Vaccination of carp against SVCV with an oral DNA vaccine or an insect cells-based subunit vaccine

Abstract

We recently reported on a successful vaccine for carp against SVCV based on the intramuscular injection of a DNA plasmid encoding the SVCV glycoprotein (SVCV-G). This shows that the intramuscular (i.m.) route of vaccination is suitable to trigger protective responses against SVCV, and that the SVCV G-protein is a suitable vaccine antigen. Yet, despite the general success of DNA vaccines, especially against fish rhabdoviruses, their practical implementation still faces legislative as well as consumer's acceptance concerns. Furthermore, the i.m. route of plasmid administration is not easily combined with most of the current vaccination regimes largely based on intraperitoneal or immersion vaccination. For this reason, in the current study we evaluated possible alternatives to a DNA-based i.m. injectable vaccine using the SVCV-G protein as the vaccine antigen. To this end, we tested two parallel approaches: the first based on the optimization of an alginate encapsulation method for oral delivery of DNA and protein antigens; the second based on the baculovirus recombinant expression of transmembrane SVCV-G protein in insect cells, administered as whole-cell subunit vaccine through the oral and injection route. In addition, in the case of the oral DNA vaccine, we also investigated the potential benefits of the mucosal adjuvants Escherichia coli lymphotoxin subunit B (LTB). Despite the use of various vaccine types, doses, regimes, and administration routes, no protection was observed, contrary to the full protection obtained with our reference i.m. DNA vaccine. The limited protection observed under the various conditions used in this study, the nature of the host, of the pathogen, the type of vaccine and encapsulation method, will therefore be discussed in details to provide an outlook for future vaccination strategies against SVCV.

A DNA Vaccine Encoding the VAA Gene of Vibrio anguillarum Induces a Protective Immune Response in Flounder

“…A possible explanation for this observation may be that the expression of the VAA protein increases the percentage of sIgM + lymphocytes. Indeed, similar results have been noted in previous studies demonstrating the induction of sIgM + B lymphocytes following intramuscular or oral immunization with DNA plasmids (13,42,70). Taken together, these results suggest that the intramuscularly administrated pVAA vaccine induced a humoral immune response in flounder.…”

Cyprinid viral diseases and vaccine development

“…In all trials, immunized fish demonstrate a strong protective response against SVCV, with relative survival ranging from 50% to 88% [209]. Vaccination with an oral or injection subunit vaccine based on the baculovirus recombinant expression of transmembrane SVCV-G protein in insect cells shows positive immune protection [210]. Taken together, these studies put forward the validation for the potential utilization of G gene for DNA vaccine as a prophylactic therapy against SVCV infection.…”

Antiviral activity of anisomycin against spring viraemia of carp virus in epithelioma papulosum cyprini cells and zebrafish

“…As one of the most lethal pathogens of the isolated rhabdovirus, SVCV has profoundly threatened the lives of cyprinids (Ashraf et al, 2016). A number of researches have been conducted to probe into its pathogenic mechanisms and develop new vaccines for its prevention (Zhao et al, 2018;Embregts et al, 2019). However, the use of vaccine in aquaculture is still restricted due to the handling stress on fish, as well as high laboring and production costs (Life, 2008).…”

“…Traditionally, vaccination of host fish is an effective way to protect them from SVCV infection. New DNA vaccines have been developed against SVCV and are evoking protection even after oral application (Emmenegger and Kurath, 2008;Cui et al, 2015;Embregts et al, 2019). However, there is no commercial vaccine currently available for the disease.…”