Characterization of a virulent ranavirus isolated from marine ornamental fish in India

Abstract

A viral agent implicated in the mortality of marine ornamental "Similar Damselfish" ( Allen, 1991) was isolated and characterized. The virus grew well in marine and freshwater fish cell lines from seabass and snakehead. The virus was sensitive to chloroform, acidic pH (3.0) and heat treatment at 56 °C. Biochemical characterisation indicated that the virus had double stranded DNA genome. Transmission electron microscopic analysis of ultrathin sections of infected cell pellets showed iridovirus-like icosahedral virus particles of 120-130 nm. Purified virus had six structural protein bands that ranged from of 44 to 132 kDa. PCR analysis confirmed the presence of viral DNA in infected cell cultures and sequence analysis of the major capsid protein gene showed an identity of 99.82% to that of largemouth bass virus. Serum neutralization studies involving the viral agent and koi ranavirus (KIRV) indicated partial homogeneity between the two isolates. Experimental infection of seabass () and similar damselfish () fingerlings with the similar damselfish virus showed cumulative mortalities of 68.75 and 93.33%. The biophysical and biochemical properties of the viral agent isolated, serological characteristics, size of major capsid proteins and the sequence similarity of the MCP gene proved that the virus belongs to the genus of the family. Ability of the virus to grow in marine and freshwater fish cell lines and its pathogenicity to one of the cultivable marine fish shows the wide host range of the virus. This is the first report of ranavirus induced mortality in marine fish in India.

Application of Outer Membrane Protein-Based Vaccines Against Major Bacterial Fish Pathogens in India

“…The major diseases of finfish in Indian aquaculture are caused by bacterial infections ( 7 , 11 ). Viral pathogens like tilapia lake virus (TiLV) ( 12 ), nodavirus ( 13 ), Koi herpesvirus virus (KHV) ( 14 ), and red sea bream iridovirus (RSBIV) ( 15 , 16 ) are not pathogens of top farmed fish species in India. The major parasite-causing disease in fish in India is Ichthyophthirius mulifiliis ( 11 ) whose impact is not severe compared to bacterial pathogens.…”

Immune Gene Expression against Similar Damselfish Virus (SRDV) Induced by Immunization with Inactivated Vaccine in Juvenile Koi Carp

“…The core of the virion consists of a nucleoprotein filament surrounded by a lipid membrane containing transmembrane proteins and a capsid composed of identical capsomers (Jancovich et al, 2011). We have isolated and characterised a ranavirus from similar damselfish, which was found to be pathogenic to seabass and similar damselfish (John and George, 2011;Sivasankar, 2014).…”

“…Similar damselfish virus (SRDV) isolated from similar damselfish (Pomacentrus similis) and characterized in our laboratory was used for the present study (John and George, 2011;Sivasankar, 2014). Stock preparation of SRDV was prepared in EPC cell line.…”

Experimental Infection with Koi Ranavirus (KIRV) of Common Carp (Cyprinus carpio L.) and Rohu (Labeo rohita H.)

“…EHNV was the first ranavirus isolated from fish during a disease outbreak of redfin perch (Perca fluviatilis) and rainbow trout (Salmo gairdneri) in Australia (Langdon, 1989;Langdon et al, 1988). Recently, a marine ranavirus (similar damselfish virus, SRDV) has been reported to be causing high mortalities in seabass (Lates calcarifer) and similar damselfish (P. similis) fingerlings (Sivasankar et al, 2017). The first documentation to the isolation of virus resembling Santee-Cooper ranavirus infection in koi was reported from India (George et al, 2015), where the corresponding viral agent was detected and successfully isolated and named as koi ranavirus (KIRV).…”