Effect of an Oral Bivalent Vaccine on Immune Response and Immune Gene Profiling in Vaccinated Red Tilapia (Oreochromis spp.) during Infections with Streptococcus iniae and Aeromonas hydrophila

Abstract

Streptococcosis and aeromonasis inflicted by Streptococcus iniae and Aeromonas hydrophila, respectively, have affected tilapia industries worldwide. In this study, we investigated antibody responses and explored the mechanisms of protection rendered by an oral bivalent vaccine in red tilapia following challenges with S. iniae and A. hydrophila. The results of specific IgM antibody response revealed that the IgM titers against S. iniae and A. hydrophila in the bivalent incorporated (BI) vaccine group were significantly higher (p < 0.05) than those in the bivalent spray (BS) vaccine fish and unvaccinated control fish throughout the experiment. Real-time qPCR results also showed that the gene expression of CD4, MHC-I, MHC-II, IgT, C-type lysozyme, IL-1β, TNF-α, and TGF-β remained significantly higher (p < 0.05) than that of the controls between 24 and 72 h post-infection (hpi) in both mucosal (hindgut) and systemic (spleen and head–kidney) organs of BI vaccinated fish. Furthermore, the highest relative expression of the TGF-β, C-type lysozyme, and IgT genes in the BI vaccinated group was observed in the challenged fish’s spleen (8.8-fold), head kidney (4.4-fold), and hindgut (19.7-fold) tissues, respectively. The present study suggests that the bivalent incorporated (BI) vaccine could effectively improve the immune function and activate both humoral and cell-mediated immunities in vaccinated red tilapia following the bacterial challenges.

In vivo antibacterial activity of medicinal plant Sophora flavescens against Streptococcus agalactiae infection

“…As important components of innate immunity, lysozymes play important roles in aquatic animals against pathogen invasion by destroying the integrity of bacterial cell wall (Song et al, 2021). In the present study, SF significantly increased the relative expression of c-type lysozyme in GBS-infected tilapia, indicating that SF inhibited GBS infection in tilapia at least by increasing the expression of c-type lysozyme (Monir et al, 2022). Myeloid differentiation factor 88 (MyD88) is a main component of MyD88-dependent pathway, which can lead to the production of inflammatory cytokines (Gao et al, 2022).…”

“…In our study, SF significantly increased the relative expression levels of cat in GBS‐infected tilapia, which is believed to be beneficial for clearing GBS (Ding et al, 2021). The innate immune system is the first line of defence against pathogenic microbial infection (Monir et al, 2022). As important components of innate immunity, lysozymes play important roles in aquatic animals against pathogen invasion by destroying the integrity of bacterial cell wall (Song et al, 2021).…”

Genome-wide association study for Streptococcus iniae in Nile tilapia (Oreochromis niloticus) identifies a significant QTL for disease resistance

“…Frontiers in Genetics frontiersin.org known to play an important role in excitatory synaptic transmission in the central nervous system (Nenadic et al, 2012). Gene ebf3a is located downstream of the most significant SNP in humans, homologous genes have been found to be implicated in the function of mature B cells (Vilagos et al, 2012), B cells are central the fish's adaptative immune response (Monir et al, 2022).…”

Current status and development prospects of aquatic vaccines

“…While large molecule particle antigens are the first uptake by macrophages into the cells after processing, then transported to the relevant lymphatic tissues or cells, then transported to the circulatory system, and finally transported to the lymph nodes via blood or lymphatic fluid to produce the relevant immune response ( 332 ). A large number of lymphocytes, mainly including macrophages, granulocytes and plasma cells, are distributed in the entire intestine of fish, especially in the hindgut ( 333 , 334 ). It is now generally accepted that the hindgut is the main site of antigen uptake and processing in fish and that antigens entering the hindgut are taken up by macrophages to induce an immune response in the fish ( 334 , 335 ).…”

“…A large number of lymphocytes, mainly including macrophages, granulocytes and plasma cells, are distributed in the entire intestine of fish, especially in the hindgut ( 333 , 334 ). It is now generally accepted that the hindgut is the main site of antigen uptake and processing in fish and that antigens entering the hindgut are taken up by macrophages to induce an immune response in the fish ( 334 , 335 ). Companjen et al.…”