TRANSGENIC EXPRESSION OF A CD46 (MEMBRANE COFACTOR PROTEIN) MINIGENE - STUDIES OF XENOTRANSPLANTATION AND MEASLES-VIRUS INFECTION

CD46 (membrane cofactor protein) is a human cell-surface regulator of activated complement and a receptor for the measles virus. A CD46 tran sgenic mouse line with an expression pattern similar to that of human tissues has been produced, to develop an animal model of (i) the contr ol of complement activation by complement regulators in hyperacute rej ection of xenografts, and (ii) measles virus infection. The mouse line was made using a CD46 minigene that includes promoter sequence and th e first two introns of genomic CD46, which was coinjected into mouse o va with chicken lysozyme matrix attachment region DNA. A high level of CD46 expression in homozygotic transgenic mice was obtained with sple en cells having approximately 75 % of the level found on human periphe ral blood mononuclear cells. CD46 was detected in all tissues examined by immunohistochemistry, radioimmunoassay and Western blotting, showi ng that these mice were suitable for transplantation and measles virus infection studies. It also indicated that the transgene included the important regulatory elements of the CD46 promoter. Transgenic spleen cells were significantly protected in vitro from human complement acti vated by either the classical or alternative pathways and from alterna tive pathway rat complement. Furthermore, transgenic mouse hearts tran splanted to rats regulated complement deposition in an in vivo model o f antibody-dependent hyperacute xenograft rejection. Similar to human lymphocytes, transgenic lymphoblasts could be infected in vitro with m easles virus; infected cells expressed viral proteins and produced inf ectious viral particles. The data demonstrate the suitability of this minigene for obtaining high-level CD46 expression sufficient for enhan ced resistance of transgenic cells to complement attack and for obtain ing wide tissue distribution of CD46, analogous to human tissues and, therefore, useful for comparative studies.