Study On The Proliferation Profile Of BHV-1 In MDBK Cells And Its Effect On Expression Of TLR2 And TLR9 Of Bovine Monocyte-macrophage

Bovine herpesvirus type I (BHV-1) is a serious hazard pathogen, which has a great effect to cattle industry. This pathogen has a strong infection ability and can be formed in vivo latent infection in cattle. It makes the bovine in poor growth, decreases milk production and so on. The cattle industry has a huge economic loss because of this pathogen. As an important pattern recognition receptors, Toll-like receptor (TLR) play a pivotal role in the body against viral infections. It has been reported that TLRs involved in the infection process of the herpes virus. Meanwhile, the herpes virus forming a variety of mechanisms to against TLRs to evade the innate immunity in the long evolutionary process, which leading to the latent infection. So, we designed experiments to explore the proliferation profile of BHV-1 in Madin-Darby bovine kidney cells (MDBK). Furthermore, we studied the changes of expression levels of TLR2 and TLR9 in the monocyte-derived macrophages (MDM) cells after infected with BHV-1 at different time.The result showed that BHV-1 were proliferated slowly when the cells infected within 6 h to 12 h, and rapidly between 24 h and 48 h. Viral copy achieved the highest value between 48 h and 144 h. After the MDM cells infected with BHV-1, the expression level of TLR2 mRNA increased significantly at 6 h and 12 h (P<0.01), at 24 h the level was significantly lower than the control group (P<0.01), and the gene expression level was not significant between infection group and control group at 48 h. The expression level of TLR9 mRNA increased at 6h after the MDM cells infected with BHV-1 (P<0.01), but at 12 h and 48 h it was not significantly difference between infection group and contral group, at 24 h the expression level of control group was higher than the infection one (P<0.05). The level of TLR2 protein increased at 6 h and 12h after the MDM cells infected with BHV-1 (P<0.01), at 24 h the TLR2 protein level is downregulated (P<0.05) and at 48 h the level between control group and infection group was not significant.This study provided the basic data for the study of the replication process of BHV-1 in MDBK cells and its immune regulation mechanism in the MDM. It makes people have a deeper understanding for pathogenesis and innate immunity of BHV-1.