FIG 7.

Effects of VP1-31 substitution on virus binding and RNA release. (a) VP1-31G and VP1-31D viruses were absorbed to DLD-1, RD, and SK-N-SH cells, as indicated. Bound viruses were quantified by ELISA. Values and error bars are the mean ±1 standard deviation, respectively. (b) DLD-1, RD, and SK-N-SH cells were infected with neutral red-labeled VP1-31G and VP1-31D viruses, as indicated. Based on the characteristics of a neutral red-labeled virus, which can be inactivated under light exposure unless the virus releases its RNA, the numbers of viruses that released their RNA genome into the cells were determined using the infectious center assay. Values and error bars are the mean ±1 standard deviation, as indicated. A paired Student's t test was used to calculate P values. The error bars represent 1 standard deviation from triplicate experimental results.