Comparison of non-magnetic and magnetic beads multiplex assay for assessment of Plasmodium falciparum antibodies

Bartholomew N Ondigo; Gregory S Park; Cyrus Ayieko; Donald D Nyangahu; Ronald Wasswa; Chandy C John

doi:10.7717/peerj.6120

Comparison of non-magnetic and magnetic beads multiplex assay for assessment of Plasmodium falciparum antibodies

PeerJ. 2019 Jan 3:7:e6120. doi: 10.7717/peerj.6120. eCollection 2019.

Authors

Bartholomew N Ondigo^{1

2}, Gregory S Park³, Cyrus Ayieko⁴, Donald D Nyangahu^{5

6}, Ronald Wasswa⁷, Chandy C John^{2

8}

Affiliations

¹ Department of Biochemistry and Molecular Biology, Egerton University, Nakuru, Kenya.
² Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya.
³ Office of the Vice President for Research, University of Minnesota, Minneapolis, MN, USA.
⁴ Department of Zoology, Maseno University, Kisumu, Kenya.
⁵ Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, USA.
⁶ Department of Pediatrics, University of Washington, Seattle, WA, USA.
⁷ Global Health Uganda, Kampala, Uganda.
⁸ Ryan White Center for Pediatric Infectious Diseases and Global Health, Indiana University School of Medicine, Indianapolis, IN, USA.

Abstract

Background: New reagents have emerged allowing researchers to assess a growing number of vaccine-associated immune parameters. Multiplex immunoassay(s) are emerging as efficient high-throughput assays in malaria serology. Currently, commercial vendors market several bead reagents for cytometric bead assays (CBA) but relative performances are not well published. We have compared two types of bead-based multiplex assays to measure relative antibody levels to malarial antigens.

Methods: Assays for the measurement of antibodies to five Plasmodium falciparum vaccine candidates using non-magnetic and magnetic fluorescent microspheres were compared for their performances with a Bio-Plex²⁰⁰ instrument. Mean fluorescence intensity (MFI) was determined from individuals from western Kenya and compared to known positive and negative control plasma samples.

Results: P. falciparum recombinant antigens were successfully coupled to both non-magnetic and magnetic beads in multiplex assays. MFIs between the two bead types were comparable for all antigens tested. Bead recovery was superior with magnetic beads for all antigens. MFI values of stored non-magnetic coupled beads did not differ from freshly coupled beads, though they showed higher levels of bead aggregation.

Discussion: Magnetic and non-magnetic beads performed similarly in P. falciparum antibody assays. Magnetic beads were more expensive, but had higher bead recovery, were more convenient to use, and provided rapid and easy protocol manipulation. Magnetic beads are a suitable alternative to non-magnetic beads in malarial antibody serology.

Keywords: Bio-Plex; Magnetic; Multiplex; Non-magnetic; Plasmodium falciparum antigens.

Grants and funding

This work was supported by grants from the National Institute of Allergy and Infectious Disease (U01 AI056270) to CCJ, Fogarty International Center (D43 TW0080085) to BNO, and Fogarty International Center, National Institute of Mental Health, and NIH Office of the Director, Office of Women’s Health and Office of Aids Research (R25 TW009345) to BNO. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.