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xMAP® Assays Reveal More About Immune Response than Traditional Vaccine ELISAs

May 30th, 2018 / Hilary Graham

Serotype-specific assays pinpoint threshold values missed by standard tests

If you use ELISAs to test immunological responses, Siân Faustini from the University of Birmingham has this advice: “Serotype-specific assays are the way to go.” In her 20-minute webinar presentation from xMAP® Connect 2017, “Exploring immunological assays to assess responses to pneumococcal polysaccharide and conjugate vaccines in HIV,” Faustini shares data from a research study of pneumococcal vaccination response using both Luminex bead-based assays and traditional ELISAs.

Assessing Individual Serotypes

Among the most eye-opening parts of the presentation was Faustini’s finding that traditional vaccine response assays were not carefully assessing individual serotypes, which she had measured one by one using xMAP® Technology research reagents. “When our serotype data was compared with the whole PCP IgG assay, 36.4% of patients that were deemed protected by the whole PCP IgG assay had a significant number of serotypes that failed to reach threshold,” she reported. “What that’s saying is that the whole PCP IgG assay is actually misdiagnosing patients if you’re comparing it to the pneumococcal specific IgG assays.”

Multiplexed Bead Approach

To complete this work, Faustini developed serotype-specific assays with xMAP Technology and conjugated the Pneumovax-23 and Prevenar-13 vaccines to beads for a multiplexed approach. Luminex-based assays measured total antibodies for IgG, IgG1, IgG2, IgG3, and IgG4 from 50 HIV patient serum samples to 11 different serotypes. In the webinar, she reported, “The subclass analysis offers a further understanding of the IgG response to different vaccines and also shows the granularity of the response because it’s very different for each serotype.” Her analysis included both absolute values and fold changes, which showed different patterns.

In addition, Faustini presented “tips and tricks” for using Luminex-based multiplex assays. She recommends daily calibration, sonicating the needle before and after use, and monthly validation of the machine and needles. For more data and advice, check out the full webinar.

The presentation is supplied by the presenter listed and is not endorsed by Luminex Corporation.

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