IFN-I responses are essential but MyD88 and Ly49H partly redundant to protect against MCMV infection.

<p>(A) Survival of mice at d21 post-infection (Y-axis) as a function of the doses of MCMV inoculum (X-axis). Indicated mice were infected with between 1.6x10³ and 7x10⁴ PFU of MCMV, with overlaps for several doses between strains of mice, and their survival was followed for 21d. Data is shown as percentage of survival. In total, 8 different doses were tested in 9 different experiments in order to determine the susceptibility of each mouse strain, with 2 to 4 mouse strains simultaneously studied in each experiment. Data was derived from the following numbers of mice and tested doses of MCMV inoculum: BALB/c-Ly49H⁺: 24 mice for 4 doses; BALB/c-Ly49H⁺ MyD88^-/-: 37 mice for 6 doses; BALB/c-Ly49H⁺ IFNAR^-/-: 8 mice for 2 doses; BALB/c: 43 mice for 5 doses; BALB/c MyD88^-/-: 15 mice for 4 doses; BALB/c IFNAR^-/-: 6 mice for 2 doses. The median lethal dose that causes 50% of lethality in each mouse strain (LD₅₀) was calculated from the graph as the dose on the X-axis that corresponds to 50% mortality on the Y-axis as represented by the horizontal dotted line labeled “LD₅₀ calculation”. LD₅₀ BALB/c-Ly49H⁺: ≥10⁵ pfu/mouse; LD₅₀ BALB/c-Ly49H⁺ MyD88^-/-: 3.3x10⁴ pfu; LD₅₀ BALB/c-Ly49H⁺ IFNAR^-/-: 2x10³ pfu; LD₅₀ BALB/c: 2.2x10⁴ pfu; LD₅₀ BALB/c MyD88^-/-: 8x10³ pfu; LD₅₀ BALB/c IFNAR^-/-: 2x10³ pfu. (B) Splenic viral titers were measured at d1.5, 3 and 6 post-infection. Data (mean±SEM) are shown from 2 to 4 pooled independent experiments, each with 2 to 3 mice per group.