Document Details
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Document Type |
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Thesis |
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Document Title |
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IDENTIFICATION OF EPITOME RECOGNIZED BY AMYLOID BETA CONFORMATION DEPENDENT ANTIBODIES FOR ALZHEIMER’S DISEASE تحديد نموذج معترف به من قبل الأجسام المضادة المعتمدة على تشكل الأميلويد بيتا لمرض الزهايمر |
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Subject |
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Faculty of Science |
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Document Language |
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Arabic |
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Abstract |
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Alzheimer’s disease (AD) is a well-known disease with increasing incidence and no effective cure. Even in Saudi Arabia, AD incidence is increasing and becoming the 6th highest cause of morbidity among elderly. Targeting the immune system to develop autoantibodies against amyloid beta (Aβ), the main causes of AD, that recognize only the toxic Aβ structures and help in their clearance and prevent their deposition in the brain is an important field of AD research. Current research groups are showing encouraging results about passive immunization using anti-Aß monoclonal antibodies (mAbs), especially if Aß deposition is still low so the antibody might have a prophylactic effect from AD. However, other mAbs were not as efficient in humans, so not all antibodies are equally effective. Since, these conformation dependent mAbs are promising therapeutic agents, it’s helpful to obtain greater knowledge about what they recognize and which of their epitopes are correlated in avoiding AD. Thus, this research aims include the discovery of all the peptide sequences recognized by a set of amyloid conformation dependent antisera and antibodies that include the mostly used antibodies in AD research. To thoroughly characterize the binding specificity of these antibodies, we used immunoselection of random peptide sequences from phage display library followed by deep sequencing and analyzed the resulting patterns from thousands of immunoselected sequences. Findings were, for the mAb 6E10 the minimum sequence required for binding is R-x-D with over half (53%) of the immunoselected sequences conforming to this pattern. The vast majority of these sequences contained an H at position x (R-H-D), corresponding to residues 5-7 of the Aß target sequences, but Y is also permitted at this position in a minority of sequences. For 4G8, we found that the most frequent pattern is F-x-A contained in approximately 30% of the sequences, followed by F-A, L-x(3)-A, L-x-F and F-F each accounting for approximately 18% of the sequences. The F-x-A motif also occurs in islet amyloid poly peptide which may explain why 4G8 also recognizes amyloid fibrils of this peptide. Since, the conformation dependent anti-Aß sera OC, A11 and α-APF are polyclonal, it was expected to have different major patterns for each one. For OC, findings were able to identify patterns that correspond to some of its mAbs such as A-x-F-R and F-R. For, A11 and α-APF patterns obtained were unclear since their epitope is not identified yet, but they had preference for certain subsequences such as FHL and VH for A11 and S-S and A-N-x-L for α-APF. Immunoselection and deep sequencing may also be a facile and efficient means of determining residues critical for antibody binding and validating the antibodies specificity. Findings indicate that mAbs display a preference for a unique set of amino acid sequences “fingerprint”, which provides insight about its epitope structure and it can be used to identify the antibody in complex mixtures like serum. These fingerprints can be used to identify antibodies that are correlated with AD, antibodies predictive for AD or subtypes of AD and antibodies that are protective for AD. |
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Supervisor |
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Prof. Khalid Omar Abulnaja |
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Thesis Type |
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Doctorate Thesis |
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Publishing Year |
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1440 AH
2018 AD |
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Added Date |
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Monday, December 31, 2018 |
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Researchers
| إبتسام محمد باغلاب | Baghallab, Ibtisam Mohammed | Researcher | Doctorate | |
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