title: Emergence of carp edema virus in cultured ornamental koi carp, Cyprinus carpio koi, in India.
abstract: A disease outbreak was reported in adult koi, Cyprinus carpio koi, from a fish farm in Kerala, India, during June 2015. The clinical signs were observed only in recently introduced adult koi, and an existing population of fish did not show any clinical signs or mortality. Microscopic examination of wet mounts from the gills of affected koi revealed minor infestation of Dactylogyrus sp. in a few koi. In bacteriological studies, only opportunistic bacteria were isolated from the gills of affected fish. The histopathological examination of the affected fish revealed necrotic changes in gills and, importantly, virus particles were demonstrated in cytoplasm of gill epithelial cells in transmission electron microscopy. The tissue samples from affected koi were negative for common viruses reported from koi viz. cyprinid herpesvirus 3, spring viraemia of carp virus, koi ranavirus and red sea bream iridovirus in PCR screening. However, gill tissue from affected koi carp was positive for carp edema virus (CEV) in the first step of nested PCR, and sequencing of PCR amplicons confirmed infection with CEV. No cytopathic effect was observed in six fish cell lines following inoculation of filtered tissue homogenate prepared from gills of affected fish. In bioassay, the symptoms could be reproduced by inoculation of naive koi with filtrate from gill tissue homogenate of CEV-positive fish. Subsequently, screening of koi showing clinical signs similar to koi sleepy disease from different locations revealed that CEV infection was widespread. To our knowledge, this is the first report of infection with CEV in koi from India.
authors.affiliation: Peninsular and Marine Fish Genetic Resources Centre of National Bureau of Fish Genetic Resources, Indian Council of Agricultural Research, Central Marine Fisheries Research Institute Campus, Kochi 682018, India.
authors.forename: T Raja
authors.initials: TR
authors.lastname: Swaminathan
authors.affiliation: Peninsular and Marine Fish Genetic Resources Centre of National Bureau of Fish Genetic Resources, Indian Council of Agricultural Research, Central Marine Fisheries Research Institute Campus, Kochi 682018, India.
authors.forename: Raj
authors.initials: R
authors.lastname: Kumar
authors.affiliation: Peninsular and Marine Fish Genetic Resources Centre of National Bureau of Fish Genetic Resources, Indian Council of Agricultural Research, Central Marine Fisheries Research Institute Campus, Kochi 682018, India.
authors.forename: Arathi
authors.initials: A
authors.lastname: Dharmaratnam
authors.affiliation: Peninsular and Marine Fish Genetic Resources Centre of National Bureau of Fish Genetic Resources, Indian Council of Agricultural Research, Central Marine Fisheries Research Institute Campus, Kochi 682018, India.
authors.forename: V S
authors.initials: VS
authors.lastname: Basheer
authors.affiliation: National Bureau of Fish Genetic Resources, Indian Council of Agricultural Research, Lucknow 226002, India.
authors.forename: Neeraj
authors.initials: N
authors.lastname: Sood
authors.affiliation: National Bureau of Fish Genetic Resources, Indian Council of Agricultural Research, Lucknow 226002, India.
authors.forename: P K
authors.initials: PK
authors.lastname: Pradhan
authors.affiliation: Central Marine Fisheries Research Institute, Indian Council of Agricultural Research, Kochi 682018, India.
authors.forename: N K
authors.initials: NK
authors.lastname: Sanil
authors.affiliation: Central Marine Fisheries Research Institute, Indian Council of Agricultural Research, Kochi 682018, India.
authors.forename: P
authors.initials: P
authors.lastname: Vijayagopal
authors.affiliation: Division of Fisheries Science, Indian Council of Agricultural Research, Krishi Anusandhan Bhawan-II, Pusa, New Delhi 110012, India.
authors.forename: J K
authors.initials: JK
authors.lastname: Jena
mesh_terms: D000818:Animals; D017756:Aquaculture; D002347:Carps / Q000254:growth & development / Q000821:virology*; D002478:Cells, Cultured; D004266:DNA Virus Infections / Q000662:veterinary* / Q000821:virology; D005393:Fish Diseases / Q000821:virology*; D005880:Gills / Q000821:virology; D007194:India; D007497:Iridoviridae / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*