Scientific article
Open access

A single-domain antibody for the detection of pathological Tau protein in the early stages of oligomerization

Published inJournal of translational medicine, vol. 22, no. 1, 163
Publication date2024-02-16
First online date2024-02-16


Soluble oligomeric forms of Tau protein have emerged as crucial players in the propagation of Tau pathology in Alzheimer’s disease (AD). Our objective is to introduce a single-domain antibody (sdAb) named 2C5 as a novel radiotracer for the efficient detection and longitudinal monitoring of oligomeric Tau species in the human brain.


The development and production of 2C5 involved llama immunization with the largest human Tau isoform oligomers of different maturation states. Subsequently, 2C5 underwent comprehensive in vitro characterization for affinity and specificity via Enzyme-Linked Immunosorbent Assay and immunohistochemistry on human brain slices. Technetium-99m was employed to radiolabel 2C5, followed by its administration to healthy mice for biodistribution analysis.


2C5 exhibited robust binding affinity towards Tau oligomers (Kd = 6.280 nM ± 0.557) and to Tau fibers (Kd = 5.024 nM ± 0.453), with relatively weaker binding observed for native Tau protein (Kd = 1791 nM ± 8.714) and amyloid peptide (Kd > 10,000 nM). Remarkably, this SdAb facilitated immuno-histological labeling of pathological forms of Tau in neurons and neuritic plaques, yielding a high-contrast outcome in AD patients, closely mirroring the performance of reference antibodies AT8 and T22. Furthermore, 2C5 SdAb was successfully radiolabeled with 99mTc, preserving stability for up to 6 h post-radiolabeling (radiochemical purity > 93%). However, following intravenous injection into healthy mice, the predominant uptake occurred in kidneys, amounting to 115.32 ± 3.67, 97.70 ± 43.14 and 168.20 ± 34.52% of injected dose per gram (% ID/g) at 5, 10 and 45 min respectively. Conversely, brain uptake remained minimal at all measured time points, registering at 0.17 ± 0.03, 0.12 ± 0.07 and 0.02 ± 0.01% ID/g at 5, 10 and 45 min post-injection respectively.


2C5 demonstrates excellent affinity and specificity for pathological Tau oligomers, particularly in their early stages of oligomerization. However, the current limitation of insufficient blood–brain barrier penetration necessitates further modifications before considering its application in nuclear medicine imaging for humans.

  • Alzheimer’s disease
  • BBB
  • Biomarker
  • Oligomers
  • Tau protein
  • Tc-99m
  • SdAb
Citation (ISO format)
DE LEIRIS, Nicolas et al. A single-domain antibody for the detection of pathological Tau protein in the early stages of oligomerization. In: Journal of translational medicine, 2024, vol. 22, n° 1, p. 163. doi: 10.1186/s12967-024-04987-1
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Article (Published version)
ISSN of the journal1479-5876

Technical informations

Creation03/13/2024 12:20:02 PM
First validation05/14/2024 9:23:47 AM
Update time05/14/2024 9:23:47 AM
Status update05/14/2024 9:23:47 AM
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