Coronavirus and influenza virus triggers antiviral RNAi immunity [IBV_miRNA-seq]

RNA interference (RNAi) is a key antiviral immune mechanism in eukaryotes. However, in vertebrates such as birds and mammals, antiviral RNAi has only been observed in cells with poor interferon systems (stem cells and oocytes) or in viral suppressors of RNAi (VSR) deficiency virus infections. Our research originally discovered that infecting macrophages with wild-type coronavirus (Infectious bronchitis virus, IBV) and influenza viruses (Avian influenza virus, AIV) can trigger RNAi antiviral immunity and produce a certain amount of virus-derived siRNA (vsiRNA). These vsiRNAs have an inhibitory effect on the virus and carry out targeted silencing along the Dicer-Ago2-vsiRNA axis. Notably, these vsiRNAs are distributed throughout of the virus’s entire genome, with a predilection for A/U at the 5’ and 3’ termini of vsiRNA. In addition, Dicer cleavage produces vsiRNA based on the RWM motif, where R represents A/G, W represents A/C, and M represents A/U. Additionally, we discovered that avian LGP2 and MDA5 proteins positively impact the expression of the Dicer protein and the Dicer subtype “DicerM”, which exhibits a potent antiviral activity compared to Dicer itself. Most importantly, the psilencer4.1-plasmid constructed based on vsiRNA combined with nanomaterial polyetherimide (PEI) showed excellent anti-virus activity in specific-pathogen-free (SPF) chickens. These findings show that RNA viruses trigger the production of the vsiRNA in avian somatic cells, which is of great significance for the application of therapeutic vaccines in poultry. For HD11 cell experiments, the infection level of IBV-QX is 5 MOI. They were incubated at 37℃ with 5% CO2 for 2 h and then cleaned using RPMI 1640. The non-infected virus cells for the Blank group. The RNA samples were collected according to the indicated time (24 h). The group contain the NO1, NO2, NO3, NO4, NO5, and NO6.