ClavF derived from Clavanins as a promising candidate for fighting infections from multiple-drug resistance Aeromonas hydrophila.

The antimicrobial peptide ClavF was designed based on the natural antimicrobial peptide Clavanins, derived from the hemocytes of the stalked ascidian, using the amino acid substitution method. The antimicrobial activity of ClavF was tested against various multiple-drug resistance (MDR) pathogenic bacteria (Staphylococcus aureus, Aeromonas hydrophila, Escherichia coli and Salmonella pullorum), with minimal inhibitory concentrations (MICs) as low as 2 μM and the half-maximal inhibitory concentration (IC) for Ctenopharyngodon idella kidney (CIK) cells is 50 μM. Its bactericidal mechanism against A. hydrophila primarily involves disrupting the bacterial cell membrane, leading to leakage of cellular contents. In the infected grass carps by MDR A. hydrophila, treatment with 100 μL of ClavF (200 μM) significantly increased the survival rate of infected fish, reduced spleen and intestinal damage, and effectively alleviated systemic inflammation caused by the infection. ClavF regulates the dynamic balance of inflammatory factors in key immune organs, such as the spleen and intestine, by significantly inhibiting the overexpression of pro-inflammatory factors like IL-1β and TNF-α during the early stages of infection. These results indicate that ClavF exhibits antibacterial and anti-inflammatory properties, making it a potent lead molecule for enhancing the comprehensive prevention and control of bacterial diseases.