Reduced Macrophage Infiltration and Demyelination in Mice Lacking the Chemokine Receptor CCR5 Following Infection with a Neurotropic Coronavirus

AbstractStudies were performed to investigate the contributions of the CC chemokine receptor CCR5 in host defense and disease development following intracranial infection with mouse hepatitis virus (MHV). T cell recruitment was impaired in MHV-infected CCR5−/− mice at day 7 postinfection (pi), which correlated with increased (P ≤ 0.03) titers within the brain. However, by day 12 pi, T cell infiltration into the CNS of infected CCR5−/− and CCR5+/+ mice was similar and both strains exhibited comparable viral titers, indicating that CCR5 expression is not essential for host defense. Following MHV infection of CCR5+/+ mice, greater than 50% of cells expressing CCR5 antigen were activated macrophage/microglia (determined by F4/80 antigen expression). In addition, infected CCR5−/− mice exhibited reduced (P ≤ 0.02) macrophage (CD45highF4/80+) infiltration, which correlated with a significant reduction (P ≤ 0.001) in the severity of demyelination compared to CCR5+/+ mice. These data indicate that CCR5 contributes to MHV-induced demyelination by allowing macrophages to traffic into the CNS