A vaccine for humans against Lyme disease caused by B. burgdorferi is currently not available due to market acceptance and safety of an injectable vaccine based on outer surface protein A (OspA). An alternate approach to protecting humans from Lyme disease is to vaccinate the disease reservoirs to reduce or eliminate B. burgdorferi from vector ticks, thereby suppressing enzootic transmission and preventing them from passing the disease to humans. A number of studies have shown that orally administered OspA based vaccines successfully vaccinate rodents, and reduce prevalence of infection in ticks. In the present proposal, we plan to develop a novel approach for preventing human exposure to Lyme disease spirochetes by significantly reducing infection prevalence in the tick vector, Ixodes scapularis, using reservoir targeted vaccines (RTVs) derived from rice. We will develop stable homozygous rice lines from our first generation transformants that can be used to produce rOspA for the present study and for future large scale production and community-wide distribution. We will formulate the rOspA and test the effectiveness of a reservoir targeting vaccine in laboratory animals. Finally, we will conduct purification and in vitro characterization of rOspA for use in future regulatory approval of rOspA based vaccines. Since rice grain is naturally a food of many of the animals expected to serve as B. burgdorferi reservoirs, producing rOspA in rice provides a distinct advantage over other expression systems and more importantly, rice-based rOspA will offer an excellent safety profile to humans, animals and the environment. Public Health Relevance: Lyme disease, caused by a bite from ticks carrying B. burgdorferi, is a major threat to human health in many areas of the United States. Previous studies show that the prevalence of B. burgdorferi in ticks can be dramatically reduced by vaccinating rodent reservoirs with outer surface protein A from B. burgdorferi. Development of an affordable oral vaccine would enable large scale vaccination of animal reservoirs, and decrease the risk of transmitting Lyme disease to humans.
Lyme disease, caused by a bite from ticks carrying B. burgdorferi, is a major threat to human health in many areas of the United States. Previous studies show that the prevalence of B. burgdorferi in ticks can be dramatically reduced by vaccinating rodent reservoirs with outer surface protein A from B. burgdorferi. Development of an affordable oral vaccine would enable large scale vaccination of animal reservoirs, and decrease the risk of transmitting Lyme disease to humans.
