Oral vaccination with recombinant Lactobacillus casei expressing Aha1 fused with CTB as an adjuvant against Aeromonas veronii in common carp (Cyprinus carpio)

Abstract

Aeromonas veronii (A. veronii) is a pathogenic that can infect human, animal and aquatic organisms, in which poses a huge threat to the health of many aquatic organisms such as Cyprinus carpio. In this study, Lactobacillus casei (L. casei) strain CC16 was used as antigen deliver carrier and fused with cholera toxin B subunit (CTB) as an adjuvant to construct the recombinant L. casei pPG-Aha1/Lc CC16(surface-displayed) and pPG-Aha1-CTB/Lc CC16(surface-displayed) expressing Aha1 protein of A. veronii, respectively. And the immune responses in Cyprinus carpio by oral route was explored. Our results demonstrated that the recombinant strains could stimulate high serum specific antibody immunoglobulin M (IgM) and induce a stronger acid phosphatase (ACP), alkaline phosphatase (AKP), C3, C4, lysozyme (LZM), Lectin and superoxide dismutase (SOD) activity in Cyprinus carpio compared with control groups. Meanwhile, the expression of Interleukin-10 (IL-10), Interleukin-1β (IL-1β), Tumor Necrosis Factor-α (TNF-α), immunoglobulin Z1 (IgZ1) and immunoglobulin Z2 (IgZ2) in the tissues were significantly upregulated compared with Lc-pPG or PBS groups, indicating that humoral and cell immune response were triggered. Additionally, recombinant L. casei could survive and colonize in fish intestine. Significantly, recombinant L. casei provides immune protection against A. veronii infection, which Cyprinus carpio received pPG-Aha1-CTB/Lc CC16 (64.29%) and pPG-Aha1/Lc CC16 (53.57%) had higher survival rates compared with the controls. Thus, we demonstrated that recombinant pPG-Aha1/Lc CC16 and pPG-Aha1-CTB/Lc CC16 may be the promising strategy for the development of an oral vaccine against A. veronii.

Efficient Production of Self-Assembled Bioconjugate Nanovaccines against Klebsiella pneumoniae O2 Serotype in Engineered Escherichia coli

“…CTB is usually recognized as a mucosal adjuvant due to its ability to bind to GM1 on the surface of mucosal epithelial cells, thereby facilitating antigen endocytosis [ 43 , 44 , 45 ]. However, the G33D mutation deprives this binding capacity [ 41 ].…”

Importance of Probiotics in Fish Aquaculture: Towards the Identification and Design of Novel Probiotics

“…L. lactis has also been used to immunize against hirame novirhabdovirus (HIRRV) in flounder ( Paralichthys olivaceus ) [ 131 ]. In C. carpio (common carp), oral administration of recombinant L. casei expressing epitopes of A. veronii [ 132 , 133 , 134 , 135 ] or A. hydrophila confers protection against these pathogens [ 136 ], while the administration of L. plantarum expressing G protein of spring viremia of carp virus (SVCV) [ 137 ] and the ORF81 protein of koi herpesvirus (KHV) grants protection against both viruses in challenge assays, with high titers of IgM after its oral administration to C. carpio [ 138 ]. L. lactis has also been successful in triggering immunization against SVCV in C. carpio [ 139 ].…”

“…The oral administration of these probiotics either, in the feed or by intubation every 3 days, was enough to induce the presence of IgM in serum mucosa in Nile tilapia and rainbow trout 4 days post-immunization [ 125 , 126 , 127 , 128 , 129 , 130 , 142 ]. The level of antibodies increased in the case of a booster applied in most cases 30 days after the first immunization [ 128 , 129 , 130 , 131 , 132 , 133 , 134 , 135 , 136 , 137 , 138 , 140 , 141 ] ( Table 2 ). The fusion of the antigen to a CWA domain did not increase the level of serum antibodies with respect to the construction without the CWA domain.…”

“…In the case of L. plantarum NC8 expressing the IAG-52X antigen from I. multifiliis , oral administration for four weeks was enough to induce the expression of C3, IgM, and MHC-I and increase survival from 40% to 60% in challenge assays [ 144 ]. L. casei CC16 expressing outer membrane protein of A. veronii TH0426 [ 132 , 133 , 134 , 135 , 140 ] or A. hydrophila [ 136 , 142 ] was also able to stimulate immune responses, increasing lysozyme activity, alkaline and acid phosphatases, and superoxide dismutase activity in serum, which suggests stimulation of the innate immune response. This stimulation was also associated with an induction of the expression of IL-1β and IFN-γ in the spleen, and TNF-α in the head-kidney.…”

Isolation, Identification, and Characterization of Aeromonas veronii from Chinese Soft-Shelled Turtle (Trionyx sinensis)

“…A. veronii is widely distributed in the aquatic environment. Moreover, it multiplies faster under the following conditions: during summer and autumn, in water with deteriorated quality, and in physically traumatized or immunocompromised aquatic animals [ 12 ]. A. veronii infections exhibit high mortality rates, with hemorrhage and ascites being the main pathological features of the affected aquatic animals [ 13 ].…”