Expression Profiling of Innate Immune Genes in Nile Tilapia (Oreochromis niloticus Linnaeus, 1758) Upon Short Term Immunization with Bacterial Lipopolysaccharide (LPS) and Peptidoglycan (PGN)

Tilapia aquaculture is emerging throughout the world because of its fast growth and adaptability. However, disease is one of the impediments in emerging this sector. Boosting the immunity of tilapia by using immunostimulants can help in fighting the diseases. This study investigates how bacterial pathogen-associated molecular patterns (PAMPs), specifically lipopolysaccharide (LPS) and peptidoglycan (PGN), influence the regulation of expression of innate immune genes in Nile tilapia. In the current study, E. coli derived LPS and PGN were injected at 100 μg LPS/kg and 100 μg PGN/kg intraperitonially in treatment group and 100 μg PBS/kg in control group. Significant upregulation of TLR2, TLR3, TLR8, and TLR9 was observed in the spleen, liver, gill, and brain at various time points post-treatment (P<0.05). Additionally, increased expression of IRF3 and TGF-β was noted in multiple organs, along with elevated levels of pro-inflammatory cytokines IL-1β and IL-10, and antiviral protein viperin. These molecular responses suggest that E. coli derived LPS and PGN can effectively modulate inflammatory pathways, enhancing the immune defense mechanisms of tilapia. The findings highlight the potential of bacterial PAMPs to improve fish health, reduce mortality rates, and increase profitability in aquaculture by reducing the reliance on antibiotics.