CD46 expression does not overcome the intracellular block of measles virus replication in transgenic rats.

The study of measles pathogenesis and the testing of improved vaccine candidates is hampered by the lack of a small animal model which is susceptible to infection by the intranasal route. With the identification of CD46 as a measles virus (MV) receptor, it was feasible to generate transgenic rats to overcome this problem. Although there was widespread expression of CD46 in the transgenic Sprague-Dawley rats, no measles-like disease could be induced after various routes of infection. The expressed transgenic protein was functionally intact since it mediated MV fusion and was downregulated by contact with MV hemagglutinin. In vitro studies revealed that CD46-expressing rat fibroblasts take up MV but do not allow viral replication, which explains the nonpermissiveness of the transgenic rats for in vivo infection.