Expression of human complement regulatory protein CD46 restricts measles virus replication in mouse macrophages

Measles virus (MV) can infect mouse macrophages to cause a prolonged non-cytopathic infection that produces low levels of infectious virus for days. We have generated RAW264.7 mouse macrophages expressing human CD46, a cell surface complement regulatory protein that serves as a receptor for laboratory-adapted strains of MV. Laboratory-adapted MV strains efficiently enter the CD46-positive mouse macrophages to cause a cytopathic infection with extensive multinucleated cells and pseudopodia-like extensions. However, MV infection of mouse macrophages through CD46 is self-limiting. Both viral protein synthesis and infectious virus production are abruptly terminated after the second day of infection. This novel virus-cell interaction is seen only in mouse macrophages but not in mouse or hamster fibroblasts expressing human CD46. The possible role of CD46 in macrophage antiviral response restricting MV replication is discussed.