Fig. 4.

Effect of platelet depletion on viral clearance and virus-specific CTL responses. (A) Quantification by plaque assay of the viral titers in the serum of groups of B10D2 mice (n = 6) injected with α-Irr (white bars) or α-PLT (black bars) before LCMV Arm infection (10⁶ pfu per mouse) and killed at the indicated time points after infection. Results (mean ± SD) are expressed as log pfu/ml. (B–D) Content of LCMV-specific transcripts in the total RNA isolated from the spleen (B), liver (C), and brain (D) of the animals described in A. Analysis was performed by Northern blot, and quantification was obtained by measuring band intensities after phosphor imaging; results in arbitrary units (A.U.) were normalized to the content of the housekeeping gene GAPDH. (E–G) Assessment by intracellular IFN-γ staining of the absolute number of NP118-specific CD8⁺ T cells recovered from blood (E), spleens (F), or livers (G) of the animals described in A and killed at the indicated time points after infection. Results are expressed as mean ± SD. (H) In vivo cytotoxicity assay in mice infected with LCMV Arm (10⁶ pfu per mouse) and injected at day 8 after infection with α-Irr or α-PLT 3 h before the injection of target cells. The animals were killed 45 min later.