General Information: Bartonella henselae str. Houston-1 (ATCC 49882) was isolated from human blood in Houston Texas. Causative agent of cat scratch fever. This group of alpha proteobacteria are unique among pathogens in that they cause angiogenic lesions. This organism was identified as the causative agent of cat scratch fever, a disease found commonly in children or in immunocompromised adults. The proliferation of the vascular endothelium (bacillary angiomatosis) is characterisitic of Bartonella infection and results in multiplication of the bacterium's host cells. Infected macrophages are stimulated to release vascular endothelial growth factor (VEGF) and interleukin 1 beta, both of which promote angiogenesis. Endothelial cells are also stimulated to grow and divide by direct contact with bacterial cells. In addition, programmed cell death (apoptosis) of endothelial cells is inhibited, combatting a common mechanism eukaryotic cells use to deal with bacterial infection. Other pathogenicity factors include pili and outer membrane adhesins for attachment to host cells.