IDENTIFICATION OF A BORRELIA-BURGDORFERI OSPA T-CELL EPITOPE THAT PROMOTES ANTI-OSPA IGG IN MICE

Lyme disease, due to infection with the tick-borne spirochete Borrelia burgdorferi, is a multisystem disorder that can lead to chronic disab ling symptoms, Abs to the outer surface protein A (OspA) of B. burgdor feri provide protection against infection, and OspA is now the basis o f a first generation recombinant vaccine undergoing phase III efficacy studies, Recent studies have suggested that T cells reactive with N-t erminal epitopes in OspA could contribute to the development of treatm ent-resistant Lyme arthritis, In the present studies, we use the murin e model of Lyme borreliosis to define an OspA T cell epitope located i n the carboxyl terminus that accelerates anti-OspA Ige production afte r infection, In addition, we show that this T cell epitope is elicited by immunization with rOspA or with a truncated form of OspA that cont ains the B cell epitope targeted by protective OspA mAb, Polyclonal an tisera to the truncated OspA fragment can protect mice from challenge infection, These results are the first demonstration of a B, burgdorfe ri-specific peptide that elicits a biologically important T cell respo nse in vivo and have implications for the design of a second generatio n OspA-based subunit vaccine.