Sustained APC infection in Ly49H⁻ mice, but not in Ly49H⁺ mice. (A) Ly49H⁻ (BALB/c) and Ly49H⁺ (BALB.B6-CT8) mice were infected with 5 × 10³ PFU of MCMV-K181-LacZ, and the frequency of infected APCs in the spleen was measured 2, 4, and 6 d pi using FDG. Histograms represent the expression of FDG-LacZ in CD11c⁺ MHC-II⁺ cells from the spleen. The proportion of FDG⁺ cells was first corrected for background fluorescence by subtracting the FDG⁺ values measured in uninfected controls. Arithmetic means and standard errors are shown. Uninfected controls are shown as a solid black line. Infected mice are shown as gray-filled histograms. The frequencies of infected FDG⁺ cells are shown and represent data from three mice. The data are representative of two independent experiments. (B) The number of infected MHC-II⁺ APC in the spleens of MCMV infected mice at days 2, 4, and 6 d pi are shown. The numbers of infected MHC-II⁺ APC were determined using FDG after correction for background fluorescence. Arithmetic means and standard errors are shown. (C) Ly49H⁺ BALB.B6-Cmv1r and BALB.B6-Cmv1r.pfp^−/− mice were infected with 5 × 10³ PFU of MCMV-K181-LacZ. Histograms represent the expression of FDG-LacZ in CD11c⁺ MHC-II⁺ cells purified from the spleen. Uninfected controls are shown as a solid black line. Infected mice (n = 3) are shown as gray filled histograms. The data are representative of 3 independent experiments.