The Asian swamp eel （Monopterus albus） is one of the most economically important freshwater fish in East Asia, but data on the immune genes of M. albus are scarce compared to other commercially important fish. A better understanding of the eel＇s immune responses may help in developing strategies for disease management, potentially improving yields and mitigating losses. In mammals, interferon regulatory factors （IRFs） play a vital role in both the innate and adaptive immune system; though among teleosts IRF4 and IRFIO have seldom been studied. In this study, we characterized IRF4 and IRFIO from M. albus （malRF4 and malRFlO） and found that malRF4 cDNA consists of 1 716 nucleotides encoding a 451 amino acid （aa） protein, while malRFlO consists of 1 744 nucleotides including an open reading frame （ORF） of 1 236 nt encoding 411 aa. The malRFlO gene was constitutively expressed at high levels in a variety of tissues, while malRF4 showed a very limited expression pattern. Expression of malRF4 and malRFlO in head kidney, and spleen tissues was significantly up-regulated from 12 h to 48 h post-stimulation with polyinosinic： polycytidylic acid （poly I：C）, lipopolysaccharide （LPS） and a common pathogenic bacteria Aeromonas hydrophila. These results suggest that IRF4 and IRF10 play roles in immune responses to both viral and bacterial infections in M. albus.
Qiao-Qing XUDai-Qin YANGRui TUOJing WANMing-Xian CHANGPin NIE
