The development of vaccines against sea lice in the salmon farming production is a complex, expensive and long process for the commercial validation. Hence, transcriptomic studies in sea lice have provided valuable information to understand the molecular mechanisms involved in the host-parasite interaction. However, the bottleneck is the in vivo testing of several candidate recombinant proteins, dosage and also polyvalent formulation strategies. This study explored a cell-based platform to prospect antigens as candidate vaccines against sea lice. The experimental model used is the Atlantic salmon Salmo salar and the sea louse Caligus rogercresseyi. Herein, secretome/excretory-related proteins (SEPs) were identified in C. rogercresseyi, cloned and expressed in Escherichia coli. Then, SHK-1 cell line were stimulated with candidate recombinant proteins and evaluated through RNA-seq analysis. The experiment was conducted with 25, 50, and 100 ng/mL of SEPs, and a combination of them during 24 hours. Cell exposure to the SEPs showed significant cell damage comparing with the control group exposed to BSA. Significant changes in the transcriptome profiles of SHK-1 were found in cell groups exposed to SEPs compared to the control groups composed by BSA and LPS. Furthermore, RNA-seq and qPCR analyses determined that Cathepsin has the highest impact on the immune-related genes. The findings archived by the in vitro model was used to formulate and test a candidate vaccine, showing a 44% and 57% of efficacy at 7 and 25 dpi, respectively. This study provides a novel approach to develop sea lice vaccines, improving the antigens identification process and their selection for commercial validation.
Funding: ANID-Chile through the grant FONDECYT (#1210852), and FONDAP (#15110027).