F. Hassantabar - ۱Department of Fisheries, Faculty of Animal Science and Fisheries, Sari Agricultural Sciences and Natural Resources University, PO Box: ۵۷۸, Sari, I.R. Iran.
M.J. Zorriehzahra - Scientific Information and Communication Dept., Iranian Fisheries Science Research Institute (IFSRI), Agricultural Research Education and Extension Organization (AREEO), Tehran, I.R. Iran.
F. Firouzbakhsh - Department of Fisheries, Faculty of Animal Science and Fisheries, Sari Agricultural Sciences and Natural Resources University, PO Box: ۵۷۸, Sari, I.R. Iran
K.D. Thompson - ۳Aquaculture Research Group, Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Midlothian, EH۲۶ ۰PZ, UK

Viral Nervous Necrosis (VNN), caused by betabodavirus, is considered as one of the most important threats for mariculture and aquaculture globally. The disease was previously reported in wild golden grey mullet (Chelon aurata) from the Caspian Sea in ۲۰۰۴. To update these findings and to examine the phylogenetic relationship of the betanodavirus involved in disease outbreaks in Iran with other betanodavirus genotypes, forty golden grey mullets were screened for the presence of betanodavirus using real-time RT-PCR targeting the T۴ region of RNA۲ coat protein gene. The results showed that all ۴۰ fish has positive test for the virus, which was also confirmed by immunohistochemistry. The phylogenetic relationship of betanodavirus involved in disease outbreaks in Iran from ۲۰۱۶ to ۲۰۱۷ was compared with betanodavirus genotypes sequenced from elsewhere, and the ۳۰۰ bp product from the real-time RT-PCR sequenced was found to have a ۹۸–۱۰۰% homology with red-spotted grouper nervous necrosis virus (RGNVV), confirming that the betanodavirus detected in wild golden grey mullet in the southern parts of the Caspian Sea adjacent to Iran determined to be the RGNNV genotype.

Betanodavirus, Viral Nervous Necrosis, Phylogenetic analysis, Real-time RT-PCR, Immunohistochemistry, Golden grey mullet.