Specific in situ hybridization of Haemobartonella felis with a DNA probe and tyramide signal amplification

Haemobartonella felis is an epierythrocytic bacterium suspected to be the c ausative agent of feline infectious anemia. Previous studies with a polymer ase chain reaction assay have identified a mycoplasmal 16S rRNA gene sequen ce that coincides with clinical disease and the presence of organisms in th e blood. Tissues from a cat experimentally infected with H. felis were used for in situ hybridization studies to physically link this 16S rRNA gene to the organisms on the red cells. A biotin-labeled probe was used in conjunc tion with tyramide signal amplification to visualize the hybridization sign al. This study clearly demonstrates a specific hybridization signal on the red cells in the tissues of the H. felis-infected cat. This in situ hybridi zation study is the final step in fulfilling the molecular guidelines for d isease causation and proves that H. felis, a mycoplasmal organism, is the c ausative agent of feline infectious anemia.