Figure 4From: Secretory pathway antagonism by calicivirus homologues of Norwalk virus nonstructural protein p22 is restricted to norovirusesEffect of calicivirus homologues of NV p22 on cellular protein secretion. 293T (A) or CRFK (B) cells were transfected with the vector pCMV-UTR-SEAP expressing the indicated proteins with N terminal GFP tags. Cells were washed and fresh medium was added at 22 hours-post transfection (hpt). At 24 hpt the media (containing extracellular SEAP) was collected, cells were washed 2X in cold 0.01M PBS and lysed in media containing 0.1% Triton X-100 (yielding the intracellular SEAP fraction). SEAP secretion was calculated by assaying both fractions for enzymatic SEAP activity, which were then used in the equation: SEAP secretion (%) = (SEAPextracellular/[SEAPextracellular + SEAPintracellular]) x 100. Data are representative of at least two experiments; n = 3 for each sample; errors bars indicate standard deviations. One hundred percent of the cells expressing p22 homologue-EGFP and SEAP were viable as assessed by trypan blue exclusion (0.2% final concentration for 5 min) at 24 hpt.Back to article page