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- Title
Field-Evaluation of a New Lateral Flow Assay for Detection of Cellular and Humoral Immunity against Mycobacterium leprae.
- Authors
Bobosha, Kidist; Tjon Kon Fat, Elisa M.; van den Eeden, Susan J. F.; Bekele, Yonas; van der Ploeg-van Schip, Jolien J.; de Dood, Claudia J.; Dijkman, Karin; Franken, Kees L. M. C.; Wilson, Louis; Aseffa, Abraham; Spencer, John S.; Ottenhoff, Tom H. M.; Corstjens, Paul L. A. M.; Geluk, Annemieke
- Abstract
Background: Field-applicable tests detecting asymptomatic Mycobacterium leprae (M. leprae) infection or predicting progression to leprosy, are urgently required. Since the outcome of M. leprae infection is determined by cellular- and humoral immunity, we aim to develop diagnostic tests detecting pro-/anti-inflammatory and regulatory cytokines as well as antibodies against M. leprae. Previously, we developed lateral flow assays (LFA) for detection of cytokines and anti-PGL-I antibodies. Here we evaluate progress of newly developed LFAs for applications in resource-poor settings. Methods: The combined diagnostic value of IP-10, IL-10 and anti-PGL-I antibodies was tested using M. leprae-stimulated blood of leprosy patients and endemic controls (EC). For reduction of the overall test-to-result time the minimal whole blood assay time required to detect distinctive responses was investigated. To accommodate LFAs for field settings, dry-format LFAs for IP-10 and anti-PGL-I antibodies were developed allowing storage and shipment at ambient temperatures. Additionally, a multiplex LFA-format was applied for simultaneous detection of anti-PGL-I antibodies and IP-10. For improved sensitivity and quantitation upconverting phosphor (UCP) reporter technology was applied in all LFAs. Results: Single and multiplex UCP-LFAs correlated well with ELISAs. The performance of dry reagent assays and portable, lightweight UCP-LF strip readers indicated excellent field-robustness. Notably, detection of IP-10 levels in stimulated samples allowed a reduction of the whole blood assay time from 24 h to 6 h. Moreover, IP-10/IL-10 ratios in unstimulated plasma differed significantly between patients and EC, indicating the feasibility to identify M. leprae infection in endemic areas. Conclusions: Dry-format UCP-LFAs are low-tech, robust assays allowing detection of relevant cytokines and antibodies in response to M. leprae in the field. The high levels of IP-10 and the required shorter whole blood assay time, render this cytokine useful to discriminate between leprosy patients and EC. Author Summary: Leprosy is one of the six diseases considered by WHO as a major threat in developing countries and often results in severe, life-long disabilities and deformities due to delayed diagnosis. Early detection of Mycobacterium leprae (M. leprae) infection, followed by effective interventions, is considered vital to interrupt transmission. Thus, field-friendly tests that detect asymptomatic M. leprae infection are urgently required. The clinical outcome after M. leprae infection is determined by the balance of pro- and anti-inflammatory cytokines and antibodies in response to M. leprae. In this study, we developed lateral flow assays (LFA) for detection of pro-inflammatory (IP-10) vs. anti-inflammatory/regulatory (IL-10) cellular immunity as well as antibodies against M. leprae and evaluated these in a field setting in Ethiopia using lightweight, portable readers. We show that detection of IP-10 allowed a significant reduction of the overall test-to-result time from 24 h to 6 h. Moreover, IP-10/IL-10 ratios in unstimulated plasma differed significantly between patients and EC, which can provide means to identify M. leprae infection. Thus, the LFAs are low-tech, robust assays that can be applied in resource-poor settings measuring immunity to M. leprae and can be used as tools for early diagnosis of leprosy leading to timely treatment and reduced transmission.
- Subjects
ETHIOPIA; MYCOBACTERIUM leprae; HUMORAL immunity; CELLULAR immunity; MYCOPLASMA pneumoniae infections; ENDEMIC diseases; ANTIBODY formation; MOUTH; B cells
- Publication
PLoS Neglected Tropical Diseases, 2014, Vol 8, Issue 5, p1
- ISSN
1935-2727
- Publication type
Article
- DOI
10.1371/journal.pntd.0002845