Ticks are hematophagus arthropods intimately associated with symbiotic rickettsia-like bacteria.  In addition to maintaining intracellular symbionts, ticks vector many bacterial, viral and protozoan pathogens.  The objective of my research is to study how the tick immune system responds to bacterial challenge and if the immune response is modified by the presence of symbiotic bacteria. I examined defensin and lysozyme expression in Rickettsia peacockii infected and uninfected Ixodes scapularis cell lines ISE6 and IDE12, and the Dermacentor andersoni cell line DAE15 following bacterial challenge.  I measured RNA expression by reverse-transcription PCR and northern blotting, and lysozyme translation by western blotting and microtiter plate-based assays.