Development of a bio-inkjet printed LAMP test kit for detecting human African trypanosomiasis

Human African trypanosomiasis (HAT) is one of the neglected tropical diseases in sub-Saharan Africa. Early diagnosis and treatment prior to disease progression are crucial for the survival of HAT patients. We had previously established a loop-mediated isothermal amplification (LAMP) method for HAT diagnosis in which the reagents were dried for field-use purposes. In this study, we used a semi-automated process to produce the test tubes using a bio-inkjet printer to achieve an accurate production. The performance of the inkjet printer-produced dried LAMP test (CZC-LAMP) was found to be stable after storage for up to 180 days at 30 degrees C. The diagnostic accuracy of CZC-LAMP HAT was evaluated using DNA samples that were extracted from 116Trypanosoma brucei gambiensepatients and 66T.b.rhodesiensepatients. The sensitivity was 72% forT.b.gambiense(95%CI: 63%-80%) and 80% forT.b.rhodesiense(95%CI: 69%-89%). The specificity determined using DNA from 116 endemic control DNA samples was 95% (95%CI: 89%-98%). The performance of the CZC-LAMP HAT and CZC-LAMP rHAT were also evaluated using 14 crude blood lysate samples obtained fromT.b.rhodesiensepatients and endemic control samples collected from Rumphi District in Malawi. The sensitivity and specificity were both 100% (95%CI: 77%-100%). As the developed CZC-LAMP test does not require a cold chain or a sophisticated laboratory, it holds promise for use as a routine simple molecular tool for point-of-care HAT diagnosis in endemic areas. Author summary Nucleic acid amplification methods allow for a sensitive detection and specific identification of a number of pathogens, includingTrypanosomaparasites that cause human African trypanosomiasis (HAT). However, conventional molecular tools such as the polymerase chain reaction (PCR) are highly resource-demanding and time-consuming and are seldom used in HAT-endemic countries. The loop-mediated isothermal amplification method (LAMP) provides a promising alternative to the conventional PCR, as this technique can amplify nucleic acids under isothermal conditions using minimal resources within one hour. In this study, we established a protocol to produce a dried-format LAMP kit for the diagnosis of HAT, that used a bio-ink-jet printer machine. The produced test kit (CZC-LAMP HAT and CZC-LAMP rHAT) was determined to be stable for up to 180 days at room temperature. The test provided a good performance for the detection of the trypanosome parasites using both DNA and crude blood samples, and the test results were comparable to those obtained from PCR. The findings from this study suggest that the dried LAMP test can be useful for the diagnosis of HAT, particularly in areas where laboratory resources are limited.