La pathogenèse du virus du syndrome reproducteur et respiratoire porcin (VSRRP) dans un nouveau modèle de cellules épithéliales des voies respiratoires du porc génétiquement modifiées (NPTr-CD163)
Porcine reproductive and respiratory syndrome (PRRS) is a widely spread disease in North America that causes huge economic losses in porcine industry. The PRRS virus (PRRSV) needs a lot of receptors to enter the cells. One of them is CD163, a crucial receptor to the virus internalization. Due to the importance of this receptor, researchers have genetically modified pigs to not express the CD163 receptor, providing them a resistance to PRRSV. Recently, a porcine cell-line was genetically modified to study PRRSV co-infection pathogenesis with other swine pathogens. More precisely, newborn pig trachea cells (NPTr) were modified to express the CD163 receptor, to allow PRRSV infection. However, PRRSV is known to trigger death of permissive infected cells through apoptosis, such as porcine alveolar macrophages (PAM), and MARC-145 cells. Interestingly, PRRSV can replicates into NPTr-CD163 cells at a similar rate than in MARC-145 infected cells but without inducing cell death. Also, PRRSV genome possesses high mutation rate, allowing possibility to adapt to cells without CD163 receptor. Those observations lead to the following question: how does PRRSV affect gene expression in MARC-145 cells and in NPTr-CD163 cells. Our hypothesis is that NPTr-CD163 cells response against PRRSV infection is better adapted which allow cells survival compared to MARC-145 infected cells. We also think that PRRSV could adapt to cells without CD163 receptor. Therefore, type-2 PRRSV strain, IAF-Klop, was used to infect cells at several passages containing lower to higher ratios of NPTr cells without CD163 receptor (called NPTr-N2). Also, mRNA expression modulation of the MARC-145 and the NPTr-CD163 infected cells was determined by an RNA-Seq experiment using the Illumina technology. Surprisingly, PRRSV was not able to adapt and infect NPTr-N2 cells. For the RNA-Seq experiment, an activation of the genes involved in the apoptosis pathway could be observed in NPTr-CD163 cells, but a lot of surviving genes were also expressed. This experiment gave us important insights in regards to the different mechanisms involved into PRRSV pathogenicity.
CD163 NPTr MARC-145 Co-culture PRRS PRRSV RNA-Seq mRNA