Echinococcus multilocularis: characterization of an alveolar hydatid cyst-induced amyloid enhancing factor.

Alveolar hydatid cysts, the larvae of Echinococcus multilocularis, were shown to induce the formation of an amyloid enhancing-like factor (AEF) called alveolar hydatid cyst-AEF (AHC-AEF) in the spleens of infected animals, 5 to 6 weeks post-infection. The adoptive transfer of AHC-AEF results in rapid induction and deposition of amyloid fibrils in the spleens following AgNO3 injection within 24 h. When injected concomitantly with alveolar hydatid cysts, it shortens the induction phase from 5 or 12 weeks to 1 week in C57BL/6J and A/JAX mice respectively. Preliminary characterization of this factor indicates that its bioactivity may be detected in the non-lipid moiety of spleen cell extracts and the sediment of ultracentrifugation. The factor is resistant to trypsin, pepsin, DNA-ase and RNA-ase treatments. It is sensitive to low or high pH (pH 3.0 and 9.5) and boiling. It resists freeze drying, dialysis, and storage at 4 degrees C for 2 weeks or -70 degrees C for more than a year. It may be fractionated using borate buffered saline, pH 7.4, on Sephacryl S-300 gel column. The active moiety eluted mainly in the first peak.