Basal interferon signaling and therapeutic use of interferons in controlling peste des petits ruminants virus infection

Peste des Petits Ruminants Virus Exhibits Cell-Dependent Interferon Active Response

Peste des petits ruminants (PPR) is an acute and highly pathogenic infectious disease caused by peste des petits ruminants virus (PPRV), which can infect goats and sheep and poses a major threat to the small ruminants industry. The innate immune response plays an important role as a line of defense against the virus. The effect of PPRV on the active innate immune response has been described in several studies, with different conclusions. We infected three goat-derived cell lines with PPRV and tested their innate immune response. PPRV proliferated in caprine endometrial epithelial cells (EECs), caprine skin fibroblasts cells (GSFs), and goat fibroblast cells (GFs), and all cells expressed interferon (IFN) by poly (I: C) stimulation. PPRV infection stimulated expression of type I and type III IFN on EECs, and expression of the latter was significantly stronger, but IFN was not stimulated in fibroblasts (GSFs and GFs). Our results suggested that the effect of PPRV on IFN was cell-type specific. Nine IFN-stimulated genes (ISGs) were detected in EECs, but only ISG15 and RSAD2 were significantly upregulated. The effects of PPRV on IFN and IFN-induced ISGs were cell-type specific, which advances our understanding of the innate immune response induced by PPRV and creates new possibilities for the control of PPRV infection.

Inhibiting pyrimidine biosynthesis impairs Peste des Petits Ruminants Virus replication through depletion of nucleoside pools and activation of cellular immunity

Replication of peste des petits ruminants virus (PPRV) strongly depends on the cellular environment and resources of host cells including nucleoside pool. Thus, enzymes involved in nucleoside biosynthesis (such as pyrimidine biosynthesis pathway) are regarded as attractive targets for antiviral drug development. Here, we demonstrate that brequinar (BQR) and leflunomide (LFM) which are two specific inhibitors of DHODH enzyme and 6-azauracil (6-AU) which is an ODase enzyme inhibitor robustly inhibit PPRV replication in HEK293T cell line as well as in peripheral blood mononuclear cells isolated from goat. We further demonstrate that these agents exert anti-PPRV activity via the depletion of purimidine nucleotide. Interestingly, these inhibitors can trigger the transcription of antiviral interferon-stimulated genes (ISGs). However, the induction of ISGs is largely independent of the classical JAK-STAT pathway. Combination of BQR with interferons (IFNs) exerts enhanced ISG induction and anti-PPRV activity. Taken together, this study reveals an unconventional novel mechanism of crosstalk between nucleotide biosynthesis pathways and cellular antiviral immunity in inhibiting PPRV replication. In conclusion, targeting pyrimidine biosynthesis represents a potential strategy for developing antiviral strategies against PPRV.

Antiviral responses of ATG13 to the infection of peste des petits ruminants virus through activation of interferon response

Not only are autophagy-related (ATG) proteins the essential orchestrators of the autophagy machinery, but also they regulate many other cellular pathways. Here, we demonstrated that ATG13 exerted an obviously antiviral activity against the infection of peste des petits ruminants virus (PPRV) in cell culture model. We found that PPRV infection or the treatment with interferon (IFN) against PPRV infection significantly induced ATG13 expression. Mechanistically, ATG13 stimulated interferon expression and the subsequent activation of the JAK-STAT cascade. These activations triggered the transcription of interferon-stimulated genes (ISGs) to exert antiviral activity. Conversely, the loss of ATG13 significantly attenuated the potency of RIG-IN in activating IFN responses. In summary, we have demonstrated that basal ATG13 was involved in host antiviral activities against PPRV infection and the over-expression of ATG13 activated IFN production to inhibit PPRV replication in an unconventional fashion.

Epidemic and evolutionary characteristics of peste des petits ruminants virus infecting Procapra przewalskii in Western China

Due to the migration or transboundary spread of domestic and wild animals, peste des petits ruminants virus posed a high potential threat to them. In this study, we initially detected that a class of animal named Procapra przewalskii was infected with peste des petits ruminants virus (PPRV ChinaGS2018) in Gansu province. According to phylogenetic relationships analysis, we found that ChinaGS2018 comprised of 15,954 nucleotides and was classified into IV genotypes. In addition, indirect immunofluorescence assay (IFA) showed that ChinaGS2018 could infect isolated primary goat tracheal epithelium cells (GTC). Comparing with full-length genome sequences revealed that ChinaGS2018 strain has high identity to the reference complete genomes (87.16-99.55%) at the nucleotide level. Multiple sequence alignment showed that F protein has the highest identity of 99.8%, and H protein has the highest nucleotide substitution ratio. Our study also suggested this strain may be transmitted from Xinjiang, China. Along with the migratory of Procapraprzewalskii, this wild ruminant infected with PPRV can pose a huge threat to other wild ruminants and domestic ones. This is the first report describing infected with PPRV which will provide insights into the epidemiology and pathogenesis of this important virus.