PubMed · 4805421
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G M Maruashvili, T E Abuladze, N L Lomidze. [Experimental ancylostomiasis in dogs].. https://pubmed.ncbi.nlm.nih.gov/4805421/
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Infective stages of several nematode parasites are known to release proteases in excretory/secretory products. These enzymes are believed to facilitate tissue invasion, although direct evidence is lacking. For these investigations, we employed an assay that uses the resumption of feeding as a marker for early events in the infectious process. When Ancylostoma caninum third-stage infective larvae are stimulated to feed in vitro, they release proteases of approximately 50,000 and 90,000 molecular weight, as determined by substrate gel electrophoresis. The enzymes are inhibited by the zinc chelator 1,10-phenanthroline, but not by the nonchelating isomer 4,7-phenanthroline, indicating that the proteolytic activity is zinc-dependent. Both compounds inhibit in vitro feeding, although inhibition by 1,10-phenanthroline is zinc-dependent, whereas inhibition by 4,7-phenanthroline is zinc-independent. The specific release of proteases associated with the initiation of feeding suggests that the metalloprotease serves an integral function in the transition of the free-living stage to parasitism.
Experiments were carried out to compare the sensitivity of Ancylostoma ceylanicum and Necator americanus to ivermectin (IVM) and pyrantel in vitro. Loss of motility and inhibition of ingestion by IVM were compared and A. ceylanicum was found to be approximately 40-50 times more sensitive to IVM than N. americanus. Both species showed a similar sensitivity to pyrantel. Uptake of [3H]IVM across the cuticle was compared and shown to be unlikely to account for the differences in sensitivity to IVM between the two species.
Human eosinophilic enteritis (EE) may result from hypersensitivity to the excretory/secretory (ES) antigens of adult Ancylostoma caninum. The origin of several antigens were identified by probing adult A. caninum with mouse monoclonal antibodies (MoAbs), sera from mice vaccinated with ES antigens and sera from human EE patients. Six MoAbs (AC/ES 1-6) were produced against ES antigens, two being IgG3 and four IgM. Western blots demonstrated four different antigen specificities: MoAb AC/ES 1 bound strongly to an ES product at about 30 kDa; AC/ES 2 recognized a broad band ranging from 50-200 kDa; AC/ES 3, AC/ES 5 and AC/ES 6 reacted at about 68 kDa, and AC/ES 4 at about 97 kDa. Sections of formalin-fixed, paraffin embedded adult A. caninum were then incubated with these MoAbs and immunostained by the peroxidase-anti-peroxidase (PAP) technique. The target epitope of MoAb AC/ES 1 was found mainly in the oesophageal, amphidial and excretory glands; AC/ES 2 reacted weakly with many structures in the sections; AC/ES 3, AC/ES 5 and AC/ES 6 were specific for excretory glands only, and AC/ES 4 bound to amphidial glands. Sera from immunized mice reacted with all three (especially the excretory) glands and the cuticle. In an indirect assay, worm sections probes with three human EE patient sera demonstrated maximal staining in the amphidial glands. Our findings confirm that ES products of A. caninum include immunogenic glandular secretions which may be involved in the pathogenesis of human EE.