TABLE 3

Time after final immunization required to confer protection on mice challenged by syringe inoculationa

ImmunogenTime (wk) between last immunization and challengeNo. of tissue samples positive/totalNo. of mice protected/total
PBS-NMS119/251/5b
Δp66 bacteria10/25c5/5d
p66cp bacteria12/25c4/5e
PBS-NMS2618/250/5
Δp66 bacteria263/25c2/5f
p66cp bacteria260/25c5/5d
  • a All mice received four immunizations and were challenged with 1 × 105 B. burgdorferi B31-A3 bacteria via subcutaneous injection. Mice were euthanized 2 weeks after the bacterial challenge. In the Δp66-immunized group challenged 26 weeks later, three ear tissue samples were culture positive. No other tissue samples from the immunized mice were culture positive. In each group, Δp66- or p66cp-immunized mice were compared to the PBS-NMS-treated controls with Fisher's exact test in GraphPad Prism.

  • b One mouse in the group was not infected.

  • c P < 0.0001.

  • d P < 0.01.

  • e P < 0.05.

  • f No statistically significant difference.