The Experts below are selected from a list of 282 Experts worldwide ranked by ideXlab platform
Bryony C Bonning - One of the best experts on this subject based on the ideXlab platform.
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Role of Pea Enation Mosaic Virus Coat Protein in the Host Plant and Aphid Vector
Viruses, 2016Co-Authors: Juliette Doumayrou, Melissa Sheber, Bryony C Bonning, Wyatt Allen MillerAbstract:Understanding the molecular mechanisms involved in plant virus–vector interactions is essential for the development of effective control measures for aphid-vectored epidemic plant diseases. The coat proteins (CP) are the main component of the viral capsids, and they are implicated in practically every stage of the viral infection cycle. Pea enation mosaic virus 1 (PEMV1, Enamovirus, Luteoviridae) and Pea enation mosaic virus 2 (PEMV2, Umbravirus, Tombusviridae) are two RNA viruses in an obligate symbiosis causing the pea enation mosaic disease. Sixteen mutant viruses were generated with mutations in different domains of the CP to evaluate the role of specific amino acids in viral replication, virion assembly, long-distance movement in Pisum sativum, and aphid transmission. Twelve mutant viruses were unable to assemble but were able to replicate in inoculated leaves, move long-distance, and express the CP in newly infected leaves. Four mutant viruses produced virions, but three were not transmissible by the pea aphid, Acyrthosiphon pisum. Three-dimensional modeling of the PEMV CP, combined with biological assays for virion assembly and aphid transmission, allowed for a model of the assembly of PEMV coat protein subunits.
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A peptide that binds the pea aphid gut impedes entry of Pea enation mosaic virus into the aphid hemocoel
Virology, 2010Co-Authors: Sijun Liu, Wendy O. Sparks, Sri Sivakumar, W. Allen Miller, Bryony C BonningAbstract:Development of ways to block virus transmission by aphids could lead to novel and broad-spectrum means of controlling plant viruses. Viruses in the Luteoviridae enhanced are obligately transmitted by aphids in a persistent manner that requires virion accumulation in the aphid hemocoel. To enter the hemocoel, the virion must bind and traverse the aphid gut epithelium. By screening a phage display library, we identified a 12-residue gut binding peptide (GBP3.1) that binds to the midgut and hindgut of the pea aphid Acyrthosiphon pisum. Binding was confirmed by labeling the aphid gut with a GBP3.1-green fluorescent protein fusion. GBP3.1 reduced uptake of Pea enation mosaic virus (Luteoviridae) from the pea aphid gut into the hemocoel. GBP3.1 also bound to the gut epithelia of the green peach aphid and the soybean aphid. These results suggest a novel strategy for inhibiting plant virus transmission by at least three major aphid pest species. © 2010 Elsevier Inc.
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The readthrough domain of pea enation mosaic virus coat protein is not essential for virus stability in the hemolymph of the pea aphid
Archives of Virology, 2009Co-Authors: S. Sivakumar, Bryony C Bonning, Zhaohui Wang, W. Allen MillerAbstract:A fraction of the coat protein (CP) subunits in virions of members of the family Luteoviridae contain a C-terminal extension called the readthrough domain (RTD). The RTD is necessary for persistent aphid transmission, but its role is unknown. It has been reported to be required for virion stability in the hemolymph. Here, we tested whether this was the case for pea enation mosaic virus (PEMV) virions in the pea aphid ( Acyrthosiphon pisum ) using RNA1Δ, a natural deletion mutant lacking the middle portion of the RTD ORF, and CPΔRTD, in which the entire RTD ORF was deleted. In infected plants, RNA1Δ virions were as abundant and stable as wild-type (WT) virions, while CPΔRTD virions were unstable. No RTD of any size was translated from artificial subgenomic mRNA of CPΔRTD or RNA1Δ in vitro. Thus, only the major CP was present in the mutant virions. Using real-time RT-PCR to detect virion RNA, no significant differences in the concentration or stability of WT and RNA1Δ virions were detected in the aphid hemolymph at much longer times than are necessary for virus transmission. Thus, the RTD is not necessary for stability of PEMV RNA in the aphid hemolymph, and it must play another role in aphid transmission.
Stephen P. Goff - One of the best experts on this subject based on the ideXlab platform.
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the role of gag in human immunodeficiency virus type 1 virion morphogenesis and early steps of the viral life cycle
Journal of Virology, 1996Co-Authors: Alise S Reicin, Asa Ohagen, Stefan Hoglund, Stephen P. GoffAbstract:The phenotypes of a series of mutant human immunodeficiency virus type 1 proviruses with linker insertion and deletion mutations within the gag coding region were characterized. These mutants, with mutations in the matrix, capsid, and p2 coding regions, produced replication-defective virion particles with defects in the early steps of the viral life cycle. To investigate this phenotype further, the abilities of mutant virion particles to enter T cells, initiate and complete reverse transcription, and transport the newly transcribed proviral DNA were investigated. Only 4 of 10 of the mutants appeared to make wild-type levels of viral DNA. Biochemical analyses of the mutants revealed the middle region of CA as being important in determining virion particle density and sedimentation in velocity gradients. This region also appears to be critical in determining the morphology of mature virion particles by electron microscopy. Particles with aberrant morphology were uninfectious, and only those mutants which displayed cone-shaped cores were capable of carrying out the early steps of the viral life cycle. Thus, the normal morphology of human immunodeficiency virus type 1 appears to be critical to infectivity.
Ronald C Montelaro - One of the best experts on this subject based on the ideXlab platform.
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functions of early ap 2 and late aip1 alix endocytic proteins in equine infectious anemia virus budding
Journal of Biological Chemistry, 2005Co-Authors: Chaoping Chen, Olivier Vincent, Ora A Weisz, Ronald C MontelaroAbstract:Abstract The proline-rich L domains of human immunodeficiency virus 1 (HIV-1) and other retroviruses interact with late endocytic proteins during virion assembly and budding. In contrast, the YPDL L domain of equine infectious anemia virus (EIAV) is apparently unique in its reported ability to interact both with the μ2 subunit of the AP-2 adaptor protein complex and with ALG-2-interacting protein 1 (AIP1/Alix) protein factors involved in early and late endosome formation, respectively. To define further the mechanisms by which EIAV adapts vesicle trafficking machinery to facilitate virion production, we have examined the specificity of EIAV p9 binding to endocytic factors and the effects on virion production of alterations in early and late endocytic protein expression. The results of these studies demonstrated that (i) an ∼300-residue region of AIP1/Alix-(409-715) was sufficient for binding to the EIAV YPDL motif; (ii) overexpression of AIP1/Alix or AP-2 μ2 subunit specifically inhibited YPDL-mediated EIAV budding; (iii) virion budding from a replication-competent EIAV variant with its L domain replaced by the HIV PTAP sequence was inhibited by wild type or mutant μ2 to a level similar to that observed when a dominant-negative mutant of Tsg101 was expressed; and (iv) overexpression or siRNA silencing of AIP1/Alix and AP-2 revealed additive suppression of YPDL-mediated EIAV budding. Taken together, these results indicated that both early and late endocytic proteins facilitate EIAV production mediated by either YPDL or PTAP L domains, suggesting a comprehensive involvement of endocytic factors in retroviral assembly and budding that can be accessed by distinct L domain specificities.
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differential effects of actin cytoskeleton dynamics on equine infectious anemia virus particle production
Journal of Virology, 2004Co-Authors: Chaoping Chen, Ora A Weisz, Donna B Stolz, Simon C Watkins, Ronald C MontelaroAbstract:Retrovirus assembly and budding involve a highly dynamic and concerted interaction of viral and cellular proteins. Previous studies have shown that retroviral Gag proteins interact with actin filaments, but the significance of these interactions remains to be defined. Using equine infectious anemia virus (EIAV), we now demonstrate differential effects of cellular actin dynamics at distinct stages of retrovirus assembly and budding. First, virion production was reduced when EIAV-infected cells were treated with phallacidin, a cell-permeable reagent that stabilizes actin filaments by slowing down their depolymerization. Confocal microscopy confirmed that the inhibition of EIAV production correlated temporally over several days with the incorporation dynamics of phallacidin into the actin cytoskeleton. Although the overall structure of the actin cytoskeleton and expression of viral protein appeared to be unaffected, phallacidin treatment dramatically reduced the amount of full-length Gag protein associated with the actin cytoskeleton. These data suggest that an association of full-length Gag proteins with de novo actin filaments might contribute to Gag assembly and budding. On the other hand, virion production was enhanced when EIAV-infected cells were incubated briefly (2 h) with the actin-depolymerizing drugs cytochalasin D and latrunculin B. Interestingly, the enhanced virion production induced by cytochalasin D required a functional late (L) domain, either the EIAV YPDL L-domain or the proline-rich L domains derived from human immunodeficiency virus type 1 or Rous sarcoma virus, respectively. Thus, depolymerization of actin filaments may be a common function mediated by retrovirus L domains during late stages of viral budding. Taken together, these observations indicate that dynamic actin polymerization and depolymerization may be associated with different stages of viral production.
Michael Emerman - One of the best experts on this subject based on the ideXlab platform.
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uracil dna glycosylase is dispensable for human immunodeficiency virus type 1 replication and does not contribute to the antiviral effects of the cytidine deaminase apobec3g
Journal of Virology, 2006Co-Authors: Shari M Kaiser, Michael EmermanAbstract:It is well established that many host factors are involved in the replication of human immunodeficiency virus (HIV) type 1. One host protein, uracil DNA glycosylase 2 (UNG2), binds to multiple viral proteins and is packaged into HIV type 1 virions. UNG initiates the removal of uracils from DNA, and this has been proposed to be important both for reverse transcription and as a mediator to the antiviral effect of virion-incorporated Apobec3G, a cytidine deaminase that generates numerous uracils in the viral DNA during virus replication. We used a natural human UNG−/− cell line as well as cells that express a potent catalytic active-site inhibitor of UNG to assess the effects of removing UNG activity on HIV infectivity. In both cases, we find UNG2 activity and protein to be completely dispensable for virus replication. Moreover, we find that virion-associated UNG2 does not affect the loss of infectivity caused by Apobec3G.
W. Allen Miller - One of the best experts on this subject based on the ideXlab platform.
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The readthrough domain of pea enation mosaic virus coat protein is not essential for virus stability in the hemolymph of the pea aphid
Archives of Virology, 2009Co-Authors: S. Sivakumar, Bryony C Bonning, Zhaohui Wang, W. Allen MillerAbstract:A fraction of the coat protein (CP) subunits in virions of members of the family Luteoviridae contain a C-terminal extension called the readthrough domain (RTD). The RTD is necessary for persistent aphid transmission, but its role is unknown. It has been reported to be required for virion stability in the hemolymph. Here, we tested whether this was the case for pea enation mosaic virus (PEMV) virions in the pea aphid ( Acyrthosiphon pisum ) using RNA1Δ, a natural deletion mutant lacking the middle portion of the RTD ORF, and CPΔRTD, in which the entire RTD ORF was deleted. In infected plants, RNA1Δ virions were as abundant and stable as wild-type (WT) virions, while CPΔRTD virions were unstable. No RTD of any size was translated from artificial subgenomic mRNA of CPΔRTD or RNA1Δ in vitro. Thus, only the major CP was present in the mutant virions. Using real-time RT-PCR to detect virion RNA, no significant differences in the concentration or stability of WT and RNA1Δ virions were detected in the aphid hemolymph at much longer times than are necessary for virus transmission. Thus, the RTD is not necessary for stability of PEMV RNA in the aphid hemolymph, and it must play another role in aphid transmission.
