Ascaris suum: localization by immunochemical and fluorescent probes of host proteases and parasite proteinase inhibitors in cross-sections.

Cross-sections of muscle, intestine, and genital tract fluoresced in defined locations when live Ascaris suum adults were incubated in medium containing chymotrypsin liganded with fluorescein-5-isothiocyanate. This suggests that the protease, or portions of it, are assimilated by A. suum. A. suum chymotrypsin/elastase isoinhibitors were found in muscle sarcolemma, eggs, sperm, and intestine, and host chymotrypsin was localized in the same regions of these tissues by immunofluorescence and immunoperoxidase techniques. These experiments demonstrate that host chymotrypsin enters the parasite, that it is present in specific regions of Ascaris, and that it probably exists as an enzyme-inhibitor complex.