Table 3

ΔflaB mutant-infected nymphal ticks do not transmit the organism to naive mice

B. burgdorferi clone in nymphal ticksNo. of mice infected/no. challengedaNo. of viable spirochetes per fed nymphb
Wild type4/443,167 ± 4,527c
ΔflaB#4 mutant0/54,800 ± 944
ΔflaB#6 mutant0/53,117 ± 1,577
  • a Ten wild-type- or 30 mutant-infected nymphs were allowed to feed per C3H/HeN mouse. Mouse infectivity was determined by reisolation of B. burgdorferi from sacrificed mouse tissues.

  • b Spirochete burden in infected nymphs was determined 7 days postrepletion as described for Table 2 (average ± standard error of the mean; 4 or 5 positive ticks/strain). Results shown are representative of two independent assays.

  • c P = 0.0001 (calculated by Student's t test) for wild-type to ΔflaB spirochete burden in the tick.