RT-PCR |
Why in News: The Health Ministry has issued a directive urging all states to enhance their screening efforts, promptly report cases of influenza-like and severe acute respiratory illnesses, increase RT-PCR tests and submit positive samples for genome sequencing.
About RT-PCR
PCR leverages the capability of DNA polymerase enzymes to generate new DNA strands that complement the provided template strand.
- The term “chain reaction” denotes the exponential copying of DNA fragments: one fragment yields two, two yield four, and so forth.
Adapting PCR for RNA Viruses:
- SARS–COV–2, an RNA virus, necessitates conversion into DNA for PCR analysis.
- Reverse Transcription (RT) process facilitates this conversion, carried out by Reverse Transcriptase enzyme, which synthesizes complementary DNA (cDNA) from RNA.
Challenges and Solutions:
- RNA’s single-stranded and unstable nature poses challenges for manipulation.
- RT-PCR overcomes this hurdle, allowing RNA as a template, followed by amplification of DNA copies.
Detection Method and Specificity:
- Fluorescent DNA binding dye, known as the “probe,” indicates the presence of the virus.
- RT-PCR enables differentiation between SARS–COV–2 and other viruses.
Enhanced Efficiency and Time Savings:
- Realtime RT-PCR testing has reduced sample processing time to approximately 4.5 hours, compared to the previous duration of around 6 hours.
- RT-PCR serves as the current gold standard for diagnosing active infections.
Limitations and Requirements:
- RT-PCR tests ascertain the presence of live or recently deceased virus in the body at the time of sample collection.
- Despite accuracy, RT-PCR necessitates advanced equipment, specific settings, and trained personnel for execution.
Key Difference from PCR:
- While PCR employs double-stranded DNA as the template, RT-PCR utilizes RNA as the starting material.
DNA Profiling |
Why in News: Supreme Court seeks government’s view on DNA profiling of unidentified bodies.
About DNA profiling
DNA fingerprinting reveals the genetic makeup of organisms by identifying differences in satellite DNA regions within the genome.
Alternative Names and Origin:
- Also referred to as DNA profiling, DNA testing, DNA analysis, genetic profile, DNA identification, genetic fingerprinting, and genetic analysis.
- Alec Jeffreys pioneered this technique in 1984.
Sources of DNA:
- DNA can be sourced from various bodily materials such as hair, bone, teeth, saliva, blood, and more.
- Even minute quantities of bodily fluid or tissue contain sufficient DNA for analysis, given its presence in most cells of the human body.
DNA Profiling: Contemporary DNA profiling, known as Short Tandem Repeat (STR) analysis, diverges from traditional DNA fingerprinting by utilizing microsatellites instead of minisatellites. Understanding Microsatellites (STRs): l Microsatellites, or short tandem repeats (STRs), are abbreviated sequences typically consisting of two to five base pairs. l These sequences, like minisatellites, are recurrently found in multiple regions of the human genome, often displayed as repetitions of a sequence (e.g., ‘TATATATATATA’). Inheritance of STRs: Since individuals inherit half of their DNA from each parent, STRs are transmitted from parents to their offspring. |
DNA Fingerprinting Advancements in India:
- Lalji Singh conducted groundbreaking research in this field at the Centre for Cellular and Molecular Biology (CCMB) in Hyderabad.
Key Centers for DNA Fingerprinting:
Besides CCMB in Hyderabad, other prominent centers include:
- Centre for DNA Fingerprinting & Diagnostics, Hyderabad.
- Central Forensic Science Laboratory in Kolkata.
- National Bureau of Plant Genetic Resource (NBPGR) in New Delhi.
- National Institute of Plant and Genetic Research (NIPGR) in New Delhi.
Metagenomics |
Why in News: Recently, researchers at the Nigerian Centre for Disease Control undertook a study employing metagenomic sequencing to monitor pathogens.
About Metagenomics
Metagenomics delves into the study of microbes within their natural habitats, exploring the intricate microbial communities they inhabit.
Understanding the Concept:
- This field involves scrutinizing the genomic makeup of entire organisms, encompassing all the microbes residing within them.
- Metagenomics facilitates direct sequencing of patient samples, eliminating the necessity for prior identification of the infectious agent.
Example of Microbial Diversity:
- For instance, a mere gram of soil hosts a staggering 4000 to 5000 diverse microbial species, while the human intestines harbor around 500 bacterial types.
Exploring Microbial Dynamics:
- Metagenomics empowers researchers to comprehend the diversity, abundance, and interactions among microbes within any given system.
Divergence from Traditional Methods:
- Unlike conventional sequencing techniques, which entail culturing or isolating individual species before genome sequencing, metagenomics bypasses this prerequisite.
Aspect | Traditional Genome Sequencing Methods | Metagenomics |
Methodology | Involves culturing or isolating individual microbial species prior to sequencing. | Studies the collective genetic material of the entire microbial community directly. |
Focus | Concentrates on the genomes of individual organisms. | Aims to study the genetic makeup of the entire microbial community within an environment. |
Conceptualization of Microbes | Views microbes and the host as distinct entities. | Considers microbes and the host as interconnected species within a community. |
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Xenotransplantation |
Why in News: The gene-edited pig heart transplanted into a human recipient experienced a delayed onset of beating compared to typical hearts. Regrettably, the recipient survived for only 61 days following the transplant.
About Xenotransplantation
Xenotransplantation pertains to the transfer of nonhuman organs or tissues into human recipients.
Significance of the Transplant:
- This marks the inaugural successful transplantation of a pig’s heart into a human recipient.
- However, it remains premature to ascertain the long-term efficacy of the procedure.
Innovative Approach:
- The transplant utilized a genetically modified pig heart, engineered to eliminate a sugar in its cells responsible for rapid organ rejection.
Understanding Genome Editing:
- Genome editing, also known as gene editing, encompasses a set of technologies enabling scientists to modify an organism’s DNA.
Historical Context:
- Previous attempts at such transplants, known as xenotransplantation, have been unsuccessful.
- Organ rejection stands as a major obstacle in transplantation endeavors.
Why pigs are most used for xenotransplantation? Availability and Reproduction: l Pigs are easily raised and reach adult human size within six months. l They typically produce large litters, offering a potentially unlimited supply of organs, tissues, and cells. Physiological Similarities to Humans: l Pigs share anatomical and physiological similarities with humans. l Physiological parameters such as cardiac output and stroke volume, crucial for cardiac function, are comparable between pigs and humans. Genetic Engineering Potential: l Pigs are highly amenable to genetic modification, making them suitable for engineering approaches to minimize rejection by the human body. Ethical Considerations: l Pigs are primarily bred for food, resulting in fewer ethical concerns surrounding their use for organ transplantation compared to other animals like primates. |
CAR-T Cell Therapy |
Why in News: President Droupadi Murmu has introduced ‘NexCAR19,’ India’s inaugural domestically produced CAR T-cell therapy designed for treating cancer.
About CAR T-cell therapy
CAR-T cell therapy, short for Chimeric Antigen Receptor T cell therapy, is a form of cancer immunotherapy.
Mechanism: It harnesses the patient’s own T cells, which are genetically modified in a laboratory to heighten their ability to identify and eliminate cancer cells.
Working Principle:
- T Cell Function: T cells, a type of white blood cell, play a pivotal role in recognizing and combating illness and infections.
- Recognition of Antigens:Each T cell possesses a receptor capable of identifying antigens, which are proteins or molecules recognized by the immune system.
- Targeting Cancer Cells:CAR-T cells are engineered in the lab to express a novel receptor that can bind to cancer cells, effectively leading to their destruction.
Therapeutic Procedure:
- T Cell Collection:Initially, blood is drawn from the patient’s arm, and T cells are isolated from the blood using an apheresis machine.
- T Cell Modification:In the laboratory, the T cells are genetically altered by introducing a synthetic CAR, after which they undergo multiplication and expansion.
- CAR-T Cell Infusion: Once a sufficient quantity of CAR-T cells is prepared, they are reintroduced into the patient’s arm through infusion.
- Adjunctive Chemotherapy:Chemotherapy may be administered before CAR-T cell infusion to augment treatment efficacy.
- Treatment Setting:This process can be conducted either in an outpatient infusion center or a hospital environment.
NexCAR19
Aspect | Details |
About | India’s inaugural indigenous CAR-T cell therapy. |
Developed by | Collaborative effort of IIT Bombay, Tata Memorial Centre, and ImmunoACT. |
Purpose | Specifically targets cancer cells harboring the CD19 protein. |
Recommended for | Individuals with B-cell lymphomas unresponsive to standard treatments like chemotherapy, leading to cancer relapse or recurrence. |
Treatment Process | 1. Patients donate blood at a transfusion center. The blood is sent to the lab for genetic modification of T-cells. 2. Within a week to 10 days, modified cells return to the clinic for patient infusion. |
Recovery | 1. Typically, recovery occurs within two weeks following one treatment cycle. 2. In the conducted study, around 70% of patients respond to the treatment, with varying outcomes between leukemia and lymphoma cases. Approximately 50% of these responsive patients achieve complete remission. |
Significance | India stands as one of the pioneering developing nations to possess its indigenous CAR-T and gene therapy platform. |
