Fig 4. Evasion of MHC-I antigen-presentation and CD8⁺ T cells is critical for viral persistence at site of entry and replication in the salivary gland.

A. WT-MCMV persists in the nasal mucosa and spreads to the salivary gland within 14 days after i.n. infection. Virus titers in the nasal mucosa, lungs and salivary glands of C57BL/6 mice with or without CD4⁺ T cells depletion before infection at 7, 14 and 28 days after i.n. inoculation of WT-MCMV. Each symbol represents an individual animal. The solid line shows the mean titer, and error bars represent the SEM. Dashed lines show the detection limit (50 PFU/g). Data are combined from two independent experiments. B. Lack of MHC-I evasion genes prevents viral persistence in the nasal mucosa and spread to the salivary gland. Viral titers in the nasal mucosa, lungs and salivary gland 7, 14 and 28 days after i.n. inoculation of C57BL/6 mice infected with TKO-MCMV. Infected mice were treated with an isotype control antibody or depleted of CD4⁺ or CD8⁺ T cells before infection. Data are displayed as in A and are combined from at least two independent experiments. C. NK cell depletion before infection does not rescue TKO-MCMV replication in the salivary glands after i.n. infection of C57BL/6 mice. Shown are virus titers in the nasal mucosa, lungs and salivary glands at 14 days post infection. Data are displayed as in A and are combined from two independent experiments. D. CD8⁺ T cells can control TKO-MCMV if they are primed in the presence of CD4⁺ T cell help. Virus titers in the indicated organs at day 28 post infection are shown. C57BL/6 mice were depleted of either CD4⁺ T cells or both CD4⁺ and CD8⁺ T cells, beginning at day 7 after i.n. infection of TKO-MCMV. Data are displayed as in A and are combined from two independent experiments.