Measles is an acute contagious disease that remains a major cause of childhood mortality worldwide, especially in developing countries (6). Measles virus (MV), a member of the family Paramyxoviridae, is an enveloped virus with a nonsegmented single-stranded negative-sense RNA genome (15). Upon MV infection, cells produce alpha/beta interferon (IFN-␣/) following recognition of the virus by RNA helicases encoded by retinoic acid-inducible gene I (RIG-I) and melanoma differentiation-associated gene 5 (MDA5) (22, 43) or Toll-like receptor (TLR) 7 (51). MV encodes phosphoprotein (P) and V and C proteins, which can counteract the host IFN response (11,34,36,54,64). Among these viral proteins, the V protein is the most versatile antagonist. It blocks IFN-␣/ signal transduction in infected cells (9,11,13,36,38,47,59,64) and inhibits TLR7-mediated IFN-␣ production in human plasmacytoid dendritic cells (42). Furthermore, the MV V protein, like that of other paramyxoviruses, interacts with MDA5 and inhibits its function with respect to IFN induction (2). The N-terminal domain of the V protein (Vn), which is common to the P and V proteins, has been shown to interact with STAT1 (signal transducer and activator of transcription 1) and Jak1, which are involved in IFN signaling (9), whereas the unique cysteine-rich C-terminal domain of the V protein (Vc) was found to interact with MDA5 (39), STAT2 (47), and IB kinase ␣ (IKK␣), which is involved in the activation of interferon-regulatory factor 7 through TLR7 (42). Furthermore, Vc interacts with the NF-B subunit p65 (RelA) to suppress NF-B activity (53). The mechanism by which the MV C protein acts as an IFN antagonist is not well understood, but it probably suppresses IFN induction by regulating viral RNA synthesis (34).Secretion of the inflammatory cytokines interleukin-1 (IL-1) and IL-18 is tightly regulated by the inflammasomes known as caspase-1-activating molecular complexes (32). Recognition of pathogens by pattern recognition receptors such as TLRs induces pro-IL-1 and pro-IL-18 in the cytoplasm. The activation of the inflammasomes leads to the conversion of procaspase-1 to caspase-1, which cleaves procytokines into mature IL-1 and IL-18, which are then secreted. The best-characterized inflammasome is the NOD-like receptor (NLR)-family pyrin domain-containing 3 (NLRP3, also known as Nalp3 or cryopyrin) inflammasome, which can be activated by a wide range of stimuli, such as endogenous danger signals from damaged cells, bacterial components, and environmental irritants (52).Infection by RNA viruses such as influenza virus (1,19,20,61), encephalomyocarditis virus (EMCV) (44, 45), and vesicular stomatitis virus (VSV) (45) also stimulates NLRP3, which then recruits the apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) and procaspase-1, forming the NLRP3 inflammasome. How RNA viruses are recognized by NLRP3 is not well-known, but in the case of influenza virus, the proton-selective ion channel M2 protein, not genomic RNA, has been sho...