CD4 and demyelinating disease: To determine the effects of varying viral doses and the preexisting virus-specific naive CD4+ T cells on the development of TMEV-induced demyelinating disease, we adoptively transferred purified normal or VP2-TCR-Tg CD4+ T cells (1 × 106) into naive SJL mice and then infected them with varying doses (2 × 105, 1 × 106 and 5 × 106 PFU) of TMEV (Figure 3A).