Fluorescent multivalent opsonophagocytic assay for measurement of functional antibodies to Streptococcus pneumoniae

Area of Science:

• Microbiology
• Immunology
• Assay Development

Background:

• Streptococcus pneumoniae causes significant global disease burden.
• Accurate serotyping is crucial for vaccine development and efficacy assessment.
• Existing methods for opsonophagocytic assays can be time-consuming and labor-intensive.

Purpose of the Study:

• To develop and validate novel fluorescent opsonophagocytic assays (fOPA and fmOPA) for Streptococcus pneumoniae.
• To enable simultaneous detection of multiple serotypes.
• To improve the efficiency and reduce the workload of pneumococcal serotyping.

Main Methods:

• Development of fluorescent mono- and multivalent opsonophagocytic assays (fOPA and fmOPA).
• Specific targeting of seven Streptococcus pneumoniae serotypes (4, 6B, 9V, 14, 18C, 19F, and 23F).
• Quantification of bacterial survival using alamar blue, a fluorescent metabolic indicator.

Main Results:

• Both fOPA and fmOPA demonstrated high agreement with the reference method for determining viability endpoints.
• The multivalent assay (fmOPA) effectively eliminated the need for colony counting.
• The fmOPA significantly reduced serum volume requirements and yielded results within 1 day.

Conclusions:

• Fluorescent opsonophagocytic assays provide a reliable and efficient method for Streptococcus pneumoniae serotyping.
• The multivalent assay (fmOPA) offers a streamlined, high-throughput alternative to traditional methods.
• These assays are valuable tools for pneumococcal research, vaccine evaluation, and diagnostics.