Abstract
Grouper E pinephelus spp. is one of the most important mariculture fish species in C hina and S outh‐East A sian countries. The emerging viral diseases, evoked by iridovirus which belongs to genus M egalocytivirus and R anavirus, have been well characterized in recent years. To date, few data on lymphocystis disease in grouper which caused by lymphocystis disease virus ( LCDV ) were described. Here, a novel LCDV isolate was identified and characterized. Based on the sequence of LCDV major capsid protein ( MCP ) and DNA polymerase gene, we found that the causative agents from different species of diseased groupers were the same one and herein were uniformly defined as grouper LCDV ( GLCDV ). Furthermore, H & E staining revealed that the nodules on the skin were composed of giant cells that contained inclusion bodies in the cytoplasm. Numerous virus particles with >210 nm in diameter and with hexagonal profiles were observed in the cytoplasm. In addition, phylogenetic analysis based on four iridovirus core genes, MCP , DNA polymerase, myristoylated membrane protein ( MMP ) and ribonucleotide reductase ( RNR ), consistently showed that GLCDV was mostly related to LCDV ‐ C , followed by LCDV ‐1. Taken together, our data firstly provided the molecular evidence that GLCDV was a novel emerging iridovirus pathogen in grouper culture.