Research progress of fish microRNA in innate immunity

Innate immunity is the first line of defense for hosts to recognize pathogens and eliminate pathogen infection. Pattern recognition receptors are the main molecules involved in the recognition of foreign pathogen invasion, including Toll-like receptors, RIG-I like receptors, NOD-like receptors and CLR-like receptors. After recognizing the molecular patterns associated with pathogens, pattern recognition receptors activate innate immune signaling pathways and induce the production of inflammatory cytokines and interferons, thereby initiating immune responses against pathogen invasion. Accumulating evidence suggests that the activation, maintenance and termination of immune responses need to be tightly regulated so that the body can maintain a certain immune strength while avoiding hyperimmune responses. MicroRNAs are small non-coding RNAs of 18-23 nt in length, which are important regulators in the innate immune response network of fish. Recently, a large number of studies have been conducted on microRNA in fish innate immunity, but there is no comprehensive and up to date review of such studies at home or abroad. In view of this, this paper reviews the research progress on miRNA in fish innate immune response in recent years, so as to provide some ideas for molecular disease-resistance breeding and disease prevention and control of fish.