Engineered MCMV Tracing Cassette for Stronger In Vivo Imaging
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Solution Overview
Problem
Existing murine cytomegalovirus (MCMV) models for tracing virus infection, such as MCMV-EGFP and MCMV-LUC, suffer from weak fluorescence and limited expression levels, hindering real-time imaging and evaluation of viral replication and distribution in vivo.
Innovation Solution
A genetically engineered MCMV-K181 strain-derived tool virus is developed, incorporating a tracing elements expression cassette between M06 and M07 open reading frames, comprising a BAC backbone with a sequence order of first fluorescent protein, linker, second fluorescent protein, luciferase, and polyA, enhancing tracing fluorescence intensity and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If MCMV is genetically modified to insert single luciferase or EGFP gene for labeling infected cells, then in vivo imaging and tracing of virus infection is enabled, but the fluorescence intensity and expression level remain weak, limiting real-time imaging capability
Solution Approach 1:
The patent combines multiple tracing elements (luciferase, EGFP, and other fluorescent proteins) into a single expression cassette inserted into the MCMV genome. This merging approach amplifies the total fluorescence signal by co-expressing multiple reporter genes simultaneously, while managing genome complexity through unified cassette design with shared regulatory elements.
Solution Approach 2:
The invention creates a composite tracing system by integrating multiple different reporter genes (luciferase from firefly, EGFP, and other fluorescent proteins) into one viral genome. This composite approach allows simultaneous detection through multiple imaging modalities (bioluminescence and fluorescence), enhancing overall tracing capability and signal intensity.
2Measurement precision
If multiple tracing elements are co-expressed in a single expression cassette, then fluorescence intensity and sensitivity are enhanced for real-time imaging, but the virus genome structure becomes more complex
Solution Approach 1:
The expression cassette is segmented into distinct functional modules: promoter region, multiple coding sequences for different tracing elements separated by internal ribosome entry sites (IRES) or 2A peptides, and polyadenylation signal. This segmentation allows independent optimization of each element while maintaining overall cassette functionality and simplifying construction through modular assembly.
Solution Approach 2:
The single expression cassette is designed to universally express multiple types of tracing elements (bioluminescent and fluorescent) simultaneously under one regulatory control system. This multi-functional cassette can be adapted to different imaging requirements by changing the specific reporter genes included, providing universal applicability across various experimental conditions.
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
The engineered MCMV-K181 strain allows for non-invasive, real-time monitoring of MCMV infection and replication levels in vivo, enabling accurate evaluation of viral distribution and the effectiveness of anti-viral drugs and vaccines.
Implementation Method 1
incorporating a tracing elements expression cassette between M06 and M07 open reading frames, comprising a BAC backbone with a sequence order of first fluorescent protein, linker, second fluorescent protein, luciferase, and polyA, enhancing tracing fluorescence intensity and sensitivity
Implementation Method 2
comprising a BAC backbone with a sequence order of first fluorescent protein, linker, second fluorescent protein, luciferase, and polyA
Data Source
AI summary
A tool virus derived from genetically engineered MCMV K181 strain for tracing MCMV infection, wherein the tool virus is a recombinant MCMV K181 strain comprising a tracing elements expression cassette and a BAC backbone, wherein the BAC backbone and the tracing elements expression cassette are inserted together between M06 open reading frame and M07 open reading frame of K181 strain genome; wherein the tracing elements expression cassette comprises three tracing elements coding sequences; and wherein the tracing elements expression cassette from 5′ to 3′ sequentially comprises a first fluorescent protein, a first linker, a second fluorescent protein, a second linker, a luciferase and a polyA.