Identification of the Immediate-Early Genes of Cyprinid Herpesvirus 2

Abstract

Cyprinid herpesvirus 2 (CyHV-2), which infects goldfish and crucian carp causing high mortality, is an emerging viral pathogen worldwide. The genome of CyHV-2 is large and comprises double-stranded DNA, including several genes similar to cyprinid herpesvirus 1, ictalurid herpesvirus-1, cyprinid herpesvirus 3, and ranid herpesvirus-1. Genes of DNA viruses are expressed in three temporal phases: immediate-early (IE), early (E), and late (L) genes. Viral IE genes initiate transcription as soon as the virus enters the host, without viral DNA replication. IE gene products enable the efficient expression of E and L genes or regulate the host to initiate virus replication. In the present study, five IE genes of CyHV-2 were identified, including open reading frame (ORF)54, ORF121, ORF141, ORF147, and ORF155. Time course analysis and reverse transcription polymerase chain reaction confirmed five IE genes, thirty-four E genes, and thirty-nine L genes. In addition, all 150 ORFs identified in the CyHV-2 genome are transcribed, and are expressed in chronological order, similar to other herpesviruses. This study is the first to identify the IE genes of CyHV-2, which will provide more information for viral molecular characterization.

Susceptibility of Goldfish to Cyprinid Herpesvirus 2 (CyHV-2) SH01 Isolated from Cultured Crucian Carp

“…The pelleted viruses were dissolved with TN buffer, and aliquots were stored at -80 • C. Additionally, complete genome sequencing of CyHV-2 SH01 was performed using next generation sequencing by the NextOmics company (Wuhan, China). Virus titer values were determined using an established protocol [26]. DNA extracted from purified CyHV-2 particles was sequenced, and CyHV-2 SH01 genome sequencing was commercially performed by the NextOmics company (Wuhan, China).…”

Generation and application of a monoclonal antibody specific for the ORF121 of cyprinid herpesvirus 2

“…Five immediate‐early IE genes of CyHV‐2 were identified, including open reading frame (ORF)54, ORF121, ORF141, ORF147 and ORF155 (Tang et al, 2020). Viral proteins can be divided into three stages according to their respective peak synthesis periods, namely immediate‐early (A) protein, early (B) protein and late protein.…”

“…Immunological diagnostic methods are important in viral studies, including detection and localization of additional gene products for analysis of protein function. ORF121 gene of CyHV‐2 is highly expressed in the blood and tissues of diseased fish (Wang et al., 2016), and it was proved as an immediate‐early (IE) gene (Tang et al., 2020). Therefore, the pORF121 protein was selected as an antigen for the preparation of mAbs against CyHV‐2, which were subsequently used to establish immunofluorescence assay (IFA) and western‐blotting methods for CyHV‐2 detection in infected fish tissues and cells.…”

“…Immunological diagnostic methods are important in viral studies, including detection and localization of additional gene products for analysis of protein function. ORF121 gene of CyHV-2 is highly expressed in the blood and tissues of diseased fish (Wang et al, 2016), and it was proved as an immediate-early (IE) gene (Tang et al, 2020).…”

Induction of Reactive Oxygen Species Is Necessary for Efficient Onset of Cyprinid Herpesvirus 2 Replication: Implications for Novel Antiviral Strategy With Antioxidants

“…To confirm the antiviral effects of BBH and EGCG, we continued to investigate the transcriptional and translational expression levels of ORF121, an immediately early gene encoded by CyHV-2 (Tang et al, 2020). The infected RyuF-2 cells in the presence of 20 µg/ml BBH or 10 µg/ml EGCG were harvested at 24, 48, and 72 h post-infection, and total protein samples were extracted from the infected cells for ORF121 detection by western blot analysis; total RNA samples were extracted from the infected cells for ORF121 mRNA detection by real-time RT-PCR analysis.…”