• Extremely active at high temperatures (55 °C to 80 °C): Improves specificity of cDNA Synthesis from diverse RNA templates
• Sensitive: Detects 100 copies of RNA in two-step RT-qPCR assays
• Short reaction time (5 minutes or less): Streamlined RT-qPCR workflow and faster time to results
• Stable at room temperature (> 3 months): Simplifies setup on automation decks (no cold storage required) and enables use in environments with limited cold-storage
• Lyo-compatible: Enzyme formulation is free of glycerol -and other components- that are known to interfere with downstream lyophilisation
• Batch to batch reproducibility: Manufactured in an ISO 13485-certified facility

RapiDxFire Thermostable Reverse Transcriptase is a significant advancement over popular MMLV- and AMV reverse transcriptases. Originally identified in hot springs, this robust bacteriophage enzyme exhibits increasingly high activity at elevated temperatures (~60% activity remains after 10 min at 90 °C) and maintains its core activity after >3 months storage at 20-25°C. This enzyme lacks RNAse H and 3’ 5’ exonuclease activity and efficiently synthesises short cDNA fragments (≤ 1 Kb). Like other reverse transcriptases, RapiDxFire RT possesses DNA polymerase activity but lacks 5′ 3′ exonuclease activity. Supplied in a glycerol-free, Triton™ X-100-free storage buffer, the enzyme formulation can be further optimised for downstream lyophilisation.

Figure 1. Reaction temperature profile for RapiDxFire Thermostable Reverse Transcriptase. Reverse transcription reactions were set up on ice using each manufacturer’s recommended buffer system and Poly (rC) /p(dG)12-18 template/primer substrate. Reactions were transferred from ice to the indicated temperatures (37, 50, 55, 60, 65, 70, 75, and 80 °C) and incubated for 40 minutes. Following incubation, RNA/cDNA heteroduplex product is quantified as a measure of polymerisation activity, utilising PicoGreen® fluorescence on a Tecan Infinite® M1000 Pro. RapiDxFire Thermostable RT exhibits increasing activity as the reaction temperature is increased, up to 80 °C (highest temperature tested); ~60% activity remains after 10 min at 90 °C (data not shown).

Figure 2. cDNA synthesis time course studies in a 2-step RT-qPCR reaction with different thermostable RTs. A) qPCR curve after a 1 minute reverse transcription reaction. Zika cDNA synthesis was conducted for each enzyme in duplicate using target-specific primers and recommended reaction buffer and incubation temperatures per suppliers’ guidelines (RapiDxFire= 60 °C, Supplier B= 50 °C, and Supplier T= 55 °C). After cDNA synthesis real time PCR was performed using one-tenth volume of each of the cDNA samples. PCR was performed using EconoTaq and its supplied buffer (Item No. 30031-3). Detection of PCR products were done real time using an intercalating dye (Dyomics Cat No. V13-01184) and BioRad CFX C1000 Touch™ with absorption/emission of 481nm/526nm. B) Reverse transcription time course study prior to performing second-step real-time PCR. Encircled data points are derived from data represented in the qPCR curve in A).

Figure 3. RapiDxFire Thermostable RT was stored in separate aliquots per time point at ambient and -20 °C. At each time point RapiDxFire Thermostable RT was evaluated by measuring first-strand cDNA synthesis of 10000 copies MS2 RNA. cDNA synthesis was carried out using a gene-specific primer for MS2 at reaction temperature of 60 °C for 5 minutes. cDNA was measured using real time PCR and MS2 primers design around a 520 base pair amplicon.

Legal Information/Updates:
US Patent 8093030 for RapiDxFire™ is owned by LGC, Biosearch Technologies. For research use only. Not for use in diagnostic procedures.