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Selection and Characterization of CSFV-Specific Single-Domain Antibodies and Their Application along with Immunomagnetic Nanobeads and Quantum Dots
摘要： Outbreak of classical swine fever (CSF) results in high mortality and thus causes severe economic losses in the swine industry. Single-domain antibody (sdAb) is the smallest antigen-binding molecule derived from camelid heavy-chain antibodies and has the potential to be used as a molecular probe for detection of CSF virus (CSFV). In this study, two sdAb fragments against the E2 antigen of CSFV were obtained, expressed in vitro. The functional characteristics analysis indicated that the recombinant sdAbE2-1 and sdAbE2-2 have excellent binding activity, specificity, and high affinity with equilibrium constant value of 3.34 × 10? 7 and 1.35 × 10? 8 M to E2 protein. Then, sdAbE2s were conjugated with quantum dots (QD)/AF488 to synthesize two molecular probes for imaging CSFV distribution in cells. The sdAbE2-1 was also labeled with carboxyl-magnetic beads to construct immuno-magnetic nanobeads (IMNBs) able to capture CSFV virions and recombinant E2 protein. QD/AF455-sdAbE2s probes colocalised with CSFV virions in swine testis cells, and IMNBs were used as a detection template and proved to bind specifically with CSFV virions and E2 protein. The selected sdAb fragments and sdAb-based molecular probes may be used for the rapid identification of CSFV during field outbreaks and for research on CSFV and host interactions.
关键词： single-domain antibody,immunomagnetic nanobeads,CSFV,classical swine fever,quantum dots
更新于2025-09-23 15:19:57
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Clinical Translation of [68Ga]Ga-NOTA-anti-MMR-sdAb for PET/CT Imaging of Protumorigenic Macrophages
摘要： Purpose: Macrophage mannose receptor (MMR, CD206) expressing tumor-associated macrophages (TAM) are protumorigenic and was reported to negatively impact therapy responsiveness and is associated with higher chances of tumor relapse following multiple treatment regimens in preclinical tumor models. Since the distribution of immune cells within the tumor is often heterogeneous, sampling errors using tissue biopsies will occur. In order to overcome this limitation, we propose positron emission tomography (PET)/X-ray computed tomography (CT) imaging using 68Ga-labeled anti-MMR single-domain antibody fragment (sdAb) to assess the presence of these protumorigenic TAM. Procedures: Cross-reactive anti-MMR-sdAb was produced according to good manufacturing practice (GMP) and conjugated to p-SCN-Bn-NOTA bifunctional chelator for 68Ga-labeling. Biodistribution and PET/CT studies were performed in wild-type and MMR-deficient 3LL-R tumor-bearing mice. Biodistribution data obtained in mice were extrapolated to calculate radiation dose estimates for the human adult using OLINDA software. A 7-day repeated dose toxicity study for NOTA-anti-MMR-sdAb was performed in healthy mice up to a dose of 1.68 mg/kg. Results: [68Ga]Ga-NOTA-anti-MMR-sdAb was obtained with 76 ± 2 % radiochemical yield, 99 ± 1 % radiochemical purity, and apparent molar activity of 57 ± 11 GBq/μmol. In vivo biodistribution analysis showed fast clearance via the kidneys and retention in MMR-expressing organs and tumor, with tumor-to-blood and tumor-to-muscle ratios of 6.80 ± 0.62 and 5.47 ± 1.82, respectively. The calculated effective dose was 0.027 mSv/MBq and 0.034 mSv/MBq for male and female, respectively, which means that a proposed dose of 185 MBq in humans would yield a radiation dose of 5.0 and 6.3 mSv to male and female patients, respectively. In the toxicity study, no adverse effects were observed. Conclusions: Preclinical validation of [68Ga]Ga-NOTA-anti-MMR-sdAb showed high specific uptake of this tracer in MMR-expressing TAM and organs, with no observed toxicity. [68Ga]Ga-NOTA-anti-MMR-sdAb is ready for a phase I clinical trial.
关键词： Single-domain antibody (sdAb),PET,Tumor-associated macrophages (TAM),Macrophage mannose receptor (MMR)
更新于2025-09-19 17:15:36
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Labeling Single Domain Antibody Fragments with Fluorine-18 Using 2,3,5,6-Tetrafluorophenyl 6-[ <sup>18</sup> F]Fluoronicotinate Resulting in High Tumor to Kidney Ratios
摘要： ImmunoPET agents are being investigated to assess the status of epidermal growth factor receptor 2 (HER2) in breast cancer patients with the goal of selecting those likely to benefit from HER2-targeted therapies and monitoring their progress after these treatments. We have been exploring the use of single domain antibody fragments (sdAbs) labeled with 18F using residualizing prosthetic agents for this purpose. In this study, we have labeled two sdAbs that bind to different domains on the HER2 receptor — 2Rs15d and 5F7 — using 2,3,5,6-tetrafluorophenyl 6-[18F]fluoronicotinate ([18F]TFPFN) and evaluated their HER2 targeting properties in vitro and in vivo. The overall decay-corrected radiochemical yield for the synthesis of [18F]TFPFN-2Rs15d and [18F]TFPFN-5F7 was 5.7 ± 3.6% and 4.0 ± 2.0%, respectively. Radiochemical purity of labeled sdAbs was >95%; immunoreactive fractions were about 60% and affinity was in the low nanomolar range. Intracellularly trapped activity from [18F]TFPFN-2Rs15d and [18F]TFPFN-5F7 in HER2-expressing SKOV-3 ovarian and BT474M1 breast carcinoma cells were similar to the sdAbs labeled using the previously validated radioiodination residualizing prosthetic agents N-succinimidyl 4-guanidinomethyl-3-[125I]iodobenzoate ([125I]SGMIB) and N-succinimidyl 3-guanidinomethyl-5-[125I]iodobenzoate (iso-[125I]SGMIB). Intracellular activity was about 2-fold higher for radiolabeled 5F7 compared with 2Rs15d for both 18F and 125I. While tumor uptake of both [18F]TFPFN-2Rs15d and [18F]TFPFN-5F7 was comparable to those for the co-administered 125I-labeled sdAb, renal uptake of the 18F-labeled sdAbs was substantially lower. In microPET images, tumor was clearly delineated in SKOV-3 and BT474 xenograft-bearing athymic mice with low levels of background activity in normal tissues except bladder. These results indicate that the [18F]TFPFN prosthetic group could be a valuable reagent for developing sdAb-based immunoPET imaging agents.
关键词： N-Succinimidyl 4-fluorobenzoate (SFB),2,3,5,6-etrafluorophenyl 6-fluoronicotinate (TFPFN),single domain antibody fragment,immunoPET,fluorine-18,HER2
更新于2025-09-11 14:15:04