Analysis of koi herpesvirus latency in wild common carp and ornamental koi in Oregon, USA

• Published in: Journal of virological methods 2013-02, Vol.187 (2), p.372-379
• Main Authors: Xu, Jia-Rong, Bently, Jennifer, Beck, Linda, Reed, Aimee, Miller-Morgan, Tim, Heidel, Jerry R., Kent, Michael L., Rockey, Daniel D., Jin, Ling
• Format: Article
• Language: English
• Subjects: acute course; Animals; Base Sequence; Biological and medical sciences; Carps - virology; Cyprinid herpesvirus 3; Cyprinus carpio; Cyprinus carpio carpio; DNA; DNA, Viral - chemistry; DNA, Viral - genetics; Fish Diseases - virology; Freshwater; Fundamental and applied biological sciences. Psychology; Herpesviridae - pathogenicity; Herpesviridae Infections - veterinary; Herpesviridae Infections - virology; infectious diseases; interleukin-10; Interleukin-10 - genetics; KHV; koi; koi herpesvirus; Latency; leukocytes; Leukocytes - virology; Microbiology; Molecular Sequence Data; mortality; Open Reading Frames; Oregon; Polymorphism, Genetic; population; Receptors, Tumor Necrosis Factor - genetics; Sequence Alignment; Sequence Analysis, DNA; Sequence Homology; suppressor genes; Techniques used in virology; Variant; Virology; Virus Latency; Wild common carp
• ISSN: 0166-0934; 1879-0984
• DOI: 10.1016/j.jviromet.2012.11.015

► This is the first report of KHV latency in wild common carp in populations without the history of KHV outbreak in Oregon, USA. ► KHV variants detected in these wild common carp have genetic features different from those KHV from koi. ► A unique set of nested PCR was reported here to detect different variants of KHV. Koi herpesvirus (KHV) infection is associated with high mortalities in both common carp (Cyprinus carpio carpio) and koi carp (Cyprinus carpio koi) worldwide. Although acute infection has been reported in both domestic and wild common carp, the status of KHV latent infection is largely unknown in wild common carp. To investigate whether KHV latency is present in wild common carp, the distribution of KHV latent infection was investigated in two geographically distinct populations of wild common carp in Oregon, as well as in koi from an Oregon-based commercial supplier. Latent KHV infection was demonstrated in white blood cells from each of these populations. Although KHV isolated from acute infections has two distinct genetic groups, Asian and European, KHV detected in wild carp has not been genetically characterized. DNA sequences from ORF 25 to 26 that are unique between Asian and European were investigated in this study. KHV from captive koi and some wild common carp were found to have ORF-25–26 sequences similar to KHV-J (Asian), while the majority of KHV DNA detected in wild common carp has similarity to KHV-U/-I (European). In addition, DNA sequences from IL-10, and TNFR were sequenced and compared with no differences found, which suggests immune suppressor genes of KHV are conserved between KHV in wild common carp and koi, and is consistent with KHV-U, -I, -J.