title: Detection and quantification of virulent Aeromonas hydrophila in channel catfish tissues following waterborne challenge.
abstract: The aim of this study was to understand the pathogenesis of motile aeromonas septicemia caused by an emergent, high virulent Aeromonas hydrophila (vAh) in channel catfish, Ictalurus punctatus Adipose fin clipped catfish were challenged with vAh using a waterborne challenge method, and the distribution of vAh over a time course was detected and quantified using real-time polymerase chain reaction. The results showed that 77.8% of fish died within 48 h post challenge with mean day to death of 1.5 days. At 2 h post challenge, vAh (inferred from genomic DNA copies or genome equivalents) was detected in all external and internal tissues sampled. Gill had the highest vAh cells at 1 h post challenge. Spleen harbored the most vAh cells among internal organs at 4 h post challenge. The tissues/organs with most vAh cells detected at 8 h post challenge were adipose fin, blood, intestine, kidney and skin, while liver showed the highest vAh cells at 24 h post challenge. These results suggest that vAh was able to rapidly proliferate and spread, following wound infection, through the fish blood circulation system and cause mortality within 8-24 h.
authors.affiliation: United States Department of Agriculture, Agricultural Research Service, Aquatic Animal Health Research Unit, 990 Wire Road, Auburn, AL 36832-4352, USA dunhua.zhang@ars.usda.gov.
authors.forename: Dunhua
authors.initials: D
authors.lastname: Zhang
authors.affiliation: Laboratory of Parasitology, College of Animal Science and Food Engineering, University of São Paulo (USP), Av. Duque de Caxias Norte, 225, Pirassununga, SP 13635-900, Brazil.
authors.forename: Gabriel S A
authors.initials: GS
authors.lastname: Moreira
authors.affiliation: United States Department of Agriculture, Agricultural Research Service, Aquatic Animal Health Research Unit, 990 Wire Road, Auburn, AL 36832-4352, USA.
authors.forename: Craig
authors.initials: C
authors.lastname: Shoemaker
authors.affiliation: Department of Pathobiology, Auburn University College of Veterinary Medicine, Auburn, AL 36849, USA.
authors.forename: Joseph C
authors.initials: JC
authors.lastname: Newton
authors.affiliation: United States Department of Agriculture, Agricultural Research Service, Aquatic Animal Health Research Unit, 990 Wire Road, Auburn, AL 36832-4352, USA.
authors.forename: De-Hai
authors.initials: DH
authors.lastname: Xu
mesh_terms: D016980:Aeromonas hydrophila / Q000235:genetics / Q000302:isolation & purification* / Q000472:pathogenicity*; D058500:Animal Fins / Q000382:microbiology; D000818:Animals; D016470:Bacteremia / Q000382:microbiology / Q000662:veterinary; D005393:Fish Diseases / Q000382:microbiology*; D005880:Gills / Q000382:microbiology; D016905:Gram-Negative Bacterial Infections / Q000382:microbiology / Q000662:veterinary*; D007059:Ictaluridae / Q000382:microbiology*; D010802:Phylogeny; D060888:Real-Time Polymerase Chain Reaction; D013154:Spleen / Q000382:microbiology; D013997:Time Factors
keywords: adipose fin; channel catfish; qPCR; tissue distribution; virulent Aeromonas hydrophila; waterborne challenge