MAMA-Based Real-Time PCR for Cryptococcus Genotyping
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Solution Overview
Problem
Current methods for genotyping Cryptococcus gattii, such as PCR-RFLP and AFLP, require extensive lab work and are not readily transferable between laboratories, while MLST and MLMT need DNA sequencing or expensive MALDI-TOF MS instrumentation, limiting their accessibility for public health laboratories.
Innovation Solution
Development of a panel of real-time PCR assays based on mismatch amplification mutation assay (MAMA) methodology using specific primers to rapidly and sensitively detect and genotype Cryptococcus gattii molecular types (VGI-VGIV) and VGII subtypes (VGIIa-c) by calculating cycle threshold (Ct) values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PCR-RFLP and AFLP methods are used for genotyping Cryptococcus gattii, then genotyping can be performed, but extensive lab work is required and results are not readily transferable between laboratories
Solution Approach 1:
The patent replaces complex mechanical/physical methods (PCR-RFLP requiring restriction enzyme digestion and gel electrophoresis, AFLP requiring amplification and separation) with a molecular recognition system based on sequence-specific primers and fluorescent labeling, enabling automated detection without complex physical separation processes
Solution Approach 2:
The patent creates a standardized molecular copy system using fluorescently labeled probes that can be detected by automated fluorescence scanners, replacing the need for physical gel bands and manual interpretation, thereby enabling easy transfer of results between laboratories
2Measurement precision
If MLST and MLMT methods are used for genotyping Cryptococcus gattii, then accurate genotyping is achieved, but DNA sequencing or expensive MALDI-TOF MS instrumentation is required, limiting accessibility
Solution Approach 1:
The patent employs disposable fluorescently labeled probes and primers that can be easily discarded after use, replacing the need for expensive, maintainable instrumentation like MALDI-TOF MS or dedicated sequencing equipment, thereby making high-accuracy genotyping accessible to smaller laboratories
Solution Approach 2:
The patent substitutes expensive physical instrumentation (MALDI-TOF MS, sequencing machines) with a simpler fluorescence-based detection system using standard PCR thermocyclers and fluorescent scanners, maintaining high measurement precision while dramatically reducing equipment requirements and costs
3Ease of manufacture
If real-time PCR instruments are used for genotyping, then accessibility and cost-effectiveness are improved, but the method must be highly sensitive and reproducible to ensure accurate genotype identification
Solution Approach 1:
The patent designs primers and probes with specific local chemical properties (fluorescent labels, fluorescent quenchers, mismatched bases) that enable differentiation between genotype types based on localized molecular recognition, ensuring accurate identification while maintaining cost-effectiveness through simplified reagents
Solution Approach 2:
The patent incorporates fluorescent signals that provide real-time feedback during PCR cycles, allowing automated detection and quantification of genotype-specific amplification products, thereby ensuring high reproducibility and accuracy without requiring expensive instrumentation
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 MAMA-based real-time PCR assays provide a cost-effective, accessible, and highly sensitive method for genotyping C. gattii, ensuring accurate identification of genotypes with high reproducibility and sensitivity, suitable for widespread molecular epidemiological efforts.
Implementation Method 1
MAMA, a form of allele-specific PCR (ASPCR), employs primers that are designed for SNP genotyping
Implementation Method 2
MAMA, a form of allele-specific PCR (ASPCR), employs primers that are designed for SNP genotyping
Implementation Method 3
detecting a presence or an absence of a VGIIc genotype of the Cryptococcus gattii sample by detecting the nucleic acid amplifications of the first and second mixtures
Data Source
AI summary
Embodiments of the invention provide a method of genotyping a C. gattii sample, which can include forming a plurality of mixtures for nucleic amplification. The method can include amplification of specific sequences within the C. gattii genome that can provide definitive genotype information to distinguish between one or more types or subtypes of C. gattii.