Fig. 4.

The 165-kDa Vi-CRM₁₉₇ conjugate vaccine induces hyporesponsiveness, resulting in fewer Vi-specific ASCs that home to and persist in the BM. The mice were immunized with two doses of 42.7-kDa fVi-CRM₁₉₇ or 165-kDa Vi-CRM₁₉₇ at a 3-wk interval, and at day 35 the mice received a different booster: saline (blue circles), unconjugated 42.7-kDa fVi (yellow circles), unconjugated 165-kDa Vi (green circles), or comparable conjugate as in first two immunizations (red circles). Vi-specific IgG⁺ ASCs were enumerated at day 154 in spleen (A) and BM (B). Results are expressed as number of spots/10⁶ cells (mean ± SD) in seven or eight mice per group in one experiment; individual mice are represented by dots. The Mann–Whitney U test was used to compare ASC numbers at day 154 in mice immunized with two doses of 42.7-kDa fVi-CRM₁₉₇ or 165-kDa Vi-CRM₁₉₇ and receiving comparable boosters.