Plays a role in the inhibition of host innate immunity by inducing the degradation of key host factors required to activate interferon production such as IRF3, IRF5 or IRF7. Associates with components of cullin RING ligases (CRLs) including CUL1 or CUL3, which are essential multisubunit ubiquitination complexes, to modulate their activities. Recognizes the host NF-kappa-B regulator BTRC through the presence of a DSGXS motif in the C-terminal substrate recognition domain. Interacts (via C-terminus) with host IRF3; this interaction leads to IRF3 degradation. Interacts with host IRF7; this interaction leads to IRF7 degradation. Interacts with host CUL1 and CUL3. Interacts with host BTRC. The integrity of the zinc-binding domain in NSP1 is important for degradation of host IRF3. The pLxIS motif targets host IRF3 for degradation; however phosphorylation of NSP1 pLxIS motif is not required for its activity. The C-terminal region is phosphorylated by host CKII/CSNK2A1. Phosphorylation of the DSGXS motif is essential for host NF-kappa-B inhibition. Belongs to the rotavirus NSP1 family. NSP1 has been shown (PubMed:17251580) to be almost unable to bind and degrade IRF3 in cell culture. However, this does not implies that it is the case in vivo, since the down-regulation of host antiviral state is not essential for the virus in cell culture and the used cells were not of porcine origin.