Activation of , , and in Target Organs From Piglets Infected With the Virulent PRRSV-1 Lena Strain.

Transcription factors (TFs) modulate genes involved in cell-type-specific proliferative and migratory properties, metabolic features, and effector functions. Porcine reproductive and respiratory syndrome virus (PRRSV) is one of the most important pathogen agents in the porcine industry; however, TFs have been poorly studied during the course of this disease. Therefore, we aimed to evaluate the expressions of the TFs , , , and Eomesodermin () in target organs (the lung, tracheobronchial lymph node, and thymus) and those of different effector cytokines (, , and ) and the Fas ligand () during the early phase of infection with PRRSV-1 strains of different virulence. Target organs from mock-, virulent Lena-, and low virulent 3249-infected animals humanely euthanized at 1, 3, 6, 8, and 13 days post-infection (dpi) were collected to analyze the PRRSV viral load, histopathological lesions, and relative quantification through reverse transcription quantitative PCR (RT-qPCR) of the TFs and cytokines. Animals belonging to both infected groups, but mainly those infected with the virulent Lena strain, showed upregulation of the TFs , , and , together with an increase of the cytokine in target organs at the end of the study (approximately 2 weeks post-infection). These results are suggestive of a stronger polarization to Th1 cells and regulatory T cells (Tregs), but also CD4 cytotoxic T lymphocytes (CTLs), effector CD8 T cells, and γδT cells in virulent PRRSV-1-infected animals; however, their biological functionality should be the object of further studies.