A new crustin-like gene from the redclaw crayfish Cherax quadricarinatus and its response to decapod iridescent virus 1 (DIV1) challenge

Crustin, a widely-studied antimicrobial peptides (AMPs), has been proven to be involved in mediating innate immune responses against intruding pathogens. In this study, a novel crustin-like gene, Cqcarc1, was characterized from the redclaw crayfish Cherax quadricarinatus. The full-length cDNA sequence was 488 bp, and the open reading frame encoded 101 amino acids with a signal peptide in the N-terminus and a conserved WAP domain in the C-terminus. Similar to the Crustin2 gene (CqCrs) in C. quadricarinatus, the highest expression level of Cqcarc1 was also detected in the hemocyte organ. Moreover, RNAi-mediated gene silencing of Cqcarc1 could increase the DIV1 copy number compared with the control group, suggesting its involvement in the immune defense against the DIV1 challenge. Furthermore, RNA interference analysis also showed that Cqcarc1 plays positive regulatory roles in the expressions of CqToll and CqCrs during DIV infection. In summary, the current findings suggested the Toll-crustin signal pathway as a potential target for improving immunity from the DIV1 challenge.