Rotavirus NSP1 activates human NLRP1 inflammasome

Abstract

While inflammasomes detect and defend against pathogens, the precise mechanisms by which enteric viruses trigger these complexes, and the specific viral components involved remain incompletely understood. In this study, we demonstrate that rotavirus infection robustly induced human NLRP1 inflammasome activation via p38 mitogen-activated protein kinase (MAPK)-dependent and -independent pathways. Utilizing cell lines reconstituted with NLRP1 signaling and reverse genetics-rescued recombinant rotaviruses, we identified non-structural protein 1 (NSP1), a well-characterized viral antagonist of host interferon signaling, as an activator of the NLRP1 inflammasome in the absence of double-stranded RNA. Domain mapping analysis revealed that the C-terminus of NSP1 but not the C-terminal IRF3-binding site was essential for triggering inflammasome activation. Mechanistically, we show that NSP1 induced the proteasomal degradation of NLRP1 to elicit its activation, a process dependent on host neddylation pathways and the Cullin-3/Elongin B/C ubiquitin ligase complex. Together, these findings suggest that RV engages parallel NLRP1 surveillance pathways, including a p38-dependent response to infection, and a novel NSP1-dependent pathway involving the ubiquitin-proteosome system, where a viral strategy aimed at host protein degradation inadvertently trips the human NLRP1 inflammasome wire.