Gas Vesicle Gene Optimization for Nonlinear Ultrasound Imaging
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Solution Overview
Problem
Current genetically encodable acoustic reporter genes (ARGs) for ultrasound imaging in vivo face limitations such as poor expression at 37°C, high metabolic burden, and inability to produce nonlinear ultrasound contrast, restricting their use for monitoring gene expression in bacteria and mammalian cells.
Innovation Solution
Development of nucleic acid compositions and cell compositions that include promoters operably connected to gas vesicle (GV) genes, enabling the formation of gas vesicles capable of producing nonlinear ultrasound contrast in mammalian and probiotic bacterial cells, allowing for robust and sustained expression under physiological conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If first-generation acoustic reporter genes (ARGs) are used for ultrasound imaging, then genetic encoding capability is achieved, but expression at 37°C is poor and metabolic burden is high
Solution Approach 1:
The patent modifies the gas vesicle gene sequences through site-directed mutagenesis and selection processes to optimize expression parameters for mammalian cells at 37°C. Specific amino acid substitutions in GvpA and other GV proteins enhance thermal stability and expression efficiency while reducing metabolic burden on host cells.
Solution Approach 2:
The patent creates improved copies of gas vesicle genes (gvpA, gvpC, gvpN, etc.) with optimized sequences for mammalian expression. These copied and modified genes are assembled into expression cassettes that function efficiently in eukaryotic cells, replacing the original bacterial-optimized sequences.
2Measurement precision
If first-generation ARGs are used for ultrasound imaging, then genetic encoding capability is achieved, but nonlinear ultrasound contrast is not produced
Solution Approach 1:
The patent modifies protein structural parameters through gene sequence optimization to enhance the nonlinear acoustic properties of gas vesicles. Specific mutations in GvpA and assembly proteins improve the mechanical properties and acoustic response of GVs, enabling strong nonlinear contrast that distinguishes them from background tissues.
Solution Approach 2:
The patent creates composite genetic constructs combining multiple optimized gas vesicle genes (gvpA, gvpC, gvpN, gvpF, gvpG, etc.) with mammalian cell-compatible regulatory elements. This composite approach integrates structural, assembly, and regulatory components to achieve robust nonlinear ultrasound contrast in mammalian cells.
3Reliability
If first-generation mammalian ARGs are used, then linear ultrasound contrast is produced, but cell-to-cell variability limits robust imaging
Solution Approach 1:
The patent designs universal expression cassettes that function across different mammalian cell types and conditions. The optimized gas vesicle gene constructs are compatible with various promoters and cell lines, reducing cell-to-cell variability and enabling robust imaging across heterogeneous cell populations without requiring cell selection.
4Measurement precision
If destructive ultrasound pulse sequences are used to achieve nonlinear signal, then contrast is enhanced, but GVs are destroyed and dynamic imaging is limited
Solution Approach 1:
The patent optimizes the mechanical and acoustic parameters of gas vesicles through gene sequence modifications. The improved GV structures can withstand higher acoustic pressures without destruction, enabling the use of high-power ultrasound pulse sequences for nonlinear imaging while maintaining GV integrity for sustained dynamic imaging over time.
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
Enables long-term noninvasive imaging of gene expression with enhanced nonlinear ultrasound contrast and reduced metabolic burden, facilitating broader in vivo applications.
Implementation Method 1
The low density and high compressibility of their air-filled interiors compared to surrounding tissues allow GVs to scatter sound waves and thereby produce ultrasound contrast when heterologously expressed as acoustic reporter genes (ARGs) in genetically engineered bacteria or mammalian cells.
Implementation Method 2
can scatter ultrasound nonlinearly (making them difficult to distinguish from background tissues)
Data Source
AI summary
Disclosed herein include methods, compositions, and kits suitable for use in dynamic non-destructive imaging. The non-destructive imaging can be nonlinear ultrasound imaging. There are provided, in some embodiments, nucleic acid compositions encoding gas vesicles (GVs) capable of producing nonlinear ultrasound contrast upon expression in a prokaryotic cell (e.g., a probiotic bacterial cell) or a eukaryotic cell (e.g., a therapeutic mammalian cell).