VAPB and infection: Importantly, although the transcript levels of the vapBC operon increased during the first 2 days of infection, bacterial counts increased from ∼8 × 105 CFU/cm hypocotyl at the inoculation time to approximately 1.3 × 108 and 4.4 × 108 CFU/cm hypocotyl at 2 and 4 d.a.i, respectively, thus indicating that no apparent growth arrest of A. citrulli occurred during the time of vapC expression.