Theses and Dissertations


Adef Kordon

Issuing Body

Mississippi State University


Pinchuk, Lesya M.

Committee Member

Karsi, Attila

Committee Member

Pharr, G. Todd

Committee Member

Petrie-Hanson, Lora

Committee Member

Baumgartner, Wes

Date of Degree


Original embargo terms


Document Type

Dissertation - Open Access


Veterinary Medical Science

Degree Name

Doctor of Philosophy


College of Veterinary Medicine


Veterinary Medical Science Program


Vaccination against intracellular pathogens requires generation of pool of memory T cells, which can respond upon infection and mediate immune responses by either killing of infected host cells or induce killing mechanisms in infected cells. T cell-inducing vaccines aim to deliver the antigen to antigen presenting cells (APCs) by presenting on MHC molecules thus bridging innate and adaptive immunity. The intracellular pathogen Edwardsiella ictaluri causes enteric septicemia of catfish (ESC), which is a devastating disease in catfish industry. E. ictaluri can survive in professional phagocytes and use them as an infection source. Two new live attenuated vaccine (LAV) strains, EiDELTAevpB and ESC-NDKL, were developed by our group. However, the role of LAVs in phagocytosis, bacterial killing, and antigen presentation is unexplored. Therefore, further research is necessary to determine immune responses in channel catfish against LAVs. The long-term goal of this project is to identify immunological APC-dependent mechanisms that underscore E. ictaluri pathogenesis to enable development of effective control strategies for ESC. The overall goal of this project is to assess the role of three professional APCs, dendritic cells (DCs), macrophages and B cells in the LAV-induced innate and adaptive immune responses in catfish. The central hypothesis is that efficacious LAV strains will enhance phagocytosis and microbial killing, and promote the generation of T cells that regulate and control protective B cell-mediated immunity. The rationale for this research is that more detailed knowledge about phenotype and function of catfish APCs will not only help gain insight into the evolution of vertebrate adaptive immune system but will provide valuable information for development and optimization of immunotherapies and vaccination protocols for aquaculture use. In this study, we first identified DC-like cells in immune-related organs of catfish and assessed their expression patterns in lymphoid organs of catfish in E. ictaluri infection. Although WT strain induces the functional inability of DC-like cells in migration and maturation, LAVs strains promote the migration and maturation of DC-like cells for antigen presentation. Two LAVs enhanced the phagocytosis and killing activity in catfish macrophages and B cells. Also, LAVs induce high expression of T cell-related genes without causing inflammation.