a nonsignificant trendP = 0.138
B2 strains exhibited higher virulence scores than non-B2 strains (10.7 ± 2.7 versus 5.8 ± 4.0, P = 0.002), with a nonsignificant trend toward a lower score in B2a than B2b (10.0 ± 2.4 versus 11.5 ± 3.0, P = 0.138) ( Supplemental Figure 2 ).