Bacillus subtilis spores as an adjuvant to enhance the protection efficacy of the SVCV subunit vaccine (SVCV‐M protein) in German mirror carp ( Cyprirnus Carpio Songpa Linnaeus Mirror )

Abstract

Spring viraemia of carp (SVC) is an acute infectious disease caused by the spring viraemia of carp virus (SVCV). As a well-known disease of aquatic animals that is recognized by the International Office of Epizootics, SVC has the characteristics of high infectivity and high mortality (Ahne et al., 2002;Embregts et al., 2017;Teng et al., 2007).Cyprinids, including zebrafish (Danio rerio), silver carp (Hypophthal michthys molitri x), gold fish (Carassius auratus), catfish (Silurus glanis) and grass carp (Ctenopharyngodon idella), face a grave threat due to SVC, and huge economic losses are caused by SVC (Ahne et al., 2002;Ashraf et al., 2016;Zhang et al., 2020). SVC is widely prevalent in Europe, Asia and the Americas, and it occurs commonly in the spring when water temperatures are low (Audrey et al., 2004;Xiao et al., 2014). Under natural conditions, when SVCV infects cyprinids, it usually first invades the gill epithelial cells, then gradually infects other tissues, ultimately affects the health of the cyprinids and even leads to death (Fu et al., 2006). There is currently no effective method or drug to cure SVC. The

Oral vaccination of fish against vibriosis using spore-display technology

“…The mortality of orally vaccinated European seabass was reduced from 40% to 13%. The previously reported adjuvant properties of B. subtilis spores ( 45 , 72 , 73 , 99 ) together with the immunomodulatory capacity of their metabolites ( 40 , 102 ) might have contributed to the protection observed ( 14 ).…”

“…Further, survival of unvaccinated larvae or larvae "vaccinated" with spores of the WT parental strain (not carrying the CotY-OmpK) was not significantly different from each other, indicating that it was the antigen and not the spore itself responsible for the increased protection observed. Nevertheless, an adjuvant contribution of the spores cannot be ruled out, as it has been previously described both in mammals and in fish (45,72,73,99).…”

“…Spores’ direct incorporation into animal feed, circumventing further protection processes, such as encapsulation, together with their simple production and long shelf-life without needing refrigeration ( 51 , 69 ), are also attractive characteristics from the industrial point of view ( 70 ). Adding to this “needle-free” and “refrigeration-free” potential, B. subtilis spores adjuvant properties ( 18 , 19 , 71 – 73 ) and contribution to GALT (gut associated lymphoid tissue) development ( 67 , 74 – 76 ), increases their potential as oral delivery systems of antigens. Previous reports have shown the application of B. subtilis spores as oral (or mucosal) vaccines in different animals, including aquatic animals ( 20 , 24 , 26 – 29 , 31 , 32 , 60 , 64 – 68 ).…”

Effects of Bacillus halophilus on growth, intestinal flora and metabolism of Larimichthys crocea

“…Peptidoglycans acting on bacterial walls promote hydrolysis of the link between n-acetyl- d -glucosamine and n-acetyluric acid and play a role in mediating resistance to microbial invasion [ 44 ]. Examples include Cyprirnus Carpio Songpa Linnaeus Mirror [ 45 ], olive flounder ( Paralichthys olivaceus ) [ 46 ], and tilapia ( Oreochromis niloticus ) The study of niloticus [ 47 ] showed that feed addition of Bacillus subtilis could increase the activity of LZM in aquatic animals. In this experiment, the activity of lysozyme (LZM) in the blood of the FC8 group significantly increased ( P < 0.05), while there was no significant difference between the liver control and the experimental groups ( P > 0.05), which was similar to the results of feeding juvenile cobia with Bacillus subtilis .…”

Oral vaccination for sustainable disease prevention in aquaculture—an encapsulation approach

“…For example, certain analyses have proven the possible role of lipopolysaccharides in protection aiding in the vaccine's efficacy. Some pathogenic fish viruses, such as infectious pancreatic necrosis virus (IPNV), infectious hematopoietic necrosis virus (IHNV), viral hemorrhagic septicemia virus (VHSV), and spring viremia of carp virus (SVCV), have inactivated vaccinations (Liu et al 2021). Inactivation can be done with various physical and chemical agents; for example, when inoculated at high concentrations with formalin-inactivated IHNV, rainbow trout were shown to be protected against deadly IHNV (Salgado-Miranda et al 2013).…”