NK-lysin from Oreochromis niloticus improves antimicrobial defence against bacterial pathogens. Issue 72 (January 2018)

• Record Type: Journal Article
• Authors: Huang, Yu; Zheng, Qi; Niu, Jinzhong; Tang, Jufen; Wang, Bei; Abarike, Emmanuel Delwin; Lu, Yishan; Cai, Jia; Jian, Jichang
• Is Part Of: Fish & shellfish immunology. Issue 72(2018)
• Page Start: 259
• Page End: 265
• Publication Date: 2018-01
• Subjects: Oreochromis niloticus -- NK-Lysin -- Streptococcus agalactiae -- Antibacterial activity -- Antimicrobial peptide; Fishes -- Immunology -- Periodicals; Shellfish -- Immunology -- Periodicals; Poissons -- Immunologie -- Périodiques; Crustacés -- Immunologie -- Périodiques; 571.9617
• DOI: 10.1016/j.fsi.2017.11.002
• Languages: English
• ISSNs: 1050-4648

Abstract

Abstract: NK-lysin, an effector of cytotoxic T cells and natural killer cells, is a potent antimicrobial peptide widely distributed in mammals. Homologues of NK-lysin have been discovered in several teleost species, but only several of their natural functions was recorded so far. Here we identified an NK-lysin from Nile tilapia ( Oreochromis niloticus ), On-NKL, and analysed its expression model and biological effects on pathogen infection. The open reading frame of On-NKL sequence spans 432 bp, codes for 143 amino acids and shares 27%–62% overall sequence identities with NK-lysin of other species. The deduced mature peptide of On-NKL possesses a saposin B domain and six well-conserved cysteine residues that essential for antimicrobial activity by forming three intrachain disulphide bonds. The results of qRT-PCR showed that On-NKL expression was observed in multiple tissues and head kidney leucocytes and nonspecific cytotoxic cells (NCCs) and is most abundant in gills. After bacterial challenge, On-NKL expression significantly varied in different tissues and NCCs. Following bacterial infection, On-NKL-overexpressing fish featured significantly lower pathogen loads in tissues than control fish. On-NKL-overexpressing fish also exhibited 33.3% relative percent survival compare with control groups. Findings suggested that On-NKL could be the potential effector of NCCs and act as immune-related gene that enhances antimicrobial defence. Highlights: Homologue of NK-lysin gene (On-NKL) was identified from Nile tilapia, Oreochromis niloticus. On-NKL could respond to bacterial challenge in immune tissue and brain. Overexpression of On-NKL apparently enhanced the survival rate after bacterial infection. On-NKL could be a potential effector of NCCs.