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J Clin Microbiol. 2020 Feb 26. pii: JCM.01879-19. doi: 10.1128/JCM.01879-19. [Epub ahead of print]

Recombinase polymerase amplification and lateral flow assay for ultrasensitive detection of low-density Plasmodium falciparum infection from controlled human malaria infection studies and naturally acquired infections.

Author information

1
Institut für Tropenmedizin, Universität Tübingen and German Center for Infection Research, Tübingen, Germany.
2
Vietnamese - German Center of Excellence in Medical Research, Hanoi, Vietnam.
3
Centre de Recherches Médicales de Lambaréné and African Partner Institution, German Center for Infection Research, Lambaréné, Gabon.
4
Department of Parasitology, Leiden University Medical Center, Leiden, The Netherlands.
5
Department of Tropical Medicine, Bernhard Nocht Institute for Tropical Medicine and I. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
6
Sanaria Inc., Rockville, Maryland, USA.
7
Institut für Tropenmedizin, Universität Tübingen and German Center for Infection Research, Tübingen, Germany benjamin.mordmueller@uni-tuebingen.de.

Abstract

Microscopy and rapid diagnostic tests (RDTs) are the main diagnostic tools for malaria but fail to detect low-density parasitemia that are important for maintaining malaria transmission. To complement existing diagnostic methods, an isothermal reverse transcription recombinase polymerase amplification and lateral flow assay (RT-RPA) was developed. We compared the performance with ultrasensitive reverse transcription qPCR (RT-qPCR) using nucleic acid extracts from blood (n=114) obtained after standardized controlled human malaria infection (CHMI) with Plasmodium falciparum sporozoites. As a preliminary investigation, we also sampled asymptomatic individuals (n=28) in a malaria endemic area (Lambaréné, Gabon) to validate RT-RPA and assess its performance with unprocessed blood samples (dbRT-RPA). In 114 samples analyzed from CHMI-trials, the positive percent agreement to uRT-qPCR was 90% (95% CI: 80-96). The negative percent agreement was 100% (95% CI: 92-100). The lower limit of detection was 64 parasites/ml. In Gabon, RT-RPA was 100% accurate with asymptomatic volunteers (n=28) while, simplified dbRT-RPA showed 89% accuracy. In a subgroup analysis, RT-RPA detected 9/10 of RT-qPCR positive samples, while loop-mediated isothermal amplification (LAMP) detected 2/10. RT-RPA is a reliable diagnostic test for asymptomatic low-density infections. It is particularly useful in settings where uRT-qPCR is difficult to implement.

PMID:
32102854
DOI:
10.1128/JCM.01879-19

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