Membrane proteins located within or as attachments to the cell membrane play critical roles in many essential cellular functions and host-pathogen interactions. Knowledge of the structure and function of membrane proteins in pathogenic species can allow for the development of specific vaccines and therapeutic agents against the pathogen. Francisella tularensis is an intracellular pathogen that is the causative agent of the severe, life-threatening infection, tularemia, in humans and other small mammals. F. tularensis is prevalent within the environment and is a potential bioterrorism agent due to its high virulence and its ability to be spread easily as an aerosol. The CapBCA membrane protein complex has been identified as a virulence factor of F. tularensis. This project, derived from the Membrane Proteins in Infections Diseases (MPID) Project, aims to successfully express the membrane proteins CapBCA, which are crucial to the pathogenic properties of F. tularensis. To accomplish this goal, methods for in vivo recombinant expression and purification of membrane proteins are in the process of being developed. The expression of the CapA component has been successful for some time, therefore, the goal of this study is to develop an approach toward recombinant in vivo membrane protein expression of both the CapB and CapC components of the CapBCA membrane protein complex. In this study, the CapB and CapC components were expressed for the first time in vivo through the use of the novel MPID vector, pelB-MBP. The expression of the CapB and CapC components will allow for large-scale expressions to commence with the end goal of determining the crystal structures of the individual proteins or the complex. Ultimately, it is hoped that knowledge of these molecular structures can lead to the development of a vaccine or other therapeutic agents against this pathogen.