Hepcidin mRNA transcripts are up-regulated in mice infected with B burgdorferi. (A) Serum was isolated from blood samples obtained weekly from B burgdorferi-infected and uninfected C3H mice over a 4-week experimental period. IL-6 levels were measured by enzyme-linked immunosorbent assay. (B) C3H mice were infected with B burgdorferi and sacrificed after 4 weeks of infection. RNA was isolated and purified from the livers and spleens, and IL-6 and actin transcripts were analyzed by RT-PCR. (C) Serum hepcidin levels were measured in uninfected WT C57BL/6 mice, infected WT C57BL/6 mice, and infected C57BL/6 mice deficient for MyD88^−/−, TLR9^−/−, or TLR2^−/− after 4 weeks of infection.