scholarly journals Molecular dissection of the potato virus Y VPg virulence factor reveals complex adaptations to the pvr2 resistance allelic series in pepper

2007 ◽  
Vol 88 (5) ◽  
pp. 1594-1601 ◽  
Author(s):  
Valérie Ayme ◽  
Julien Petit-Pierre ◽  
Sylvie Souche ◽  
Alain Palloix ◽  
Benoît Moury
Keyword(s):  
Amino Acid ◽  
Potato Virus ◽  
Plant Virus ◽  
Potato Virus Y ◽  
Amino Acid Substitutions ◽  
Molecular Dissection ◽  
Allelic Series ◽  
Trade Offs ◽  
Virulence Spectrum ◽  
Virulence Properties

The virulence properties of potato virus Y (PVY) towards an allelic series at the pvr2 locus in pepper genotypes are related to variations in the genome-linked viral protein (VPg). Eleven amino acid substitutions in the central part of the VPg were identified in strains differing by their virulenceproperties and were introduced, either singly or in combination, in an infectious PVY clone to get an in-depth genetic analysis of the virulence determinant. The virulence spectrum of these mutants was evaluated by inoculation of four pepper genotypes carrying different alleles at the pvr2 locus. The mutations introduced had complex effects on virulence, including antagonisticepistasis and trade-offs for virulence towards different pvr2 alleles. In addition, several mutants showed new virulence properties that were unknown in the natural environment. Such complex effects of mutations on plant virus virulence are unprecedented. They provide a better understanding of the variable levels of durability of the resistance conferred by the different pvr2 alleles, and have important consequences for a durable management of the resistances.

scholarly journals Different Mutations in the Genome-Linked Protein VPg of Potato virus Y Confer Virulence on the pvr23 Resistance in Pepper

2006 ◽  
Vol 19 (5) ◽  
pp. 557-563 ◽  
Author(s):  
Valérie Ayme ◽  
Sylvie Souche ◽  
Carole Caranta ◽  
Mireille Jacquemond ◽  
Joël Chadœuf ◽  
...  
Keyword(s):  
Amino Acid ◽  
Genetic Drift ◽  
Potato Virus ◽  
High Frequency ◽  
Potato Virus Y ◽  
Relative Fitness ◽  
Amino Acid Substitutions ◽  
Nucleotide Substitutions ◽  
Single Nucleotide ◽  
Pepper Plants

Five different amino acid substitutions in the VPg of Potato virus Y were shown to be independently responsible for virulence toward pvr23 resistance gene of pepper. A consequence of these multiple mutations toward virulence involving single nucleotide substitutions is a particularly high frequency of resistance breaking (37% of inoculated plants from the first inoculation) and suggests a potentially low durability of pvr23 resistance. These five mutants were observed with significantly different frequencies, one of them being overrepresented. Genetic drift alone could not explain the observed distribution of virulent mutants. More plausible scenarios were obtained by taking into account either the relative substitution rates, the relative fitness of the mutants in pvr23 pepper plants, or both.

scholarly journals Mutations in Potato virus Y Genome-Linked Protein Determine Virulence Toward Recessive Resistances in Capsicum annuum and Lycopersicon hirsutum

2004 ◽  
Vol 17 (3) ◽  
pp. 322-329 ◽  
Author(s):  
Benoît Moury ◽  
Caroline Morel ◽  
Elisabeth Johansen ◽  
Laurent Guilbaud ◽  
Sylvie Souche ◽  
...  
Keyword(s):  
Amino Acid ◽  
Capsicum Annuum ◽  
Potato Virus ◽  
Potato Virus Y ◽  
Cdna Clones ◽  
Lycopersicon Hirsutum ◽  
Potato Virus A ◽  
Single Nucleotide Change ◽  
Protein Encoding

The recessive resistance genes pot-1 and pvr2 in Lycopersicon hirsutum and Capsicum annuum, respectively, control Potato virus Y (PVY) accumulation in the inoculated leaves. Infectious cDNA molecules from two PVY isolates differing in their virulence toward these resistances were obtained using two different strategies. Chimeras constructed with these cDNA clones showed that a single nucleotide change corresponding to an amino acid substitution (Arg119His) in the central part of the viral protein genome-linked (VPg) was involved in virulence toward the pot-1 resistance. On the other hand, 15 nucleotide changes corresponding to five putative amino acid differences in the same region of the VPg affected virulence toward the pvr21 and pvr22 resistances. Substitution models identified six and five codons within the central and C terminal parts of the VPg for PVY and for the related potyvirus Potato virus A, respectively, which undergo positive selection. This suggests that the role of the VPg-encoding region is determined by the protein and not by the viral RNA apart from its protein-encoding capacity.

scholarly journals OXA-48-Mediated Ceftazidime-Avibactam Resistance Is Associated with Evolutionary Trade-Offs

mSphere ◽  
2019 ◽  
Vol 4 (2) ◽  
Author(s):  
Christopher Fröhlich ◽  
Vidar Sørum ◽  
Ane Molden Thomassen ◽  
Pål Jarle Johnsen ◽  
Hanna-Kirsti S. Leiros ◽  
...  
Keyword(s):  
Amino Acid ◽  
Inhibitory Activity ◽  
Treatment Options ◽  
Inhibitory Effect ◽  
Amino Acid Substitutions ◽  
Gram Negative ◽  
Content Type ◽  
Mortality And Morbidity ◽  
Trade Offs ◽  
Collateral Effects

ABSTRACTInfections due to carbapenemase-producing Gram-negative pathogens are associated with limited treatment options and consequently lead to increased mortality and morbidity. In response, combinations of existing β-lactams and novel β-lactamase inhibitors, such as ceftazidime-avibactam (CAZ-AVI), have been developed as alternative treatment options. To understand the development of resistance and evolutionary trajectories under CAZ-AVI exposure, we studied the effects of ceftazidime (CAZ) and CAZ-AVI on the carbapenemase OXA-48 and the epidemic OXA-48 plasmid inEscherichia coli. Exposure of CAZ and CAZ-AVI resulted in single (P68A) and double (P68A,Y211S) amino acid substitutions in OXA-48, respectively. The antimicrobial susceptibility data and enzyme kinetics showed that the P68A substitution was responsible for an increased activity toward CAZ, whereas P68A,Y211S led to a decrease in the inhibitory activity of AVI. X-ray crystallography and molecular modeling of the mutants demonstrated increased flexibility within the active site, which could explain the elevated CAZ hydrolysis and reduced inhibitory activity of AVI. Interestingly, these substitutions resulted in collateral effects compromising the activity of OXA-48 toward carbapenems and penicillins. Moreover, exposure to CAZ-AVI selected for mutations within the OXA-48-encoding plasmid that severely reduced fitness in the absence of antimicrobial selection. These evolutionary trade-offs may contribute to limit the evolution of OXA-48-mediated CAZ and CAZ-AVI resistance, as well as potentially resensitize isolates toward other therapeutic alternatives.IMPORTANCEThe recent introduction of novel β-lactam/β-lactamase inhibitor combinations like ceftazidime-avibactam has increased our ability to treat infections caused by multidrug-resistant Gram-negative bacteria, including carbapenemase-producingEnterobacterales. However, the increasing number of cases of reported resistance to ceftazidime-avibactam is a concern. OXA-48 is a carbapenemase that has no significant effect on ceftazidime, but is inhibited by avibactam. Since isolates with OXA-48 frequently harbor extended-spectrum β-lactamases that are inhibited by avibactam, it is likely that ceftazidime-avibactam will be used to treat infections caused by OXA-48-producingEnterobacterales.Our data show that exposure to ceftazidime-avibactam can lead to changes in OXA-48, resulting in increased ability to hydrolyze ceftazidime and withstand the inhibitory effect of avibactam. Thus, resistance toward ceftazidime-avibactam among OXA-48-producingEnterobacteralesshould be monitored. Interestingly, the compromising effect of the amino acid substitutions in OXA-48 on other β-lactams and the effect of ceftazidime-avibactam exposure on the epidemic OXA-48 plasmid indicate that the evolution of ceftazidime-avibactam resistance comes with collateral effects.

scholarly journals Fluorescently Tagged Potato virus Y: A Versatile Tool for Functional Analysis of Plant-Virus Interactions

2015 ◽  
Vol 28 (7) ◽  
pp. 739-750 ◽  
Author(s):  
Matevz Rupar ◽  
Florence Faurez ◽  
Michel Tribodet ◽  
Ion Gutiérrez-Aguirre ◽  
Agnès Delaunay ◽  
...  
Keyword(s):  
Functional Analysis ◽  
Potato Virus ◽  
Plant Virus ◽  
Potato Virus Y ◽  
Fluorescent Protein ◽  
Ex Vivo ◽  
Cell Movement ◽  
Long Distance ◽  
Green Fluorescent

Potato virus Y (PVY) is an economically important plant virus that infects Solanaceous crops such as tobacco and potato. To date, studies into the localization and movement of PVY in plants have been limited to detection of viral RNA or proteins ex vivo. Here, a PVY N605 isolate was tagged with green fluorescent protein (GFP), characterized and used for in vivo tracking. In Nicotiana tabacum cv. Xanthi, PVY N605-GFP was biologically comparable to nontagged PVY N605, stable through three plant-to-plant passages and persisted for four months in infected plants. GFP was detected before symptoms and fluorescence intensity correlated with PVY RNA concentrations. PVY N605-GFP provided in vivo tracking of long-distance movement, allowing estimation of the cell-to-cell movement rate of PVY in N. tabacum cv. Xanthi (7.1 ± 1.5 cells per hour). PVY N605-GFP was adequately stable in Solanum tuberosum cvs. Désirée and NahG-Désirée and able to infect S. tuberosum cvs. Bintje and Bea, Nicotiana benthamiana, and wild potato relatives. PVY N605-GFP is therefore a powerful tool for future studies of PVY-host interactions, such as functional analysis of viral and plant genes involved in viral movement.

scholarly journals Helper Component Mutations in Nonconserved Residues Associated with Aphid Transmission Efficiency of a Pepper Isolate of Potato Virus Y

1999 ◽  
Vol 89 (12) ◽  
pp. 1176-1181 ◽  
Author(s):  
César Llave ◽  
Belén Martínez ◽  
J. R. Díaz-Ruíz ◽  
D. López-Abella
Keyword(s):  
Amino Acid ◽  
Potato Virus ◽  
Potato Virus Y ◽  
Aphid Transmission ◽  
Transmission Efficiency ◽  
Binding Assays ◽  
Helper Component ◽  
Rich Domain ◽  
Pepper Isolate

The aphid transmission properties of a pepper isolate of potato virus Y belonging to the pathotype 1–2 (PVY 1–2) have been characterized. PVY 1–2 was not transmitted in plant-to-plant experiments, although purified virus particles were efficiently transmitted when supplemented with heterologous helper component (HC) of the transmissible isolate PVY 0 AT through membrane acquisition assays, indicating that its coat protein was functional in transmission. Additionally, virions of PVY 1–2 were able to bind to different HCs in in vitro binding assays. Analysis of the sequence of the PVY 1–2 HC gene and comparison with that of PVY 0 AT revealed 19 nucleotide differences, but only 2 resulted in amino acid changes, one of which induced a change of charge. Neither of these two amino acid changes occurred within the cysteine-rich domain, nor did they coincide with conserved motifs of the HC protein known to be involved in aphid transmission and which are present in all known potyvi-ruses. However, both changes are located in positions highly conserved among PVY strains. The possible role of both mutations on the activity of the PVY 1–2 HC in aphid transmission is discussed.

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