ATG3 and infection: Deletion of 4b in attenuated MERS-CoV-MA-Δ4b increased mRNA levels of autophagy mediators BECN1, ATG3 and LC3A, as compared to infection with virulent viruses MERS-CoV-MA-WT and MERS-CoV-MA-mNLS, suggesting that 4b protein was contributing to the modulation of autophagy in vivo, independently of the presence or the absence of 4b-NLS, (Fig 3C).