Color-coded molecular beacons for multiplex PCR screening assays.

Area of Science:

• Molecular Biology
• Biochemistry
• Genetics

Background:

• Standard PCR screening assays are limited by the number of distinguishable fluorescent colors, restricting the number of detectable targets.
• Identifying multiple bacterial species in clinical samples, such as blood for sepsis diagnosis, necessitates assays capable of detecting numerous targets simultaneously.

Purpose of the Study:

• To develop a novel multiplex PCR screening assay that increases the number of detectable targets beyond the limitation of available fluorescent colors.
• To demonstrate the feasibility of using unique two-color combinations for probe identification to expand multiplexing capabilities.

Main Methods:

• Designed molecular beacon probes labeled with unique combinations of two fluorophores from a set of six distinguishable colors.
• Created a multiplex PCR assay incorporating 15 pairs of these dual-color probes, each specific for a bacterial 16S ribosomal RNA gene sequence.
• Performed real-time PCR using samples containing DNA from different bacterial species to assess probe performance.

Main Results:

• Each unique two-color combination accurately identified the specific bacterial target sequence present in the PCR assays.
• The assay demonstrated high specificity and sensitivity, attributed to the low background of molecular beacon probes.
• Threshold cycle values correlated with the abundance of the target bacterial DNA in the samples.

Conclusions:

• Utilizing dual-color fluorescent labeling significantly increases the multiplexing capacity of PCR screening assays.
• This innovative approach enables the simultaneous detection of a greater number of targets, with potential applications in rapid clinical diagnostics like sepsis identification.