Diarrhea duration, clinical symptoms, and colonization after oral immunization of A. nancymaae with live-attenuated vaccine strain SC602 or S. flexneri 2a strain 2457T and oral challenge with S. flexneri 2a 2457Ta

TreatmentNo. of animalsDiarrheabColonizationc
No. of casesMean no. of days to onset (range)Mean no. of days illness (range)% IncidenceMedian no. of days to onsetMedian no. of days duration (range)
SC602 (1 × 1010 CFU)7d13410017.9 (3–10)
SC602 (1 × 1011 CFU)7d12210018.4 (4–10)
S. flexneri 2a 2457T (1 × 109 CFU)835 (3–6)3 (2–5)10016.6 (2–10)
PBS1073.3 (1–7)4.6 (2–8)10018.0 (4–10)
  • a Groups of monkeys were orally immunized on days 0, 14, and 42 with either live-attenuated Shigella vaccine strain SC602 or with wild-type S. flexneri 2a 2457T at a subclinical dose. The animals were then orally challenged with 1 × 1011 CFU of S. flexneri 2a 2457T on day 70.

  • b Diarrhea defined as at least one loose-watery stool on at least two consecutive days during the observation period (10 days).

  • c Colonization assessed by plating of HE agar with confirmatory slide agglutination or colony blotting. Negative samples confirmed with IpaH-specific PCR on frozen stool specimens.

  • d One animal excluded from data analysis due to diarrhea prior to the challenge.