Toll-like receptors, which are a class of cell-surface proteins, have been regarded as the most important pattern recognition receptors in the innate immunity and play a vital role in multiple innate immune responses against pathogen invasion. The full-length cDNA of a novel Toll-like receptor (MrToll3) was identified from Macrobrachium rosenbergii in the current research. The nucleotide sequence of MrToll3 is 4481 bp long and contains a 3726-bp open reading frame encoding a putative protein of 1241 amino acids. MrToll3 was constitutively expressed in all the examined tissues, and high expression of MrToll3 was detected in gill, heart, and ganglion. The result of RNA interference assay revealed that silencing of MrToll1 remarkably suppressed the prophenoloxidase (proPO) expression and phenoloxidase (PO) activities while enhancing MrToll2 expression in the prawns. Furthermore, the expression of myeloid differentiation factor 88 (MyD88), anti-lipopolysaccharide factor (ALF) and crustin was remarkably down-regulated in the MrToll1-silenced prawns after white spot syndrome virus (WSSV) or Vibrio alginolyticus challenge. MrToll2-silenced prawns exhibited the significant decline of ALF and crustin expression post the pathogen challenges, and silencing of MrToll3 obviously improved the immune deficiency (IMD) expression during the whole RNA interference assay. Additionally, higher mortality was observed in MrToll1-or MrToll2-silenced prawns after V. alginolyticus challenge, and the MrToll1-silenced prawns also showed the obviously enhanced susceptibility to WSSV. These results suggested that MrToll1, 2, and 3 were involved in the innate immune responses against WSSV and V. alginolyticus in M. rosenbergii.

Toll样受体是一类细胞表面蛋白，被认为是先天免疫中最重要的模式识别受体，并且在抵抗病原体入侵的多种先天免疫应答中起着至关重要的作用。从罗氏沼虾中鉴定出新型Toll样受体（MrToll3）的全长cDNA在目前的研究中。MrToll3的核苷酸序列长4481 bp，包含一个3726 bp的开放阅读框，编码1244个氨基酸的推测蛋白。MrToll3在所有检查的组织中组成性表达，并且在g，心脏和神经节中检测到MrToll3的高表达。RNA干扰分析的结果表明，MrToll1的沉默显着抑制了对虾酚氧化酶原（proPO）的表达和酚氧化酶（PO）的活性，同时增强了对虾的MrToll2表达。此外，在白斑综合症病毒（WSSV）或溶藻弧菌感染后，MrToll1沉默的对虾中髓样分化因子88（MyD88），抗脂多糖因子（ALF）和克鲁斯汀的表达显着下调。挑战。在病原体攻击后，MrToll2沉默的对虾表现出ALF和克鲁斯汀表达的显着下降，MrToll3的沉默显着改善了整个RNA干扰测定期间的免疫缺陷（IMD）表达。此外，在溶藻弧菌攻击后，在MrToll1或MrToll2沉默的对虾中观察到更高的死亡率，而MrToll1沉默的对虾对WSSV的敏感性也明显增强。这些结果表明，MrToll1，2和3参与了对WSSV和先天免疫反应溶藻弧菌在罗氏沼虾。