Figure 1. Stability of RNA and DNA stored in Norgen's Total Nucleic Acid Preservative. GAPDH (for DNA) and β-actin (for RNA) were monitored over an 18 week period for DNA and 60 days for RNA from swab samples stored at ambient temperature in Norgen’s Total Nucleic Acid Preservation Tubes. RNA was isolated from 250 µL of preserved swab samples on day 0, day 4, day 6, day 10, day 16, day 30 and day 60 using Norgen’s Total RNA Isolation Kit (Cat.# 17200). DNA was isolated from 250 µL of preserved swab samples on day 0 and 18 weeks using Norgen’s Saliva DNA Isolation Kit (Cat# Dx45400). Next, 4 µL of elution was used in a 20 µL real-time PCR reaction using CFX96 Touch™ Real-Time PCR Detection System (Bio-Rad). RNA can be stored in Norgen’s Total Nucleic Acid Preservative for up to 60 days and DNA can be stored for up to 18 weeks at room temperature with no change in quality and quantity of RNA and DNA.
Figure 2. Stability of RNA from different swab sample types stored in Norgen's Total Nucleic Acid Preservative. Amplification of the RNase Protein (RP) gene from 5 oropharyngeal swab samples and 5 nasopharyngeal swab samples purified using Norgen’s Total RNA Purification Kit were successfully validated from both swab sample types with high efficiency (<40 Ct.) by TaqMan One-Step RT-PCR.
Figure 3. Stability of DNA from different swab sample types stored in Norgen's Total Nucleic Acid Preservative. Amplification of the GAPDH gene from 5 oropharyngeal swab samples and from 5 nasopharyngeal swab samples purified using Norgen's Saliva DNA Isolation Kit were successfully validated from both swab sample types with high efficiency (<40 Ct.) by TaqMan PCR.
Figure 4. Inhibitory Effects of Norgen’s Total Nucleic Acid Preservative on the Growth of Bacteria, Yeast and Viruses. The effect of Norgen’s Total Nucleic Acid Preservative on the growth of microorganisms clearly demonstrated that Norgen’s preservative inhibits the growth of virus, bacteria and yeast, thereby resulting in non-infectious samples that can be handled and shipped safely.
Figure 5. Downstream Application of Preserved Swab RNA & DNA. The application of the RNA or DNA purified from preserved oropharyngeal swab samples was evaluated to detect RNase P (house keeping gene) and 16S rRNA (bacterial DNA) from swab samples collected from 60 donors and the preserved at room temperature overnight. Each individual swab sample contains different levels of cells, contributing to the variable Ct of each gene detection, but all passed the acceptance criteria for valid RT-PCR and PCR (< 35Ct, red line) in the 20 µL reaction, indicating that preserved swab RNA and DNA stored in Norgen’s Total Nucleic Acid Preservative is of high quality for downstream applications, such as real-time RT-PCR and PCR.
The tubes should be kept tightly sealed and stored at room temperature for up to 1 year without any reduction in performance (The collection due date is written on the device label and the kit box label).
Once collected, RNA is stable for up to 2 months and DNA is stable for up to 4 months when the tubes are kept tightly sealed and stored at room temperature.
