Introduction: Caligus rogecresseyi is a copepod ectoparasite that affects salmonid species, causing significant economic losses in the aquaculture industry. Several antiparasitic drugs have been approved as treatment, such as avermectins, pyrethroids, benzoylureas, organophosphates, among others. However, recurrent caligidosis outbreaks associated with drug resistance have been reported. To address this issue, it is necessary to identify protein factors underlying resistance mechanisms. In this context, the main goal of this study was to evaluate the role of phase III transporters of xenobiotic metabolism (specifically ABCC1) in modulating sensitivity to commonly used antiparasitics (e.g., deltamethrin), using an RNA interference (RNAi) approach.
Methodology: Double-stranded RNAs (dsRNAs) targeting ABCC1 and a control sequence were synthesized using MEGAScript® kit. These dsRNA were then used to incubate copepodites to induce ABCC1 knockdown. The ABCC1 knockdown was verified by RT-qPCR. Subsequently, the functional effect of knockdown was evaluated through deltamethrin dose-response curves, obtaining EC50 values to determine the effect on sensitivity to this antiparasitic comparing with the respective controls.
Results: A significant knockdown for ABCC1 was achieved, increasing sensitivity to deltamethrin, which was reflected in decreased EC50 values compared to control conditions.
Conclusions: These findings demonstrate functionally that ABCC1 play a role in deltamethrin resistance mechanism observed in C. rogercresseyi, allowing us to advance in the knowledge of drug resistance mechanisms involved in caligidosis.
Acknowledgments: Beca Fortalecimiento de las capacidades de I+D para el Desarrollo de la Macrozona Sur Austral (INID210009), Centro Interdisciplinario para la Investigación Acuícola, INCAR (Proyectos FONDAP 1522A0004 y FONDAP-ANID 1523A0007), Proyecto FONDECYT 1241788.