PROGRESS TOWARDS A VACCINE FOR LYME-DISEASE

Although Lyme disease was first described no more than 20 years ago, knowledge has accumulated to the point that prototype vaccines are currently in advanced stages of clinical trials. A mouse model of Lyme disease facilitated efforts to describe protective immunity, which appears to depend mainly on the presence of antispirochaetal antibody. A recombinant major outer surface protein A (rOspA) fully protects mice and other hosts against infection and disease. A unique mode of action is apparent in that circulating antibody is ingested during the bloodmeal taken by the infectious tick, and serves to attenuate or destroy spirochaetes before they are transmitted to the vaccinated host. To date, 2 prototype Lyme disease vaccines, based upon rOspA, appear to be immunogenic and safe in humans. Testing such vaccines for efficacy will require careful surveillance of thousands of subjects and may take many years for completion, given the chronic nature of Lyme disease and the requirement that a vaccine induce a response that prevents infection as well as disease.