The predicted impact of each substitution (Figure 3 ) on the secondary structure of SL6 is shown in Figure 4 . The plaque characteristics, cpe and growth dynamics of each mutant compared with those of original pGGVs virus (Table 1 and Figure 5 ). Single-step growth curves revealed differences of $1 log 10 between the mutants early after infection (12-16 h p.i.) which were reproducible and statistically significant ( Figure 5) .