DAO 57:19-26 (2003)  -  doi:10.3354/dao057019

Serological relationships among genotypic variants of betanodavirus

K. Mori1, T. Mangyoku2, T. Iwamoto1, M. Arimoto1, S. Tanaka3, T. Nakai2,*

1Kamiura Station, Japan Sea-Farming Association, Oita 879-2602, Japan
2Fish Pathobiology Laboratory, Graduate School of Biosphere Science, Hiroshima University, Higashihiroshima 738-8528, Japan
3Owase Fisheries Laboratory, Fisheries Research Division, Mie Prefectural Science and Technology Promotion Center, Owase, Mie 519-3602, Japan
*Corresponding author. Email:

ABSTRACT: Betanodaviruses, the causative agents of viral nervous necrosis or viral encephalopathy and retinopathy, are divided into 4 genotypes based on the coat protein gene (RNA2). In the present study, serological relationships among betanodavirus genotypic variants were examined by virus neutralization tests using rabbit antisera raised against purified virions of strains representative of each genotype. All 20 isolates examined shared epitopes for neutralizing, but they fell into 3 major serotypes (A, B, C). This sero-grouping is in part consistent with their genotypes, i.e. Serotype A for striped jack nervous necrosis virus (SJNNV) genotype, Serotype B for tiger puffer nervous necrosis virus (TPNNV) genotype, and Serotype C for both redspotted grouper nervous necrosis virus (RGNNV) and barfin flounder nervous necrosis virus (BFNNV) genotypes. The serological relatedness between RGNNV and BFNNV genotypes may result from their relatively higher similarity in RNA2 sequences. In neutralization tests using antisera of kelp grouper Epinephelus moara, which were raised against recombinant coat proteins representing each genotype, anti-SJNNV and anti-TPNNV sera neutralized only the homologous strain, and anti-RGNNV and anti-BFNNV sera reacted with both RGNNV and BFNNV strains. The present serological findings will be important in investigating the infectivity and host-specificity of betanodaviruses and in developing vaccines for the disease.

KEY WORDS: Betanodavirus · Viral nervous necrosis · Viral encephalopathy · Viral retinopathy · Serotyping · Virus neutralization · Recombinant protein

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