Location: Aquatic Animal Health Research
Project Number: 6010-32000-026-11-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Jun 1, 2018
End Date: May 31, 2020
Severe outbreaks of motile Aeromonas septicemia (MAS) disease in catfish farms have caused significant economic losses in catfish aquaculture since 2009 while no effective prevention/control method is available for fish farmers to curb outbreaks of MAS. Based on recent comparative genomic analyses, the causative agent associated with the persistent outbreaks of MAS is a new virulent pathotype of Aeromonas (A.) hydrophila (vAh). All strains/isolates of vAh possess additional metabolic pathways and genetic loci, compared with non-epidemic MAS-causing strains of A. hydrophila. Functionalities of these new genetic elements and their contributions to enhanced pathogenesis in vAh are largely unknown. The objective of this project is to identify and define genes and associated components that regulate pathogenicity of vAh using genome editing techniques. It is anticipated that this research will help develop immunogen-specific vaccines against vAh infection.
Targeted genome editing with CRISPR-Cas9 is a recently developed and well-accepted molecular tool for making reliable and precise changes to the genome of living cells. Our Cooperator has successfully adapted the CRISPR-Cas9 system and developed protocols for bacterial genome editing in bacterial pathogens of warmwater farmed fish. In collaboration with this group, we will modify a set of virulence-associated genes (deletion or mutation) in the vAh genome with the CRISPR-Cas9 technique. Individual gene-modified vAh clones will be tested in vitro and/or in vivo for their changes in phenotypes and pathogenicity at Agency's facility by the Agency.