Many blood-feeding arthropods pose a threat to human health by serving as vectors of infectious agents. Studies on vector-borne pathogens have tended to focus on events that occur within the vertebrate host and, with a few notable exceptions, we know little about the development of these agents within the arthropod. In this laboratory we study Borrelia burgdorferi- the tick-transmitted spirochete that causes Lyme disease—as a model for understanding vector-borne transmission. The major goals of the work in the laboratory are 1) to study the cellular and molecular interactions between Borrelia and ticks to understand how spirochetes successfully complete the stages of the life cycle within, 2) to develop novel strategies for preventing vector ticks from acquiring or transmitting infectious agents. 

Recent studies point to the Lyme spirochete adapting to different environments by selectively expressing certain genes within the vertebrate host or arthropod. A major focus of the work in the laboratory is to identify spirochete genes that are selectively expressed in the arthropod since these genes may be involved in the survival within the tick or in transmission from tick to host. 

Outer surface proteins (Osp) A and C are two genes that are differentially expressed by spirochetes within ticks. OspA is synthesized selectively by spirochetes prior to tick feeding whereas OspC is induced during the blood meal. The aim of the second project in the laboratory is to characterize the mechanism that triggers differential gene expression by Borrelia during the blood meal. 

Lyme disease spirochetes colonize the gut lumen of ticks. Therefore, the spirochetes are readily exposed to antibodies in the blood meal. Another project in the laboratory involves testing Borrelia surface antigens selectively expressed within ticks as vaccine candidates which block transmission from vector to host. This unusual strategy of targeting antigens expressed in the vector as vaccine candidates has already proven promising. The Lyme vaccine that has recently been developed for human use is based on OspA, which is an antigen that is selectively expressed within the vector.