Gene expression changes in chicken NLRC5 signal pathway associated with in vitro avian leukosis virus subgroup J infection.

Nucleotide-binding oligomerization domain-like receptors (NLRs) play a key role in the innate immune response as pattern-recognition receptors. However, the role of NLRC5, which is a member of the NLR family, in NF-κB activation and MHC-I expression remains debatable. Infection with the J group avian leukosis virus (ALV-J) can result in immunosuppression and a subsequent increase in susceptibility to secondary infection. This results in huge economic losses to the poultry industry worldwide. Using quantitative real-time polymerase chain reaction (qRT-PCR), we investigated the mRNA expression levels of NLRC5 signal pathway-related genes in secondary chicken embryo fibroblasts 7 days after infection with ALV-J. The results indicated that, compared with the control groups, the expression levels of TLR7, MHC-I, and IL-18 increased significantly in the infected groups at 7 days post-infection (d.p.i.). The expression levels of NLRC5 and IL-6 were conspicuously downregulated at 7 d.p.i., but the expression levels of NF-κB, STAT1, and STAT3 were not significantly altered. These results suggest that NLRC5 and some genes involved in the NLRC5 pathway play a key role in antiviral immunity, typically the response to ALV-J infection. Moreover, MHC-I expression levels vary between different cell types.