furthermore , schistosomes isolated from the portal circulation 2 1/2 weeks after infection showed no evidence of surface-bound immunoglobulin in a quantitative immunofluorescence assay , nor did antisera from chronically infected mice ( cis ) or mice vaccinated with irradiated cercariae ( vs ) react with the surface of these parasites in vitro , making the possibility of direct antibody-dependent killing mechanisms unlikely .
C0020960
antisera
C0003241
antibody