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Active release of surface proteins: a mechanism associated with the immune escape of Acanthocheilonema viteae
Abstract:
Living Acanthocheilonema viteae microfilariae obtained from peripheral blood of parasitised Meriones unguiculatus were surface-labelled with 125I. Four major surface exposed proteins of approximately 14.50, 14.55, 17.5, 19 kDa and one less abundant protein of 40 kDa were identified. Under non-reducing conditions the low-molecular-weight (LMW) proteins were isolated as multimers suggesting the presence of intermolecular disulphide linkages. In gels containing Triton X-100 the labelled epicuticular proteins behaved lipophilically. By cultivation of surface-labelled and metabolically labelled microfilaria in vitro, a continuous shedding of two LMW proteins was demonstrated. These proteins were produced in large amounts and released into the culture supernatant as monomeric and pentameric molecules. Concomitant with this release, one of the proteins appeared to lose its lipophilic character, giving rise to a hydrophilic 14.50-kDa entity. Although most of the extracted surface proteins reacted with sera from patent jirds, these sera failed to recognise the surface of living microfilariae. However, microfilariae pretreated with glutaraldehyde or attenuated with Na-azide could be labelled with surface specific antibodies.
Insights
Researchers identified key surface proteins on Acanthocheilonema viteae microfilariae, revealing shedding of low-molecular-weight proteins and potential immune evasion strategies. These findings offer insights into filarial worm biology and host interactions.
Area of Science:
- Parasitology
- Molecular Biology
- Immunology
Background:
- Acanthocheilonema viteae microfilariae are parasitic worms.
- Understanding their surface proteins is crucial for studying host-parasite interactions and developing control strategies.
Purpose of the Study:
- To identify and characterize surface-exposed proteins of Acanthocheilonema viteae microfilariae.
- To investigate the shedding and properties of these proteins during in vitro cultivation.
Main Methods:
- Surface labeling of microfilariae with 125I.
- Protein identification using SDS-PAGE and Triton X-100 gels.
- In vitro cultivation of labeled microfilariae.
- Analysis of protein shedding and molecular forms (monomeric, pentameric).
- Immunological assays using sera from infected jirds.
Main Results:
- Four major surface proteins (14.50, 14.55, 17.5, 19 kDa) and a 40 kDa protein were identified.
- Low-molecular-weight proteins formed multimers, indicating disulfide linkages.
- Cultured microfilariae shed two low-molecular-weight proteins as monomers and pentamers.
- One shed protein transitioned from lipophilic to hydrophilic.
- Host sera recognized extracted proteins but not the surface of living microfilariae.
Conclusions:
- Acanthocheilonema viteae microfilariae shed specific low-molecular-weight proteins that change in lipophilicity.
- The parasite may employ immune evasion mechanisms by altering surface protein recognition.
- Further research into these surface proteins could inform diagnostics and therapeutics for filarial infections.