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MicroRNAs (miRNAs) are short RNAs that regulate the expression of complementary messenger RNAs and are involved in numerous human diseases. However, current detection techniques lack the sensitivity to detect miRNAs of low abundance. Moreover, at a length of 20-25 bases, miRNAs are too short for the reverse transcription (RT) polymerase chain reaction (PCR). Here we have developed a new, rapid, and simple miRNA detection system utilizing an RT primer containing a DNA tag at the 5'-end to increase the length of the cDNA. This strategy increases the length of the hybridized tagged primer and the complementary template DNA, as well as the melting temperature of the primer⋅template DNA duplex. PCR efficiency is thus increased, thereby enhancing miRNA detection sensitivity., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A molecular diagnostic platform with DANP-anchored hairpin primer was developed and evaluated for the rapid and cost-effective detection of Chikungunya virus (CHIKV) with high sensitivity and specificity. The molecule 2, 7-diamino-1, 8-naphthyridine (DANP) binds to a cytosine-bulge and emits fluorescence at 450 nm when it is excited by 400 nm light. Thus, by measuring the decline in fluorescence emitted from DANP-primer complexes after PCR reaction, we could monitor the PCR progress. By adapting this property of DANP, we have previously developed the first generation DANP-coupled hairpin RT-PCR assay. In the current study, we improved the assay performance by conjugating the DANP molecule covalently onto the hairpin primer to fix the DANP/primer ratio at 1:1; and adjusting the excitation emission wavelength to 365/430 nm to minimize the background signal and a 'turn-on' system is achieved. After optimizing the PCR cycle number to 30, we not only shortened the total assay turnaround time to 60 minutes, but also further reduced the background fluorescence. The detection limit of our assay was 0.001 PFU per reaction. The DANP-anchored hairpin primer, targeting nsP2 gene of CHIKV genome, is highly specific to CHIKV, having no cross-reactivity to a panel of other RNA viruses tested. In conclusion, we report here a molecular diagnostic assay that is sensitive, specific, rapid and cost effective for CHIKV detection and can be performed where no real time PCR instrumentation is required. Our results from patient samples indicated 93.62% sensitivity and 100% specificity of this method, ensuring that it can be a useful tool for rapid detection of CHIKV for outbreaks in many parts of the world., Competing Interests: The authors have declared that no competing interests exist.

Chikungunya has re-emerged as an important arboviral infection of global health significance. Because of lack of a vaccine and effective treatment, rapid diagnosis plays an important role in early clinical management of patients. In this study, we have developed a novel molecular diagnostic platform that ensures a rapid and cost-effective one-step RT-PCR assay, with high sensitivity and specificity, for the early detection of the Chikungunya virus (CHIKV). It uses 2,7-diamino-1,8-naphthyridine derivative (DANP)-labeled cytosine-bulge hairpin primers to amplify the nsP2 region of the CHIKV genome, followed by measurement of the fluorescence emitted from DANP-primer complexes after PCRs. The detection limit of our assay was 0.01 plaque-forming units per reaction of CHIKV. Furthermore, the HP-nsP2 primers were highly specific in detecting CHIKV, without any cross-reactivity with the panel of RNA viruses validated in this study. The feasibility of the DANP-coupled hairpin RT-PCR for clinical diagnosis was evaluated using clinical serum samples from CHIKV-infected patients, and the specificity and sensitivity were 100% (95% CI, 80.0% to 100%) and 95.5% (95% CI, 75.1% to 99.8%), respectively. These findings confirmed its potential as a point-of-care clinical molecular diagnostic assay for CHIKV in acute-phase patient serum samples., (Copyright © 2013 American Society for Investigative Pathology and the Association for Molecular Pathology. Published by Elsevier Inc. All rights reserved.)

The study demonstrates an advanced method—reverse transcription-hairpin-probe-polymerase chain reaction (RT-Hpro-PCR)—to specifically and efficiently identify miRNAs that differ even by one base. The technique developed here could help uncover the unprecedented opportunity to understand the normal biological processes of miRNAs and their roles in the development of disease. [Display omitted] • MicroRNAs (miRNAs) in the same family have similar sequences and are hard to identify. • Reverse transcription-hairpin-probe-polymerase chain reaction (RT-Hpro-PCR) reported. • RT-Hpro-PCR uses an RT primer with a DNA tag to detect miRNAs with similar sequences. • RT-Hpro-PCR can precisely detect miRNAs with similar sequences. • This technique may help explore the roles of miRNAs in several biological processes. MicroRNAs (miRNAs) belonging to the same family have similar sequences and are difficult to identify. Herein, we report the reverse transcription-hairpin-probe-polymerase chain reaction (RT-Hpro-PCR) technique, which utilises a reverse transcription (RT) primer containing a 5′-end deoxyribonucleic acid (DNA) tag, to detect miRNAs with similar sequences. This strategy follows a two-step RT-PCR method using 6–7-mer RT-primers with a ~ 10-mer tag sequence at the 5′-end and a probe with a hairpin structure (Hpro), including two C-bulges, attached. The findings demonstrate that the specificity of RT could be increased by shortening the complementary part of the RT primer containing a different base, wherein the PCR could successfully progress with the use of 5′-end DNA tag because of an increase in the length of the hybridised tagged primer. This study shows the potential of RT-Hpro-PCR to precisely detect miRNAs with similar sequences, which could help explore the roles of miRNAs in several biological processes. [ABSTRACT FROM AUTHOR]

Abstract: We developed a novel single-step virus detection system using the fluorescent molecule with a hairpin primer on the reverse transcription (RT)-polymerase chain reaction (PCR). Primers that are specific to Hepatitis C virus (HCV) having a hairpin tag at the 5′-end were used for RT and PCR. The HCV-RNA template was reverse transcribed by reverse transcriptase with the hairpin primer (HP), and the resulting cDNA was amplified directly by HP-PCR (RT-HP-PCR). Using the RT-HP-PCR, we succeeded in demonstrating the detection of HCV-RNA in single-step. The RT-HP-PCR selectively detected HCV-RNA extracted from patients’ sera containing contaminant materials. The method could be applicable to the quantitative detection of HCV. [Copyright &y& Elsevier]