Expression of EGFP, EGFP-NS1 and EGFP-NS1K334E. (A) The COS-7 cells transfected with pEGFP, pEGFP-NS1 or pEGFP-NS1K334E were observed under phase contrast (upper panel) and fluorescence microscope (middle panel). The fluorescence intensity was also detected using flowcytometry (lower panel). The (B) mRNA and (C) protein expressions of B19-NS1 were detected by RT-PCR and Immunoblottings. E, N and K indicate EGFP, EGFP-NS1 and EGFP-NS1K334E, respectively.