Interferon-inducible Mx proteins in fish


  • Acknowledgements
    This research was supported by the United States Department of Agriculture (to the Western Regional Aquaculture Consortium) under grant 92-38S00-719S, project no. 92080441; by an Oregon Sea Grant with funds from the National Oceanic and Atmospheric Administration, Office of Sea Grant, Department of Commerce, under grant NA 89AA-D-SG108, project R/FSD-16, and grant NA36RG45 1, project R/FSD-23 and amendment no. 2; and by a grant from the USDA-NRI competitive grants program, CO 140 A, Parts of the review were taken from the doctoral thesis work of Grant Trobridge, Oregon State University. Oregon Agricultural Experiment Station Technical Paper No. 11448.

Jo-Ann C. Leong, Dept. of Microbiology, Center for Salmon Disease Research, Oregon State University, Corvallis OR 9733-3804, USA, Fax: 1 541 737 0496, e-mail: leongj@orst.edn


Summary: Mx proteins are members of a family of hiterferon-inducible genes expressed when cells are treated with double-stranded RNA or virus infection. These proteins are important components of the antiviral response and form the first line of the body's defense against virus infections. The exact mechanism of action for these proteins has not been discovered, but mice missing the Mx genes are extremely sensitive to influenza virus infection. Mammals have between two and three Mx genes whose functions may vary with regard to the inhibition of a specific virus, cellular localization, and activity. The cDNA of three rainbow trout Mx proteins has been cloned and a comparison of their sequences with that of avian and mammalian species reveals striking conservation of domains. They all maintain the tripartite ATP/GTP binditig domain and the dynamin family signature in the amino terminal half of the protein. In the carboxyl terminal half of the Mx proteins are che Iocalization signals and the leucine zipper motifs which account for the trimerization of Mx in the cell. Like the rat and human Mx proteins, the different trout Mx proteins exhibit distinctly different immunohistochemical staining patterns in cells transfected with plasmids expressing RBTMx1, RBTMx2, or RBTMx3, To date, the antiviral function of the trout Mx proteins has not been satisfactorily established.