Antimicrobial peptide Pleurocidin enhances tilapia anti-streptococcosis immunity elicited by glyceraldehyde-3-phosphate dehydrogenase of Streptococcus iniae.

Autor: An, Ping-Zao, 安平兆
Rok vydání: 2014
Druh dokumentu: 學位論文 ; thesis
Popis: 103
Tilapia is one of the most important species in the aquaculture industry in Taiwan. However, the Streptococcus iniae often causes streptococcosis in fish farming and results in serious economic losses. Virulence factors, such as glyceraldehyde 3-phosphate dehydrogenase (GAPDH), play critical roles in the host-invasion process to assist bacteria to escape from host immune system. Thus, GAPDH protein could be a key candidate in the vaccine development against S. iniae. On the other hand, antimicrobial peptides inhibit the growth and invasion of pathogenic bacteria. In addition, antimicrobial peptides are able to regulate host innate immune responses to link subsequent adaptive immune responses. In other words, antimicrobial peptides may display potential adjuvant capacity to enhance the immunogenicity of given antigens. Pleurocidin (Ple), a cationic 25-residueAMP, is found in the skin-secreted mucous fluid of winter flounder (Pleuronectes americanus). In this study, D form Ple (D-Ple) was designed as an adjuvant to mixed with E.coli-based recombinant GAPDH (rGAPDH), which had been recognized by tilapia anti-S.iniae sera by immunoblotting assay. The aim of the present study is to evaluate if the D-Ple could enhance the immune response to co-injected antigens in tilapia. In the first animal experiment, tilapia were vaccinated intraperitoneally (I.P.) with D-Ple (64 μg/fish) plus rGAPDH. After three weeks, second vaccination was conducted. Sera were collected on days 14, 21, 28 and 35 after the first vaccination and analyzed by ELISA. Results showed that specific antibodies were significantly increased on Day 14 in fish vaccinated with rGAPDH plus D-Ple. Three weeks after booster, fish were challenged with 1x108 CFU S.iniae and then monitored for mortalities for 21days. The relative percent of survival (RPS) for each group was calculated. The results showed that D-Plecould enhance immune response to protect fish against S. iniae.Thus, D-Ple is able to use as a peptide adjuvant for the subunit antigen rGAPDH.
Databáze: Networked Digital Library of Theses & Dissertations
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