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Research Project: Pathogen Characterization, Host Immune Response and Development of Strategies to Reduce Losses to Disease in Aquaculture

Location: Aquatic Animal Health Research

Title: Vaccination with theronts of Ichthyophthirius multifiliis enhanced channel catfish molecular immune response

item Xu, Dehai
item ZHANG, QI-ZHONG - Jinan University
item Shoemaker, Craig
item Zhang, Dunhua
item MOREIRA, GABRIEL - Sao Paulo State University (UNESP)

Submitted to: International Aquaculture Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 6/24/2018
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: The parasite Ichthyophthirius multifiliis (Ich) infects various freshwater fishes worldwide and results in heavy losses in aquaculture. The fish surviving natural infections or vaccinated with live theronts develop strong immune responses. Little is known about how immune genes are induced or how they interact and lead to specific immunity against I. multifiliis in channel catfish Ictalurus punctatus. This study vaccinated channel catfish by intraperitoneal (IP) injection of live Ich theronts and evaluated the differential expression of immune-related genes by quantitative PCR, including immunoglobulin, immune cell receptors, cytokine, complement factor and toll-like receptors in channel catfish at different time points after vaccination with live theronts of I. multifiliis. The vaccinated fish showed significantly higher anti-Ich antibody than those of control fish. Most of immunized fish (95%) survived the parasite challenge. Expression of IgM and IgD heavy chain genes exhibited a rapid increase from 4 hours (h4) to 2 days (d2) post vaccination. Expression of immune cell receptor genes (CD4, CD8-a, MHC I, MHC II ß, TcR-a, and TcR-ß) showed up-regulation from h4 to d6 post vaccination, indicating that different immune cells were actively involved in cellular immune response. Cytokine gene expression (IL-1ßa, IL-1ßb, IFN-'' and TNF-a) increased rapidly at h4 post immunization and were at an up-regulated level until d2 compared to the bovine serum albumin control. Expression of complement factor and toll-like receptor genes exhibited a rapid increase from h4 to d2 post immunization. This study demonstrated differential expression of genes involved in the innate and adaptive immune response post immunization and the response to vaccination imparted protection against infection by I. multifiliis in catfish. Results of this study may allow for development of alternative control strategies for Ich by leading to a better understanding of the immune response of fish to this parasite.