Human ACE2 Mouse Model for Accurate COVID-19 Infection Replication
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Solution Overview
Problem
Current transgenic mouse models for SARS-CoV and SARS-CoV-2 are limited by poor tissue tropism and neuroinvasion patterns that do not accurately represent human COVID-19, making them unsuitable for evaluating therapeutics and vaccines effectively.
Innovation Solution
A genetically modified mouse model with a full-length human ACE2 gene, expressed in multiple tissues, using CRISPR/Cas-mediated BAC transgenesis to replicate human ACE2 gene expression and tissue distribution, allowing for accurate infection and disease replication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional transgenic technologies are used to express human ACE2 in mice, then the mice can be infected by SARS-CoV-2, but the tissue distribution and neuroinvasion patterns do not accurately represent human COVID-19
Solution Approach 1:
The patent uses tissue-specific promoters (such as the human ACE2 promoter) to drive expression of human ACE2 in specific tissues where it is naturally expressed in humans, rather than uniform expression throughout the body. This creates locally appropriate protein expression patterns that match human physiology, improving the accuracy of viral tropism and disease manifestation in the mouse model.
Solution Approach 2:
The patent modifies the expression parameters of ACE2 by using full-length human ACE2 coding sequences with human regulatory elements, rather than truncated versions or mouse ACE2. This changes the expression level, tissue distribution, and functional properties of ACE2 in the mouse model to better match human parameters, thereby improving reliability of the disease model.
2Ease of manufacture
If mouse ACE2 is used for viral entry, then the model is simpler to maintain, but it cannot effectively evaluate human monoclonal antibodies and vaccines targeting the receptor-binding domain
Solution Approach 1:
The patent introduces a copy of the human ACE2 gene into the mouse genome, creating a humanized version of the essential viral receptor. This copied human ACE2 sequence allows the mouse model to express the human receptor that SARS-CoV-2 uses for entry, enabling evaluation of human therapeutics while maintaining the simplicity of a mouse model.
Solution Approach 2:
The human ACE2 transgene serves multiple functions: it enables viral entry (replacing mouse ACE2 function), allows evaluation of human monoclonal antibodies and vaccines, and maintains mouse physiology for ease of model maintenance. This multi-functionality resolves the contradiction between simplicity and therapeutic evaluation capability.
3Reliability
If high viral load inoculation is used to achieve infection, then infection can be established, but lethal encephalitis and pneumonia occur that are not representative of human clinical pictures
Solution Approach 1:
The patent changes the viral receptor parameter from mouse ACE2 to human ACE2, which has different binding affinity and specificity for SARS-CoV-2. This parameter change allows infection to be established at lower viral loads and produces disease pathology that more closely resembles human COVID-19, reducing non-representative harmful outcomes like lethal encephalitis.
Data Source
AI summary
A genetically modified non-human animal comprising a genome containing an endogenous non-human ACE2 locus genetically modified to encode a complete human ACE2 gene. According to a further embodiment the genome is genetically modified to encode a second, a third, and a fourth complete human ACE2 gene, the human ACE2 gene is at least 85 percent identical to SEQ ID No: 1, the animal of is a mouse, the human ACE2 gene encodes six protein variants, an endogenous Tmprss2 gene is unmodified, a LoxP gene flanks each of a 5′ and a 3′ end of a nucleic acid sequence of the human ACE2 gene, and the human ACE2 gene is expressed in a lung, kidney, spleen, stomach, liver, intestine, heart, and skeletal muscle of the animal, and a cortex, striatum, middle brain, hippocampus, olfactory bulb, and cerebellum of a brain of the animal.