Brain slice culture for analysis of developmental brain disorders with special reference to congenital cytomegalovirus infection.

Cytomegalovirus (CMV) is the most significant infectious cause of congenital abnormalities of the central nervous system (CNS) with variation from the fatal cytomegalic inclusion disease to functional brain disorder. The phenotype and degree of the brain disorder depends on infection time during the developing stage, virulence, route of infection and the viral susceptibility of the cells. The pathogenesis of the CMV infection to the CNS seems to be strongly related to neural migration, neural death, cellular compositions and the immune system of the brain. To understand the complex mechanism of this disorder, we used organotypic brain slice cultures. In the brain slice culture system, migration of CMV-infected neuronal cells was observed, which reflects infectious dynamics in vivo. Neural progenitor cells or glial immature cells in the subventricular zone and marginal area are most susceptible to murine cytomegalovirus (MCMV) infection in this system. The susceptibility declined as the number of immature glial cells decreased with age. The immature glial cells proliferated in brain slice cultures during prolonged incubation, and the susceptibility to MCMV infection also increased in association with the proliferation of these cells. The brain slice from an immunocompromised mouse (Beige-SCID mouse) unexpectedly showed lower susceptibility than that of an immunocompetent mouse during any prolonged incubation. These results suggest that the number of immature glial cells might determine the susceptibility of CMV infection to the brain, independent of the immune system. We reviewed recent findings of CMV infection to the brain from the perspective of brain slice cultures and the possibility that this system could be a useful method to investigate mechanisms of congenital anomaly of the brain.