DNA Packaging Mutant: Repression of the Vaccinia Virus A32 Gene Results in Noninfectious, DNA-Deficient, Spherical, Enveloped Particles
AUTOR(ES)
Cassetti, Maria Cristina
FONTE
American Society for Microbiology
RESUMO
The vaccinia virus A32 open reading frame was predicted to encode a protein with a nucleoside triphosphate-binding motif and a mass of 34 kDa. To investigate the role of this protein, we constructed a mutant in which the original A32 gene was replaced by an inducible copy. The recombinant virus, vA32i, has a conditional lethal phenotype: infectious virus formation was dependent on isopropyl-β-d-thiogalactopyranoside (IPTG). Under nonpermissive conditions, the mutant synthesized early- and late-stage viral proteins, as well as viral DNA that was processed into unit-length genomes. Electron microscopy of cells infected in the absence of IPTG revealed normal-appearing crescents and immature virus particles but very few with nucleoids. Instead of brick-shaped mature particles with defined core structures, there were numerous electron-dense, spherical particles. Some of these spherical particles were wrapped with cisternal membranes, analogous to intracellular and extracellular enveloped virions. Mutant viral particles, purified by sucrose density gradient centrifugation, had low infectivity and transcriptional activity, and the majority were spherical and lacked DNA. Nevertheless, the particle preparation contained representative membrane proteins, cleaved and uncleaved core proteins, the viral RNA polymerase, the early transcription factor and several enzymes, suggesting that incorporation of these components is not strictly coupled to DNA packaging.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=110378Documentos Relacionados
- Noninfectious vesicular stomatitis virus particles deficient in the viral nucleocapsid.
- Adsorption and penetration of enveloped and naked vaccinia virus particles.
- Noninfectious virus-like particles produced by Moloney murine leukemia virus-based retrovirus packaging cells deficient in viral envelope become infectious in the presence of lipofection reagents
- Target Volume Analysis of Vaccinia Virus: Influence of Virus Dispersion and Noninfectious Particles
- Partial inhibition of the human immunodeficiency virus type 1 protease results in aberrant virus assembly and the formation of noninfectious particles.