Abstract
Human enterovirus 71 (EV71) is the major causative agent of hand, foot, and mouth disease (HFMD) worldwide and has been associated with neurological complications which resulted in fatalities during recent outbreak in Asia pacific region. A direct reverse transcription loop-mediated isothermal amplification (direct RT-LAMP) assay using heat-treated samples without RNA extraction was developed and evaluated for the detection of EV71 subgenotype C4 in nasopharyngeal swab specimens. The analytical sensitivity and specificity of the direct RT-LAMP assay were examined. The detection limit of the direct RT-LAMP assays was 1.6 of a 50% tissue culture infective dose (TCID50) per reaction and no cross-reaction was observed with control viruses including Cosackievirus A (CVA) viruses (CVA2,4,5,7,9,10,14,16, and 24), Coxsackievirus B (CVB) viruses (CVB1,2,3,4, and 5) or ECHO viruses (ECHO3,6,11, and 19). The direct RT-LAMP assay was evaluated and compared to both RT-LAMP and quantitative real-time PCR (qRT-PCR) in detecting EV71 infection with 145 nasopharyngeal swab specimens. The clinical performance demonstrated the sensitivity and specificity of direct RT-LAMP was reported to be 90.3% and 100% respectively, compared to RT-LAMP, and 86.83% and 100% respectively, compared to qRT-PCR. These data demonstrated that the direct RT-LAMP assay can potentially be developed for the point of care screening of EV71 infection in China.
Highlights
Human enteroviruses (HEV) comprise more than 100 serotypes in four species (HEV-A to HEV-D) in the genus Enterovirus, family Picornaviridae
No crossreaction was observed with control viruses including Cosackievirus A (CVA) viruses (CVA2,4,5,7,9,10,14,16, and 24), Coxsackievirus B(CVB) viruses (CVB1,2,3,4, and 5) or ECHO viruses (ECHO3,6,11, and 19) for both RT-Loop-mediated isothermal amplification (LAMP) and direct RT-LAMP assays
Rapidity and simplicity of the methods for the enterovirus 71 (EV71) detection are critical for community hospital laboratory or field use, RTLAMP assays with RNA extraction for the rapid diagnosis of EV71 infection have been reported previously [11,12,13,14]
Summary
Human enteroviruses (HEV) comprise more than 100 serotypes in four species (HEV-A to HEV-D) in the genus Enterovirus, family Picornaviridae. Routine methods for EV71 detection are virus isolation, neutralization, and quantitative real time PCR (qRT-PCR) [1,2,3]. A few commercial qRT-PCR diagnostic kits for EV71 are available and approved by the State Food and Drug Administration of China and have been widely used in Center for disease control and prevention (CDC) of provincial and municipal regions in China for HFMD pathogens surveillance. These methods either are with low specificity and sensitivity (virus isolation and neutralization) or need large expense for equipments and a relative long reaction time (qRT-PCR)
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