The University of Georgia College of Veterinary Medicine

Georgia Veterinary Scholar Program

Georgia Veterinary Scholar	Faculty Mentor

Dodd Sledge University of Georgia Class of 2006	Dr. Corrie Brown

**Distribution of Babesia microti in experimentally infected hamsters, as determined by in situ hybridization**

Babesia microti is an intraerythrocytic parasite that is increasingly incriminated as a cause of disease in humans. The natural reservoir is Peromyscus leucopus, the white-footed mouse, and the parasite is transmitted by Ixodes sp. ticks. Hamsters have previously been used as an experimental model of the disease. In this experiment, we developed a method of in situ hybridization to determine location of parasites. A portion of the 16S-like small subunit rRNA (598 bp) was amplified from blood collected from hamsters experimentally infected with B. microti. Resulting PCR product was cloned into a transcription plasmid and both positive and negative sense digoxigenin-labeled riboprobes were generated. In situ hybridization on formalin-fixed paraffin-embedded samples of liver, lung, kidney, spleen, brain and heart from both infected and noninfected hamsters enabled the visualization of replicating parasites. All sections stained with the positive-sense ribo probe were consistently negative, as expected. With the negative-sense riboprobe, which detects the ribosomal RNA, positive staining was most prominent in erythrocytes within blood vessels , especially those in the heart, spleen, and lung. Minimal staining was seen in other organs.