BEI Inactivated Vaccine Induces Innate and Adaptive Responses and Elicits Partial Protection upon Reassortant Betanodavirus Infection in Senegalese Sole

Abstract

Nervous necrosis virus (NNV), the causative agent of viral encephalopathy and retinopathy (VER), is one of the most threatening viruses affecting marine and freshwater fish species worldwide. Senegalese sole is a promising fish species in Mediterranean aquaculture but also highly susceptible to NNV and VER outbreaks, that puts its farming at risk. The development of vaccines for aquaculture is one of best tools to prevent viral spread and sudden outbreaks, and virus inactivation is the simplest and most cost-effective method available. In this work, we have designed two inactivated vaccines based on the use of formalin or binary ethylenimine (BEI) to inactivate a reassortant NNV strain. After vaccination, the BEI-inactivated vaccine triggered the production of specific IgM-NNV antibodies and stimulated innate and adaptive immune responses at transcriptional level (rtp3, mx, mhcii and tcrb coding genes). Moreover, it partially improved survival after an NNV in vivo challenge, reducing the mid-term viral load and avoiding the down-regulation of immune response post-challenge. On the other hand, the formalin-inactivated vaccine improved the survival of fish upon infection without inducing the production of IgM-NNV antibodies and only stimulating the expression of herc4 and mhcii genes (in head-kidney and brain, respectively) during the vaccination period; this suggests that other immune-related pathways may be involved in the partial protection provoked. Although these vaccines against NNV showed encouraging results, further studies are needed to improve sole protection and to fully understand the underlying immune mechanism.

A Simulation Analysis of an Influenza Vaccine Production Plant in Areas of High Humanitarian Flow. A Case Study for the Region of Norte de Santander (Colombia)

“…Inactivation plays a vital role in this phase since it is only necessary to leave the genetic material inactive and the surface proteins unchanged so that it can be recognized by the immune system without affecting it, generating specialized antibodies for the destruction of its envelope, so the virion particles are chemically inactivated with binary ethylamine (BEI) [15] and subsequently purified by salting out, these residual salts that allow the concentration of the vaccine are removed by microfiltration (P-8/MF-101) after washing to facilitate the permeation of the components and eliminate suspended solids, bacteria, proteins or some dyes that may have been immersed in the inactivated virus [16]. Finally, the entire purified volume is mixed with adjuvants, Penicillin, Streptomycin, Amphotericin B, and salts as an antibiotic, antifungal, and preservative of the compound.…”

Update on the Inactivation Procedures for the Vaccine Development Prospects of a New Highly Virulent RGNNV Isolate

“…However, observable CPE after 3 successive passages was only abolished in incubations with 0.2% formalin after 7 and 3 days at 24 and 30 • C, respectively. All these differences might be due to the virus strain used, and thus authors using this method for vaccination trials usually opt for higher doses varying in formalin percentage, incubation time, and temperature in order to ensure full NNV inactivation and the safety of the final antigen product [46,[70][71][72].…”

A Simulation Analysis of an Influenza Vaccine Production Plant in Areas of High Humanitarian Flow. A Preliminary Study for the Region of Norte de Santander (Colombia)

“…Inactivation plays a vital role in this phase since it is only necessary to leave the genetic material inactive and the surface proteins unchanged so that it can be recognized by the immune system without affecting it, generating specialized antibodies for the destruction of its envelope. This allows the virion particles to be chemically inactivated with binary ethylamine (BEI) [23] and subsequently purified by salting out. These residual salts that allow the concentration of the vaccine are removed by microfiltration (P-8/MF-101) after washing to facilitate the permeation of the components and eliminate suspended solids, bacteria, proteins, or some dyes that may have been immersed in the inactivated virus [24].…”