Among the structural and nonstructural proteins of severe acute respiratory syndrome coronavirus (SARS-CoV), the nucleocapsid (N) protein plays pivotal roles in the biology and pathogenesis of viral infection. N protein is thought to dysregulate cell signalling and the transcription of cellular genes, including , which encodes a prothrombinase implicated in vascular thrombosis, fibrin deposition and pneumocyte necrosis. Here, we showed that N protein expressed in cultured human cells was predominantly found in the cytoplasm and was competent in repressing the transcriptional activity driven by interferon-stimulated response elements. However, the expression of N protein did not influence the transcription from the promoter. More importantly, N protein did not modulate the expression of FGL2 mRNA or protein in transfected or SARS-CoV-infected cells. Taken together, our findings did not support the model in which SARS-CoV N protein specifically modulates transcription of the gene to cause fibrosis and vascular thrombosis.


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