Figure 2. Evolution of Le expression of H. pylori strain J166 in four rhesus monkeys of different Le phenotypes. Le^x and Le^y expression of strain J166 preinoculation was determined in eight single colony-derived cell populations. At 40 wk, the Le phenotype of the strains recovered from the two Le^a–b+ animals [C (82A49), D (8PZ)] showed predominance of Le^y expression (bottom). In contrast, in the two Le^a+b– animals [A (E6C), B (85D08)] at 40 wk, the predominant Le expression of the J166 populations had shifted from Le^y to Le^x.