Significant borreliacidal antibody was induced in volunteers and hamsters 60 days after primary and secondary vaccination with high concentrations of recombinant outer surface protein A (rOspA). However, the borreliacidal antibody response waned rapidly. Only 1 person had detectable cidal activity 180 days after vaccination. Similarly, the borreliacidal antibody response waned rapidly in hamsters by week 10 of vaccination. By contrast, the total anti-rOspA antibody response remained elevated in volunteers and hamsters. When isolates of Borrelia burgdorferi sensu lato were incubated in sera from vaccinated humans or hamsters, only the vaccine- specific isolate was killed. These results were confirmed by challenging rOspA-vaccinated hamsters with different isolates of B. burgdorferi sensu lato. The results showed that monitoring total rOspA antibody is inappropriate for evaluating the efficacy of an rOspA vaccine. The rOspA vaccine must be improved to yield comprehensive protection and maintain sustained levels of protective borreliacidal antibodies.
Bibliographical noteFunding Information:
Received 16 November 1995; revised 7 June 1996. Informed consent was obtained from all study participants. Financial support: Gundersen Medical Foundation and National Institutes of Health (AI-30706). Reprints or correspondence: Dr. Steven M. Callister, Microbiology Research Laboratory, Gundersen Medical Foundation, 1836 South Ave., La Crosse, Wisconsin 54601.