FIG 3.

Mutations in the E′F′ loop of the P domain mediate MNV-1 escape from MAb A6.2 neutralization in culture. WT MNV and nine A′B′ loop single point mutants (A), nine E′F′ loop single point mutants (B), and three naturally occurring mutants as well as one double mutant (C) were subjected to in vitro MAb A6.2 neutralization. Virus was incubated with indicated concentrations of MAb A6.2 for 30 min at 37°C before infection of RAW 264.7 cells. Viral titers were measured by plaque assay. Percent infectivity of virus titers at different concentrations of MAb A6.2 was calculated relative to the control without MAb A6.2 set to 100%. Data are presented as means ± SE from at least three independent experiments.