Affinity is an important determinant of the anti-trypanosome activity of nanobodies.
BACKGROUND: The discovery of Nanobodies (Nbs) with a direct toxic activity against African trypanosomes is a recent advancement towards a new strategy against these extracellular parasites. The anti-trypanosomal activity relies on perturbing the highly active recycling of the Variant-specific Surfac...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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Public Library of Science (PLoS)
2012-01-01
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| Series: | PLoS Neglected Tropical Diseases |
| Online Access: | http://europepmc.org/articles/PMC3499403?pdf=render |
| _version_ | 1818989145381404672 |
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| author | Guy Caljon Benoît Stijlemans Dirk Saerens Jan Van Den Abbeele Serge Muyldermans Stefan Magez Patrick De Baetselier |
| author_facet | Guy Caljon Benoît Stijlemans Dirk Saerens Jan Van Den Abbeele Serge Muyldermans Stefan Magez Patrick De Baetselier |
| author_sort | Guy Caljon |
| collection | DOAJ |
| description | BACKGROUND: The discovery of Nanobodies (Nbs) with a direct toxic activity against African trypanosomes is a recent advancement towards a new strategy against these extracellular parasites. The anti-trypanosomal activity relies on perturbing the highly active recycling of the Variant-specific Surface Glycoprotein (VSG) that occurs in the parasite's flagellar pocket. METHODOLOGY/PRINCIPAL FINDINGS: Here we expand the existing panel of Nbs with anti-Trypanosoma brucei potential and identify four categories based on their epitope specificity. We modified the binding properties of previously identified Nanobodies Nb_An05 and Nb_An33 by site-directed mutagenesis in the paratope and found this to strongly affect trypanotoxicity despite retention of antigen-targeting properties. Affinity measurements for all identified anti-trypanosomal Nbs reveal a strong correlation between trypanotoxicity and affinity (K(D)), suggesting that it is a crucial determinant for this activity. Half maximal effective (50%) affinity of 57 nM was calculated from the non-linear dose-response curves. In line with these observations, Nb humanizing mutations only preserved the trypanotoxic activity if the K(D) remained unaffected. CONCLUSIONS/SIGNIFICANCE: This study reveals that the binding properties of Nanobodies need to be compatible with achieving an occupancy of >95% saturation of the parasite surface VSG in order to exert an anti-trypanosomal activity. As such, Nb-based approaches directed against the VSG target would require binding to an accessible, conserved epitope with high affinity. |
| first_indexed | 2024-12-20T19:33:49Z |
| format | Article |
| id | doaj.art-3894b70394804fe885feec3f4191e617 |
| institution | Directory Open Access Journal |
| issn | 1935-2727 1935-2735 |
| language | English |
| last_indexed | 2024-12-20T19:33:49Z |
| publishDate | 2012-01-01 |
| publisher | Public Library of Science (PLoS) |
| record_format | Article |
| series | PLoS Neglected Tropical Diseases |
| spelling | doaj.art-3894b70394804fe885feec3f4191e6172022-12-21T19:28:42ZengPublic Library of Science (PLoS)PLoS Neglected Tropical Diseases1935-27271935-27352012-01-01611e190210.1371/journal.pntd.0001902Affinity is an important determinant of the anti-trypanosome activity of nanobodies.Guy CaljonBenoît StijlemansDirk SaerensJan Van Den AbbeeleSerge MuyldermansStefan MagezPatrick De BaetselierBACKGROUND: The discovery of Nanobodies (Nbs) with a direct toxic activity against African trypanosomes is a recent advancement towards a new strategy against these extracellular parasites. The anti-trypanosomal activity relies on perturbing the highly active recycling of the Variant-specific Surface Glycoprotein (VSG) that occurs in the parasite's flagellar pocket. METHODOLOGY/PRINCIPAL FINDINGS: Here we expand the existing panel of Nbs with anti-Trypanosoma brucei potential and identify four categories based on their epitope specificity. We modified the binding properties of previously identified Nanobodies Nb_An05 and Nb_An33 by site-directed mutagenesis in the paratope and found this to strongly affect trypanotoxicity despite retention of antigen-targeting properties. Affinity measurements for all identified anti-trypanosomal Nbs reveal a strong correlation between trypanotoxicity and affinity (K(D)), suggesting that it is a crucial determinant for this activity. Half maximal effective (50%) affinity of 57 nM was calculated from the non-linear dose-response curves. In line with these observations, Nb humanizing mutations only preserved the trypanotoxic activity if the K(D) remained unaffected. CONCLUSIONS/SIGNIFICANCE: This study reveals that the binding properties of Nanobodies need to be compatible with achieving an occupancy of >95% saturation of the parasite surface VSG in order to exert an anti-trypanosomal activity. As such, Nb-based approaches directed against the VSG target would require binding to an accessible, conserved epitope with high affinity.http://europepmc.org/articles/PMC3499403?pdf=render |
| spellingShingle | Guy Caljon Benoît Stijlemans Dirk Saerens Jan Van Den Abbeele Serge Muyldermans Stefan Magez Patrick De Baetselier Affinity is an important determinant of the anti-trypanosome activity of nanobodies. PLoS Neglected Tropical Diseases |
| title | Affinity is an important determinant of the anti-trypanosome activity of nanobodies. |
| title_full | Affinity is an important determinant of the anti-trypanosome activity of nanobodies. |
| title_fullStr | Affinity is an important determinant of the anti-trypanosome activity of nanobodies. |
| title_full_unstemmed | Affinity is an important determinant of the anti-trypanosome activity of nanobodies. |
| title_short | Affinity is an important determinant of the anti-trypanosome activity of nanobodies. |
| title_sort | affinity is an important determinant of the anti trypanosome activity of nanobodies |
| url | http://europepmc.org/articles/PMC3499403?pdf=render |
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