MOLECULAR CLONING AND EXPRESSION CHARACTERISTICS OF MX1 GENE IN SQUALIOBARBUS CURRICULUS

In order to investigate whether the Myxovirus resistance isoform (Mx1) exists in Squaliobarbus curriculus and gets involved in antiviral immune response, the full-length cDNA of ScMx1 was cloned and characterized by using RACE-PCRs technology. The expression levels of ScMx1 and ScIFN-I were detected after injection with grass carp reovirus (GCRV) with qPCR. The full-length cDNA of ScMx1 was 3000 bp including a 5′-terminal untranslated region of 124 bp, a 3′-terminal untranslated region of 893 bp and an open reading frame of 1893 bp encoding a polypeptide of 630 amino acid residues. The ScMx1 protein consisted of Dynamin GTPase domain, Dynamin central domain and Dynamin GTPase effector domain. The BLAST analysis showed that ScMx1 shared high identity (97%) with Mylopharyngodon piceus Mx1, and low identity (50%) with ScMx. The expression of ScMx1 could be detected in all tested tissues, with the highest expression in spleen. After injection with GCRV, the ScMx1 and ScIFN-I expression levels were up-regulated to 168h in liver and trunk kidney, and peaked at 72h in spleen and head kidney. There was a significant correlation between ScMx1 and ScIFN-I expressions in spleen (r=0.94, P=0.018). These results indicated that there were ScMx1 gene existed in Squaliobarbus curriculus, and it may play an important role in the immune response of against GCRV.