EvaGreen-based real-time PCR assay for sensitive detection of salmonid alphavirus

Development of a rapid and sensitive reverse transcription real-time quantitative PCR assay for detection and quantification of grass carp reovirus II

Hemorrhagic disease of grass carp, which is induced by grass carp reovirus II (GCRV-II), leads to mass mortality in grass carp culture and causes enormous economic loss. However, there is currently no quantitative analysis method for the detection of GCRV-II, which is greatly restricted the etiological and epidemiological study of the disease. In this study a reverse transcription TaqMan PCR (RT-qPCR) assay was developed for the quantitative detection of GCRV-II. The probe and primers targeted location is the segment 6 (S6) region of the GCRV-II genome which is highly conserved. Standard curves were drawn and criteria were confirmed after the determination of the optimum reaction conditions. The species-specific assay showed that the method is highly specific and has no cross reactions with other pathogens. The assay was sufficiently sensitive to detect as low as 10 copies of virus RNA. Moreover, the method has a very good repeatability for batches and inter-batches sample detection. Then the method was applied to detect the virus in tissue samples from clinically infected grass carp, compared with conventional RT-seminested PCR, the RT-qPCR represents a specific value for detection rate of positive samples. In summary, the RT-qPCR was applied and achieved high sensitivity and specificity for GCRV-II detection.

Development of a TaqMan Based Real-Time Fluorescent Quantitative PCR Assay for Detection of Porcine Cytomegalovirus in Semen

This study described a TaqMan based real-time fluorescent quantitative PCR (qPCR) method to detect porcine cytomegalovirus (PCMV) infection, targeting the conserved region of the DNA polymerase (DPOL) gene. The standard curve showed a linear regression relationship with a coefficient of 0.999 and a slope of y = -3.249x + 38.958 corresponding to the amplification efficiency at 99.8%. The limit of the qPCR method was 51.9 copies/μl. The established qPCR method showed excellent specificity, with no cross-reaction observed with common porcine pathogens. The coefficient of variation for intra-assay and interassay variability ranged up to 1.51% and 2.24%, respectively. PCMV positive signals can be found in semen using this qPCR method, which suggested that we should pay more attention to PCMV contamination in semen in order to eliminate PCMV infection in artificial insemination and xenotransplantation.

EvaGreen-based real-time PCR assay for sensitive detection of enzootic nasal tumor virus 2

Enzootic nasal tumor virus 2 (ENTV-2), the aetiological agent of enzootic nasal adenocarcinoma in goats, is prevalent in China; resulting in substantial economic losses to the goat-breeding industry. Therefore, it is necessary to establish an efficient detection method for the diagnosis and prevention of ENTV-2 infection. More recently, EvaGreen is emerging as a novel alternative fluorescent dye for quantitative real-time PCR because of its low cost, specific amplification and high resolution. In this study, we developed a specific, sensitive, and cost-effective detection method-an EvaGreen-based real-time PCR assay for the detection of ENTV-2. This assay exhibited high specificity and sensitivity and was able to detect ENTV-2 at concentrations as low as 3.0 × 10¹ copies, which was more sensitive than the conventional PCR method (detection limit, 3.0 × 10² copies). In addition, the reproducibility test indicated that EvaGreen dye in our assay had a good reproducibility. In conclusion, we report that a highly sensitive, specific, and cost-effective EvaGreen-based real-time PCR assay is successful for the rapid detection of ENTV-2.