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Cell Host Microbe. 2011 Jun 16;9(6):496-507. doi: 10.1016/j.chom.2011.05.006.

Viral infection augments Nod1/2 signaling to potentiate lethality associated with secondary bacterial infections.

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  • 1Department of Pathology, University of Michigan Medical School, Ann Arbor, MI 48109, USA.


Secondary bacterial infection is a common sequela to viral infection and is associated with increased lethality and morbidity. However, the underlying mechanisms remain poorly understood. We show that the TLR3/MDA5 agonist poly I:C or viral infection dramatically augments signaling via the NLRs Nod1 and Nod2 and enhances the production of proinflammatory cytokines. Enhanced Nod1 and Nod2 signaling by poly I:C required the TLR3/MDA5 adaptors TRIF and IPS-1 and was mediated by type I IFNs. Mechanistically, poly I:C or IFN-β induced the expression of Nod1, Nod2, and the Nod-signaling adaptor Rip2. Systemic administration of poly I:C or IFN-β or infection with murine norovirus-1 promoted inflammation and lethality in mice superinfected with E. coli, which was independent of bacterial burden but attenuated in the absence of Nod1/Nod2 or Rip2. Thus, crosstalk between type I IFNs and Nod1/Nod2 signaling promotes bacterial recognition, but induces harmful effects in the virally infected host.

Copyright © 2011 Elsevier Inc. All rights reserved.

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