The publication data currently available has been vetted by Vanderbilt faculty, staff, administrators and trainees. The data itself is retrieved directly from NCBI's PubMed and is automatically updated on a weekly basis to ensure accuracy and completeness.
If you have any questions or comments, please contact us.
Efficient and productive virus infection often requires viral countermeasures that block innate immunity. The IFN-inducible 2',5'-oligoadenylate (2-5A) synthetases (OASs) and ribonuclease (RNase) L are components of a potent host antiviral pathway. We previously showed that murine coronavirus (MHV) accessory protein ns2, a 2H phosphoesterase superfamily member, is a phosphodiesterase (PDE) that cleaves 2-5A, thereby preventing activation of RNase L. The PDE activity of ns2 is required for MHV replication in macrophages and for hepatitis. Here, we show that group A rotavirus (RVA), an important cause of acute gastroenteritis in children worldwide, encodes a similar PDE. The RVA PDE forms the carboxy-terminal domain of the minor core protein VP3 (VP3-CTD) and shares sequence and predicted structural homology with ns2, including two catalytic HxT/S motifs. Bacterially expressed VP3-CTD exhibited 2',5'-PDE activity, which cleaved 2-5A in vitro. In addition, VP3-CTD expressed transiently in mammalian cells depleted 2-5A levels induced by OAS activation with poly(rI):poly(rC), preventing RNase L activation. In the context of recombinant chimeric MHV expressing inactive ns2, VP3-CTD restored the ability of the virus to replicate efficiently in macrophages or in the livers of infected mice, whereas mutant viruses expressing inactive VP3-CTD (H718A or H798R) were attenuated. In addition, chimeric viruses expressing either active ns2 or VP3-CTD, but not nonfunctional equivalents, were able to protect ribosomal RNA from RNase L-mediated degradation. Thus, VP3-CTD is a 2',5'-PDE able to functionally substitute for ns2 in MHV infection. Remarkably, therefore, two disparate RNA viruses encode proteins with homologous 2',5'-PDEs that antagonize activation of innate immunity.
Barley stripe mosaic virus (BSMV) is the type member of the genus Hordeivirus, rigid, rod-shaped viruses in the family Virgaviridae. We have used fiber diffraction and cryo-electron microscopy to determine the helical symmetry of BSMV to be 23.2 subunits per turn of the viral helix, and to obtain a low-resolution model of the virus by helical reconstruction methods. Features in the model support a structural relationship between the coat proteins of the hordeiviruses and the tobamoviruses.
Copyright © 2013 Elsevier Inc. All rights reserved.
Viruses modulate the actin cytoskeleton at almost every step of their cellular journey from entry to egress. Cellular sensing of these cytoskeletal changes may function in the recognition of viral infection. Here we show that focal adhesion kinase (FAK), a focal adhesion localized tyrosine kinase that transmits signals between the extracellular matrix and the cytoplasm, serves as a RIG-I-like receptor antiviral signaling component by directing mitochondrial antiviral signaling adaptor (MAVS) activation. Cells deficient in FAK are highly susceptible to RNA virus infection and attenuated in antiviral signaling. We show that FAK interacts with MAVS at the mitochondrial membrane in a virus infection-dependent manner and potentiates MAVS-mediated signaling via a kinase-independent mechanism. A cysteine protease encoded by enteroviruses cleaves FAK to suppress its role in innate immune signaling. These findings suggest that FAK serves as a link between cytoskeletal perturbations that occur during virus infection and activation of innate immune signaling.
Copyright Â© 2012 Elsevier Inc. All rights reserved.
Mammalian orthoreoviruses (reoviruses) are highly tractable experimental models for studies of double-stranded (ds) RNA virus replication and pathogenesis. Reoviruses infect respiratory and intestinal epithelium and disseminate systemically in newborn animals. Until now, a strategy to rescue infectious virus from cloned cDNA has not been available for any member of the Reoviridae family of dsRNA viruses. We report the generation of viable reovirus following plasmid transfection of murine L929 (L) cells using a strategy free of helper virus and independent of selection. We used the reovirus reverse genetics system to introduce mutations into viral capsid proteins sigma1 and sigma3 and to rescue a virus that expresses a green fluorescent protein (GFP) transgene, thus demonstrating the tractability of this technology. The plasmid-based reverse genetics approach described here can be exploited for studies of reovirus replication and pathogenesis and used to develop reovirus as a vaccine vector.