ENHANCED INVASION OF TYZZER ORGANISM INTO CULTURED MOUSE HEPATOCYTES BY CYTOCHALASIN-D

The effects of cytoskeleton inhibitors on the invasion of Tyzzer's org anism, an obligate intracellular bacterium, into cultured mouse hepato cytes were examined by double immunofluorescence observation and plaqu e assay. The two techniques gave comparable results. Invasion of bacte ria was significantly enhanced by cytochalasin D, a microfilament disr upting drug, and markedly suppressed by vinblastine, a microtubule inh ibitor. Another microtubule inhibitor, colchicine, did not show any su bstantial effect. However, the cytoskeletal system of cultured mouse h epatocytes was sensitive to these three drugs, as judged by inhibition of FITC-dextran uptake. These results suggest that Tyzzer's organisms invade host cells by a unique mechanism that is suppressed by the nor mal functions of host cell microfilaments. (C) 1998 Federation of Euro pean Microbiological Societies. Published by Elsevier Science B.V.