Poliovirus 3A Protein Limits Interleukin-6 (IL-6), IL-8, and Beta Interferon Secretion during Viral Infection

Abstract

During viral infections, the host secretory pathway is crucial for both innate and acquired immune responses. For example, the export of most proinflammatory and antiviral cytokines, which recruit lymphocytes and initiate antiviral defenses, requires traffic through the host secretory pathway. To investigate potential effects of the known inhibition of cellular protein secretion during poliovirus infection on pathogenesis, cytokine secretion from cells infected with wild-type virus and with 3A-2, a mutant virus carrying an insertion in viral protein 3A which renders the virus defective in the inhibition of protein secretion, was tested. We show here that cells infected with 3A-2 mutant virus secrete greater amounts of cytokines interleukin-6 (IL-6), IL-8, and beta interferon than cells infected with wild-type poliovirus. Increased cytokine secretion from the mutant-infected cells can be attributed to the reduced inhibition of host protein secretion, because no significant differences between 3A-2-and wild-type-infected cells were observed in the inhibition of viral growth, host cell translation, or the ability of wild-type-or 3A-2-infected cells to support the transcriptional induction of beta interferon mRNA. We surmise that the wild-type function of 3A in inhibiting ER-to-Golgi traffic is not required for viral replication in tissue culture but, by altering the amount of secreted cytokines, could have substantial effects on pathogenesis within an infected host. The global inhibition of protein secretion by poliovirus may reflect a general mechanism by which pathogens that do not require a functional protein secretory apparatus can reduce the native immune response and inflammation associated with infection.

Nonstructural Protein Precursor NS4A/B from Hepatitis C Virus Alters Function and Ultrastructure of Host Secretory Apparatus

“…Second, two different proteins encoded by poliovirus, another positive-strand RNA virus, slow the rate of ER- to-Golgi traffic when expressed in isolation, with a protein termed 3A having the stronger effect (23). For poliovirusinfected cells, the reduction in the rate of protein secretion by the wild-type 3A protein is sufficient to reduce the presentation of antigens on the cell surface in the context of MHC-I (20) and the amounts of interleukin-6 (IL-6), IL-8, and beta interferon secreted by three-to fivefold (21). Here, we showed that HCV NS protein NS4A/B can, in isolation, significantly slow the rate of ER-to-Golgi traffic ( Fig.…”

Poliovirus Protein 3A Binds and Deregulates LIS1, Causing Block of Membrane Protein Trafficking and Deregulation of Cell Division

“…Chumakov, Center for Biologics Evaluation and Research, Food and Drug Administration), as previously described. 8,[13][14][15] GST pulldown assay. MicroSpin GST Purification Module (Amersham Pharmacia Biothech) was used to purify GST and GST-fused proteins.…”

“…This poliovirus function is exerted, at least in part, through 3A, a multifunctional viral protein that is involved in poliovirus RNA replication, 9 virus-induced rearrangement of cytoplasmic membrane structures, 10 and suppression of protein trafficking between the endoplasmic reticulum (ER) and Golgi apparatus, 11,12 an essential step in plasma membrane and secreted protein processing. As a result, the secretion and plasma membrane presentation of newly synthesized proteins are affected in poliovirus-infected cells; 8,[13][14][15] the infected cells secrete less of interleukins, cytokines, and interferons, 14 are less capable of MHCI-dependent antigen presentation 13 and acquire resistance to TNF, TRAIL, and interferons. 8 To decipher the mechanism of 3A activity, we have identified cellular protein counterparts of 3A, using yeast two-hybrid screening followed by confirmation of the interaction in a mammalian cell context.…”

Membrane Topography of the Hydrophobic Anchor Sequence of Poliovirus 3A and 3AB Proteins and the Functional Effect of 3A/3AB Membrane Association upon RNA Replication

“…The 3A protein itself possesses additional functions beside those that are in the context of 3AB. In vivo 3A inhibits ER-to Golgi membrane and secretory protein traffic and induces specific translocation of different members of the ARF family (ADPribosylation factor) to membranes (25)(26)(27)(28). Both a mammalian and a yeast two-hybrid system showed that 3A multimerizes and interacts with 2B and 2C ATPase (9,29) (Yin, Paul and Wimmer, unpublished observations).…”