Protection of dogs from Lyme disease with a vaccine containing outer surface protein (Osp) A, OspB, and the saponin adjuvant QS21.

A vaccine consisting of purified Escherichia coli-expressed recombinant full-length outer surface proteins A (OspA) and B (OspB) and the saponin adjuvant QS21 was evaluated for protection against Borrelia burgdorferi infection. Eleven beagles were vaccinated twice and then challenged with 10 field-collected adult female Ixodes scapularis. Xenodiagnosis revealed that all 11 nonvaccinated control dogs and 2 of 10 vaccinated dogs were infected with B. burgdorferi. Six of 11 control dogs also developed fever (0.75 +/- 0.38 degrees C) and were lethargic. One of the control dogs also developed a limp. Both of the infected vaccinated dogs were asymptomatic. Thus, the vaccine prevented tick-vectored infection and associated symptoms of Lyme disease.