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Diseases of Aquatic Organisms

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DAO 148:95-112 (2022)  -  DOI:

Comparative virulence of spring viremia of carp virus (SVCV) genotypes in two koi varieties

Eveline J. Emmenegger1,*, Emma K. Bueren1,7, Peng Jia2,3,4, Noble Hendrix5,6, Hong Liu2,3

1US Geological Survey, Western Fisheries Research Center, Seattle, WA 98115, USA
2Shenzhen Academy of Inspection and Quarantine Sciences, Shenzhen 518045, PR China
3Shenzhen Customs District, Shenzhen 518045, PR China
4Shenzhen Technology University, Shenzhen Guangdong 518118, PR China
5QEDA Consulting, 4007 Densmore Ave N, Seattle, WA 98103, USA
6School of Aquatic and Fishery Sciences, University of Washington, 1122 NE Boat St, Seattle, WA 98195-5020, USA
7Present address: Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
*Corresponding author:

ABSTRACT: Spring viremia of carp virus (SVCV), is a lethal freshwater pathogen of cyprinid fish, and Cyprinus carpio koi is a primary host species. The virus was initially described in the 1960s after outbreaks occurred in Europe, but a global expansion of SVCV has been ongoing since the late 1990s. Genetic typing of SVCV isolates separates them into 4 genotypes that are correlated with geographic origin: Ia (Asia), Ib and Ic (Eastern Europe), and Id (Central Europe). We compared infectivity and virulence of 8 SVCV strains, including 4 uncharacterized Chinese Ia isolates and representatives of genotypes Ia-d in 2 morphologically distinct varieties of koi: long-fin semi-scaled Beni Kikokuryu koi and short-fin fully scaled Sanke koi. Mortality ranged from 4 to 82% in the Beni Kikokuryu koi and 0 to 94% in the Sanke koi following immersion challenge. Genotype Ia isolates of Asian origin had a wide range in virulence (0-94%). Single isolates representing the European genotypes Ib and Ic were moderately virulent (38-56%). Each virus strain produced similar levels of mortality in both koi breeds, with the exception of the SVCV Id strain that appeared to have both moderate and high virulence phenotypes (60% in Beni Kikokuryu koi vs. 87% in Sanke koi). Overall SVCV strain virulence appeared to be a dominant factor in determining disease outcomes, whereas intraspecies variation, based on koi variety, had less of an impact. This study is the first side-by-side comparison of Chinese SVCV isolates and genotype Ia-d strain virulence in a highly susceptible host.

KEY WORDS: SVCV · Genotype · Strain · Virulence · Koi

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Cite this article as: Emmenegger EJ, Bueren EK, Jia P, Hendrix N, Liu H (2022) Comparative virulence of spring viremia of carp virus (SVCV) genotypes in two koi varieties. Dis Aquat Org 148:95-112.

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