CD4⁺, without CD8⁺ T cells, are incapable to protect mice against lethal HSV-1 infection.

<p>(<b>A</b>) Schematic representation of the adoptive transfer strategy. Details of this procedure are described in the <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1003637#s4" target="_blank">Materials and Methods</a> (<i>Cell transfer experiments and NK depletion</i> section). (<b>B</b>) <i>Ptprc^L3X/+</i> and <i>Ptprc^L3X</i> mice received 2×10⁷ total splenocytes from either <i>Ptprc^L3X/+</i> or <i>Ptprc^L3X</i> mice. After two hours, these mice were infected i.p. with 1×10⁴ pfu of HSV-1 and their survival was monitored for two weeks (n = 6). (<b>C</b>) <i>Ptprc^L3X/+</i> mice were treated with either anti-asialo GM1 antibody or PBS. After 24 hours, these mice were infected i.p. with 1×10⁴ pfu of HSV-1 and their survival was monitored for two weeks (n = 6). The injection of either anti-asialo GM1 antibody or PBS was performed every three days until the experimental endpoint. (<b>D</b>) <i>Ptprc^L3X</i> mice received either 5×10⁶ T cells or 1.2×10⁷ B cells from <i>Ptprc^L3X/+</i> mice. <i>Ptprc^L3X/+</i> and <i>Ptprc^L3X</i> mice that received only PBS respectively correspond to the positive and negative controls. After two hours, all mice were infected i.p. with 1×10⁴ pfu of HSV-1 and survival was monitored for two weeks (n≥6). (<b>E</b>) <i>Ptprc^L3X</i> mice received either 2.5×10⁶ CD8⁺ or 2.5×10⁶ CD4⁺ T cells from either <i>Ptprc^L3X/+</i> or <i>B6.H2-D^bK^b</i> knock-out (only for the CD4⁺ T cells transfer) mice, whose <i>H2-D^bK^b</i> make them depleted in CD8⁺ T cells (CD8^−/−). <i>Ptprc^L3X/+</i> mice that received only PBS correspond to the positive control. After two hours, all mice were infected i.p. with 1×10⁴ pfu of HSV-1 and survival was monitored for two weeks (n≥6). Data represent two independent experiments. (<b>B–E</b>).