Infection of monocytes or immature dendritic cells (DCs) with an attenuated rabies virus results in DC maturation and a strong activation of the NFkappaB signaling pathway.

To assess the potential role of dendritic cells (DCs) or monocytes in the development of a protective immune response, we infected human immature DCs or monocytes with a live rabies virus (RV) vaccine strain (SPBNGAS-GAS) and a pathogenic RV (DOG4). Both cell types were infected with SPBNGAS-GAS and DOG4 and both RVs were similarly potent in inducing maturation of immature DCs or monocytes. However, in contrast to DOG4, SPBNGAS-GAS induced very high levels of IFN-alpha1 mRNA in monocytes and DCs. Furthermore, at least 26 other genes related to the NFkappaB signaling pathway were strongly upregulated in SPBNGAS-GAS-infected DCs, but only somewhat increased in DOG4-infected cells. Thus, the extent of upregulation of NFkappaB pathway-related genes in DCs infected with the live RV vaccine strain might explain the strong protective activity of SPBNGAS-GAS.