Recombinant nodavirus vaccine produced in bacteria and administered without purification elicits humoral immunity and protects European sea bass against infection

Viral necrosis virus (NNV) or nodavirus causes fish viral encephalopathy and retinopathy worldwide. In some cases, mortalities in aquaculture industry can reach up to 100%, some species being especially sensitive as is the case of European sea bass (Dicentrarchus labrax), one of the main cultured species in the Mediterranean, with the consequent economical loses. Development of new vaccines against NNV is in the spotlight though few re- searches have focused in European sea bass. In this study we have generated a recombinant NNV (rNNV) vaccine produced in Escherichia coli expressing the capsid protein and administered it to European sea bass juveniles by two different routes (intraperitoneal and oral). The last being considered non-stressful and desired for fish farming of small fish, which in fact are the most affected by NNV. Oral vaccine was composed of feed pellets containing the recombinant whole bacteria, and injected vaccine was composed of recombinant bacteria pre- viously lysed. Our results revealed production of specific anti-NNV IgM following the two vaccination proce- dures, levels that were further increased in orally-vaccinated group after challenge with NNV. Genes related to interferon (IFN), T-cell and immunoglobulin markers were scarcely regulated in head-kidney (HK), gut or brain. Vaccination by either route elicited a relative survival response of 100% after NNV challenge. To our knowledge, this is the first report of a recombinant vaccine followed by no purification steps which resulted in a complete protection in European sea bass when challenged with NNV.Versión del edito

Diferencias sexuales en la respuesta inmune innata de la gónada en lubinas

Nodavirus (NNV) es un virus con probada transmisión sexual tanto en hembras como en machos. En este trabajo hemos analizado la respuesta citotóxica, fagocítica y de producción de reactivos de oxigeno (ROIs) por primera vez en gónada, tanto en ovario como en testículo, de lubinas (Dicentrarchus labrax). Los resultados demuestran que la actividad citotóxica y producción de ROIs es semejante en ambos sexos, no así la actividad fagocítica ya que hay más proporción de células fagocíticas en el testículo que en el ovario de lubina. Este estudio representa un estudio preliminar que demuestra ciertos niveles de actividad citotóxica en la gónada de lubina, la cual es inducible tras una infección por NNV

Comparative skin mucus and serum humoral defence mechanism in the teleost gilthead seabream (Sparus aurata)

Mucosal surfaces of fish, including skin, gill and gut, contain numerous immune substances poorly studied that act as the first line of defence against a broad spectrum of pathogens. This study aimed to identify and characterize for the first time different constitutive humoral defence mechanisms of the skin mucus of gilthead seabream (Sparus aurata). To do this, the levels of total immunoglobulin M, several enzymes and proteins (peroxidase, lysozyme, alkaline phosphatase, esterases, proteases and antiproteases), as well as the bactericidal activity against opportunist fish pathogens (Vibrio harveyi, Vibrio angillarum, Photobacterium damselae) and non-pathogenic bacteria (Escherichia coli, Bacillus subtilis) were measured in the skin mucus and compared with those found in the serum. This study demonstrates that gilthead seabream skin mucus contains lower levels of IgM, similar levels of lysozyme, alkaline phosphatase and proteases, and higher esterase, peroxidase and antiprotease activities than serum. In addition, skin mucus revealed stronger bactericidal activity against tested fish pathogen bacteria compared to the serum activity, while human bacteria can even grow more in the presence of mucus. The results could be useful for better understanding the role of the skin mucus as a key component of the innate immune system with potential application for the aquaculture.Postprin