pinecone/core-2020-05-10-deduplication huggingface dataset:
Antigenicity and Vaccine Potential of Marburg Virus Glycoprotein Expressed by Baculovirus Recombinants

AbstractThere is no effective vaccine for Marburg virus (MBGV) or any other filovirus, nor enough pertinent information to expedite rational vaccine development. To ascertain some of the minimal requirements for a MBGV vaccine, we determined whether whole inactivated MBGV, or a baculovirus-expressed virion subunit, could be used to immunize guinea pigs against a lethal infection. Baculovirus recombinants were made to express the MBGV glycoprotein (GP) either as a full-length, cell-associated molecule or a slightly truncated (5.4%) product secreted into medium; the latter, for its far greater ease in manipulation, was tested for its vaccine potential. Like MBGV GP, both the full-length and truncated GP expressed by baculovirus recombinants were abundantly glycosylated with both N- and O-linked glycans; differences in glycosylation were detectable, but these could not be shown to affect antigenicity with respect to available antibodies. The recombinant truncated glycoprotein elicited protection against lethal challenge with the MBGV isolate from which it was constructed and less effectively against an antigenically disparate MBGV isolate. Killed (irradiated) MBGV antigen was protective, in a reciprocal fashion, against both MBGV types. In a preliminary assessment of possible protective mechanisms, serum antibodies from immune animals were shown to be sufficient for protecting naive guinea pigs from lethal MBGV infection
Contributions of Antibody and T Cell Subsets to Protection Elicited by Immunization with a Replication-Defective Mutant of Herpes Simplex Virus Type 1

AbstractReplication-defective mutants of herpes simplex virus 1 (HSV-1) elicit immune responses in mice that reduce acute and latent infection after corneal challenge and are protective against development of disease. To understand the basis for the protective immunity induced by this new form of immunization, we investigated the contribution of various components of the immune response to protection against corneal infection and disease. Passive transfer of sera from mice immunized with the replication-defective mutant virus,d301, its parental HSV-1 strain, or uninfected cell lysate was used to examine the role of antibody. Despite posttransfer neutralizing antibody titers equivalent to those in control mice directly immunized with mutant virus, recipients of immune serum showed no reductions in primary replication in the eye, keratitis, or latent infection of the nervous system. However, immune serum protected mice from encephalitis and death. To examine the contribution of T cell subsets to protection, mice were immunized once with mutant virus and then were depletedin vivoof CD4+or CD8+T cells prior to corneal challenge. CD4 depletion resulted in higher titers of challenge virus in the eye at 3 to 4 days after challenge compared to control mice. Latent infection of the nervous system was increased by depletion of CD4+T cells but not by depletion of CD8+T cells. Keratitis developed only in a portion of the CD8+T cell-depleted mice, suggesting that an immunopathologic potential of CD4+T cells is held in check when immune CD8+T cells are also present. Taken together, these data support a role for antibody induced by immunization with a replication-defective virus principally in protecting the central nervous system from disease, roles for CD4+T cells in reducing primary replication in the eye and protecting against latent infection of the nervous system, and a role for CD8+T cells in regulating the immunopathologic activity of CD4+T cells
The Relative Ability of Human Papillomavirus Type 6 and Human Papillomavirus Type 16 E7 Proteins to Transactivate E2F-Responsive Elements Is Promoter- and Cell-Dependent

AbstractThe human papillomavirus 16 E7 protein (HPV 16 E7) transactivates the adenovirus E2 promoter (AdE2) by altering interactions between retinoblastoma (pRb) family members and the transcription factor E2F. To understand factors limiting the oncogenic potential of HPV 6, the relative ability of HPV 6 E7 as compared to HPV 16 E7 to transactivate the AdE2 promoter was determined. In primary baby rat kidney cells and human foreskin keratinocytes, HPV 16 E7 transactivated the AdE2 promoter to a greater extent than HPV 6 E7, consistent with the observation that HPV 16 E7 binds pRb with greater affinity. HPV 6 E7 gain of function correlated with increasing the affinity of the HPV 6 E7 pRb binding site of conserved region 2 (CR2). In keratinocytes, in contrast to the AdE2 promoter, the abilities of the two E7 proteins to transactivate the B-mybpromoter, a promoter regulated by E2F bound to p107/p130, were comparable. Introducing a negative charge into the N-terminus (CR1) and a high affinity pRb binding site into CR2 of HPV 6 E7 resulted in a transactivator with greater activity than HPV 16 E7 for both the AdE2 and B-mybpromoters. Both of the promoters were negatively regulated by E2F and transactivation by the E7 proteins required an intact E2F site. In C33-A cells, which contain a mutated pRb, the two E7 proteins had comparable transactivating activity on both the AdE2 and B-mybpromoters. The data are consistent with the interpretation that HPV 16 E7 affects interactions of pRb and p107/p130 with the E2F transcription factor, whereas HPV 6 E7 only affects interactions of p107/p130
The Effect of Herpes Simplex Virus Type 1 L-Particles on Virus Entry, Replication, and the Infectivity of Naked Herpesvirus DNA

AbstractHerpes simplex virus type 1(HSV-1) L-particles are known to be composed mainly of envelope and tegument proteins, to lack the nucleocapsid, and to be noninfectious. Thus L-particles represent interesting vaccine candidates. L-particles at >1000/cell interfered with HSV-1 virion adsorption and penetration. While L-particles did not affect HSV-1 growth kinetics in resting or nonresting BHK cultures infected with purified virions, treatment with L-particles before, or after, transfection with HSV-1 DNA resulted in a progressive increase in plaque numbers (five- to sixfold at 1000 L-particles/cell). Transfection assays using HSV-1tsmutant DNA (ts1201) revealed that enhancement was due to induction of otherwise nonreplicating genomes. The enhancement obtained with L-particles produced by WT HSV-1 or by mutants that are either deleted, or defective, in certain gene products was compared. Most important were the Vmw110 (ICP0) and Vmw65 (α-TIF) proteins, but VP11/12, VP13/14, and vhs also have a role. The L-particle-associated Vmw175 (ICP 4) protein did not appear be involved. The effect of homologous and heterologous combinations of pseudorabies virus, equineherpesvirus-1, and HSV-1 DNA's and L-particles was investigated in transfection assays. The L-particles of each virus, to varying extent, enhanced the plaquing efficiency of their own DNA but were also effective in heterologous combinations
The Myxoma Virus M-T4 Gene Encodes a Novel RDEL-Containing Protein That Is Retained within the Endoplasmic Reticulum and Is Important for the Productive Infection of Lymphocytes

AbstractTo investigate the contribution of the myxoma virus M-T4 gene to viral virulence, both copies of the M-T4 gene were inactivated by disruption and insertion of theEscherichia coliguanosine phosphoribosyltransferase gene. Infection of European rabbits with the recombinant M-T4-deleted virus, vMyxlacT4−, resulted in disease attenuation. In contrast, infection of rabbits with vMyxlac elicited the classical features of lethal myxomatosis. A notable decrease in the number of secondary lesions in animals infected with vMyxlacT4−suggested an inability of the virus to disseminatein vivo.Infection of either a rabbit CD4+T cell line, RL-5, or primary rabbit peripheral blood lymphocytes with vMyxlacT4−resulted in the rapid induction of apoptosis. Sequence analysis of M-T4 revealed both an N-terminal signal sequence and a C-terminal -RDEL sequence, suggesting that M-T4 resides in the endoplasmic reticulum. The M-T4 protein was found to be sensitive to endo H digestion and confocal fluorescence microscopy demonstrated that M-T4 colocalized with calreticulin, indicating that M-T4 is retained within the endoplasmic reticulum. Our results indicate that M-T4 is the first example of an intracellular virulence factor in myxoma virus that functions from within the endoplasmic reticulum and is necessary for the productive infection of lymphocytes
Efficient Virus Transmission from Dendritic Cells to CD4+T Cells in Response to Antigen Depends on Close Contact through Adhesion Molecules

AbstractMonocyte-derived cultured dendritic cells (DCs) are potent antigen-presenting cells (APCs) and are susceptible to HIV-1Laiinfection. Compared to the low level of virus production by HIV-1-infected DCs alone, a level of virus two to three orders of magnitude higher was produced by cocultivation of HIV-1-infected DCs with autologous resting CD4+T cells in the presence of a nominal antigen. In this coculture system, direct contact of HIV-1-infected DCs with T cells was crucial for efficient virus transmission and subsequent virus production. Blocking of the LFA-1/ICAM-1 or LFA-3/CD2 interaction between these cells substantially reduced virus production, without influence on IL-2 production by activated T cells. In contrast, cell–cell transmission of HIV between non-APCs and activated T cells was not blocked by an antibody against LFA-3. Since a low level of virus production by HIV-infected DCs was upregulated by cross-linking of CD40, it was suggested that not only focal adhesion, but also mutual activation of HIV-infected DCs and T cells through adhesion molecules, may potentiate virus transmission and production and that such activation signals to HIV may be distinct from signals responsible for IL-2 production in activated T cells
Phylogenetic Analysis of the Human Papillomavirus Type 2 (HPV-2), HPV-27, and HPV-57 Group, Which Is Associated with Common Warts

AbstractHuman papillomavirus types 2 (HPV-2), HPV-27, and HPV-57, are three closely related viruses within the phylogenetic supergroup formed by the remotely related genital papillomaviruses. In contrast to this phylogenetic association, these three viruses are most often found in common warts at nongenital sites, but also occasionally in genital warts and mucosal lesions of the nasopharyngeal cavity. We studied the genomic diversity of HPV sequences in skin warts presumably caused by these viruses. These biopsies were sampled from 75 patients living in Germany, Japan, or Singapore. Among 27 warts with HPV-2, we found seven new genomic variants and among 32 with HPV-57, eight new variants. In both cases, we did not detect the original prototype genomes. In contrast, 13 of 16 warts with HPV-27 contained the prototype genome, and only one new variant was found in three patients. We did not find variants clearly intermediate between any two types, although HPV-2 and HPV-27 are among the most closely related of the extent HPV types. We also did not detect novel HPV types, although the samples were examined with polymerase chain reaction protocols that would have detected remotely related HPVs. So we propose that the phylogenetic group formed by HPV-2, HPV-27, and HPV-57 has no or only very rare additional members. One of the HPV-57 variants found, HPV-57-G44, was most likely identical to the subtype HPV-57b, previously proposed to be associated with nasal neoplasia, but found here frequently in common skin warts. Our publication establishes a foundation for pathological and phylogenetic comparisons of HPV types in skin warts
Viability and Pathogenicity of Intersubgroup Viroid Chimeras Suggest Possible Involvement of the Terminal Right Region in Replication

AbstractTo investigate the structural determinants regulating viroid replication and pathogenicity, we have examined the biological properties of four chimeric viroids containing sequences derived from hop stunt (HSVd) and citrus exocortis (CEVd) viroids. The viability of each chimera — CEHS (CEVd left half + HSVd right half), HSCE (HSVd left half + CEVd right half), CE/HS-TR (CEVd + HSVd right terminal loop), and HS/CE-TR (HSVd + CEVd right terminal loop)—was tested by inoculation onto cucumber and tomato seedlings. Chimeras CEHS and HSCE were not infectious, but CE/HS-TR and HS/CE-TR replicated stably and produced disease symptoms when inoculated onto tomato or cucumber, respectively. Progeny accumulation was reduced 10-fold or more compared to that of CEVd in tomato or HSVd in cucumber. The results suggested that the TR, like the TL and P regions, forms a relatively independent structural unit that contributes to the total function of a viroid. The effect of sequences in the right terminal loop on pathogenicity appears to be indirect, modulating the efficiency of viroid replication (or accumulation) efficiency rather than symptom expression per se
Murine Cytomegalovirus Infection-Induced Polyclonal B Cell Activation Is Independent of CD4+T Cells and CD40

AbstractThe results of this study demonstrate that murine cytomegalovirus (MCMV) induces polyclonal B cell activation in mice during the acute phase of primary infection. First, flow cytometric analysis revealed that surface expression of CD45R, IgM, and Igκ by splenocytes from MCMV-infected mice was significantly reduced with a concomitant increase in the frequency of surface IgG-expressing cells. Second, ELIspot assays demonstrated that the changes revealed by flow cytometry were paralleled by increases in the numbers of IgG-producing cells, especially those secreting IgG2a. Third, the IgG antibodies from MCMV-infected animals reacted against a variety of self and foreign antigens. MCMV-induced B cell activation was independent of CD4+T-cell-mediated help and CD40, since activation was observed in two models of mice deficient for this T cell subset and in mice deficient for CD40. Reverse transcription–polymerase chain reaction analysis showed that mRNA transcripts for the cytokines IL-6, IL-10, and IFN-γ were rapidly induced following infection with MCMV, but only IL-6 and IFN-γ proteins were detectable by ELISA. In addition, the numbers of cells producing IL-6 and IFN-γ were significantly increased in the spleen. The magnitude of the polyclonal B cell activation response was diminished by 50% in IL-6-deficient mice but not in mice lacking IFN-γ. In the absence of IFN-γ, surface expression and serum levels of IgG2awere reduced while IgG1expression was increased
Activation of a Ras–MAPK-Dependent Pathway by Epstein–Barr Virus Latent Membrane Protein 1 Is Essential for Cellular Transformation

AbstractThe latent membrane protein 1 (LMP1) of Epstein–Barr virus (EBV) is the only EBV protein which possesses the properties of an oncogene. In studies initiated to evaluate the mechanisms involved in EBV-induced malignant transformation, the extracellular response kinase (ERK) 1/2 were found to be activated 2 days after EBV infection of purified resting human B cells. Transfection studies in Rat-1 fibroblasts, an established rodent cell line, showed that LMP1 mediates ERK 1/2 activation. Cotransfection experiments with a dominant negative ras mutant demonstrated that such MAPK activation occurs via a ras-dependent pathway. Finally, cotransfection studies showed that ras activation is required for LMP-1-mediated malignant transformation of Rat-1 cells
Variation in the Glycoprotein and VP35 Genes of Marburg Virus Strains

AbstractMarburg virus, the prototype of the familyFiloviridae,differs genetically, serologically, and morphologically from Ebola viruses. To better define the genetic variation within the species, VP35 and glycoprotein (GP) genes of representative human isolates from four known episodes of Marburg virus hemorrhagic fever were analyzed. The percentage nucleotide differences in the GP gene coding regions of Marburg viruses (0.1–21%) was nearly equal to the percentage amino acid changes (0–23%), while the percentage nucleotide differences in VP35 coding regions (0.3–20.9%) were higher than the percentage amino acid changes (0.9–6.1%), indicating a greater number of nonsynonymous changes occurring in the GP gene. The higher variation in the GP gene and the corresponding protein, especially those changes in the variable middle region of the GP, suggests that the variability may be the result of responses to natural host pressures. Analysis of the GP gene open reading frame shows a nonrandom distribution of nonsynonymous mutations that may indicate positive Darwinian selection is operating within the variable region. A heptad repeat region and an adjoining predicted fusion peptide are found in the C-terminal third of Marburg virus GPs, as has been previously shown for Ebola virus, and are similar to those found in transmembrane glycoproteins of retroviruses, paramyxoviruses, coronaviruses, and influenza viruses. Comparative analyses showed that there are two lineages within the Marburg virus species of filoviruses. The most recent isolate from Kenya (1987) represents a separate genetic lineage within the Marburg virus species (21–23% amino acid difference). However, this lineage likely does not represent a separate Marburg subtype, as the extent of divergence is less than that separating Ebola virus subtypes
Autographa californicaNuclear Polyhedrosis Virus: Subcellular Localization and Protein Trafficking of BV/ODV-E26 to Intranuclear Membranes and Viral Envelopes

AbstractTheAutographa californicanuclear polyhedrosis virusda26gene codes for an envelope protein of both budded virus (BV) and occlusion derived virus (ODV). Western blot and temporal analysis of infected cell extracts detected a protein of 26 kDa by 4 h postinfection (p.i.). The amount of protein increased by 16 h p.i. and remained at high levels throughout infection. By 36 h p.i. several additional immunoreactive proteins were detected which migrated at ≈18 kDa and remained through 96 h p.i. Western blot analysis of purified virus envelope and nucleocapsid preparations revealed that both the 26- and 18-kDa proteins are structural proteins of the envelope of BV and ODV. Immunoelectron microscopy performed at a time when only the 26-kDa species of the protein was present confirmed that the protein located to ODV envelope. The protein was named BV/ODV-E26 to designate incorporation into viral progeny, envelope location, and apparent molecular weight. Studies designed to follow localization of BV/ODV-E26 demonstrated that early in infection, the protein was incorporated into cytoplasmic vesicles and by 16 h p.i., BV/ODV-E26 was detected in the nucleus associated with virus-induced intranuclear microvesicles and ODV envelope. Coimmunoprecipitation and yeast two-hybrid assays showed that BV/ODV-E26 and FP25K were capable of interacting with each other to form a complex and coimmunoprecipitation assays indicated that cellular actin was a third component of this complex. Together, these data suggest that FP25K and cellular actin may participate in the regulation, or movement through the cell, of baculovirus proteins and/or virus nucleocapsids
Two Closely Related Adenovirus Genome Types with Kidney or Respiratory Tract Tropism Differ in Their Binding to Epithelial Cells of Various Origins

AbstractThe host–cell interactions of the genome types Ad11p and Ad11a of human adenovirus serotype 11, displaying kidney or respiratory tropism, were compared using FACS analysis. Kinetic experiments indicated that the virus binding started immediately and reached a plateau after 30 min. The binding of biotinylated virions to seven continuous cell lines: A549, A498, J82, HeLa, CHO, MDCK, and human diploid fibroblasts (HEDF), was quantitated by FACS analysis. The binding capacities of the two viruses to all human cell lines but A549 cells appeared to differ. Ad11p virions manifested high affinities, whereas Ad11a virions presented low affinities. Neither of the two viruses bound to CHO or MDCK cells. Reciprocal competition experiments showed that the Ad11a virions could be weakly blocked by the Ad11p virions, whereas the Ad11p virions could not be competed at all by the Ad11a virions. The binding of the Ad11p virions to cells could be blocked by the rfiber antiserum of Ad11p, but not by the corresponding antiserum against Ad11a or Ad35p. A comparison of the cytopathogenicity of the seven cell lines infected by Ad11p and Ad11a demonstrated that the efficiency of the initial event of an adenovirus infection directly affects the outcome of the viral infection. The Ad11a in the A498, J82, HeLa, or HEDF cells that presented lower affinity and receptor concentration showed 100 times less infectivity than that in A549 cells displaying high affinity and receptor concentration. These results indicate that the cell susceptibility to Ad11p and Ad11a infection strongly depends on both the number of fiber receptors on the host cells and the receptor affinity for ligands on the fiber knob. Our findings also suggest that the receptors for Ad11p and Ad11a on the surface of different cell types may be different or on different sites
Amino Terminus of Reovirus Nonstructural Protein ςNS Is Important for ssRNA Binding and Nucleoprotein Complex Formation

AbstractReovirus nonstructural protein ςNS exhibits a ssRNA-binding activity thought to be involved in assembling the reovirus mRNAs for genome replication and virion morphogenesis. To extend analysis of this activity, recombinant ςNS (rςNS) was expressed in insect cells using a recombinant baculovirus. In infected-cell extracts, rςNS was found in large complexes (≥30 S) that were disassembled into smaller, 13–19 S complexes upon treatment with RNase A. RςNS also bound to poly(A)–Sepharose beads both before and after purification. Treatment with high salt during purification caused rςNS to sediment in even smaller, 7–9 S complexes, consistent with more complete loss of RNA. To localize the RNA-binding site, limited proteolysis was used to fragment the rςNS protein. Upon mild treatment with thermolysin, 11 amino acids were removed from the amino terminus of rςNS, and the resulting protein no longer bound to poly(A). In addition, when rςNS in cell extracts was treated with thermolysin to generate the amino-terminally truncated form, it sedimented at 7–9 S, also consistent with the loss of RNA-binding capacity. To confirm these findings, a deletion mutant lacking amino acids 2–11 was constructed and expressed in insect cells from a recombinant baculovirus. The mutant protein in cell extracts showed greatly reduced poly(A)-binding activity and sedimented as 7–9 S complexes. These data suggest that the first 11 amino acids of ςNS, which are predicted to form an amphipathic α-helix, are important for both ssRNA binding and formation of complexes larger than 7–9 S
Rubella Virus Replication Complexes Are Virus-Modified Lysosomes

AbstractReplication complexes are membrane-bound cytoplasmic vacuoles involved in rubella virus (RV) replication. These structures can be identified by their characteristic morphology at the electron microscopy (EM) level and by their association with double-stranded (ds) RNA in immunogold labeling EM studies. Although these virus-induced structures bear some resemblance to lysosomes, their exact nature and origin are unknown. In this study, the localization of two lysosomal markers, lysosomal-associated membrane protein (Lamp-1) and acid phosphatase, relative to the replication complexes was examined by light and electron microscopy. Confocal microscopy using antibodies to dsRNA and Lamp-1 showed colocalization of these two markers in the cytoplasm of RV-infected cells. Immunogold labeling EM studies using antibodies to Lamp-1 confirmed that Lamp-1 was associated with RV replication complexes. EM histochemical studies demonstrated the presence of acid phosphatase in the vacuoles of RV replication complexes. Taken together, these studies show that RV replication complexes are virus-modified lysosomes