TABLE 1.

Presence of treponemes after intradermal challenge

Challenge strain or isolateTreponeme positive/totala (% positive)
ImmunizedControl
Nichols5/32 (16)b,d,e28/32 (88)
Clonal Chicago11/32 (34)b,c24/32 (75)
Chicago13/32 (41)b,c26/32 (81)
  • a Values are the number of sites with treponemes/total number of sites. The presence of treponemes was detected by dark-field microscopy in aspirates taken from inoculation sites, and 32 inoculation sites were sampled for each group.

  • b Significantly different (P < 0.001) from the value for unimmunized controls by the chi-square test with Bonferroni's correction.

  • c Significantly different (P < 0.001) from the value for immunized rabbits challenged with the Nichols strain by the chi-square test with Bonferroni's correction.

  • d Significantly different (P < 0.001) from the value for immunized rabbits challenged with the clonal Chicago strain by the chi-square test with Bonferroni's correction.

  • e Significantly different (P < 0.001) from the value for immunized rabbits challenged with the Chicago isolate by the chi-square test with Bonferroni's correction.