Two Mx genes identified in European sea bass (Dicentrarchus labrax) respond differently to VNNV infection

Mx proteins are key components of the antiviral state triggered by interferon type I in response to viral infections. In this study, two different Mx genes have been identified in European sea bass (Dicentrarchus labrax), and their sequences were cloned and characterized. MxA cDNA consists of 1881 bp coding for a putative 626 aminoacids protein, while MxB cDNA has 1920 bp and results in a protein with 639 residues. Their corresponding genomic sequences contain 3538 bp and 5326 bp, respectively, and both present 12 exons and 11 introns. The expression patterns of the two Mx genes after an in vivo challenge with the viral nervous necrosis virus (VNNV), a serious pathogen in farmed European sea bass, have been characterized by real-time PCR. The results showed interesting differences in the transcription profile of both Mx, thus suggesting a differential role for each Mx isoform in the immune response of European sea bass to VNNV, and most likely in the general viral response of this species.