Outbreaks of infectious disease in shrimp pose a serious threat to shrimp agriculture worldwide. Shrimp lack adaptive immunity and depend only on innate immunity as a defense system against infectious disease. Toll-like receptors (TLR) are reported to play a critical role in the innate immune system. In this study, we identified a Toll-like receptor gene of a species of freshwater shrimp, Macrobrachium nipponense, designated MnToll, for the first time. The sequence of MnToll encoded 935 residues arranged as 10 leucine-rich repeat (LRR) domains, a leucine-rich repeat C-terminal (LRR CT) domain and a Toll/interleukin-1 receptor (TIR) domain and displayed 90% amino acid similarity to previously identified TLRs (Toll 1 and 2) of Macrobrachium rosenbergii. We additionally evaluated mRNA expression of MnToll in various tissues, including heart, gills, stomach, digestive gland, ventral nerve cord, antennal gland and muscle. Following infection with a viral pathogen, white spot syndrome virus (WSSV), MnToll expression was significantly upregulated between 12 and 72 h. Our data collectively suggest that the newly identified MnToll gene belongs to the TLR family in shrimp and is potentially involved in innate host defense, especially against WSSV.

虾类传染病的爆发严重威胁着全世界的虾类养殖。虾缺乏适应性免疫，仅依赖先天免疫作为防御传染病的防御系统。据报道，Toll样受体（TLR）在先天免疫系统中起关键作用。在这项研究中，我们首次确定了淡水虾日本沼虾的Toll样受体基因，命名为MnToll。MnToll序列编码935个残基，排列为10个富含亮氨酸的重复（LRR）域，一个富含亮氨酸的重复C末端（LRR CT）域和Toll /白介素1受体（TIR）域，并显示90％的氨基酸与先前鉴定的罗氏沼虾的TLR（收费1和2）相似。我们还评估了MnToll在各种组织中的mRNA表达，包括心脏，腮，胃，消化腺，腹神经索，触角腺和肌肉。在被病毒病原体白斑综合症病毒（WSSV）感染后，MnToll表达在12至72小时之间显着上调。我们的数据共同表明，新近鉴定的MnToll基因属于虾的TLR家族，并可能参与先天宿主防御，特别是针对WSSV的防御。