Caveolae in the uptake and targeting of infectious agents and secreted toxins

A variety of microbial pathogens, including viruses, intracellular bacteria, and prions, as well as certain secreted bacterial toxins, can now be added to the list of ligands that enter cells via caveolae or caveolae-like membrane domains. In general, the caveolae-mediated entry pathway results in transport of these microbes and toxins to intracellular destinations that are different from that of cargo entering by other means. As a result, the caveolae-mediated entry pathway can profoundly affect the host cell–pathogen interaction long after entry has occurred. Furthermore, some microbes such as SV40 that enter via cavolae will be valuable as probes to analyze certain poorly understood intracellular trafficking pathways, such as retrograde transport to the ER. Also, viruses that enter via caveolae may have unique potential as gene and drug delivery vectors. In addition, some extracellular microbial pathogens, such as Pneumocystis carinii, may also interact with host cells via caveolae. Finally, caveolae may play a role in host immune defense mechanisms.