Re-evaluation of CspZ, a complement regulator-acquiring surface protein of the Lyme disease spirochete "Borrelia burgdorferi", as a potential vaccine target in a canine host
Austin Peay State University
Re-evaluation of CspZ, a complement regulator-acquiring surface protein of the Lyme disease spirochete Borrelia burgdorferi, as a potential vaccine target in a canine host. (Under the direction of Dr. Chad Brooks). Over the past decade, studies have revealed a collection of surface proteins, collectively known as the complement regulator-acquiring surface proteins (CRASPs), expressed by Borrelia burgdorferi which enable the pathogenic bacterium to counteract immune defenses of the complement cascade found in various mammalian hosts and establish infection. Due to the theorized necessity of these CRASPs in the life cycle of B. burgdorferi, these proteins could serve as potential vaccine targets to preventing Lyme disease. This study attempted to expand on the roles of CRASPs by characterizing the protein CspZ, also known as CRASP-2. This study hypothesized CspZ is the CRASP responsible for impeding the canine complement cascade and thereby allow the bacterium to establish infection. Immunoblotting could not reveal whether CspZ is upregulated during mammalian infection due to the inability of antibodies generated against CspZ to recognize the protein in denatured lysates. In addition, determination of cell surface localization of CspZ via indirect immunofluorescence was also inconclusive and will need to be optimized. It was determined that CspZ is involved in evasion of the canine immune system, since CspZ deficient spirochetes died in the presence of dog serum. However, the B31cF mutant contains genes that code for the other CRASPs, CspA and the ErP proteins. Therefore, it could not be concluded that CspZ is the minimally necessary and sufficient CRASP which allows the survival of spirochetes in a canine host. A knockout mutant lacking all CRASPs will need to be created and then rescued with CspZ to determine if CspZ is the necessary and minimally essential CRASP required for B. burgdorferi survival in a canine host.