Small plaque parapsoriasis

2011 ◽  
Keyword(s):  
Small Plaque

Scholtz–Dumas psoriasis small plaque bioassay

2000 ◽  
Vol 11 (1) ◽  
pp. 15-19 ◽  
Author(s):  
Martin Katz, Zafar Shaikh, Howard I Maibac
Keyword(s):  
Small Plaque

scholarly journals Natural Selection of Glycoprotein B Mutations That Rescue the Small-Plaque Phenotype of a Fusion-Impaired Herpes Simplex Virus Mutant

mBio ◽  
2018 ◽  
Vol 9 (5) ◽  
Author(s):  
Qing Fan ◽  
Sarah J. Kopp ◽  
Nina C. Byskosh ◽  
Sarah A. Connolly ◽  
Richard Longnecker
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Conformational Change ◽  
Virus Entry ◽  
Glycoprotein B ◽  
Novel Mutations ◽  
Small Plaque ◽  
Plaque Phenotype ◽  
Simplex Virus ◽  
The Impact

ABSTRACTGlycoprotein B (gB) is a conserved viral fusion protein that is required for herpesvirus entry. To mediate fusion with the cellular membrane, gB refolds from a prefusion to a postfusion conformation. We hypothesize that an interaction between the C-terminal arm and the central coiled coil of the herpes simplex virus 1 (HSV-1) gB ectodomain is critical for fusion. We previously reported that three mutations in the C-terminal arm (I671A/H681A/F683A, called gB3A) greatly reduced cell-cell fusion and that virus carrying these mutations had a small-plaque phenotype and delayed entry into cells. By serially passaging gB3A virus, we selected three revertant viruses with larger plaques. These revertant viruses acquired mutations in gB that restore the fusion function of gB3A, including gB-A683V, gB-S383F/G645R/V705I/A855V, and gB-T509M/N709H. V705I and N709H are novel mutations that map to the portion of domain V that enters domain I in the postfusion structure. S383F, G645R, and T509M are novel mutations that map to an intersection of three domains in a prefusion model of gB. We introduced these second-site mutations individually and in combination into wild-type gB and gB3A to examine the impact of the mutations on fusion and expression. V705I and A855V (a known hyperfusogenic mutation) restored the fusion function of gB3A, whereas S383F and G645R dampened fusion and T509M and N709H worked in concert to restore gB3A fusion. The results identify two regions in the gB ectodomain that modulate the fusion activity of gB, potentially by impacting intramolecular interactions and stability of the prefusion and/or postfusion gB trimer.IMPORTANCEGlycoprotein B (gB) is an essential viral protein that is conserved in all herpesviruses and is required for virus entry. gB is thought to undergo a conformational change that provides the energy to fuse the viral and cellular membranes; however, the details of this conformational change and the structure of the prefusion and intermediate conformations of gB are not known. Previously, we demonstrated that mutations in the gB “arm” region inhibit fusion and impart a small-plaque phenotype. Using serial passage of a virus carrying these mutations, we identified revertants with restored plaque size. The revertant viruses acquired novel mutations in gB that restored fusion function and mapped to two sites in the gB ectodomain. This work supports our hypothesis that an interaction between the gB arm and the core of gB is critical for gB refolding and provides details about the function of gB in herpesvirus-mediated fusion and subsequent virus entry.

Small Plaque Assay

2000 ◽  
pp. 289-293
Author(s):  
Antti I. Lauerma ◽  
Howard I. Maibach
Keyword(s):  
Plaque Assay ◽  
Small Plaque

The Operator's View

1960 ◽  
Vol 64 (594) ◽  
pp. 335-339
Author(s):  
J. W. G. James
Keyword(s):  
Flight Safety ◽  
Small Plaque ◽  
Personal Reason ◽  
The Many

It is singularly appropriate that Mr. Walter Tye should be in the Chair today, not only by reason of his membership of the Air Registration Board, that Cerberus which watches so efficiently over so many aspects of safety in the air, but also for a more personal reason. He recently received the “ Aviation Week “ Award for distinguished service in achieving safer utilisation of aircraft, and I should like to take this semi-public opportunity of adding my congratulations to the many which he has received.In many of the offices of my airline one finds displayed a small plaque. On it appears, among other words, the legend “Safety is no Accident.” Although I am no great believer in the power of an oft-repeated formula to achieve miracles, I do believe that these words hold within them much of my flight safety philosophy.

scholarly journals Characterization of Plaque Variants and the Involvement of Quasi-Species in a Population of EV-A71

Viruses ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 651
Author(s):  
Madiiha Bibi Mandary ◽  
Malihe Masomian ◽  
Seng-Kai Ong ◽  
Chit Laa Poh
Keyword(s):  
Growth Kinetics ◽  
Vaccine Development ◽  
Homology Modelling ◽  
Size Variation ◽  
Viral Fitness ◽  
Plaque Morphology ◽  
Spontaneous Mutations ◽  
Small Plaque ◽  
Live Attenuated Vaccine

Viral plaque morphologies in human cell lines are markers for growth capability and they have been used to assess the viral fitness and selection of attenuated mutants for live-attenuated vaccine development. In this study, we investigate whether the naturally occurring plaque size variation reflects the virulence of the variants of EV-A71. Variants of two different plaque sizes (big and small) from EV-A71 sub-genotype B4 strain 41 were characterized. The plaque variants displayed different in vitro growth kinetics compared to the parental wild type. The plaque variants showed specific mutations being present in each variant strain. The big plaque variants showed four mutations I97L, N104S, S246P and N282D in the VP1 while the small plaque variants showed I97T, N237T and T292A in the VP1. No other mutations were detected in the whole genome of the two variants. The variants showed stable homogenous small plaques and big plaques, respectively, when re-infected in rhabdomyosarcoma (RD) and Vero cells. The parental strain showed faster growth kinetics and had higher viral RNA copy number than both the big and small plaque variants. Homology modelling shows that both plaque variants have differences in the structure of the VP1 protein due to the presence of unique spontaneous mutations found in each plaque variant This study suggests that the EV-A71 sub-genotype B4 strain 41 has at least two variants with different plaque morphologies. These differences were likely due to the presence of spontaneous mutations that are unique to each of the plaque variants. The ability to maintain the respective plaque morphology upon passaging indicates the presence of quasi-species in the parental population.

scholarly journals PB1-mediated virulence attenuation of H5N1 influenza virus in mice is associated with PB2

2011 ◽  
Vol 92 (6) ◽  
pp. 1435-1444 ◽  
Author(s):  
Jing Li ◽  
Yongqiang Li ◽  
Yi Hu ◽  
Guohui Chang ◽  
Wei Sun ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Recombinant Virus ◽  
Influenza Viruses ◽  
H5n1 Influenza Virus ◽  
Wild Type ◽  
Small Plaque ◽  
Large Plaque ◽  
H5n1 Influenza ◽  
Virulence Attenuation ◽  
N Terminus

H5N1 avian influenza viruses demonstrate different phenotypes, such as pathogenicity after one or serial passages in mammalian hosts or cells. To establish the molecular basis of these phenotypes, we cloned isolates from the lungs of mice infected with human A/Vietnam/1194/2004 (H5N1) influenza virus. Large-plaque isolates were less pathogenic to mice than small-plaque isolates. Genome sequencing revealed that the small-plaque and large-plaque isolates differed in several amino acids. In order to assess their effects on pathogenicity in mice, two amino acid changes common to attenuated isolates, one in PB2 (I63T) and the other in PB1 (T677M), were inserted into a wild-type recombinant virus construct. The PB2 (I63T) or PB1 (T677M) mutations alone did not alter the phenotype of H5N1 virus, whereas recombinant virus with both mutations was less pathogenic than the wild-type recombinant virus. Furthermore, the PB1 (T677M) mutation showed a lower replication efficiency, although it had higher polymerase activity. The recombinant virus with the PB2 (63T) mutation replicated as well as the wild-type recombinant virus. These results suggest that the C terminus of PB1 of H5N1 influenza virus mediates virulence attenuation of H5N1 influenza virus in mice, associating with the N terminus of PB2. However, the role of the N terminus of PB2 in virulence attenuation in mice remains unclear.

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