Fig 6.

Effect of amino acid substitutions in NS4B on RNA replication efficiency. In order to assess the effect of the amino acid substitutions in NS4B on the viral RNA replication efficiency, confluent SK-L cell monolayers were inoculated at an MOI of 1.5 with the parent and mutant viruses carrying the indicated amino acid changes in NS4B. Parallel cultures of infected cells were incubated at 37°C in the presence of 5% CO₂ for 2 h, 7 h, and 12 h. Total RNA was extracted from the infected cells at the indicated times. The relative RNA copy numbers compared with the copy number at 2 h postinoculation are shown. Each bar represents the mean value from 3 independent experiments, and the error bars show the standard deviations. Pairwise comparisons of the values were carried out using the t test. *, P < 0.05.