VAMP3 and infection: We investigated whether the reduced infectious units derived from VAMP3 KD cells (Figure 4F), was due to a primary infection defect (i.e. lower number of total virions released by VAMP3 KD cells) or a secondary infection defect (i.e. same number of virions released compared to NTC, but defective virions that failed to re-infect the reporter plate).