Phylogenetic analysis and genotyping of Iranian infectious haematopoietic necrosis virus (IHNV) of rainbow trout (Oncorhynchus mykiss) based on the glycoprotein gene

Background: Infectious haematopoietic necrosis (IHN) is known as one of the most contagious systemic viral diseases in salmonids which can lead to significant mortality rates and negative impacts on the salmonid farming industry. Infectious haematopoietic necrosis virus (IHNV) was first detected in rainbow trout (Oncorhynchus mykiss) farms in Iran in 2003. Objectives: We conducted the present study to determine the detection of IHN genotypes in rainbow trout (O. mykiss) in farms in the central parts of Iran, using molecular and phylogenetic techniques. Methods: Samples were collected from fries exhibiting clinical signs such as darkening of the skin, abdominal swelling, and loss of appetite. Phylogenetic analysis was performed by the neighbour-joining method, using MEGA 5.1 software. For phylogenetic analysis and genotyping of IHNV from central parts of Iran, the sequences of the glycoprotein gene were determined for two Iranian isolates (Jahad-UT1 and Jahad-UT2). Results: Phylogenetic analysis revealed that the detected strains (Jahad-UT1 and Jahad-UT2 isolates) are closely related (97.23%-100%) to European isolates within genogroup 'E'. Conclusions: This finding indicates that Jahad-UT1 and Jahad-UT2 isolates have been widely transferred to Iran from European countries. Moreover, the nucleotide diversity of these Iranian isolates showed a dose relationship with the North American and Asian isolates, although the Iranian isolates were collected from a smaller geographical area and within a shorter time period between 2014 and 2015.