tetano
Editor, Senior Moderator
J Virol. 2014 Jun 18. pii: JVI.01383-14. [Epub ahead of print]
Interactions between the Influenza A Virus RNA Polymerase Components and Retinoic Acid-Inducible Gene I.
Li W1, Chen H1, Sutton T1, Obadan A1, Perez DR2.
Author information
Abstract
The influenza A virus genome possesses eight negative-strand RNA segments in the form of viral ribonucleoprotein particles (vRNPs) in association with the three viral RNA polymerase subunits (PB2, PB1, and PA) and the nucleoprotein (NP). Through interactions with multiple host factors, the RNP subunits play vital roles in replication, host adaptation, interspecies transmission, and pathogenicity. In order to gain insight into the potential roles of RNP subunits in the modulation of the host's innate immune response, the interactions of each RNP subunit with Retinoic Acid-Inducible Gene I protein (RIG-I) from mammalian and avian species were investigated. Studies using co-immunoprecipitation (Co-IP), bimolecular fluorescence complementation (BiFc), and co-localization using confocal microscopy, provided direct evidence for the RNA-independent binding of PB2, PB1, and PA with RIG-I from various hosts (human, swine, mouse, and duck). In contrast, the binding of NP with RIG-I was found to be RNA-dependent. Expression of the viral NS1 protein, which interacts with RIG-I, did not interfere with the association of RNA polymerase subunits with RIG-I. The association of each individual virus polymerase component with RIG-I failed to significantly affect the IFN induction elicited by RIG-I and 5' ppp-RNA in reporter assays, quantitative RT-PCR, and IRF3 phosphorylation tests. Taken together, these findings indicate that viral RNA polymerase components PB2, PB1, and PA directly target RIG-I, but the exact biological significance of these interactions in the replication and pathogenicity of influenza A virus needs to be further clarified.
IMPORTANCE:
RIG-I is an important RNA sensor to elicit innate immune response in mammals and some bird species (such as duck) upon influenza A virus infection. Although the 5' -triphosphate dsRNA panhandle structure at the end of viral genome RNA is responsible for the binding and subsequent activation of RIG-I, this structure is supposedly wrapped by RNA polymerase complex (PB2, PB1, PA), which may interfere with the induction of RIG-I signaling pathway. In the present study, PB2, PB1, and PA were found to individually interact with RIG-Is from multiple mammalian and avian species in an RNA-independent manner, without significantly affecting the generation of IFN. The data suggest that although RIG-I binding by RNA polymerase complex is conserved in different species, it does not appear to play crucial role in the modulation of IFN in vitro.
Copyright ? 2014, American Society for Microbiology. All Rights Reserved.
PMID:
24942585
[PubMed - as supplied by publisher]
http://www.ncbi.nlm.nih.gov/pubmed/24942585
Interactions between the Influenza A Virus RNA Polymerase Components and Retinoic Acid-Inducible Gene I.
Li W1, Chen H1, Sutton T1, Obadan A1, Perez DR2.
Author information
Abstract
The influenza A virus genome possesses eight negative-strand RNA segments in the form of viral ribonucleoprotein particles (vRNPs) in association with the three viral RNA polymerase subunits (PB2, PB1, and PA) and the nucleoprotein (NP). Through interactions with multiple host factors, the RNP subunits play vital roles in replication, host adaptation, interspecies transmission, and pathogenicity. In order to gain insight into the potential roles of RNP subunits in the modulation of the host's innate immune response, the interactions of each RNP subunit with Retinoic Acid-Inducible Gene I protein (RIG-I) from mammalian and avian species were investigated. Studies using co-immunoprecipitation (Co-IP), bimolecular fluorescence complementation (BiFc), and co-localization using confocal microscopy, provided direct evidence for the RNA-independent binding of PB2, PB1, and PA with RIG-I from various hosts (human, swine, mouse, and duck). In contrast, the binding of NP with RIG-I was found to be RNA-dependent. Expression of the viral NS1 protein, which interacts with RIG-I, did not interfere with the association of RNA polymerase subunits with RIG-I. The association of each individual virus polymerase component with RIG-I failed to significantly affect the IFN induction elicited by RIG-I and 5' ppp-RNA in reporter assays, quantitative RT-PCR, and IRF3 phosphorylation tests. Taken together, these findings indicate that viral RNA polymerase components PB2, PB1, and PA directly target RIG-I, but the exact biological significance of these interactions in the replication and pathogenicity of influenza A virus needs to be further clarified.
IMPORTANCE:
RIG-I is an important RNA sensor to elicit innate immune response in mammals and some bird species (such as duck) upon influenza A virus infection. Although the 5' -triphosphate dsRNA panhandle structure at the end of viral genome RNA is responsible for the binding and subsequent activation of RIG-I, this structure is supposedly wrapped by RNA polymerase complex (PB2, PB1, PA), which may interfere with the induction of RIG-I signaling pathway. In the present study, PB2, PB1, and PA were found to individually interact with RIG-Is from multiple mammalian and avian species in an RNA-independent manner, without significantly affecting the generation of IFN. The data suggest that although RIG-I binding by RNA polymerase complex is conserved in different species, it does not appear to play crucial role in the modulation of IFN in vitro.
Copyright ? 2014, American Society for Microbiology. All Rights Reserved.
PMID:
24942585
[PubMed - as supplied by publisher]
http://www.ncbi.nlm.nih.gov/pubmed/24942585