Lack of correlation between the resistances to two rhabdovirus infections in rainbow trout

• Wide range of susceptibility for both IHNV and VHSV infections in rainbow trout.
• Strong effect of body weight on susceptibility to INHV in young stages.
• No correlation between resistances to the two viruses in the set of clonal lines.
• Key role of glycoprotein in the host variability for resistances.

The Viral Hemorrhagic Septicemia Virus (VHSV) and the Infectious Hematopoietic Necrosis Virus (IHNV) are two rhabdoviruses responsible for serious outbreaks in salmonid farms. To date, little is known about the variability of host response to these viruses. Using gynogenetic clonal lines of rainbow trout exhibiting a wide range of resistance to viral infections, we showed that there was no correlation between the resistance to VHSV and IHNV. We also confirmed the importance of fish weight for its susceptibility to IHNV infection. Finally, using a chimeric recombinant IHNV expressing the VHSV glycoprotein, we showed that the glycoprotein plays a key role in the virulence and in the level of resistance observed in different genetic backgrounds. Taken together, our results provide new prospects for a better understanding of host responses to rhabdovirus infections in salmonids.