Penetration Enzymes of Schistosome Cercariae.
Abstract
With an eye toward prophylaxis by interruption of the invasive process, this phase of the schistosome life cycle was studied including: (1) snail-schistosome relationships with special reference to variability in and optimal production of the invasive cercariae; (2) cercarial penetration mechanisms, particularly activty of the penetration enzymes; and (3) postpenetration development of the invading larvae in skin. Reporting in more detail, our findings included the following. The expected variability in cercarial production and secreted penetration enzyme activity of preacetabular gland secretion was established for our schistosome strain under our maintenance conditions. The most efficient exposure level for our snails was set a 5 miracidia each. Schistosome substrain differences were found in cercarial production and cross protective capacity. A quantitative techique for penetration enzyme collection was developed using 7 to 20 ug of linolenic acid per sq cm. of area. Enzyme activity was directly proportional to the number of cercariae secreting and to cercarial infectivity. Above a certain concentration, presence of preacetabular gland secretion in skin inhibited cercarial penetration, for up to 2 days. Beyond this, it was immunogenic in inducing lgE and/or lgG antibodies, but was not protective as used. Having penetrated skin, cercariae transformed to schistosomules within 1 hr.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 12, 1982
- Accession Number
- ADA120843
Entities
People
- F. A. Lewis
- M. Stirewalt
Organizations
- Instituto de Investigaciones Biomédicas