The lack of properly induced and sustained CD8+ T cell activity in ARPC1B deficiency may underlie the severe acute and prolonged viral infections observed in many of the patients, being either systemic (CMV and EBV infections) or localized (including respiratory syncytial virus [RSV] bronchiolitis, and adenovirus pneumonitis as well as HPV and molluscum contagiosa virus [MCV] skin infections) (22). Here, ARPC1B is linked to Epstein-Barr virus infection.