FILAMENT TIP-ASSOCIATED ANTIGENS INVOLVED IN ADHERENCE TO AND INVASION OF MURINE PULMONARY EPITHELIAL-CELLS IN-VIVO AND HELA-CELLS IN-VITROBY NOCARDIA-ASTEROIDES

The interactions of Nocardia asteroides GUH-2 with pulmonary epithelia l cells of C57BL/6 mice and with HeLa cells were studied. Electron mic roscopy demonstrated that only the tips of log-phase cells penetrated pulmonary epithelial cells following intranasal administration, and no cardiae were recovered from the brain, Coccobacillary cells neither in vaded nor disseminated. Serum from immunized mice (IMS) decreased atta chment to and penetration of pulmonary epithelial cell surfaces by log -phase GUH-2 and inhibited spread to the brain. IMS was adsorbed again st stationary-phase cells, Western immunoblots suggested that this ads orbed IMS was reactive primarily with 43- and 62-kDa proteins. Immunof luorescence shelved that adsorbed IMS preferentially labeled the tips of log-phase GUH-2 cells. Since this IMS was reactive to culture filtr ate antigens, several of these proteins were cut from gels, and mice w ere immunized. Sera against 62-, 55-, 43-, 36-, 31-, and 25-kDa antige ns were obtained. The antisera against the 43- and 36-kDa proteins lab eled the filament tips of GUH-2 cells. Only the antiserum against the 43-kDa antigen increased pulmonary clearance, inhibited epical attachm ent to and penetration of pulmonary epithelial cells, and prevented sp read to the brain. An in vitro model with Hr La cells demonstrated tha t the tips of log-phase cells of GUH-2 adhered to and penetrated the s urface of HeLa cells. Invasion assays with amikacin treatment demonstr ated that nocardiae were internalized, Adsorbed IMS blocked attachment to and invasion of these tells. These data suggested that a filament tip-associated 43-kDa protein was involved in attachment to and invasi on of pulmonary epithelial cells and HeLa tells by N. asteroides oides GUH-3.