postinfection with an electrophoretic assay of DNA fragmentation and by 8 h using anin situ(TUNEL) assay. The CHOhrgene from cowpox virus, which overcomes host range restriction of VV in CHO cells, merely delayed the onset of apoptosis by approximately 3 h. Intermediate and late viral protein synthesis were not necessary for apoptosis since these events do not proceed under nonpermissive conditions. Apoptosis also occurred in the presence of cytosine arabinoside or cycloheximide, which inhibits DNA or protein synthesis, respectively, and after infection with a mutant virus that is blocked in early transcription. We also demonstrated that viral early transcription was not required for induction of apoptosis by infecting CHO cells with psoralen/UV-inactivated virus. On the other hand, apoptosis was inhibited by a neutralizing antibody to the virion L1R protein added either before or after virus attachment to cells. These results indicate that a postbinding step associated with cell entry is sufficient and required for induction of apoptosis in CHO cells. Recent progress on apoptotic signaling pathways raises the possibility that a cellular receptor for VV may be involved in apoptosis
Mutations in a Carboxy-Terminal Region of Vesicular Stomatitis Virus Glycoprotein G That Affect Membrane Fusion Activity

AbstractThe envelope glycoprotein G of vesicular stomatitis virus induces membrane fusion at acidic pH. A highly conserved amino terminal region spanning residues 123 to 137 has previously been identified as an internal fusion domain. Here we have substituted specific amino acids within a carboxy terminal region, conserved in five vesiculoviruses encompassing residues 395 to 418, and studied the effect of these mutations on membrane fusion at acid pH and pH-dependent conformational change. Substitution of conserved Gly 395, Gly 404, Gly 406, Asp 409, and Asp 411 with Glu, Ala, Ala, Asn, and Asn, respectively, decreased the cell–cell fusion efficiency, as well as reduced the pH threshold of membrane fusion. Mutation of Gly 404 and Asp 409 to Lys and Ala, respectively, abolished the fusion activity. Mutant Gly 404 Lys also showed markedly altered resistance to trypsin digestion at acidic pH. These results suggest that the region between amino acids 395 to 418 is important for the fusogenic activity of the G protein. The possible role of this domain in conformational changes involved in fusion activity of VSV G is also discussed
Assembly of Viroplasm and Virus-like Particles of Rotavirus by a Semliki Forest Virus Replicon

AbstractIn this study we have used an expression system based on Semliki Forest virus (SFV) to study assembly and intracellular localization of certain capsid proteins of rotavirus in neurons and mammalian epithelial cells. The complete genes of vp2 (vp2A) and vp6 (vp6A) of group A rotavirus (SA-11) and gene 5 encoding vp6 (vp6C) of porcine group C rotavirus (strain Cowden/AmC-1) were inserted into an SFV expression replicon. Transfection of BHK-21 cells within vitro-made SFV transcripts resulted in a high level of expression of the heterologous genes. Cotransfection with helper RNA encoding the SFV structural proteins, but lacking the genomic RNA packing signal, resulted in production of recombinant infectious virus. Immunological and biochemical analysis revealed that vp6 was expressed to high levels in primary neurons and mammalian epithelial cells and that vp6 was retained as an authentic homotrimer, stabilized by noncovalent interactions with native antigenic determinants. Thin section electron microscopy analysis revealed that vp6 alone assembled into viroplasm-like structures in the cytoplasm. While coexpression of vp2 and vp6 of group A rotavirus resulted in formation of single-shelled-like particles, no evidence of intracellular assembly was found, suggesting that other viral proteins are required for intracellular formation of single-shelled particles. A notable observation was that the vp6 proteins of group A and C rotaviruses showed different immunofluorescence patterns in BHK-21 cells; vp6C displayed an intense punctate immunofluorescence pattern, while vp6A was characterized by a pronounced filamentous staining in close vicinity to the cytoskeleton
Maize Chlorotic Mottle Machlomovirus and Wheat Streak Mosaic Rymovirus Concentrations Increase in the Synergistic Disease Corn Lethal Necrosis

AbstractCorn lethal necrosis (CLN) is caused by the synergistic interaction between maize chlorotic mottle machlomovirus (MCMV) and any potyvirus which infects cereals. Interactions between MCMV and wheat streak mosaic rymovirus (WSMV) in N28Ht corn produced MCMV concentrations that averaged 3.3- to 11.2-fold higher in doubly infected plants than the average concentrations in plants inoculated with MCMV. MCMV-negative sense RNA concentrations were similarly increased, and the ratio of full-length to subgenomic RNA was the same in singly and doubly infected plants. Contrary to most synergisms involving a potyvirus, WSMV infections were enhanced by the presence of MCMV. WSMV infection rates were higher when plants were coinoculated with MCMV, and the difference in infection rates was more pronounced at higher temperatures. Under conditions favorable for establishing high WSMV infection rates (cooler temperatures and high light intensity), WSMV concentrations in doubly infected plants averaged 2.1- to 3.1-fold higher than those in singly inoculated plants. Doubly inoculated plants with the lowest WSMV levels also had the lowest MCMV concentrations, but the concentrations of MCMV and WSMV in the most heavily infected plants did not directly correlate. These results suggest that there are genes in both MCMV and WSMV which directly or indirectly affect the replication and/or spread of the other virus in CLN
Genetic Reassortment among Viruses Causing Hantavirus Pulmonary Syndrome

AbstractIn order to determine the frequency and characteristics of reassortment among viruses causing hantavirus pulmonary syndrome (HPS), mixed infections were initiated in tissue culture by using two closely related strains of Sin Nombre virus, CC107 (from eastern California) and NMR11 (from New Mexico), which share the same species of rodent host in nature, the deer mouse (Peromyscus maniculatus). Potential reassortant virus plaques were screened by multiplex RT–PCR, using primers specific for individual genome segments of each strain. Reassortant viruses involving the M and S segments and, to a lesser extent, the L segment were detected in 8.5% of 294 progeny plaques tested. In addition, approximately 30% of the progeny virus plaques appeared to contain S or M segments originating from both parental virus strains, i.e., they were diploid. Most of these diploid virus genotypes were not stable, becoming either reassortant or parental virus strains upon plaque-to-plaque virus passage. In contrast to the results above, only one virus reassortant and four diploids were observed among 163 progeny virus plaques from mixed infections between Sin Nombre virus NMR11 and the genetically more distant Black Creek Canal virus, an HPS-causing virus from Florida, which has the cotton rat (Sigmodon hispidus) as its natural host
A Minimally Replicative HIV-2 Live-Virus Vaccine ProtectsM. nemestrinafrom Disease after HIV-2287Challenge

AbstractM. nemestrinaimmunized with an apathogenic HIV-2 molecular clone (HIV-2KR) were protected from CD4 decline and disease upon challenge with HIV-2287, after any immunizing virus could be detected. Higher but not lower inocula of HIV-2KRwere protective against intravenous inoculation of either 105or 101TCID50of HIV-2287. Protected animals displayed substantial reductions in PBMC proviral burden (1–3 logs), viral titers (1–2 logs), and plasma viral RNA (2–4 logs) compared to unprotected or naive animals as early as 1 week postinfection. Plasma viral RNA became undetectable after 24 weeks in protected animals, but remained high in unprotected animals. No viral RNA was present in the spleen of the protected animal necropsied more than a year after challenge (though viral DNA was still present). No neutralizing responses could be demonstrated, but CTL activity was detected sooner and at higher levels after challenge in protected than in unprotected macaques. In this novel HIV-2 vaccine model, protection was clearly dose-dependent, and clearance of challenge virus RNA from the plasma did not require detectable ongoing replication of the immunizing virus at the time of challenge
Expression of Hemagglutinin/Esterase by a Mouse Hepatitis Virus Coronavirus Defective–Interfering RNA Alters Viral Pathogenesis

AbstractA defective-interfering (DI) RNA of mouse hepatitis virus (MHV) was developed as a vector for expressing MHV hemagglutinin/esterase (HE) protein. The virus containing an expressed HE protein (A59-DE-HE) was generated by infecting cells with MHV-A59, which does not express HE, and transfecting thein vitro-transcribed DI RNA containing the HE gene. A similar virus (A59-DE-CAT) expressing the chloramphenicol acetyltransferase (CAT) was used as a control. These viruses were inoculated intracerebrally into mice, and the role of the HE protein in viral pathogenesis was evaluated. Results showed that all mice infected with parental A59 or A59-DE-CAT succumbed to infection by 9 days postinfection (p.i.), demonstrating that inclusion of the DI did not by itself alter pathogenesis. In contrast, 60% of mice infected with A59-DE-HE survived infection. HE- or CAT-specific subgenomic mRNAs were detected in the brains at days 1 and 2 p.i. but not later, indicating that the genes in the DI vector were expressed only in the early stage of viral infection. No significant difference in virus titer or viral antigen expression in brains was observed between A59-DE-HE- and A59-DE-CAT-infected mice, suggesting that virus replication in brain was not affected by the expression of HE. However, at day 3 p.i. there was a slight increase in the extent of inflammatory cell infiltration in the brains of the A59-DE-HE-infected mice. Surprisingly, virus titers in the livers of A59-DE-HE-infected mice were 3 log10lower than that of the A59-DE-CAT-infected mice at day 6 p.i. Also, substantially less necrosis and viral antigen were detected in the livers of the A59-DE-HE-infected mice. This may account for the reduced mortality of these mice. The possible contribution of the host immune system to this difference in pathogenesis was analyzed by comparing the expression of four cytokines. Results showed that both tumor necrosis factor-α and interleukin-6 mRNAs increased in the brains of the A59-DE-HE-infected mice at day 2 p.i., whereas interferon-γ and interleukin-1α mRNAs were similar between A59-DE-HE- and A59-DE-CAT-infected mice. These data suggest that the transient expression of HE protein enhances an early innate immune response, possibly contributing to the eventual clearance of virus from the liver. This study indicates the feasibility of the DI expression system for studying roles of viral proteins during MHV infection
Mapping Regions of the Cauliflower Mosaic Virus ORF III Product Required for Infectivity

AbstractThe open reading frame (ORF) III product (PIII) of the pararetrovirus cauliflower mosaic virus (CaMV) has nucleic acid-binding propertiesin vitro,but its biological role is not yet determined. ORF III is closely linked to ORF II and overlaps ORF IV out of frame in the CaMV genome. A new CaMV-derived vector (CaΔ) devoid of ORF III and containing unique restriction sites between ORFs II and IV was designed. Introduction of the wild-type CaMV ORF III into CaΔ results in a clone (Ca3) infectious in turnip plants. Truncated or point-mutated versions of ORF III were then inserted into CaΔ and testedin vivo.Inoculation of the different mutants into turnip revealed that the four C-terminal amino acid residues of PIII are dispensable for infectivity as well as an internal domain (amino acids 61 to 80). Taken together the results show that PIII possesses a functional two-domain organization. Moreover, the CaMV PIII function(s) cannot be replaced either by the PIII protein of another caulimovirus, the figwort mosaic virus, or by the P2 protein of the cacao swollen shoot badnavirus, a member of the second plant pararetrovirus group
Evolution of Human Immunodeficiency Virus Type 1 Envelope Sequences in Infected Individuals with Differing Disease Progression Profiles

AbstractSequence variation displayed by the human immunodeficiency virus type 1 (HIV-1) has been proposed to be linked to the pathogenesis of acquired immunodeficiency syndrome (AIDS). To assess viral evolution during the course of infection, we evaluated sequence variability in theenvvariable domains in four HIV-1-infected individuals exhibiting differing profiles of CD4+T cell decline when followed from seroconversion until the development of AIDS or loss of followup. Proviral sequences encoding the V3–V5 region of gp120 were obtained following PCR amplification of peripheral blood mononuclear cell DNA and cloning. Virus in each patient was relatively homogeneous early in infection and then diverged with time, more consistently at its nonsynonymous sites. Just prior to or coincident with a rapid decline in CD4+T cell numbers, sequences were found with basic amino acid substitutions clustered within and downstream of the gp120 V3 domain. Within the constraints of the current dataset, we conclude that the virus appears to continually accumulate changes in its amino acid sequences well into the time of marked CD4+T cell decline