DAO 125:7-18 (2017)  -  DOI: https://doi.org/10.3354/dao03134

Diversity of Veronaea botryosa from different hosts and evaluation of laboratory challenge models for phaeohyphomycosis in Acipenser transmontanus

Esteban Soto1,*, Christine Richey1, Stephen R. Reichley2, Brittany Stevens1, Kirsten V. Kenelty1, Janiee Lewis1, Barbara Byrne3, Nathan P. Wiederhold4, Thomas B. Waltzek5, Matthew F. Sheley3, Alvin C. Camus6, Matt J. Griffin

1Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, Davis, CA 95616, USA
2Department of Pathobiology and Population Medicine, College of Veterinary Medicine, Mississippi State University, Stoneville, MS 38776, USA
3Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, 4315 Vet Med 3A, Davis, CA 95616, USA
4Fungus Testing Laboratory, Department of Pathology, and Department of Microbiology & Immunology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
5University of Florida, College of Veterinary Medicine, Department of Infectious Diseases and Pathology, PO Box 110880, 2015 SW 16th Avenue, Gainesville, FL 32608, USA
6College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA
*Corresponding author:

ABSTRACT: Veronaea botryosa has been identified as a pathogen of cultured white sturgeon Acipenser transmontanus. In 2015, samples from 19 white sturgeon were received for diagnosis, of which 14 cultured positive for V. botryosa. Intraspecific variability among V. botryosa isolates from different clinically affected hosts and geographic regions was investigated using repetitive extragenic palindromic PCR fingerprinting (rep-PCR). The rep-PCR profiles of 16 V. botryosa isolates from a human, sea turtles, and cultured fish were distinct from those of other phaeoid fungi belonging to the genera Cladophialophora and Exophiala. To gain a better understanding of the pathogenesis of V. botryosa mycosis, 5 laboratory challenge methods were evaluated in white sturgeon fingerlings. Intramuscular (IM) and intracoelomic (IC) injection challenges produced cumulative mortalities of 13.3% (8/60) and 3.3% (2/60), respectively, and V. botryosa was recovered from 100% (10/10) of dead fingerlings. Affected fish exhibited abnormal orientation and/or failure to maintain neutral buoyancy, emaciation, coelomic distension, exophthalmos, cutaneous erythema, and ulcerated skin. After 6 wk, surviving fish were euthanized, and samples of liver were taken for mycological evaluation. Viable fungus was detected in 90% and 100% of fish surviving IM and IC challenge, respectively. No V. botryosa-associated mortality was detected in other groups challenged by immersion, immersion with abrasion, or orally. Both IM and IC challenge routes appear suitable for the induction of V. botryosa infection in white sturgeon and can serve as models for the study of disease pathogenesis associated with this emergent pathogen.

KEY WORDS: Fungus · Mycosis · Sturgeon · Veronaea

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Cite this article as: Soto E, Richey C, Reichley SR, Stevens B and others (2017) Diversity of Veronaea botryosa from different hosts and evaluation of laboratory challenge models for phaeohyphomycosis in Acipenser transmontanus. Dis Aquat Org 125:7-18. https://doi.org/10.3354/dao03134

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