Chikungunya virus (CHIKV) is a mosquito-borne alphavirus known to cause epidemics resulting in predominantly symptomatic infections, which in rare cases cause long term debilitating arthritis and arthralgia. Significant progress has been made in understanding the roles of canonical RNA sensing pathways in the host recognition of CHIKV; however, less is known regarding antagonism of CHIKV by cytosolic DNA sensing pathways like that of cyclic GMP-AMP synthase (cGAS) and Stimulator of Interferon Genes (STING). With the use of cGAS or STING null cells we demonstrate that the pathway restricts CHIKV replication in fibroblasts and immune cells. We show that DNA accumulates in the cytoplasm of infected cells and that CHIKV blocks DNA dependent IFN-β transcription. This antagonism of DNA sensing is via an early autophagy-mediated degradation of cGAS and expression of the CHIKV capsid protein is sufficient to induce cGAS degradation. Furthermore, we identify an interaction of CHIKV nsP1 with STING and map the interaction to 23 residues in the cytosolic loop of the adaptor protein. This interaction stabilizes the viral protein and increases the level of palmitoylated nsP1 in cells. Together, this work supports previous publications highlighting the relevance of the cGAS-STING pathway in the early detection of (+)ssRNA viruses and provides direct evidence that CHIKV interacts with and antagonizes cGAS-STING signaling.

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Role of Ammonia Oxidation in Selective Catalytic Reduction of Nitric Oxide Over Vanadia Catalysts.-Vanadia crystals preferentially exposing different crystal planes are grown either by calcination of ammonium metavanadate (O2-flow, 520 . degree.C, 50 h) or by melting V2O5 at 695 • C followed by temp.-programmed recrystallization. The V2O5 catalysts are characterized by BET surface area measurement, XRD, XPS, SEM, laser Raman spectroscopy, and 3-D imaging. Temp.-programmed reduction with NH3 and H2 and temp.-programmed desorption studies are also performed. Ammonia oxidation experiments are carried out in a steady-state fixed-bed reactor. The results indicate that NH3 adsorption occurs on at least two different sites located on the (010) and (100) planes of V2O5. V-O-V sites located on the side planes selectively reduce NO to N2, whereas V=O sites on the (010) basal plane promote the direct oxidation of NH3 to NO and the formation of N2O from NO and NH3 interaction. The V=O sites are more easily reduced with both NH3 and H2. -(OZKAN, U. S.; CAI, Y.; KUMTHEKAR, M. W.; ZHANG, L.; J.