Molecular cloning and functional characterization of porcine toll-like receptor 7 involved in recognition of single-stranded RNA virus/ssRNA.

The interest in understanding interaction between the toll-like receptor and the viral infection has increased because of its importance in disease control. Here we have cloned the porcine TLR7 (pTLR7) cDNA encoding for 1050 amino acids. The pTLR7 Exhibits 90, 87, 87, 86, 84 and 78% similarity to TLR7 from cattle, dog, horse, cat, human and mouse, respectively. RT-PCR data suggested that pTLR7 mRNA was mostly synthesized in secondary lymphoid tissues (spleen, lymph node and tonsil) and antigen-presenting cells (macrophage and B cell). The cellular experiments indicated that immunostimulatory RNA oligonucleotides (ORN) found in foot-and-mouth disease virus (FMDV) activated nuclear factor-kB and induced the expression of IFN-alpha via pTLR7. We found that the ORN induced Th1-type cytokines and activated immunocytes in PBMC. The study provides foundation for further investigation in pTLR7 interactions with its ligands and interactions between the porcine immune system and pathogens.