A multiplex real-time PCR for identifying and differentiating B. anthracis virulent types

Area of Science:

• Microbiology
• Molecular Biology
• Infectious Diseases

Background:

• Bacillus anthracis, the causative agent of anthrax, is closely related to Bacillus cereus and Bacillus thuringiensis.
• Accurate differentiation between these species is crucial for the detection of the life-threatening pathogen B. anthracis.
• Existing methods may lack the specificity or multiplexing capability required for rapid and reliable identification.

Purpose of the Study:

• To develop and validate a novel multiplex real-time PCR assay.
• To enable simultaneous specific identification of B. anthracis.
• To discriminate between different B. anthracis virulence types and closely related species.

Main Methods:

• Whole genome comparison was used to select specific B. anthracis markers.
• Primers and probes were designed for multiplex detection of B. anthracis chromosome, pXO1 and pXO2 plasmids, and an internal control.
• Assay validation involved testing against diverse B. anthracis strains, exclusivity testing with B. cereus, and inter-laboratory evaluation on multiple real-time PCR thermocyclers.

Main Results:

• The multiplex real-time PCR assay successfully identified all tested B. anthracis strains, including those from various global locations and a recent outbreak.
• The assay demonstrated high specificity, effectively distinguishing B. anthracis from genetically similar species like B. cereus.
• Robustness was confirmed through inter-laboratory validation across different countries and equipment.

Conclusions:

• The developed multiplex real-time PCR is a robust and accurate tool for the specific identification of B. anthracis.
• The assay effectively differentiates B. anthracis virulence types and distinguishes it from closely related Bacillus species.
• This method provides a reliable diagnostic approach for anthrax detection and surveillance.