Genome-wide identification of chicken bursae of Fabricius miRNAs in response to very virulent infectious bursal disease virus

The long noncoding RNA loc107053557 acts as a gga-miR-3530-5p sponge to suppress the replication of vvIBDV through regulating STAT1 expression

Infectious bursal disease virus (IBDV) causes immunosuppression and high mortality in young chickens. Long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) are important regulators during viral infection. However, detailed the regulatory mechanisms of lncRNA-miRNA-mRNA have not yet been described in IBDV infection. Here, we analysed the role of lncRNA53557/gga-miR-3530-5p/STAT1 axis in very virulent IBDV (vvIBDV) infection. Evidently upregulated expression of lncRNA53557 was observed in bursa of Fabricius and DT40 cells. Meanwhile, overexpression of lncRNA53557 promoted STAT1 expression and inhibited vvIBDV replication and vice versa, indicating that the upregulation of lncRNA53557 was part of the host antiviral defence. The subcellular fractionation assay confirmed that lncRNA53557 can be localized in the cytoplasm. Further, dual-luciferase reporter, RNA pulldown, FISH and RT-qPCR assays revealed that lncRNA53557 were directly bound to gga-miR-3530-5p and had a negative regulatory relationship between them. Subsequent mechanistic analysis showed that lncRNA53557 acted as a competing endogenous RNA (ceRNA) of gga-miR-3530-5p to relieve the repressive effect of gga-miR-3530-5p on its target STAT1, as well as Mx1, OASL, and ISG15, thereby suppressing vvIBDV replication. The study reveals that a network of enriched lncRNAs and lncRNA-associated ceRNA is involved in the regulation of IBDV infection, offering new insight into the mechanisms underlying IBDV-host interaction.

Host combats porcine reproductive and respiratory syndrome virus infection at non-coding RNAs level

Porcine reproductive and respiratory syndrome virus (PRRSV) poses a significant threat to the global swine industry. The emergence of new, highly virulent strains has precipitated recurrent outbreaks worldwide, underscoring the ongoing battle between host and virus. Thus, there is an imperative to formulate a more comprehensive and effective disease control strategy. Studies have shown that host non-coding RNA (ncRNA) is an important regulator of host - virus interactions in PRRSV infection. Hence, a thorough comprehension of the roles played by ncRNAs in PRRSV infection can augment our understanding of the pathogenic mechanisms underlying PRRSV infection. This review focuses on elucidating contemporary insights into the roles of host microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs) in PRRSV infection, providing both theoretical foundations and fresh perspectives for ongoing research into the mechanisms driving PRRSV infection and its pathogenesis.

RNA-seq reveals role of cell-cycle regulating genes in the pathogenicity of a field very virulent infectious bursal disease virus

Infectious bursal disease virus (IBDV) infection causes highly contagious and immunosuppressive disease in poultry. The thymus, serving as the primary organ for T cell maturation and differentiation, plays an important role in the pathogenicity of IBDV in the infected chickens. However, there are no reports on the molecular pathogenesis of IBDV in the thymus currently. The aim of the study was to elucidate the molecular mechanisms underlying the pathogenicity of a field very virulent (vv) IBDV strain NN1172 in the thymus of SPF chickens using integrative transcriptomic and proteomic analyses. Our results showed that a total of 4,972 Differentially expressed genes (DEGs) in the thymus of NN1172-infected chickens by transcriptomic analysis, with 2,796 up-regulated and 2,176 down-regulated. Meanwhile, the proteomic analysis identified 726 differentially expressed proteins (DEPs) in the infected thymus, with 289 up-regulated and 437 down-regulated. Overall, a total of 359 genes exhibited differentially expression at both mRNA and protein levels, with 134 consistently up-regulated and 198 genes consistently down-regulated, as confirmed through a comparison of the RNA-seq and the proteomic datasets. The gene ontology (GO) analysis unveiled the involvement of both DEGs and DEPs in diverse categories encompassing cellular components, biological processes, and molecular functions in the pathological changes in IBDV-infected thymus. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that the host mainly displayed severely disruption of cell survival/repair, proliferation and metabolism pathway, meanwhile, the infection triggers antiviral immune activation with a potential emphasis on the MDA5 pathway. Network inference analysis identified seven core hub genes, which include CDK1, TYMS, MCM5, KIF11, CCNB2, MAD2L1, and MCM4. These genes are all associated with cell-cycle regulating pathway and are likely key mediators in the pathogenesis induced by NN1172 infection in the thymus. This study discovered dominant pathways and genes which enhanced our understanding of the molecular mechanisms underlying IBDV pathogenesis in the thymus.

miRNA Expression Signatures Induced by Chicken Astrovirus Infection in Chickens

miRNAs represent ubiquitous regulators of gene expression and play an important and pivotal regulatory role in viral disease pathogenesis and virus-host interactions. Although previous studies have provided basic data for understanding the role of miRNAs in the molecular mechanisms of viral infection in birds, the role of miRNAs in the regulation of host responses to chicken astrovirus (CAstV) infection in chickens is not yet understood. In our study, we applied next-generation sequencing to profile miRNA expression in CAstV-infected chickens and to decipher miRNA-targeted specific signaling pathways engaged in potentially vital virus-infection biological processes. Among the 1354 detected miRNAs, we identified 58 mature miRNAs that were significantly differentially expressed in infected birds. Target prediction resulted in 4741 target genes. GO and KEGG pathway enrichment analyses showed that the target genes were mainly involved in the regulation of cellular processes and immune responses.

Host Combats IBDV Infection at Both Protein and RNA Levels

Infectious bursal disease (IBD) is an acute, highly contagious, and immunosuppressive avian disease caused by infectious bursal disease virus (IBDV). In recent years, with the emergence of IBDV variants and recombinant strains, IBDV still threatens the poultry industry worldwide. It seems that the battle between host and IBDV will never end. Thus, it is urgent to develop a more comprehensive and effective strategy for the control of this disease. A better understanding of the mechanisms underlying virus-host interactions would be of help in the development of novel vaccines. Recently, much progress has been made in the understanding of the host response against IBDV infection. If the battle between host and IBDV at the protein level is considered the front line, at the RNA level, it can be taken as a hidden line. The host combats IBDV infection at both the front and hidden lines. Therefore, this review focuses on our current understanding of the host response to IBDV infection at both the protein and RNA levels.