Immunofluorescent localization of intermediate filaments (IFs) in helminths using anti-mammalian IFs monoclonal antibody.

Intermediate filaments (IFs) make up the cytoskeleton of most eukaryotic cells. In vertebrates, a number of IF proteins have been identified, showing distributions unique to tissue or cell type. Information on helminth IFs is limited to some nematode species. To observe immunofluorescent localization of IFs in helminth tissues, we selected a murine hybridoma clone producing IgM antibody to multiple types of mammalian IF proteins and examined cross-reactivity to helminth proteins. The selected monoclonal antibody (HUSM-9) cross-reacted well with IFs from nematode species such as Toxocara canis, Dirofilaria immitis, Anisakis simplex, and Trichinella britovi; strong immunofluorescence on cryostat sections was detected in the hypodermis, cords, body muscle, smooth muscle of the uterus, and other epithelial structures. In platyhelminths, i.e., adult Schistosoma mansoni, larval Taenia taeniaeformis, adult Taenia crassiceps, and Echinococcus multilocularis protoscolex, the reactivity was weaker than in nematodes, and localized in the body wall muscle and subtegumental tissue. Western blotting of 8 M urea extracts of parasites with the antibody detected a pair of clear bands in nematodes but not in S. mansoni or the cestodes. These results might be explained by sparse distribution of IFs in platyhelminths, or low affinity of the used antibody to platyhelminth IF proteins, or both.