Phylogenetic analysis of viral hemorrhagic septicemia virus from recent outbreaks in some of the farmed rainbow trout, Oncorhynchus mykiss (Walbaum, ۱۷۹۲)

During a fish disease outbreaks in ۲۰۱۵-۲۰۱۶ suspected to viral hemorrhagic septicemia virus (VHSV), moribund rainbow trout fries were obtained from fish farms. Samples of kidney, heart and spleen tissues were taken  for examination. The full coding region of the G gene was amplified by RT-PCR reaction. Genotyping was carried out by phylogenetic analysis with reference sequences of four VHS genogroup. A phylogenetic tree was constructed with the maximum likelihood method and the Kumara ۲- parameter substitution model by using MEGA software version ۶.۰۶. A maximum likelihood phylogenetic analysis reveals that all the Iranian VHS   strains belonged to clade Ia-۲ of genotype Ia. The intra- sequence comparison of Iranian VHS strains ranged from ۹۹.۱% to ۱۰۰% (average was ۹۹.۵۵%). In this study, two strains (Chaharmahal and Bakhtiari (۱) and Chaharmahal and Bakhtiari (۳) showed ۱۰۰% identity but ۰.۱% differences with Isfahan strain. The Iranian strains belonging to European genogroup are related (۹۹% identity) to VHSV from recent Italian strains (VHSV/O.mykiss/I/TN/۱۳۳/Apr۱۰).

Keywords:

VHSV , Phylogenetic , Rainbow trout , Iran