Because splenic cells have been antigenically activated twice with vaccine and once with challenge infection in vivo, (d) further in vitro stimulation with TcL resulted in insignificant expansion or contraction (likely due to cell death) of T-cell subsets, but it was effective in reactivating the functional CD4+Tcm subsets in non-pregnant mice, and functional CD8+Tem subsets in pregnant mice. The gene discussed is CD4; the disease is infection.