A novel antimicrobial vermipeptide family from earthworm Eisenia fetida

In order to investigate the activity of peptides in earthworm tissue and coelomic fluid, we established the peptide separation and purification method in our laboratory. Six antimicrobial peptides were isolated and purified from earthworm tissue liquid homogenate and coelomic fluid, which contained 5–50 amino acid (AA) residues with the same or similar sequence of Ala-Met-Val-Ser-Gly, and named the antibacterial vermipeptides family (AVPF) according to their structure and antibacterial characteristics. In this paper, we introduced a general protocol of AVPF peptide preparation methods from earthworms, including crude peptide preparation and purification by ultrafiltration, ion-exchange chromatography, gel-filtration and HPLC chromatography. The AVPF includes a wide antibacterial spectrum and speciality, performs antimicrobial activities not only to Gram-positive and Gram-negative bacteria but also to fungi. Multi-functions of some peptides of AVPF have been reported. As an example, the resistance of EP3 and EP5 of AVPF to cancer cells, HeLa and MGC803 has been reported. EP5 caused apoptosis of HeLa cell. The threshold value of EP3 that causes apoptosis of HeLa cells was 0.75 mg/mL with an apoptotic rate of 48.12%. MGC803 cells showed significant morphological changes when the cells were attached by EP3. Short peptides with 5–7 amino acid residues formed multimers in the PB buffer, a more likely explanation for the antibacterial mechanism of short peptides that causes MGC803 cells to break. The antiviral effect of antimicrobial peptides (EP5) on the pseudorabies virus (PRV) was analyzed using the cytopathic effect (CPE) inhibition test. Results showed that EP5 inhibited the CPE by PRV on BHK cells. The mechanism of antiviral activity of EP5 may be explained by inhibiting the duplication of viral DNA.