A new vaccine strategy to combat viral infections in european-farmed finfish
- Autores: Rosemary Thwaite
- Directores de la Tesis: Nerea Roher Armentia (dir. tes.), Dolores Jaraquemada Pérez de Guzmán (tut. tes.)
- Lectura: En la Universitat Autònoma de Barcelona ( España ) en 2019
- Idioma: español
- Tribunal Calificador de la Tesis: Beatriz Novoa Garcia (presid.), Neus Ferrer Miralles (secret.), Juan Alberto Falco Gracia (voc.)
- Programa de doctorado: Programa de Doctorado en Inmunología Avanzada por la Universidad Autónoma de Barcelona
- Materias:
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- Resumen
The aquaculture industry is a sector of dynamic growth, providing a high quality food source in the context of diminishing wild fish stocks and the need for global food security. Viral diseases are a major threat to finfish production and therapeutics are still lacking. Typically, commercially available vaccines are in the format of inactivated virus and are targeted to only a few, high market value fish species. The production and delivery process is expensive, with individual administration via injection. In this scenario, developing new, effective, practical vaccines which could be suitable for mass vaccination is a priority in the industry.
In this thesis we have drawn on recent work in biomaterials science to seek innovative strategies. We have nanostructured antigenic fish viral proteins as bacterial inclusion bodies (IBs), produced in Escherichia coli. The attractiveness of IBs as a vaccine design for aquaculture is that they are cheap, safe and stable in vivo without encapsulation, in contrast to soluble proteins. They provide a reservoir of biologically active protein which is slowly released. Here we target three viruses relevant in European finfish farming: The emergent reassortant strain of viral nervous necrosis virus (VNNV strain RGNNV/SJNNV) affecting Mediterranean marine farmed fish, and infectious pancreatic necrosis virus (IPNV) and viral haemorrhagic septicaemia virus (VHSV), both affecting salmonids. We present a comprehensive study of the production and immune response to three protein nanoparticle IBs made of antigenic proteins from each virus, VNNV coat protein C, IPNV capsid protein VP2 and a VHSV glycoprotein G fragment.
We demonstrate the three nanoparticles are taken up by zebrafish liver cells (ZFL) using flow cytometry and confocal microscopy. Using qPCR, we show the nanoparticles have immunostimulant properties in vitro, evoking an anti-viral innate immune response in ZFL and primary trout macrophage cultures. We also demonstrate by oral gavage that zebrafish can take up the nanoparticles through the intestine as a proof of concept for oral delivery. No toxic effects were observed in vivo nor in an MTT cytotoxicity assay in vitro.
In in vivo farmed fish models using Senegalese sole (S. senegalensis) and rainbow trout (O. mykiss), we report the nanostructured viral proteins VNNV-CNP and VHSV-G-frg16NP, when injected intraperitoneally (i.p.), can raise specific, antiviral antibodies, as a surrogate of protection. Moreover, we show the anti-VHSV IgMs raised in trout are neutralizing, and upon infectious challenge with the virus, survival of vaccinated fish is consistent with protection. In Senegalese sole we also performed immune gene expression studies and compared the antibody response for i.p. and oral delivery using a novel oral intubation method. Our findings show the oral route can raise anti-viral antibodies but needs to be optimized to avoid a tolerance response.
We conclude this new approach to develop practical vaccines for farmed fish holds promise.
