Scavenger receptor class B type 2 (SR-B2) is a pattern recognition receptor involved in innate immunity in mammals; however, the immunological function of SR-Bs in fish remains unclear. In this study, the full-length cDNA sequences of SR-B2a and SR-B2b from grass carp (Ctenopharyngodon idellus) were cloned and designated as CiSR-B2a and CiSR-B2b. Multiple alignments and phylogenetic analyses deduced that CiSR-B2a and CiSR-B2b had the highest evolutionary conservation and were closely related to the zebrafish (Danio rerio) homologs, DrSR-B2a and DrSR-B2b, respectively. Both CiSR-B2a and CiSR-B2b were expressed in all the tested tissues, with the highest expression levels found in the hepatopancreas. In Ctenopharyngodon idellus kidney cells (CIK), CiSR-B2a and CiSR-B2b were mainly located in the cytoplasm, and a small amount located on the plasma membrane. After challenge with Grass Carp Reovirus (GCRV), the expression of CiSR-B2a and CiSR-B2b were significantly upregulated in the spleen (about 10.27 and 27.19 times higher than that at 0 day, p < 0.01). With CiSR-B2a or CiSR-B2b overexpressed in CIK, the relative copy number of GCRV in the cells was both significantly increased compared to that in the control group, indicating that CiSR-B2a and CiSR-B2b may be important proteins during the infection processes of GCRV.

清道夫受体 B 类 2 型 (SR-B2) 是一种参与哺乳动物先天免疫的模式识别受体；然而，SR-Bs 在鱼类中的免疫功能仍不清楚。本研究克隆了草鱼（Ctenopharyngodon idellus ） SR-B2a和SR-B2b的全长cDNA序列，命名为CiSR-B2a和CiSR-B2b。多重比对和系统发育分析推断 CiSR-B2a 和 CiSR-B2b 具有最高的进化保守性，并且分别与斑马鱼 ( Danio rerio ) 同源物 DrSR-B2a 和 DrSR-B2b 密切相关。CiSR -B2a和CiSR-B2b在所有受试组织中均有表达，在肝胰腺中表达水平最高。在Ctenopharyngodon idellus肾细胞(CIK)中，CiSR-B2a和CiSR-B2b主要位于细胞质中，少量位于质膜上。草鱼呼肠孤病毒（GCRV）攻击后，脾脏中CiSR-B2a和CiSR-B2b的表达显着上调（分别为0天时的10.27和27.19倍，p  < 0.01）。使用CiSR-B2a或CiSR-B2b在CIK中过表达，GCRV在细胞中的相对拷贝数与对照组相比均显着增加，表明CiSR-B2a和CiSR-B2b可能是GCRV感染过程中的重要蛋白。