OmpU in OMVs is required to neutralize ICP2. Titration of V. cholerae E7946 OMVs, or OMVs from E7946 OmpU G235D mutant (OmpU*), on a fixed concentration of prey (E7946) and phage ICP2 (∼10,000 PFU). n = 10 for 25 μg; n = 4 for 10, 1, and 0.2 μg of OMVs; and n = 6 for OmpU G325D. The horizontal solid lines indicate means ± standard deviations. ****, P = <0.0001 for 25 μg; *, P = 0.0121 for 10 μg and P = 0.0135 for OmpU G325D.