Pathology, Tissue Distribution, and Phylogenetic Characterization of Largemouth Bass Virus Isolated from a Wild Smallmouth Bass (Micropterus dolomieu)

Haake, Christine J. E.; Waltzek, Thomas B.; Eckstrand, Chrissy D.; Hickey, Nora; Reno, Joetta Lynn; Wolking, Rebecca M.; Sriwanayos, Preeyanan; Lovy, Jan; Renner, Elizabeth; Taylor, Kyle R.; Oliveira, Ryan

doi:10.3390/v17081031

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Pathology, Tissue Distribution, and Phylogenetic Characterization of Largemouth Bass Virus Isolated from a Wild Smallmouth Bass (Micropterus dolomieu)

by

Christine J. E. Haake

^1,2,*

,

Thomas B. Waltzek

^1,2,

Chrissy D. Eckstrand

^1,2,

Nora Hickey

¹

,

Joetta Lynn Reno

¹,

Rebecca M. Wolking

¹,

Preeyanan Sriwanayos

^1,2

,

Jan Lovy

³,

Elizabeth Renner

^4,5

,

Kyle R. Taylor

^1,2

and

Ryan Oliveira

^1,2

¹

Washington Animal Disease Diagnostic Laboratory, College of Veterinary Medicine, Washington State University, 1940 Olympia Avenue, Pullman, WA 99164, USA

²

Department of Veterinary Microbiology and Pathology, College of Veterinary Medicine, Washington State University, 1845 Ott Road, Pullman, WA 99164, USA

³

U.S. Geological Survey, Western Fisheries Research Center, Seattle, WA 98115, USA

⁴

South Dakota Game, Fish and Parks, Ft. Pierre, SD 57532, USA

⁵

School of Natural Resources, University of Nebraska Lincoln, Lincoln, NE 68583, USA

^*

Author to whom correspondence should be addressed.

Viruses 2025, 17(8), 1031; https://doi.org/10.3390/v17081031

Submission received: 25 June 2025 / Revised: 17 July 2025 / Accepted: 19 July 2025 / Published: 23 July 2025

(This article belongs to the Special Issue Iridoviruses, 2nd Edition)

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Abstract

We performed a diagnostic disease investigation on a wild smallmouth bass (Micropterus dolomieu) with skin ulcers that was collected from Lake Oahe, South Dakota, following reports from anglers of multiple fish with similar lesions. Gross and histologic lesions of ulcerative dermatitis, myositis, and lymphocytolysis within the spleen and kidneys were consistent with largemouth bass virus (LMBV) infection. LMBV was detected by conventional PCR in samples of a skin ulcer, and the complete genome sequence of the LMBV (99,184 bp) was determined from a virus isolate obtained from a homogenized skin sample. A maximum likelihood (ML) phylogenetic analysis based on the major capsid protein (MCP) gene alignment supported the LMBV isolate (LMBV-SD-2023) as a member of the species Ranavirus micropterus1, branching within the subclade of LMBV isolates recovered from North American largemouth (Micropterus salmoides) and smallmouth bass. This is the first detection of LMBV in wild smallmouth bass from South Dakota. The ultrastructure of the LMBV isolate exhibited the expected icosahedral shape of virions budding from cellular membranes. Viral nucleic acid in infected cells was visualized via in situ hybridization (ISH) within dermal granulomas, localized predominantly at the margin of epithelioid macrophages and central necrosis. Further sampling is needed to determine the geographic distribution, affected populations, and evolutionary relationship between isolates of LMBV.

Keywords: largemouth bass virus; iridovirus; ranavirus; smallmouth bass

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MDPI and ACS Style

Haake, C.J.E.; Waltzek, T.B.; Eckstrand, C.D.; Hickey, N.; Reno, J.L.; Wolking, R.M.; Sriwanayos, P.; Lovy, J.; Renner, E.; Taylor, K.R.; et al. Pathology, Tissue Distribution, and Phylogenetic Characterization of Largemouth Bass Virus Isolated from a Wild Smallmouth Bass (Micropterus dolomieu). Viruses 2025, 17, 1031. https://doi.org/10.3390/v17081031

AMA Style

Haake CJE, Waltzek TB, Eckstrand CD, Hickey N, Reno JL, Wolking RM, Sriwanayos P, Lovy J, Renner E, Taylor KR, et al. Pathology, Tissue Distribution, and Phylogenetic Characterization of Largemouth Bass Virus Isolated from a Wild Smallmouth Bass (Micropterus dolomieu). Viruses. 2025; 17(8):1031. https://doi.org/10.3390/v17081031

Chicago/Turabian Style

Haake, Christine J. E., Thomas B. Waltzek, Chrissy D. Eckstrand, Nora Hickey, Joetta Lynn Reno, Rebecca M. Wolking, Preeyanan Sriwanayos, Jan Lovy, Elizabeth Renner, Kyle R. Taylor, and et al. 2025. "Pathology, Tissue Distribution, and Phylogenetic Characterization of Largemouth Bass Virus Isolated from a Wild Smallmouth Bass (Micropterus dolomieu)" Viruses 17, no. 8: 1031. https://doi.org/10.3390/v17081031

APA Style

Haake, C. J. E., Waltzek, T. B., Eckstrand, C. D., Hickey, N., Reno, J. L., Wolking, R. M., Sriwanayos, P., Lovy, J., Renner, E., Taylor, K. R., & Oliveira, R. (2025). Pathology, Tissue Distribution, and Phylogenetic Characterization of Largemouth Bass Virus Isolated from a Wild Smallmouth Bass (Micropterus dolomieu). Viruses, 17(8), 1031. https://doi.org/10.3390/v17081031

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Pathology, Tissue Distribution, and Phylogenetic Characterization of Largemouth Bass Virus Isolated from a Wild Smallmouth Bass (Micropterus dolomieu)

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