Effects of recombinant tHsp70 on immune function of tilapia peritoneal macrophages

Abstract

We used recombinant tilapia Hsp70(tHsp70) from Pichia yeast to prepare non-covalent HSP70-antigen complexes with thallus and extracellular bacterial products(ECP) of Streptococcus iniae.We investigated the ef-fects of the antigen complexes on the cellular immune response of tilapia by detection of NO release,phagocytic activity,and related immune gene expression of peritoneal macrophages in vitro.tHsp70 can form complexes with the thallus and ECP of tilapia in vitro.In addition,tHsp70 alone and its complexes significantly stimulated growth and attachment of peritoneal macrophages and enhanced NO release and phagocytic activity of peritoneal macro-phages.In contrast,treatment with ECP significantly inhibited NO release and led to cell death,while treatment with tHsp70-ECP complex reduced the cell death.Moreover,tHsp70 alone or tHsp70-antigen complexes signifi-cantly increased the expression of immune related genes(IL-8,Hsp70,CXCR4,and PGRN) in tilapia peritoneal macrophages compared to antigen only and medium control groups.Our results suggest that tHsp70 has an im-munoadjuvant and immunopotentiator function,and provides experimental data for development of a tHsp70 based vaccine against tilapia streptococcal diseases.