The pretreatment potential effects of omy-miR-731 Antagomir in brain tissue of rainbow trout Oncorhynchus mykiss infected with viral hemorrhagic septicemia virus

Among the viral diseases in trout farming, viral hemorrhagic septicemia (VHS) could be mentioned as the most devastating worldwide viral infection. In the present investigation, the influence of the omy-miR-731 Antagomir pretreatment on VHS in rainbow trout was examined. Trout (20±1) g were examined in four main groups subdivided into three subgroups, including a negative control without any injection, a vehicle that received saline, a positive control that was infected by VHSV, and an experimental group that received omy-miR-731 Antagomir by injection, then they were challenged by VHSV. The survival rate, average weight gain, histopathology, Immunohistochemistry and Blood-brain barrier impermeability were assessed in each group. The survival rate and average weight gain in the positive control group was significantly decreased in comparison with other groups. Remarkable histopathological changes and virus detection by immunohistochemistry test were observed in the positive control, whereas no sign of the virus was observed in the vehicle and the negative control groups. The histologic changes in the experimental group were significantly less than the positive control group. Also, the Blood-brain barrier impermeability was significantly decreased in the other groups compared to the positive control group. Although more studies are needed to verify the exact mechanisms of pretreatment potential effects of omy-miR-731 Antagomir, the present results proved that pretreatment potential of omy-miR-731 Antagomir can protect the brain tissue against signs of VHS and preferably would be a new approach against VHSV infection in rainbow trout.