Genome-wide analysis of antiviral signature genes in porcine macrophages at different activation statuses

Macrophages (MФs) can be polarized to various activation statuses, including classical (M1), alternative (M2), and antiviral states. To study the antiviral activation status of porcine MФs during porcine reproductive and respiratory syndrome virus (PRRSV) infection, we used RNA Sequencing (RNA-Seq) for transcriptomic analysis of differentially expressed genes (DEGs). Sequencing assessment and quality evaluation showed that our RNA-Seq data met the criteria for genome-wide transcriptomic analysis. Comparisons of any two activation statuses revealed more than 20,000 DEGs that were normalized to filter out 153–5,303 significant DEGs [false discovery rate (FDR) ≤0.001, fold change ≥2] in each comparison. The highest 5,303 significant DEGs were found between lipopolysaccharide- (LPS) and interferon (IFN)γ-stimulated M1 cells, whereas only 153 significant DEGs were detected between interleukin (IL)-10-polarized M2 cells and control mock-activated cells. To identify signature genes for antiviral regulation pertaining to each activation status, we identified a set of DEGs that showed significant up-regulation in only one activation state. In addition, pathway analyses defined the top 20–50 significantly regulated pathways at each activation status, and we further analyzed DEGs pertinent to pathways mediated by AMP kinase (AMPK) and epigenetic mechanisms. For the first time in porcine macrophages, our transcriptomic analyses not only compared family-wide differential expression of most known immune genes at different activation statuses, but also revealed transcription evidence of multiple gene families. These findings show that using RNA-Seq transcriptomic analyses in virus-infected and status-synchronized macrophages effectively profiled signature genes and gene response pathways for antiviral regulation, which may provide a framework for optimizing antiviral immunity and immune homeostasis

Virus replicon particles expressing porcine reproductive and respiratory syndrome virus proteins elicit immune priming but do not confer protection from viremia in pigs

International audienceAbstractPorcine reproductive and respiratory syndrome virus (PRRSV) is the causative agent of one of the most devastating and economically significant viral disease of pigs worldwide. The vaccines currently available on the market elicit only limited protection. Recombinant vesicular stomatitis virus (VSV) replicon particles (VRP) have been used successfully to induce protection against influenza A virus (IAV) in chickens and bluetongue virus in sheep. In this study, VSV VRP expressing the PRRSV envelope proteins GP5, M, GP4, GP3, GP2 and the nucleocapsid protein N, individually or in combination, were generated and evaluated as a potential vector vaccine against PRRSV infection. High level expression of the recombinant PRRSV proteins was demonstrated in cell culture. However, none of the PRRSV antigens expressed from VRP, with the exception of the N protein, did induce any detectable antibody response in pigs before challenge infection with PRRSV. After challenge however, the antibody responses against GP5, GP4 and GP3 appeared in average 2 weeks earlier than in pigs vaccinated with the empty control VRP. No reduction of viremia was observed in the vaccinated group compared with the control group. When pigs were co-vaccinated with VRP expressing IAV antigens and VRP expressing PRRSV glycoproteins, only antibody responses to the IAV antigens were detectable. These data show that the VSV replicon vector can induce immune responses to heterologous proteins in pigs, but that the PRRSV envelope proteins expressed from VSV VRP are poorly immunogenic. Nevertheless, they prime the immune system for significantly earlier B-cell responses following PRRSV challenge infection