Toll-like receptors expression in the lungs of human metapneumovirus infected mice and the effects of polyI:C on viral infection / 病毒学报

ABSTRACT

To investigate the expression changes of Toll-like receptors (TLR) in the lungs of human metapneumovirus infected BALB/c mice, and to explore the effects of PolyIC on viral replication, HMPV-infected group, PolyIC+hMPV group, PolyIC+DMED group and DMEM control group were set up for this study. All mice were sacrificed on day 1, 3, 5, 7, 9 and 16 post inoculation. Lungs were used for viral titration, pulmonary histopathology and detection of TLRs mRNA expression by RT-PCR and real-time PCR. Results showed that the levels of viral replication in the lungs of PolyIC+hMPV infected mice were significantly decreased and lung inflammation were also lessened compared with those of hMPV infected mice. RT-PCR detection showed that mRNA levels of most TLRs were up-regulated (P < 0.05) in the lungs of hMPV infected group compared with DMEM group. Real time PCR assay showed that TLR7-8 mRNA significantly increased in hMPV infected group in a time-dependent manner. The level of TLR3 mRNA was significantly up-regulated in PolyIC+hMPV group at the 24 hour after intranasal inoculation. The results showed that hMPV infection up-regulated the expression of TLRs in lungs of BALB/c mice and TLR7/8 pathway might play an important role in the start of natural immune response. PolyIC was capable of inhibiting viral replication in the lung of mice and reducing lung inflammation probably through the early activation of TLR3.