Cyprinid herpesvirus 2 (CyHV-2, species Cyprinid herpesvirus 2) has been confirmed as a causative agent of the acute haematopoietic necrosis disease outbreak in farmed goldfish (Carassius auratus L.) and gibel carp (Carassius auratus gibelio Bloch). In this study, we present the genomic characteristics of a variant CyHV-2 strain (SY-C1) isolated from farmed gibel carp in mainland China and its comparative genomics analysis with the CyHV-2 reference strain ST-J1. Overall, the full-length genome of SY-C1 shares 98.8% homology with that of ST-J1. Sequence comparisons between SY-C1 and ST-J1 indicate that the variations include single-nucleotide mutations, insertions, deletions, and rearrangements, which suggested that SY-C1 is different from ST-J1 and represents a new genotype. Therefore, we propose that the identified CyHV-2 can be divided into 2 different genotypes and be named China genotype (C genotype) and Japan genotype (J genotype) according to their isolation loci. Furthermore, epidemiological surveys indicate that the dominant genotype of CyHV-2 circulating in mainland China is closer to the China genotype than the Japan genotype.

BackgroundSpring viraemia of carp virus (SVCV) has been identified as the causative agent of spring viraemia of carp (SVC) and it has caused significant losses in the cultured common carp (Cyprinus carpio) industry. The molecular mechanisms that underlie the pathogenesis of the disease remain poorly understood. In this study, deep RNA sequencing was used to analyse the transcriptome and gene expression profile of EPC cells at progressive times after SVCV infection. This study addressed the complexity of virus–cell interactions and added knowledge that may help to understand SVCV.ResultsA total of 33,849,764 clean data from 36,000,000 sequence reads, with a mean read length 100 bp, were obtained. These raw data were assembled into 88,772 contigs. Of these contigs, 19,642 and 25,966 had significant hits to the NR and Uniprot databases where they matched 17,642 and 13,351 unique protein accessions, respectively. At 24 h post SVCV infection (1.0 MOI), a total of 623 genes were differentially expressed in EPC cells compared to non-infected cells, including 288 up-regulated genes and 335 down-regulated genes. These regulated genes were primarily involved in pathways of apoptosis, oxidative stress and the interferon system, all of which may be involved in viral pathogenesis. In addition, 8 differentially expressed genes (DEGs) were validated by quantitative PCR.ConclusionsOur findings demonstrate previously unrecognised changes in gene transcription that are associated with SVCV infection in vitro, and many potential cascades identified in the study clearly warrant further experimental investigation. Our data provide new clues to the mechanism of viral susceptibility in EPC cells.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-935) contains supplementary material, which is available to authorized users.