Effects of Lysozyme and Chitinase on the Spherules of Coccidioides immitis In Vitro

Abstract

Spherules of Coccidioides immitis strain Silveira produced in vitro were treated with chitinase and lysozyme. The walls of merthiolate-killed mature endosporulating spherules were degraded by chitinase (500 ug/ml) and by lysozyme (100 and 500 Ag/ml). Thus, as was visible through the light microscope, the spherule wall was reduced in thickness from 1 to 2 ,m to less than 0.5 ,m. The degradation was evident also by release of N-acetylglucosamine, three times as much N-acetylglucosamine being released by chitinase in 12 h as was released by lysozyme in 3 days. However, the effect of lysozyme on living mature spherules was in marked contrast to the effect of chitinase in that treatment with lysozyme led to marked reduction in viability. Exposure to lysozyme (500 sg/ml) for 48 h permitted survival of only 0 to 0.2% of spherules. Thinning of the walls was observed only in the larger spherules (25-35 Mm) treated with lysozyme. By contrast, chitinase (500 ug/ml) led to complete dissolution of the walls of living mature spherules but the viability of the liberated endospores was unaffected during contact with chitinase for 48 h. Living non-endosporulating immature spherules and free endospores were also rendered nonviable by lysozyme but not by chitinase. [237][238][239][240][241][242] L. Ajello (ed.), Coccidioidomycosis. University of Arizona Press, Tucson. 26. Yphantis, D. A., J. L. Dainko, and F. Schlenk. 1967. Effect of some proteins on the yeast cell membrane. J. Bacteriol. 94:1509-1515. on July 15, 2020 by guest http://iai.asm.org/ Downloaded from

Role of lymphocytes in macrophage-induced killing of Coccidioides immitis in vitro

“…The presence of lymphocytes from immune animals in the macrophage culture resulted in enhanced fusion, as has been previously observed with N. asteroides (9), and in our investigation, fusion of the phagosomes and lysosomes correlated with the extent of fungicidal activity. Collins and Pappagianis found that lysozyme has a lethal effect in vitro on spherules (8); however, lysozyme secretion by macrophages apparently is not altered by activation of macrophages (7). Thus, future experimentation is required to determine how C. immitis is killed and to define the mechanism whereby lymphocytes activate macrophages.…”