The nature of antigens common to both the metacestodes of Taenia crassiceps and its laboratory host.

Metacestodes of Taenia crassiceps were cultured in laboratory rats and mice, washed in glycine/hydrochloric acid (Gly/Hcl) buffer pH 2.4 and phosphate buffered saline (PBS) pH 7.2 and a soluble extract of the metacestodes (SEM) was prepared from larvae washed in both buffers. The SEM and the original washings were examined for host IgG and a common host antigen (CHA). CHA was present in both the SEM and washings but IgG only in the washings and, in metacestodes from mice only in the Gly/HCl washings). Metacestodes washed in Gly/HCl were not viable. Metacestodes were also maintained in vitro in a peptide nutrient agar and 0.9% saline at 37 degrees C and a SEM was prepared from these; metacestodes from mice had neither host IgG nor CHA but those from rats had CHA but not IgG. SEM prepared from 'normal' metacestodes showed that the CHA consisted of at least two entities, only one having a common identity with the IgG. These results suggest that molecules of both host IgG and a common host antigen are present on the tegument of these parasites.