DAO 124:11-20 (2017)  -  DOI: https://doi.org/10.3354/dao03108

Co-infection of Acipenserid herpesvirus 2 (AciHV-2) and Streptococcus iniae in cultured white sturgeon Acipenser transmontanus

Esteban Soto1,*, Christine Richey1, Brittany Stevens1, Susan Yun1, Kirsten Kenelty1, Stephen Reichley2, Matt Griffin2, Tomofumi Kurobe3, Al Camus

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 Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California, Davis, Davis, CA 95616, USA
4Department of Pathology, College of Veterinary Medicine, University of Georgia Athens, Athens, GA 30602, USA
*Corresponding author:

ABSTRACT: A mortality event in cultured white sturgeon Acipenser transmontanus (Richardson, 1836) sub-adults was investigated. After transfer between farms, high mortality was observed in fish, associated with back arching, abnormal swimming, and ulcerative skin lesions. Necropsy of moribund individuals revealed hemorrhagic ascites and petechial hemorrhages in the coelomic peritoneum and serosa of internal organs. Acipenserid herpesvirus 2 (AciHV-2) was isolated from external tissue samples, then identified and genotyped by sequencing of the terminase and polymerase genes. In addition, Streptococcus iniae was recovered from internal organs of affected fish. Histologic changes were limited to interstitial hematopoietic areas of the kidney and consisted of small foci of necrosis accompanied by fibrin deposition, minimal inflammatory response, and small numbers of bacterial cocci compatible with streptococci. Identity was confirmed by partial sequencing of the 16S rRNA, rpoB, and gyrB genes. Genetic fingerprinting demonstrated a genetic profile distinct from S. iniae isolates recovered from previous outbreaks in wild and cultured fish in North America, South America, and the Caribbean. Although the isolates were resistant to white sturgeon complement in serum killing assays, in vivo challenges failed to fulfill Koch’s postulates. However, the clinical presentation, coupled with consistent recovery of S. iniae and AciHV-2 from moribund fish, suggests viral and bacterial co-infection were the proximate cause of death. To our knowledge, this represents the first report of AciHV-2 and S. iniae co-infection in cultured white sturgeon.


KEY WORDS: Acipenserid herpesvirus · Streptococcus · Sturgeon


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Cite this article as: Soto E, Richey C, Stevens B, Yun S and others (2017) Co-infection of Acipenserid herpesvirus 2 (AciHV-2) and Streptococcus iniae in cultured white sturgeon Acipenser transmontanus. Dis Aquat Org 124:11-20. https://doi.org/10.3354/dao03108

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