Identification and characterization of Lymphocystis disease virus from snakehead (Channa striata) in South Kalimantan, Indonesia

An outbreak of clinical symptoms of warts in Channa striata was reported in South Kalimantan, a snakehead producer in Indonesia. This study aimed to describe these symptoms, to confirm the presence and characterize of the disease agent. Molecular analysis was carried out by sequencing the MCP, MMP, DNAmet, RNR-L, DNApolB, and DNAprim genes of lymphocystis disease virus (LCDV) and determining their genotypes. Histological examination revealed enlarge lymphocytes containing basophilic intracytoplasmic inclusion bodies enclosed by a thick hyaline capsule in the warts. Hemorrhagic, necrotic, and accumulating inflammatory cells were found in the viscera. PCR using six primer pairs for LCDV genes revealed the specific single band at the expected size. Histology and PCR results confirmed that the snakehead in South Kalimantan were infected by an LCDV named LCDV Cs-SK. The MCP and MMP of LCDV Cs-SK share high similarity with the MCP (98.68) and MMP (97.79) of LCDV Oc-Btm, which infected Amphiprion percula in Batam, and low similarity with full genome identified LCDV species. LCDV Cs-SK shows the highest similarity with LCDV-3 in terms of MCP (91.08) and MMP (88.37). Phylogenetic reconstruction of these single genes revealed distinct clades. The concatenated phylogenetic tree of six genes showed the closest genetic evolution to LCDV 3. Low nucleotide similarity with LCDV and phylogenetic tree position indicated that LCDV Cs-SK is possibly a new LCDV species.