Immunisation with virion-loaded plasmacytoid or myeloid dendritic cells induces primary Th-1 immune responses.

Dendritic cells (DCs) induce different types of immune responses depending on their lineage and activation signals. When exposed to inactivated pseudorabiesvirus (iPRV), plasmacytoid but not myeloid DCs released IFN-alpha and IL-12. Remarkably, both iPRV-pulsed DC types were able to induce primary IFN-gamma producing T cells and IgG isotype switching in vivo.

Host-dependent type 1 cytokine responses driven by inactivated viruses may fail to default in the absence of IL-12 or IFN-alpha/beta.

Replicating viruses generally induce type 1 immune responses, with high interferon (IFN)-gamma levels and antibodies of the IgG2a isotype. In the present study we demonstrate the intrinsic ability of non-replicating virions to induce comparable immune responses in the notable absence of any adjuvant. Injection of inactivated pseudorabies virus, an alphaherpesvirus, by various routes into mice resulted in the generation of T helper (Th) 1 type immune response.