Rotavirus Degrades Multiple Interferon (IFN) Type Receptors To Inhibit IFN Signaling and Protects against Mortality from Endotoxin in Suckling Mice

Abstract

STAT1 phosphorylation in response to exogenous IFN administration can be inhibited by rotaviral replication both and In addition many rotavirus strains are resistant to the actions of different IFN types . The regulation of multiple IFN type-mediated antiviral pathways by RVs is not well understood. In this study, we find that during infection and RV significantly depletes IFN-type I, II, and III receptors (IFNRs). Regulation of IFNRs occurred exclusively within RV-infected cells and could be abrogated by inhibiting the lysosomal-endosomal degradation pathway. , IFNR degradation was conserved across multiple RV strains that differ in their modes of regulating IFN induction. In suckling mice, exogenously administered types I, II, or III IFN each induced phosphorylation of STAT1-Y701 within intestinal epithelial cells (IECs) of suckling mice. Murine EW strain RV infection transiently activated intestinal STAT1 at 1dpi, but not subsequently at 2-3dpi. In response to injection of purified IFN-α/β or -λ, IECs in EW-infected mice exhibited impaired STAT1-Y701 phosphorylation, correlating with depletion of different intestinal IFNRs and impaired IFN-mediated transcription. The ability of EW murine RV to inhibit multiple IFN types led us to test protection of suckling mice from endotoxin-mediated shock, an outcome that is dependent on the host IFN response. Compared to controls, mice infected with EW murine RV were substantially protected against mortality following parenteral endotoxin administration. These studies identify a novel mechanism of IFN subversion by RV and reveal an unexpected protective effect of RV infection on endotoxin-mediated shock in suckling mice. Antiviral functions of types 1, 2, and 3 IFN are mediated by receptor-dependent activation of STAT1. Here we find that RV degrades the types 1, 2, and 3 IFN receptors (IFNR) In a suckling mouse model, RV effectively blocked STAT1 activation and transcription following injection of different purified IFNs. This correlated with significantly decreased protein expression of intestinal types 1 and 2 IFNRs. Recent studies demonstrate that in mice, LPS-induced lethality is prevented by genetic ablation of IFN signaling genes such as IFNAR1 and STAT1. When suckling mice were infected with RV they were substantially protected from lethal exposure to endotoxin. These findings provide novel insights into the mechanisms underlying rotavirus regulation of different interferons and are likely to stimulate new research into both rotavirus pathogenesis and endotoxemia.

The Role of Innate Immunity in Regulating Rotavirus Replication, Pathogenesis, and Host Range Restriction and the Implications for Live Rotaviral Vaccine Development

“…As was discussed above, RVs are adept at inhibiting IFN induction and the RV NSP1 protein functions to degrade the essential factors β-TrCP and/or IRF3 during IFN induction in a RV strainspecific manner [66]. Interestingly, in spite of viral antagonism of IFN induction, infection with RV leads to the transcriptional induction and secretion of different IFN types in both cell culture and in vivo [8,19,26,49,52,67]. At least two factors contribute to the failure of RV to completely suppress the induction of IFN secretion.…”

“…Ectopic parenteral injection of purified IFN types I, II, or III in many species, including mice, results in the activation of the key downstream transcription factor STAT1 in small IECs (the predominant site of RV replication) [52]. Multiple lines of evidence indicate important roles for IFN types I, II, and III in restricting RV replication in the gut and in cell culture [7,26,50,51,53].…”

“…40.3). Each of these IFN types is biologically relevant in the context of modulating RV infection and spread [7,52].…”

“…Several lines of evidence indicate that RV employs potent countermeasures to subvert the antiviral state mediated by secreted IFNs during initial infection [7,19,26,52,67]. In cell culture, addition of purified exogenous IFNs after RV adsorption does not significantly hamper viral replication; instead, IFN treatment of cells prior to RV infection is required to achieve efficient RV replication restriction [69].…”

“…Direct evidence for RV subversion of the antiviral state mediated by exogenous IFNs comes from the finding that RV-infected HT-29 cells (a human IEC colonic cancer cell derived line) are able to efficiently block STAT1-Y701 phosphorylation in response to exogenously added purified IFNs I and II [52,67]. Using single-cell analytic techniques, IFN-mediated STAT1 inhibition is found to occur within RVinfected cells.…”