Development of a Rapid and Highly Sensitive Nucleic Acid Based Diagnostic Test for Schistosomes, Leveraging on Identical Multi-Repeat Sequences
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Date
2024-03
Authors
Ally, Ombeni
Kanoi, Bernard N.
Kamath, Shwetha
Shiluli, Clement
Ndombi, Eric M.
Odiere, Maurice
Misinzo, Gerald
Ger Nyanjom, Steven
Kumar, Chunduri Kiran
Ochola, Lucy
Journal Title
Journal ISSN
Volume Title
Publisher
Frontiers in Parasitology
Abstract
Introduction: Schistosomiasis (Bilharzia), a neglected tropical disease caused by
Schistosoma parasites, afflicts over 240 million people globally,
disproportionately impacting Sub-Saharan Africa. Current diagnostic tests,
despite their utility, suffer from limitations like low sensitivity. Polymerase chain
reaction (PCR) and quantitative real-time PCR (qPCR) remain the most common
and sensitive nucleic acid amplification tests. Still, the sensitivity of nucleic acid
amplification tests is significantly affected by the copy number of amplification
targets, resulting in underestimation of true Schistosoma infections, especially in
low transmission settings. Additionally, lengthy qPCR run times pose challenges
when dealing with large sample volumes and limited resources. In this study, the
identical multi-repeat sequences (IMRS) were used as a novel approach to
enhance the sensitivity of nucleic acid-based Bilharzia diagnosis.
Methods: To identify novel genomic repeat regions, we utilized the IMRS
algorithm, with modifications to enable larger target region (100-200bp)
identification instead of smaller sequences (18-30bp). These regions enabled
customised primer-probe design to suit requirements for qPCR assay. To lower
the qPCR amplification times, the assay was conducted using fast cycling
condition. Regression analysis, and qPCR data visualization was conducted
using Python programming.
Results: Using Schistosoma mansoni and S. haematobium, we found that IMRSbased qPCR, employing genus-specific primers and TaqMan probes, offers exceptional analytical sensitivity, detecting as little as a single genome copy per
microliter within 36 minutes.
Discussion: The lowest concentration of DNA detected using IMRS-based PCR
and qPCR represented tenfold improvement over conventional PCR. As part of
further development, there is a need to compare IMRS-based qPCR against other
qPCR methods for Schistosoma spp. Nonetheless, IMRS-based diagnostics
promise a significant advancement in bilharzia diagnosis, particularly in lowtransmission settings, potentially facilitating more effective control and
treatment strategies.
Description
Article
Keywords
Schistosoma mansoni, Schistosoma haematobium, schistosomiasis, PCR, qPCR, IMRS
Citation
Ally, O., Kanoi, B. N., Kamath, S., Shiluli, C., Ndombi, E. M., Odiere, M., ... & Gitaka, J. (2024). Development of a rapid and highly sensitive nucleic acid-based diagnostic test for schistosomes, leveraging on identical multi-repeat sequences. Frontiers in Parasitology, 3, 1361493.