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Effect of Protease Class-Specific Inhibitors on In vitro Development of the Third- to Fourth-Stage Larvae of Ascaris suum
M. L. Rhoads, R. H. Fetterer and J. F. Urban, Jr.
The Journal of Parasitology
Vol. 84, No. 4 (Aug., 1998), pp. 686-690
Stable URL: http://www.jstor.org/stable/3284570
Page Count: 5
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Third-stage larvae (L3) of Ascaris suum develop and molt to fourth-stage larvae (L4) during in vitro cultivation; consistently greater than 80% of the larvae develop to L4 during 7 days in culture (DIC). To assess the role of proteases in this process, the effect of protease class-specific inhibitors was studied. The presence of either a serine protease inhibitor (AEBSF, 100 µM) or an aspartic protease inhibitor (pepstatin A, 100 µM) had no effect on the percentage of L4 after 7 DIC. However, the presence of either a cysteine protease inhibitor (Z-Phe-Ala-FMK, 100 µM) or an aminopeptidase inhibitor (amastatin, 100 µM) resulted in 77% and 34% reductions, respectively, in the percentage of L4 compared to untreated cultures; viability of the larvae was not affected. The effect of Z-Phe-Ala-FMK on molting was time and dose dependent. In contrast to Z-Phe-Ala-FMK, E-64, another specific inhibitor of cysteine proteases, had no effect on molting. The data support a role for an aminopeptidase and suggest a role for a cysteine protease in the development of the L3 to L4 stage of A. suum.
The Journal of Parasitology © 1998 The American Society of Parasitologists