Fig. 6.

Isolation of 2D3.7 and 4F9.4 neutralizing escape mutants. (a) Schematic of the experimental set-up. MNV-1 was passaged through RAW 264.7 cells in the presence of increasing concentrations [40 ng for passage 1 (P1) and P2, 60 ng for P3, 100 ng for P4 and P5, 200 ng for P6–P8 and 600 ng for P9–P20] of neutralizing mAb 2D3.7 or 4F9.4 or a non-neutralizing IgA isotype control antibody. At each passage, MNV-1 (m.o.i. 0.025) was pre-incubated with the respective mAb for 30 min at 37 °C before infection for 48 h. For each antibody, two independent lineages (L1 and L2) were analysed. (b, c) Virus from the original stock (P0) and from P5, P10, P15 and P20 were incubated with 0 or 200 ng mAb 2D3.7 (b) or 4F9.4 (c) for 30 min at 37 °C and analysed by plaque neutralization assay. The dashed line indicates the level of neutralization at P0. Data are presented as means±sem of at least three independent experiments.