POLY I:C INDUCES MX TRANSCRIPTION AND PROMOTES AN ANTIVIRAL STATE AGAINST SOLE AQUABIRNAVIRUS IN THE FLATFISH SENEGALESE SOLE (SOLEA SENEGALENSIS KAUP)

Mx is an interferon (IFN)-induced protein that protects against viral infections. In this study the absolute number of Mx transcripts after poly I:C injection (a synthetic dsRNA) or sole aquabirnaviruses (solevirus) inoculation in Senegalese sole (Solea senegalensis Kaup) have been quantified. Mx expression profiles differed clearly in both experimental conditions, with a faster and more intense induction response after poly I:C injection than after solevirus inoculation. Moreover, mRNA levels of the virus capsid protein (VP2) in animals firstly inoculated with poly I:C and later challenged with solevirus were also determined by RT-PCR. VP2 transcripts were hardly detected in poly I:C pre-injected animals from 12 to 72 h after solevirus inoculation. Moreover, no induction of Mx expression associated to solevirus infection was detected. All these data suggest that poly I:C is able to induce an antiviral state that interferes solevirus replication, and support the suitability of Mx expression analysis as a marker to study the defensive response against solevirus.