Evidence for selective incorporation of host immunoglobulin by strobilocerci of Taenia taeniaeformis

Strobilocerci of Taenia taeniaeformis were obtained from laboratory rats 90 days after experimental infection. Cyst fluid, whole parasite homogenate, and rat serum each were fractionated by SDS-PAGE, immobilized on nitrocellulose by western blot, and probed with conjugated goat anti-rat IgG. Reactive bands with relative mobilities corresponding to rat IgG were found in all 3 samples. Additional bands in cyst fluid and parasite homogenate may represent enzymatic degradation of IgG. The pattern of reactive bands in the homogenate discounts the nonspecific adsorption of host molecules onto the tegument and suggests selective incorporation of serum proteins. The presence of an IgG-like molecule of atypical molecular weight is consistent with either molecular mimicry or enzymatic cleavage of IgG bound to the tegument. The relevance of serum protein utilization by the parasite to evasion of the host immune response is discussed.