Search results for "SEM"

An ancient virus type from extreme environments

2014

Assembly and Translocation of Papillomavirus Capsid Proteins

2002

ABSTRACT The major and minor capsid proteins of polyomavirus are preassembled in the cytoplasm and translocated to the nucleus only as a VP1-VP2/VP3 complex. In this study, we describe independent nuclear translocation of the L1 major protein and the L2 minor capsid protein of human papillomavirus type 33 by several approaches. First, we observed that expression and nuclear translocation of L2 in natural lesions precede expression of L1. Second, using a cell culture system for coexpression, we found that accumulation of L2 in nuclear domain 10 (ND10) subnuclear structures precedes L1 by several hours. In contrast, complexes of L2 and mutants of L1 forced to assemble in the cytoplasm are tra…

Nuclear localization but not PML protein is required for incorporation of the papillomavirus minor capsid protein L2 into virus-like particles.

2004

ABSTRACT Recent reports suggest that nuclear domain(s) 10 (ND10) is the site of papillomavirus morphogenesis. The viral genome replicates in or close to ND10. In addition, the minor capsid protein, L2, accumulates in these subnuclear structures and recruits the major capsid protein, L1. We have now used cell lines deficient for promyelocytic leukemia (PML) protein, the main structural component of ND10, to study the role of this nuclear protein for L2 incorporation into virus-like particles (VLPs). L2 expressed in PML protein knockout (PML −/− ) cells accumulated in nuclear dots, which resemble L2 aggregates forming at ND10 in PML protein-containing cells. These L2 assemblies also attracted…

Generation and neutralization of pseudovirions of human papillomavirus type 33

1997

Since human papillomaviruses (HPV) cannot be propagated in cell culture, the generation of infectious virions in vitro is a highly desirable goal. Here we report that pseudovirions can be generated by the assembly of virus-like particles (VLPs) in COS-7 cells containing multiple copies of a marker plasmid. Using recombinant vaccinia viruses, we have obtained spherical VLPs of HPV type 33 (HPV-33) which fractionate into heavy and light VLPs in cesium chloride density gradients. VLPs in the heavy fraction (1.31 g/cm3) carry the plasmid in DNase-resistant form and are capable of transferring the genetic marker located on the plasmid to COS-7 cells in a DNase-resistant way (pseudoinfection). Th…

DNA-induced structural changes in the papillomavirus capsid.

2001

ABSTRACT Human papillomavirus capsid assembly requires intercapsomeric disulfide bonds between molecules of the major capsid protein L1. Virions isolated from naturally occurring lesions have a higher degree of cross-linking than virus-like particles (VLPs), which have been generated in eukaryotic expression systems. Here we show that DNA encapsidation into VLPs leads to increased cross-linking between L1 molecules comparable to that seen in virions. A higher trypsin resistance, indicating a tighter association of capsomeres through DNA interaction, accompanies this structural change.

Baculovirus-mediated immediate-early gene expression and nuclear reorganization in human cells

2007

Baculovirus, Autographa californica multiple nucleopolyhedrovirus (AcMNPV), has the ability to transduce mammalian cell lines without replication. The general objective of this study was to detect the transcription and expression of viral immediate-early genes in human cells and to examine the interactions between viral components and subnuclear structures. Viral capsids were seen in large, discrete foci in nuclei of both dividing and non-dividing human cells. Concurrently, the transcription of viral immediate-early transregulator genes (ie-1, ie-2) and translation of IE-2 protein were detected. Quantitative microscopy imaging and analysis showed that virus transduction altered the size of …

The closest relatives of icosahedral viruses of thermophilic bacteria are among viruses and plasmids of the halophilic archaea.

2009

We have sequenced the genome and identified the structural proteins and lipids of the novel membranecontaining, icosahedral virus P23-77 of Thermus thermophilus. P23-77 has an 17-kb circular double-stranded DNA genome, which was annotated to contain 37 putative genes. Virions were subjected to dissociation analysis, and five protein species were shown to associate with the internal viral membrane, while three were constituents of the protein capsid. Analysis of the bacteriophage genome revealed it to be evolutionarily related to another Thermus phage (IN93), archaeal Halobacterium plasmid (pHH205), a genetic element integrated into Haloarcula genome (designated here as IHP for integrated Ha…

Papillomavirus assembly requires trimerization of the major capsid protein by disulfides between two highly conserved cysteines.

1998

ABSTRACT We have used viruslike particles (VLPs) of human papillomaviruses to study the structure and assembly of the viral capsid. We demonstrate that mutation of either of two highly conserved cysteines of the major capsid protein L1 to serine completely prevents the assembly of VLPs but not of capsomers, whereas mutation of all other cysteines leaves VLP assembly unaffected. These two cysteines form intercapsomeric disulfides yielding an L1 trimer. Trimerization comprises about half of the L1 molecules in VLPs but all L1 molecules in complete virions. We suggest that trimerization of L1 is indispensable for the stabilization of intercapsomeric contacts in papillomavirus capsids.

Hungarian private linguistic landscape in South-West Slovakia

2014

In the field of Linguistic Landscape research little attention has been paid to the situations where a minoritized group gives the regional majority, such as South-­‐West Slovakia where Hungarians form the majority. A clear majority of public signs, also in the region with a Hungarian majority, are only in Slovak, especially in the ‘official’, public sphere. In rural communities, signs posted by private citizens can be relatively frequent, too. In the truly non-­‐ commercial private sphere, minorities have autonomy in public language choice. I present the local practices and interpretations of the private linguistic landscape in two ‘Hungarian’ villages in South-­‐West Slovakia in the light…

A Moldvai Csángómagyar Oktatási Program kutatása és támogatása vizuális módszerekkel

2018

A Moldvai Csángómagyar Oktatási Program kutatása és támogatása egy több éves (2016– 2021), a Finn Akadémia által támogatott projekt (projektszáma, 299133), amelynek anyaga 30 moldvai településen folyatatott, 2017–2019 között végzett terepmunkából áll. A terepmunka szakaszai során számos vizuális és digitális módszertani eljárás is bevezetésre kerül, s az ezek segítségével készített anyagokból nagy terjedelmű, multimodális adatbázis jön létre. Cikkemben néhány, eddig sikeresnek bizonyult módszert mutatok be, különös tekintettel arra, hogy ezek segítségével hogyan válaszolhatók meg a kutatási kérdéseim. A kötet témájához igazodva kutatásomnak a nyelvitájkép-kutatások között elfoglalt helyét i…