Liquid Direct Fluorescent Assay for Intracellular Virus Detection
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Solution Overview
Problem
Current Direct Fluorescence Antibody (DFA) methods for virus detection are laborious, time-consuming, and require skilled technicians due to issues like non-specific staining, cell loss during processing, and the need for fixatives that disrupt protein structures, leading to inaccurate results.
Innovation Solution
A liquid direct fluorescent assay (LDFA) method using fluorescently labeled monoclonal antibodies that differentiate between viral antigens, eliminating the need for fixatives and reducing processing steps, allowing for simultaneous detection of multiple viruses in a single sample.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional DFA methods are used with fixatives and multiple processing steps, then virus detection can be performed, but the processing time is excessive and labor requirements are high
Solution Approach 1:
The patent extracts and eliminates the fixative step from the traditional DFA protocol. By using a liquid-based assay without methanol or acetone fixation, the method removes a time-consuming and potentially damaging step while maintaining antibody-antigen binding efficiency. The liquid suspension format allows direct staining without requiring cell adhesion to slides followed by chemical fixation.
Solution Approach 2:
The patent combines multiple processing steps into a single liquid-phase incubation step. The antibody staining, cell preservation, and antigen preservation functions are merged into one step performed in liquid suspension, eliminating the need for sequential drying, fixing, and staining steps required in traditional DFA methods.
2Measurement precision
If traditional DFA methods with multiple washing and staining steps are used, then viral antigens can be detected, but the procedure becomes laborious and requires skilled technicians
Solution Approach 1:
The patent implements a self-contained liquid suspension system where the antibody-conjugate automatically interacts with viral antigens in the sample without requiring manual manipulation for cell adhesion or coverslip application. The liquid format allows the assay to proceed through incubation and detection steps with minimal intervention, reducing the need for skilled technical操作.
Solution Approach 2:
The patent replaces the mechanical manipulation steps of traditional DFA (drying slides, applying coverslips, manual washing) with a liquid-phase system where samples remain in suspension. This substitution eliminates the need for precise mechanical handling and reduces operator skill requirements while maintaining detection sensitivity.
3Stability of the object's composition
If fixatives like methanol or acetone are used in DFA, then cells can be preserved for staining, but protein structures are disrupted leading to potential loss of antigenicity
Solution Approach 1:
The patent changes the physical state parameter from fixed (dried cells on slides) to liquid (suspended cells in buffer). This parameter change allows cells to be preserved in their native state without chemical fixation, maintaining protein structure integrity and antigenicity while still enabling antibody access and binding.
Solution Approach 2:
The patent converts the potential harm of skipping fixation (cell instability) into a benefit by using the liquid suspension medium itself as the preserving element. The buffered liquid environment maintains cell structure and antigen integrity without requiring harsh chemical fixatives, turning the absence of fixation from a disadvantage into an advantage for antigen preservation.
4Difficulty of detecting and measuring
If traditional DFA requires drying cells on glass slides, then samples can be examined under microscope, but cells may be lost during processing
Solution Approach 1:
The patent uses liquid hydraulics to maintain cells in suspension rather than allowing them to adhere to solid surfaces. The liquid medium provides buoyancy and mechanical support, preventing cell loss during processing steps. Detection is achieved by analyzing the liquid suspension directly or after minimal processing, eliminating the need for slide-based microscopy that causes cell loss.
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
LDFA significantly reduces processing time, improves accuracy, and simplifies the detection process, enabling faster and more reliable identification of viral infections with minimal technical expertise.
Implementation Method 1
The detection method may use antibodies that directly bind to a viral antigen thereby allowing identification as well as detection. In some instances, the antibodies are labeled monoclonal antibodies.
Implementation Method 2
a) providing: i) a biological sample comprising at least one viral antigen; ii) first and second antibodies, wherein said first antibody reacts with a first viral antigen and does not react with a second viral antigen and is labeled with a first fluorescent tag
Data Source
AI summary
The present invention describes a liquid direct fluorescence antibody assay that is rapid and sensitive to detect respiratory virus in infected cells. The assay includes centrifugation of the specimen, incubation of sample and reagents in solution, and detection of the absence or presence of respiratory virus. Sapogenin is used as a detergent to permeabilize the cells for entry of the monoclonal antibodies to react with intracellular antigens. The cells are stained with fluorescently labeled monoclonal antibodies against the viral antigens along with a background stain and a fluorescent nuclear stain. This counter staining decreases background and allows co-localization of antigen and nuclear structures for enhanced detection.