PCR detection and phylogenetic analysis of the major capsid protein gene of Lymphocystis disease virus from cultured Asian seabass (Lates calcarifer Bloch, 1790) along the west coast of Kerala, India

A sudden disease outbreak was reported in Asian seabass (Lates calcarifer) cultured in open brackish water cages along the west coast of Kerala, India. Moribund samples with typical characteristic blister-like clusters of excessively hypertrophied cells were collected from the skin and fins. These tissues (white and pink nodule like growth) were excised, analyzed, and subjected to DNA extraction using the phenol chloroform isoamyl alcohol method. PCR targeting the universal conserved region of the major capsid protein (MCP) gene of lymphocystiviruses confirmed that the causative agent belongs to the genus Lymphocystivirus within the family Iridoviridae and hence called as Lymphocystis disease virus (LCDV). Phylogenetic analysis of the obtained isolate based on the MCP gene revealed maximum nucleotide similarity (91.68%) to LCDV strain, LCDV-PGF (GV genotype) found in painted glass fish (Chanda baculis/Parambassis baculis) isolated from Japan. To the best of our knowledge, this is the first PCR detection and phylogenetic analysis report of the major capsid protein gene of LCDV from Asian seabass cultured in India.