RESUMO
The severe acute respiratory syndrome coronavirus (SARS-CoV), isolated from humans infected during the peak of epidemic, encodes two accessory proteins termed as 8a and 8b. Interestingly, the SARS-CoV isolated from animals contains an extra 29-nucleotide in this region such that these proteins are fused to become a single protein, 8ab. Here, we compared the cellular properties of the 8a, 8b and 8ab proteins by examining their cellular localizations and their abilities to interact with other SARS-CoV proteins. These results may suggest that the conformations of 8a and 8b are different from 8ab although nearly all the amino acids in 8a and 8b are found in 8ab. In addition, the expression of the structural protein, envelope (E), was down-regulated by 8b but not 8a or 8ab. Consequently, E was not detectable in SARS-CoV-infected cells that were expressing high levels of 8b. These findings suggest that 8b may modulate viral replication and/or pathogenesis.
Assuntos
Regulação Viral da Expressão Gênica , Coronavírus Relacionado à Síndrome Respiratória Aguda Grave/genética , Coronavírus Relacionado à Síndrome Respiratória Aguda Grave/fisiologia , Proteínas do Envelope Viral/biossíntese , Proteínas da Matriz Viral/genética , Proteínas da Matriz Viral/fisiologia , Proteínas Virais/genética , Proteínas Virais/fisiologia , Sequência de Aminoácidos , Animais , Western Blotting , Linhagem Celular , Núcleo Celular/química , Chlorocebus aethiops , Citoplasma/química , Humanos , Imunoprecipitação , Microscopia de Fluorescência , Dados de Sequência Molecular , Ligação Proteica , RNA Mensageiro/análise , RNA Mensageiro/genética , RNA Viral/análise , RNA Viral/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transcrição Gênica , Proteínas do Envelope Viral/análise , Proteínas da Matriz Viral/análise , Proteínas Virais/análise , Proteínas ViroporinasRESUMO
Here we analyzed the gene expression profile of cells that stably express the severe acute respiratory syndrome coronavirus (SARS-CoV) 3a protein to determine its effects on host functions. A lung epithelial cell-line, A549, was chosen for this study because the lung is the primary organ infected by SARS-CoV and fatalities resulted mainly from pulmonary complications. Our results showed that the expression of 3a up-regulates the mRNA levels of all three subunits, Aalpha, Bbeta, and gamma, of fibrinogen. Consequently, the intracellular levels as well as the secretion of fibrinogen were increased. We also observed increased fibrinogen levels in SARS-CoV-infected Vero E6 cells.
