Many Virus Infections Induce Robust Production of Type I Interferons $\alpha$

Many virus infections induce robust production of type I interferons, IFN- $\alpha$ and IFN- $\beta$ . One example is the herpes simplex virus-1 (HSV-2) , one of the most common sexually transmitted diseases in the US. Experiments that investigated the immune response to HSV-2 using a mouse model demonstrated essential roles for the DNA sensing Toll-like receptor, TLR9, and its downstream signaling adapter, MyD88, in the production of type I interferons following HSV-2 immunization. The type I interferon response to HSV-2 would be restored in Tlr9^-/- mice by transferring into these mice wild-type:

A) Macrophages
B) Conventional dendritic cells
C) Mast cells
D) Plasmacytoid dendritic cells
E) Neutrophils