of Borrelia burgdorferi and Expression of Host Cellular Genes from the Same Tissue Sample

We are investigating the neuropathogenesis of Lyme disease caused by Borrelia burgdorferi in a nonhuman primate model. In the past, two separate pieces of tissue had to be used when both analyzing for the presence of the spirochete and examining the host response to infection. We have modified a procedure to purify DNA from the same sample after the extraction of RNA. The remaining material containing the DNA was precip-itated, and residual organic reagent was removed prior to deproteinization and extraction of the DNA. This procedure now allows us to both assay for the presence of the Lyme microorganism and analyze the host response in the same tissue preparation. In investigating the nonhuman primate (NHP) model of Lyme neuroborreliosis (5–7), the detection of the presence of the spirochete and assessment of the expression of host cellular genes in the same tissue sample were desirable. In the past, these two analyses were performed on separate tissue samples (3, 9) because of the difficulties we had in obtaining DNA and RNA preparations of adequate purity from the same tissue sample (2). This report describes a modified method for pre-paring DNA from the same tissue sample after the extraction of RNA to detect the presence of Borrelia burgdorferi and assess the expression of host cellular genes. Tissue samples were from NHPs infected with B. burgdorferi, as previously described (5–7). Frozen tissue samples (15 to 30 mg) were placed into green-top FastRNA tubes (BIO-101, Vista, Calif.). While the samples were held at 280°C, 400 ml of TRIZOL (Life Technologies, Gaithersburg, Md.) was added to each, and tissues were homogenized with the Fast Prep FP12