title: Co-infection of Acipenserid herpesvirus 2 (AciHV-2) and Streptococcus iniae in cultured white sturgeon Acipenser transmontanus.
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.
authors.affiliation: Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, Davis, CA 95616, USA.
authors.forename: Esteban
authors.initials: E
authors.lastname: Soto
authors.forename: Christine
authors.initials: C
authors.lastname: Richey
authors.forename: Brittany
authors.initials: B
authors.lastname: Stevens
authors.forename: Susan
authors.initials: S
authors.lastname: Yun
authors.forename: Kirsten
authors.initials: K
authors.lastname: Kenelty
authors.forename: Stephen
authors.initials: S
authors.lastname: Reichley
authors.forename: Matt
authors.initials: M
authors.lastname: Griffin
authors.forename: Tomofumi
authors.initials: T
authors.lastname: Kurobe
authors.forename: Al
authors.initials: A
authors.lastname: Camus
mesh_terms: D000818:Animals; D017756:Aquaculture; D016000:Cluster Analysis; D060085:Coinfection / Q000662:veterinary*; D005393:Fish Diseases / Q000382:microbiology* / Q000821:virology; D005399:Fishes; D005838:Genotype; D006564:Herpesviridae / Q000145:classification; D006566:Herpesviridae Infections / Q000150:complications / Q000662:veterinary* / Q000821:virology; D010802:Phylogeny; D013290:Streptococcal Infections / Q000150:complications / Q000382:microbiology / Q000662:veterinary*; D000070058:Streptococcus iniae / Q000235:genetics
keywords: Acipenserid herpesvirus; Streptococcus; Sturgeon