Efficacy of Feed-Based Genome-Free Bacterial Vaccine Against <i>Aeromonas hydrophila</i> Infection in Red Tilapia (<i>Oreochromis</i> sp.)
<i>Aeromonas hydrophila</i> causes motile <i>Aeromonas</i> septicemia (MAS), a disease with a high mortality rate in tilapia culture. Feed-based vaccines with the incorporation of inactivated whole-cell bacteria into the feed offer promising tools to control MAS. Currently, t...
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| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2024-11-01
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| Series: | Vaccines |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2076-393X/12/11/1271 |
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| Summary: | <i>Aeromonas hydrophila</i> causes motile <i>Aeromonas</i> septicemia (MAS), a disease with a high mortality rate in tilapia culture. Feed-based vaccines with the incorporation of inactivated whole-cell bacteria into the feed offer promising tools to control MAS. Currently, the incorporation of genome-free bacteria as bacterial vaccine through the implementation of SimCells<sup>®</sup> technology into the feed has become a particular interest. <b>Background/Objectives</b>: This study investigates the efficacy of a feed-based vaccine incorporating genome-free <i>A. hydrophila</i> (FBV-GFAH) against MAS infection in red tilapia. <b>Methods</b>: The vaccine was prepared and delivered at 5% fish body weight for three consecutive days in weeks 0 (prime vaccination) and 2 (first booster vaccination), orally. Throughout a five-week experimental period, the immune-related genes (IL-1<i>β</i>, MHC-II, CD4, IgT, and IgM) expression in the hindgut and head kidney of the fish was determined using RT-qPCR assay. Lysozyme (serum) and overall IgM (serum, gut lavage, and skin mucus) productions were also detected. <b>Results</b>: Fish vaccinated with FBV-GFAH showed a significant (<i>p</i> ≤ 0.05) improvement in relative percent survival compared with unvaccinated fish following bacterial challenge. FBV-GFAH induced the expression of immune-related genes in the hindgut and head kidney, especially after booster vaccination. Furthermore, serum lysozyme activity and overall IgM production in serum, skin mucus, and gut lavage were also significantly (<i>p</i> ≤ 0.05) improved in the FBV-GFAH vaccinated fish than the unvaccinated fish. <b>Conclusions</b>: This study showed that FBV-GFAH is a promising feed-based vaccine technology to control MAS in cultured tilapia. |
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| ISSN: | 2076-393X |