Effects of TLR2/4 signalling pathway in western mosquitofish (Gambusia affinis) after Edwardsiella tarda infection.

Abstract

Gambusia affinis is regarded as an important animal model. Edwardsiella tarda is one of the most serious pathogens affecting aquaculture. The study explores the effects of TLR2/4 partial signalling pathway in G.&#xa0;affinis of E.&#xa0;tarda infection. The study collected the brain, liver, and intestine after E. tarda LDand 0.85% NaCl solution challenge at different times (0&#xa0;h, 3&#xa0;h, 9&#xa0;h, 18&#x2009;h, 24&#x2009;h, and 48&#x2009;h). In these three tissues, the mRNA levels of PI3K, AKT3, IRAK4, TAK1, IKK&#x3b2;, and IL-1&#x3b2; were substantially enhanced (p&#x2009;<&#x2009;.05) then returned to normal levels. Additionally, Rac1 and MyD88 in liver had different trend with other genes in brain and intestine, which displayed significantly indifference. The overexpression of IKK&#x3b2;, and IL-1&#x3b2; indicated that E.&#xa0;tarda also caused immune reaction in intestine and liver, which would be consistent with delayed edwardsiellosis, which causes intestinal lesions and liver and kidney necrosis. Additionally, MyD88 plays a smaller role than IRAK4 and TAK1 in this signalling pathways. This study could enrich the understanding of the immune mechanism of the TLR2/4 signalling pathway in fish and might help to prescribe preventive measures against E.&#xa0;tarda to prevent infectious diseases in fish.