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Spring viremia of carp (SVC) is listed as a notifiable viral disease by the World Organization for Animal Health (OIE). In 2016, the first official SVC outbreak was detected in the city of Gyeongsan, Korea. The present study reports the first complete genome analysis of SVC virus (SVCV, ADC-SVC2016-5) isolated from leather carp (Cyprinus carpio nudus). The results revealed that ADC-SVC2016-5 has a 11,029-bp genome containing five genes: N, P, M, G, and L. Phylogenetic analysis indicated that ADC-SVC2016-5 (accession number MG663512), isolated from leather carp, was closely related to genogroup Ia isolates of the Asian clade. This report provides additional information for studying the molecular epidemiology and evolution of spring viremia of carp virus.

A batch of wild common carp and largemouth bass died in Andong, Gyeongsangbuk-do province, South Korea, in 2016. Moribund fish showed typical signs of spring viremia of carp (SVC) disease, which causes acute hemorrhage in the skin and ascites. Thus far, SVC disease has been detected in several regions of the world but never in South Korea. Suspecting the infectious agent to be the SCV virus (SVCV), the moribund fish were sampled and screened. The isolated virus developed a cytopathic effect in EPC cells. Both viral isolates from the common carp (ADC-SVC2016-1) and largemouth bass (ADC-SVC2016-3) were identical in terms of their genome sequence, which were 11,034 bp nucleotides in length. Genome comparison exhibited greater sequence similarity with the Asian SVCV sequences available at NCBI. Phylogenetic analysis revealed that the Korean SVCV isolates were clustered within the Asian clade. More specifically, evolutionary analysis by using the P gene sequences showed that the Korean isolates were sub-cladded within the Iai genogroup but diverged from Chinese strains of SH150514 and SH160901. The Korean isolates shared more than 98% sequence similarity with the two Chinese SVCV isolates, suggesting that the spread of SVCV originated from China. The isolated virus had cytopathic effects on EPC cells. Virus transmission studies showed that the virus exhibited the highest virulence at 15 °C, which was also dependent on the method used, with the injection method being better than the immersion and cohabitation methods. This is the first study to document that Korean SVCV isolates may be epizootic in wild common carp and other susceptible animal populations in South Korea., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Carboxypeptidases (CPs) are proteases that hydrolyze C-terminal peptide bonds. They are involved in regulating the complement system of the immune system. Here, we report the molecular characterization and immune response of two carboxypeptidases, named carboxypeptidase A (Rb-CPA) and carboxypeptidase N1 (Rb-CPN1), from rock bream. The genomic sequence of Rb-CPA contains 12 exons interrupted by 11 introns, while the genomic sequence of Rb-CPN1 has 9 exons and 8 introns. The cDNA sequence of Rb-CPA encodes a 421-amino-acid (AA) polypeptide (48kDa), and the cDNA of Rb-CPN1 encodes a 448-AA polypeptide (51kDa). The amino acid sequences of Rb-CPA and Rb-CPN1 were found to harbor two characteristic Zn-binding signature domains and a peptidase-M14 Zn carboxypeptidase site. Pairwise analysis revealed that Rb-CPA and Rb-CPN1 had the highest identity with the corresponding proteins from Anoplopoma fimbria (87.6%) and Dicentrarchus labrax (96.9%), respectively. qPCR results indicated that Rb-CPA and Rb-CPN1 were constitutively expressed mainly in the kidney, heart, liver, and head kidney. Both genes were transcriptionally regulated in the liver upon challenge with pathogenic bacteria (Streptococcus iniae, Edwardsiella tarda), rock bream iridovirus (RBIV), and the immune modulators polyinosinic:polycytidylic acid and lipopolysaccharide. Taken together, our findings suggest that Rb-CPA and Rb-CPN1 have immune-related functions in rock bream., (Copyright © 2014 Elsevier B.V. All rights reserved.)