MOLECULAR-CLONING OF DOUBLE-STRANDED-RNA INDUCIBLE MX GENES FROM ATLANTIC SALMON (SALMO-SALAR L.)

Mx proteins are induced by type I interferons in mice and humans and i nhibit the replication of several negative-stranded RNA viruses. In th is work Mr genes in Atlantic salmon were studied using the double stra nded RNA, polyinosinic: polycytidylic acid (poly I:C), to induce inter feron production. Northern blot analysis showed Mr mRNA in liver, head kidney and gills 2 days after poly I:C injection of fish, but not in untreated fish or fish injected with saline or LPS. Mx transcripts of 2.4 and 1.9 kb were detected in the liver. By screening of a cDNA libr ary, three different full length Mr cDNA clones, ASMx1, ASMx2 and ASMx 3, were identified and sequenced. The deduced ASMx proteins all contai n 623 amino acids and show the tripartite GTP-binding motif typical of vertebrate Mr proteins. ASMx1 and ASMx2 may represent alleles of the same gene whereas ASMx3 represents a different gene. The deduced ASMx proteins showed 96 to 98% sequence identity with rainbow trout Mx1 and Mx3 and about 88% identity with rainbow trout Mx2 protein. (C) 1997 E lsevier Science Ltd.