Theses and Dissertations

ORCID

https://orcid.org/0000-0002-4224-405X

Issuing Body

Mississippi State University

Advisor

Lawrence, Mark L

Committee Member

Karsi, Attila

Committee Member

Abdelhamed, Hossam

Committee Member

Stilwell, Justin

Committee Member

Peterson, Daniel

Date of Degree

5-12-2023

Document Type

Dissertation - Open Access

Major

Veterinary Medical Sciences

Degree Name

Doctor of Philosophy (Ph.D)

College

College of Veterinary Medicine

Department

Department of Comparative Biomedical Sciences

Abstract

Channel catfish farming is the largest aquaculture industry in the U.S., and virulent Aeromonas hydrophila is an important re-emerging bacterial pathogen of farmed catfish. A. hydrophila is ubiquitous in the aquatic environment and causes motile Aeromonas septicemia (MAS) in farmed catfish. A. hydrophila infection is challenging to treat due to rapidly progressive mass mortalities. Although florfenicol has been used in managing outbreaks, acute onset of anorexia, drug cost, and emergence of antimicrobial-resistant strains are significant concerns. Prevention of MAS by vaccination could be a promising approach, but a commercial vaccine is not available. Thus, it is critical to develop effective vaccines against A. hydrophila to prevent losses in the catfish industry. The overall objective of this study is to develop effective live attenuated A. hydrophila vaccines and understand macrophage-A. hydrophila interactions. To achieve this, potential virulence-related genes from T6SS, secretion pathway, tat pathway, and flagellar system were deleted by in-frame, and mutants’ virulence and protection were evaluated in channel catfish. Also, macrophage-A. hydrophila interactions were explored by studying global gene expression to understand macrophage responses to A. hydrophila and A. hydrophila virulence mechanisms

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