Lymphocystis Disease Virus Infection in Clownfish Amphiprion ocellaris and Amphiprion clarkii in Taiwan

SIMPLE SUMMARY: The present research is about Lymphocystic Disease Virus (LCDV) infection in Amphiprion ocellaris and Amphiprion clarkii. Detection of LCDV depended on histopathological study, electron microscope observation of virus particles and gene sequence analysis from the MCP region. Symptoms of LCDV were sparse, multifocal, white, stiff, papilloma-like nodules on the body, skin, gills and fins. The viral particle present were virions 18–230 nm in diameter, hexagonal in shape with an inner dense nucleoid under transmission electron micrographs. The ML polygenetic tree constructed based on the MCP region of LCDV showed the LCDV genotype in the present study is closely related to LCDV from the paradise fish, Macropodus opercularis (KJ408271) (pairwise distance: 92.5%) from China. This is the first report of lymphocystis disease in A. clarkii in Taiwan. ABSTRACT: Lymphocystic disease affects over 150 species of marine and freshwater fish worldwide. In this study, the lymphocystis pathogen was found in 2 (Amphiprion ocellaris and Amphiprion clarkii) of the 9 species of clownfish. Detection of lymphocystis disease virus (LCDV) was based on histopathological study, electron microscope observation of virus particles and gene sequence analysis from the MCP region. Infected A. ocellaris hosts showed sparse, multifocal, white, stiff, papilloma-like nodules on the body, skin, gills and fins; while, on A. clarkia, nodules were found on the operculum skin. Histopathologic study showed lymphocystic cells with an irregular nucleus, enlarged cytoplasm and intracytoplasmic inclusion bodies surrounded by the cell membrane. The viral particle presents virions 180–230 nm in diameter, hexagonal in shape with an inner dense nucleoid under transmission electron micrographs (TEM). From the ML polygenetic tree, the clownfish LCVD genotype was closely related to the LCDV strain from paradise fish, Macropodus opercularis (KJ408271) (pairwise distance: 92.5%) from China, then followed by the strain from Spain (GU320726 and GU320736) (pairwise distance: 90.8–90.5%), Korea (AB299163, AB212999, AB213004, and AB299164) (pairwise distance: 91.5–80.5%) and lastly Canada (GU939626) (pairwise distance: 83%). This is the first report of lymphocystis disease in A. clarkii in Taiwan.