The formulation and immunisation of oral poly(DL-lactide-co-glycolide) microcapsules containing a plasmid vaccine against lymphocystis disease virus in Japanese flounder (Paralichthys olivaceus)

Adaptive immune responses at mucosal surfaces of teleost fish

“…Rainbow trout orally vaccinated with polyethylene glycol (PEG) coated lyophilised viral hemorrhagic septicaemia virus (VHSV; incorporated at a special low temperature) in extruded feed particles caused increased expression of mhc II and cd4 mRNAs, VHSV specific antibody levels in the blood and clear protection against the viral infection [135]. Plasmid DNA coding for lymphocystis disease virus (LCDV) incorporated in alginate microspheres [28] or PLGA microcapsules [136] were used for oral vaccination of Japanese olive flounder. Both the carriers loaded with the plasmid can be transported through the gut without being degraded, and once the plasmids are expressed in the lymphoid tissues, specific antibodies are produced.…”

“…Since mammalian M cells have a strong phagocytic capability, and epithelial transport takes place without the interference of degrading lysosomes, the uptake and transport of particles of different sizes should be studied to confirm the similarity of this trout cell type to mammalian M cells. Further, the uptake of PLGA particles by intestinal epithelium [135,136,140] and local cytotoxicity induced by anally intubated target cells [108,109] indicate the induction of phagocytosis, which may allow cellular antigens to pass the barrier. However, it is not known if this antigen transport occurs through specialized cells or regular enterocytes.…”

Immunogenic and protective effects of an oral DNA vaccine against infectious pancreatic necrosis virus in fish

“…These vaccines induced strong protection when administered intramuscularly but there are no reports of their oral use. The majority of studies on oral DNA vaccines against fish viruses have focused on the use of different materials for delivery of the lymphocystis disease virus (LCDV) [22,36]. Besides the viral peptide, the plasmid used also encodes the green fluorescent protein, and RT-PCR and immunofluorescence imaging indicated that pDNA expressed RNA and green fluorescence protein accumulated in different fish tissues from 10 to at least 90 days after oral administration.…”

“…The pcDNA3.1 vector used to generate the viral vaccine constructs contains 25 cCpG motifs and some studies of immunological gene expression responses suggest that this vector DNA is immunostimulatory [37]. In experiments with LCDV [23,36] orally administered naked pDNA did not produce positive results indicating that the plasmid must be protected in this route. Other formulations to coat pDNA plasmids and act as carriers for oral immunization have also been described, such as poly (DL-lactideco-glycolide) microcapsules or chitosan microspheres.…”

Viral vaccines for farmed finfish

“…The recently introduced ISAV vaccine from Centrovet uses a proprietary microencapsulation system designed to protect the SVP-based ISAV hemagglutinin esterase antigen from destruction [104]. While the composition of this encapsulation matrix was not disclosed by these authors, other research has been on-going using materials such as alginate and chitosan to improve oral delivery of vaccines in fish [100][101][102]107] and work on this area continues.…”