Aquaculture Reports (Nov 2021)
Comparison the function of Cyprinid herpesvirus 3 encoded two viral tumor necrosis factor receptors
Abstract
To avoid immune surveillance and elimination from the host, many viruses encode homologues of host cytokines and cytokine receptors to regulate the host immune response. Viral encoded tumor necrosis factor receptor (vTNFR) homologues are involved in immune evasion by regulating the host immune response or programmed cell death. Cyprinid herpesvirus 3 (CyHV-3), causes severe economic losses to the common carp and koi culture industry worldwide; it encodes two tumor necrosis factor receptor homologues (ORF4 and ORF12). This study was devoted to the regulatory role of CyHV-3 vTNFRs in the process of virus invasion into the host. CyHV-3 ORF4 and ORF12 were subjected to bioinformatics analysis and multiple sequence alignments, although the alignment results showed low homology. However, they still have a highly conserved cysteine-rich domain and similar tertiary structure, indicating that TNFRS and vTNFRs have conserved biological functions. Recombinant vTNFR proteins of CyHV-3 ORF4 and ORF12 were obtained using a prokaryotic expression system. Regulation of CyHV-3 vTNFRs in the expression of immune-related factors in carp head kidney macrophages and apoptosis of epithelioma papulosum cyprini (EPC) cells were studied. The results showed that CyHV-3 rvTNFRs up-regulate the levels of expression of some immune-related factors to varying degrees under a high concentration (20 μg/mL) in vitro. CyHV-3 rvTNFR induced apoptosis of EPC cells was confirmed by Hoechst33342 staining and flow cytometry. This indicates that the role of CyHV-3 encoded TNFRs in virus invasion of the host may be related to the regulation of host immune response and apoptosis.
