Q3 What Organisms Have Reverse Transcriptase
Answer: The enzyme RT is present in many organisms such as plants, animals, bacteria and viruses. The enzyme RT role is to convert an RNA sequence to a cDNA sequence. It is general in all organisms. The specific functions of RT include:
Diversity of eukaryotic mobile transposons or retrotransposons
Replication or synthesis of telomeres
Synthesis of multi-copy single-stranded DNA , extrachromosomal DNA/RNA and chimeric elements.
Q8 What Is The Difference Between Qpcr And Rt
Answer: both the techniques are inter-related and utilized to produce/amplify DNA copies. RT-PCR amplifies the RNA codes reverse transcription, while Q-PCR measures the amplification process. Q-PCR is for quantification, while RT-PCR is for amplifications. Q-PCR is quantitative, while RT-PCR is non-quantitative in nature.
What Is The Function Of Reverse Transcriptase
Reverse transcriptase is an RNA dependent DNA polymerase . The RT identifies and binds the RNA to synthesize single stood RNA . After synthesizing the cDNA, RT cleaves the RNA and start synthesizing double-stranded DNA .
reverse transcriptase has two active sites to perform two separate functions:
Polymerase active site: it comprises two finger-like domains one domain can identify the RNA and forms hydrogen bonds with phosphate groups by using side chains.
Hydrogen bond formation brings about the conformational changes and facilitates the closure of the recognition hole this results in the start of the transcription process with the help of the second domain magnesium ions.
The flexible zone governs the conformational change process this flexible zone is present between the polymerase active site domains. It is often considered a target site to inhibit RT activity during biochemical and pharmacological studies. The amino acid sequence present in the flexible zone is not conserved , which enables the virus to develop resistance.
Ribonuclease H domain: it is responsible for cleaving the RNA and ssDNA release. Magnesium ion helps ribonuclease H domain in recognition of phosphate groups. The second chain of ribonuclease H domain does not have enzymatic activity. It only interacts and stabilizes the active site.
Research is still going on the RTs exact catalytic mechanism the above-mentioned scheme is the basic idea of the catalysis done by RT.
Q2 Where Does Reverse Transcriptase Come From
Answer: The process of reverse transcription occurs in retroviruses, prokaryotes and even eukaryotes to some extent. It is involved in the synthesis of cDNA from RNA. Retroviruses have RTs, which are dependent on RNA to synthesize cDNA. Nuclear division does not involve the use of RT. An enzyme known as Telomerase is present in eukaryotes. Telomerase is an specialized RT which synthesize telomeric DNA from RNA.
Q7 Why Is Rna Converted To Cdna
Answer: reverse transcriptase usually transcribe template RNA into cDNA.
cDNA is generally used in molecular biology for cloning eukaryotic genes into the prokaryotic cell factories. Whenever we want to express a protein into a cell that normally does not synthesize such protein, we require a cDNA transformation into the prokaryotic cell factory.
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Nucleoside Reverse Transcriptase Inhibitor Options As Part Of Initial Therapy
|Available Coformulations for ART-Naive Patients||
Tenofovir Disoproxil Fumarate/emtricitabine And Tenofovir Disoproxil Fumarate/lamivudine
TDF, with either 3TC or FTC, has been studied in combination with DOR, EFV, RPV, several boosted PIs, EVG/c, RAL, and DTG in randomized clinical trials.52-61
- New onset or worsening renal impairment has been associated with TDF use.62, 63 Risk factors may include advanced HIV disease, longer treatment history, low body weight ,64 and preexisting renal impairment.65 Concomitant use of a PK-enhanced regimen can increase TDF concentrations studies have suggested that the risk of renal dysfunction is greater when TDF is used in these regimens. As previously noted, adverse effects on renal biomarkers, such as proteinuria, especially tubular proteinuria, were more frequent with TDF than with TAF.66
- Adverse renal outcomes are more likely when TDF/FTC is coadministered with PK boosters . A meta-analysis of randomized trials found that discontinuation due to renal adverse events is more frequent in people who take TDF/FTC than TAF/FTC with PK boosting.16
Other Factors and Considerations
The Panels Recommendations
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Q6 What Is The Difference Between Real
Answer: The reverse transcriptase PCR is much more sensitive than regular PCR. RT-PCR is often used to detect a particular genes expression, DNA sequencing, DNA cloning, monitoring hereditary diseases, and analysis of functional genes. In contrast, general PCR is much extensively used for DNA amplification purposes.
Lamivudine As Single Nrti
Based on the GEMINI-1 and GEMINI-2 studies9 that found DTG plus 3TC noninferior to DTG plus TDF/FTC in ART-naive patients with HIV RNA < 500,000 copies/mL, 3TC may be used as a single NRTI with DTG . In addition, based on the ANDES trial, if ABC, TDF, and TAF cannot be used, 3TC can also be used as a single NRTI with DRV/r.44
Other Factors and Considerations
- 3TC is available as an STR with DTG.
- 3TC has activity against HBV but is insufficient for HBV treatment when used alone due to the emergence of resistance. Discontinuation of 3TC can precipitate a flare in HBV if no other HBV-active drugs are in the regimen.
- 3TC is available in two brand-name formulations , but the doses are different. The dose for HIV treatment is 3TC 300 mg daily.
- The dose of 3TC should be adjusted in patients with CrCl < 50 mL/min.
- Sorbitol-containing drugs can decrease 3TC concentration, and coadministration should be avoided.
The Panels Recommendations
- The Panel recommends the use of DTG/3TC as a Recommended Initial Regimen for Most People with HIV with three exceptions. DTG/3TC is not recommended for
- Individuals with HIV RNA > 500,000 copies/mL,
- Individuals with HBV coinfection or whose HBV status is unknown, or
- Individuals starting ART before the results of genotypic resistance testing for reverse transcriptase are available.
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