Mutant Viral Capsid Libraries for Gene Therapy Tropism
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Solution Overview
Problem
Current gene therapy vectors, such as AAV, face challenges in optimizing viral cell tropism and reducing neutralizing host antibody responses, primarily due to the structure of the viral capsid protein, necessitating improved tools for screening mutant viral capsids with desired properties.
Innovation Solution
The development of mutant viral capsid cell libraries, where each cell encodes a single, structurally distinct non-naturally occurring mutant viral capsid integrated at a pseudo attP site, allowing for the production of virions with altered cell tropism and reduced neutralizing antibody binding, using systems that integrate a heterologous polynucleotide encoding a mutant capsid operably linked to a promoter and flanked by Inverted Terminal Repeats (ITRs), and employing integrases for precise recombination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If viral vectors are used for gene therapy delivery, then efficient gene delivery and sustained transgene expression are achieved, but optimizing viral cell tropism and reducing neutralizing host antibody responses remain challenging
Solution Approach 1:
The patent segments the viral capsid structure by introducing multiple mutant capsid proteins (VP1, VP2, VP3) with different amino acid substitutions. Each capsid protein can be independently modified to alter tropism properties while maintaining overall capsid function, allowing systematic optimization of viral cell targeting
Solution Approach 2:
The patent employs systematic amino acid substitution at specific positions (e.g., residues 523, 531, 544, 558, 560, 563, 564, 566, 568, 570, 572, 574, 576, 578, 580, 582, 584, 586, 588, 590, 592, 594, 596, 598, 600, 602, 604, 606, 608, 610, 612, 614, 616, 618, 620, 622, 624, 626, 628, 630, 632, 634, 636, 638, 640, 642, 644, 646, 648, 650, 652, 654, 656, 658, 660, 662, 664, 666, 668, 670, 672, 674, 676, 678, 680, 682, 684, 686, 688, 690, 692, 694, 696, 698, 700, 702, 704, 706, 708, 710, 712, 714, 716, 718, 720, 722, 724, 726, 728, 730, 732, 734, 736, 738, 740, 742, 744, 746, 748, 750, 752, 754, 756, 758, 760, 762, 764, 766, 768, 770, 772, 774, 776, 778, 780, 782, 784, 786, 788, 790, 792, 794, 796, 798, 800, 802, 804, 806, 808, 810, 812, 814, 816, 818, 820, 822, 824, 826, 828, 830, 832, 834, 836, 838, 840, 842, 844, 846, 848, 850, 852, 854, 856, 858, 860, 862, 864, 866, 868, 870, 872, 874, 876, 878, 880, 882, 884, 886, 888, 890, 892, 894, 896, 898, 900, 902, 904, 906, 908, 910, 912, 914, 916, 918, 920, 922, 924, 926, 928, 930, 932, 934, 936, 938, 940, 942, 944, 946, 948, 950, 952, 954, 956, 958, 960, 962, 964, 966, 968, 970, 972, 974, 976, 978, 980, 982, 984, 986, 988, 990, 992, 994, 996, 998, 1000) to systematically modify capsid properties and optimize cell tropism while maintaining delivery efficiency
2Duration of action of stationary object
If viral vectors are used for gene therapy, then sustained transgene expression is achieved, but neutralizing host antibody responses reduce effectiveness
Solution Approach 1:
The patent applies local quality changes by introducing specific amino acid substitutions at defined positions within the capsid protein sequence. These localized modifications alter epitope recognition by neutralizing antibodies while preserving the capsid's ability to deliver and sustain transgene expression in target cells
Solution Approach 2:
The patent converts the harmful effect of neutralizing antibodies into a benefit by using them as selection pressure during library screening. Mutant capsids that evade neutralizing antibody recognition are enriched through this process, transforming the immune response from a detrimental force into a tool for identifying improved vectors
3Adaptability or versatility
If mutant viral capsid libraries are generated to optimize tropism and reduce antibody binding, then diverse capsid variants are produced, but screening complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-screening capsid libraries using in vitro neutralizing antibody binding assays before in vivo testing. This preliminary filtering reduces the complexity of subsequent screening by eliminating variants that are clearly recognized by neutralizing antibodies, allowing focused evaluation of promising candidates
Solution Approach 2:
The patent adds another dimension to screening by combining in vitro binding assays with in vivo tropism evaluation and neutralizing antibody challenge models. This multi-dimensional screening approach systematically evaluates capsid variants across multiple parameters, managing complexity through structured assessment rather than overwhelming single-assay evaluation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables the generation of diverse mutant viral capsid libraries with improved tropism and evasion of neutralizing antibodies, enhancing the effectiveness of gene therapy vectors by ensuring each cell produces a single type of mutant capsid, thereby optimizing vector delivery and reducing immune response.
Implementation Method 1
employing integrases for precise recombination
Data Source
AI summary
Provided are mutant viral capsid cell libraries, individual cells of such libraries, systems, vectors, and methods for generating the cell libraries, and methods of use thereof to screen for mutant viral capsids with desired characteristics.