Antimicrobial peptides Hepcidin and Dicentracin produce immunomodulation and confer partial protection against Nodavirus

Aquaculture is an economic sector which is continuously growing. However, natural outbreaks of pathogens constitute an important difficulty that this sector must face. Nodavirus (NNV) is one of the most prevalent pathogens in the Mediterranean Sea, causing viral encephalopathy and retinopathy to more than 170 fish species. One of the most affected species is European sea bass (Dicentrarchus labrax L.), which is greatly important for the Spanish aquaculture sector. Antimicrobial peptides (AMPs) are short aminoacidic sequences, cationic and amphipathic with lytic activity against a broad spectrum of pathogens including viruses. Until now, scare studies have focused on AMPs antiviral activity in fish but with positive prospects. Therefore, we aimed to evaluate the potential stimulatory effects of AMPs on the European sea bass immune system, as well as their potential as a prophylactic agent against NNV. Thus, Hepcidin (Hamp) and Dicentracin (Dic) antimicrobial peptides were chemically synthesized and intramuscularly administered to European sea bass juveniles. Head-kidney (HK) and muscle were removed after one day from the treatment to evaluate the immunomodulatory capability of the AMPs. In that moment, fish were infected with NNV and sampled two days after infection, where HK, muscle and brain were removed. In all samplings, serum samples were taken in order to perform functional analysis. Mortality and clinical signs of infection (ranked according to the severity) were recorded daily. Hamp and Dic administration resulted in a local recruitment of immune cells such as macrophages, neutrophils and T and B-cells to the site of injection. Moreover, the levels of AMPs were modulated both systemic and locally. Regarding the disease pattern upon NNV infection, AMPs administration reduced the transcription levels of proinflammatory gene markers in brain, leading to the prevention of neuronal damage and ameliorating the mortality rates. In addition, Hamp is also able to prevent, to a certain extent, NNV mortalities conferring partial protection against this disease. To conclude, the use of AMPs as European sea bass could be a valuable tool to prevent NNV disease in fish farms. Funded by MCIN/AEI 10.13039/501100011033 (grants RTI2018-096625-B-C33, PID2019-105522GB-100 and PRE2020-093771 to L.C) and “Fundación Séneca” (grant 19883/GERM/15).

ALGAFISH

Evaluación de los efectos de las microalgas, incluidas en dietas de dorada, sobre el crecimiento, supervivencia y resistencia a infecciones.