Novel pan-serotype control RNA for dengue virus typing through real-time reverse transcription-polymerase chain reaction

Usefulness of an in vitro-transcribed RNA control for the detection and quantification of Yellow fever virus through real-time reverse transcription-polymerase chain reaction

INTRODUCTION

Unvaccinated individuals in endemic areas with proven enzootic transmission of Yellow fever virus are at risk of infection due to a dramatic shift in the epidemiology of the disease over recent years. For this reason, epidemiological surveillance and laboratory confirmation of cases have become mandatory.

OBJECTIVE

To develop and test a control RNA for YFV detection through real-time RT-PCR.

METHODS

A 437-bp insert containing the T7 promoter and the target sequences for two different in-house protocols was designed in the context of the pUC57 vector and obtained through gene synthesis. After T7-driven in vitro transcription, standard curves were developed for Log10 serial dilutions of the YFV control RNA with 8 replicates.

RESULTS

A dynamic range of quantification of 10 orders of magnitude was observed with a limit of detection of 6.3 GCE/µL (95% CI, 2.6 to 139.4 GCE/µL).

CONCLUSION

The plasmid construct is available for YFV molecular test validation on clinical, entomological, and epizootic samples.

Rapid Differential Detection of Japanese Encephalitis Virus and Getah Virus in Pigs or Mosquitos by a Duplex TaqMan Real-Time RT-PCR Assay

Both JEV (Japanese encephalitis virus) and GETV (Getah virus) pose huge threats to the safety of animals and public health. Pigs and mosquitoes play a primary role in JEV and GETV transmission. However, there is no way to quickly distinguish between JEV and GETV. In this study, we established a one-step duplex TaqMan RT-qPCR for rapid identification and detection of JEV and GETV. Primers and probes located in the NS1 gene of JEV and the E2 gene of GETV that could specifically distinguish JEV from GETV were selected for duplex TaqMan RT-qPCR. In duplex real-time RT-qPCR detection, the correlation coefficients (R2) of the two viruses were higher than 0.999. The RT-qPCR assay demonstrated high sensitivity, extreme specificity, and excellent repeatability. Detection of JEV and GETV in field mosquito and pig samples was 100 times and 10 times more sensitive than using traditional PCR, respectively. In addition, the new test took less time and could be completed in under an hour. Clinical sample testing revealed the prevalence of JEV and GETV in mosquitoes and pig herds in China. This complete duplex TaqMan RT-qPCR assay provided a fast, efficient, specific, and sensitive tool for the detection and differentiation of JEV and GETV.

An updated RT-qPCR assay for the simultaneous detection and quantification of chikungunya, dengue and zika viruses

The real-time reverse transcription-polymerase chain reaction (real-time RT-qPCR) has become a leading technique for the detection and quantification of arboviruses, including Chikungunya, Dengue, and Zika viruses. In this study, an updated real-time RT-qPCR assay was designed and evaluated together with a synthetic positive-control chimeric RNA for the simultaneous detection and quantification of Chikungunya, Dengue, and Zika viruses. Amplification assays were performed to verify the construct integrity and optimal reaction/thermal cycling conditions. The analytical sensitivity of the assay was determined for each virus in single and multiplex reactions, as well as the performance in the detection and viral load quantification of experimental samples. The real-time RT-qPCR assay presented here allowed for the simultaneous detection and quantification of Chikungunya, Dengue, and Zika viruses and could be applied in several studies where the accurate quantification of viral genomes is required.