Lyme disease is a vector-borne illness spread to humans by certain species of ticks prevalent in a growing portion of the United States. The primary causative agent is the bacterium Borrelia burgdorferi (Bb), which has properties known to circumvent the immune system and cause chronic systemic infection if not correctly diagnosed and treated. As a rise in cases can be seen on a yearly basis and preventative measures are lacking, the development of a Lyme disease vaccine would be ideal to stop the disease before it has a chance to develop in the body. The Curley lab has been researching the utilization of outer membrane vesicles (OMVs) as a platform for such a vaccine. OMVs are nanoparticles derived from Gram-negative bacteria and can be engineered to express various foreign proteins on their surface. Bearing a resemblance to bacteria, they are able to activate the immune system while not posing a significant threat to the body as they are non-living. My research spanning two years has evaluated the expression of various fusion proteins on OMVs with a focus on the Bb antigenic protein Outer surface protein A (OspA). I have investigated decorating OMVs with the full protein as well as a smaller portion, or epitope, that is known to still be immune reactive. Furthermore, I have explored two different proteins native to E. coli, the bacteria used to generate the OMVs, as fusion partners with these OspA epitopes in order to promote their packaging onto vesicles as well as their expression on the outer leaflet of these particles to allow for immune recognition. Concerning the full protein, I have observed how modification of the native sequence, particularly the signaling domain, has impacted fusion protein stability and orientation within the OMVs. This was done using techniques including western blot analysis, dynamic light scattering, and protease accessibility assay. This work suggests that all fusion proteins created are effectively produced by OMVs with consistent positioning on the other surface. Research is currently underway to determine the immunogenic effect of one of these particles using an in vivo animal model.
Acknowledgements: Special thanks to Union College's Faculty Research Fund (FRF) and Summer Undergraduate Research Program for funding parts of this work. This work was partially funded by NSF-ERI: "Evaluation of the Immune Response to Lyme Disease Antigens Using Bacterially-Derived Outer Membrane Vesicles" (CBET 2347479)