Infection of organotypic slice cultures from rat central nervous tissue with Trypanosoma brucei brucei

We recently described a new procedure to grow nervous tissue as organotypic culture. The main feature of these slice cultures is to maintain a well pr eserved, three-dimensional organisation of the central nervous tissue. As t hese cultures can be kept for several weeks (up to three months), we have u sed this in vitro approach to study the complex interactions between host t issue and parasites during late stages of cerebral African trypanosomiasis. Light and electron microscopical studies, as well as electrophysiological recordings demonstrate that the structure and function of the nervous tissu e is not severely affected even after several weeks of trypanosome infectio n. The presence of a large number of parasites does not seem to be deleteri ous to neuronal survival. Secondly, most of the trypanosomes are located ar ound the periphery of the nervous tissue, but many of them also penetrate i nto the nervous parenchyma. Thirdly, trypanosomes with well-conserved morph ology are found within the cytoplasm of glial cells, which in some cases we re identified as astrocytes. These "intracellular parasites" seem to active ly invade the target cells. Our study demonstrates that the presence of pro liferating trypanosomes does not per se interfere with the neural activity of CNS tissues. Secondly, it provides, to the best of our knowledge, the fi rst in vitro demonstration of intracellular forms of African trypanosomes.