SAFETY, EFFICACY, AND IMMUNOGENICITY OF A RECOMBINANT OSP SUBUNIT CANINE LYME-DISEASE VACCINE

A subunit canine Lyme disease vaccine formulated with recombinant lipi dated OspA and OspB and saponin QS21 was assessed for safety, protecti ve efficacy, and immunogenicity. Ten normal beagles were subcutaneousl y vaccinated twice at age 12 and 16 weeks, respectively. Three months after the second vaccination the vaccinates and another 10 nonvaccinat ed control beagles were challenged by feeding ticks on each dog for 5 days using eight field-collected adult female and six adult male Ixode s scapularis infected with Lyme disease spirochetes per dog. Adverse r eactions associated with the vaccinations were limited to injection si te swellings which occurred within the first 48 h and resolved within a week. The local reaction was independent of vaccination times and ti ck challenge. On the basis of typical clinical signs, xenodiagnosis, a nd diagnostic immunoblotting, all 10 controls were infected; five deve loped lameness and three of them experienced at least two to three epi sodes of limping during a 10-month monitoring period. In contrast, eig ht of ten vaccinates were protected and two infected vaccinates, as ju dged by xenodiagnosis, were asymptomatic. None of the protected vaccin ates developed antibodies to diagnostic spirochetal antigens other tha n OspA and OspB. In contrast, most controls produced antibodies to bor relial antigens, but not to OspA and OspB. Antibody production in vacc inates receiving a third vaccination 10 months postchallenge was great ly boosted, the geometric mean antibody titer was significantly higher (P<0.0001) than that tested prechallenge. Thus, the subunit canine Ly me disease vaccine was safe and protective and elicited immunological memory. Vaccinated dogs were serologically distinguishable from those naturally exposed. Copyright (C) 1996 Elsevier Science Ltd.