AUTHOR=Zhu Zhenbang , Zhang Hui , Zhang Xiaoxiao , He Sheng , Dong Wenjuan , Wang Xiaoying , Chen Yaosheng , Liu Xiaohong , Guo Chunhe TITLE=Lipopolysaccharide Downregulates CD163 Expression to Inhibit PRRSV Infection via TLR4-NF-κB Pathway JOURNAL=Frontiers in Microbiology VOLUME=11 YEAR=2020 URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.00501 DOI=10.3389/fmicb.2020.00501 ISSN=1664-302X ABSTRACT=

Porcine reproductive and respiratory syndrome virus (PRRSV) has been recognized to induce proinflammatory cytokine production and modulate the host interferon (IFN) system. Proinflammatory cytokines and type I IFNs contribute to the prevention of viral infection. Lipopolysaccharide (LPS), a specific agonist to Toll-like receptor 4 (TLR4), provokes signal transduction and activates immune response in vivo and in vitro. Here we identified LPS inhibited PRRSV infection in porcine alveolar macrophages (PAMs) and in Marc-145 cells. To investigate the possible mechanism, we found TLR4-NF-κB pathway was obviously activated in LPS-treated PAMs at the early stage of PRRSV infection. As a result, the expression of proinflammatory cytokines was strongly induced following LPS and PRRSV co-treatment. Due to the enhanced proinflammatory response, CD163 expression was significantly reduced and a disintegrin and metalloproteinase 17 was activated, which promotes the cleavage of membrane CD163. Ultimately, CD163 down-regulation led to the suppression of PRRSV replication. Our data demonstrate that LPS has an impact on PRRSV infection via inflammation response, which provides a new insight of inflammation-mediated antiviral immunity and a new strategy to control PRRSV infection.