# Immunity and Vaccines for UPSC: B and T Cells, Vaccine Platforms, ACE2, HIV and Monoclonal Antibodies Source: https://tracknation.in/story/immunity-and-vaccines-for-upsc-b-and-t-cells-vaccine-platforms-ace2-hiv-and-monoclonal-antibodies (TrackNation β€” free UPSC notes with PYQs) > Immunity and vaccines for UPSC: innate and acquired immunity, antibodies, active and passive immunity, vaccine platforms (vector, mRNA, DNA, inactivated, conjugate), COVID-19 vaccines, ACE2, HIV, monoclonal antibodies and India's 2025 vaccine pipeline. Includes practice questions, the real PYQs and exact Mains questions. ## How UPSC Tests Immunity and Vaccines 🎯 **Exam priority: Tier-1. Immunity and vaccines have been asked almost every year since COVID-19.** *UPSC asked: recombinant vector vaccines and adenoviruses versus retroviruses (2021); the term ACE2 (2021); the platforms behind Covishield, Sputnik V and Covaxin (2022); the roles of B cells and T cells (2022); pneumococcal conjugate vaccines (2020); and monoclonal antibodies, including their use against Nipah virus (2025). Mains 2022 asked for the basic principle of vaccine development and the approaches Indian manufacturers used for COVID-19.* Think in three boxes: **how the body defends itself** (innate and acquired immunity), **how vaccines train it** (types and platforms) and **when it fails or is borrowed** (HIV, passive immunity, antibodies as drugs). ## Innate, Acquired, Active and Passive Immunity ## How the body defends itself | **Type** | **Features** | **Examples** | | Innate immunity | Non-specific, present from birth; four barriers | Physical (skin, mucus), physiological (stomach acid, saliva, tears), cellular (neutrophils, monocytes, natural killer cells, macrophages) and cytokine (interferons made by virus-infected cells) | | Acquired immunity | Pathogen-specific and has memory: a weak primary response at first contact, a strong secondary (anamnestic) response later | Carried out by B-lymphocytes and T-lymphocytes | | Humoral response | B cells make antibodies, which are Y-shaped proteins of two heavy and two light chains (H2L2) | IgA, IgM, IgE and IgG are types of antibodies | | Cell-mediated response | T cells mediate it; T cells do not make antibodies but help B cells make them | Responsible for graft rejection; the body tells 'self' from 'non-self' | So **B cells and T cells together protect the body from diseases caused by pathogens**; they do not protect against allergens or act as immunosuppressants (2022 PYQ). ### Active and passive immunity - **Active immunity:** the host makes its own antibodies after exposure to an antigen, whether through infection or vaccination; it is slow. - **Passive immunity:** ready-made antibodies are given. Examples are **colostrum**, the mother's first milk rich in IgA, antibodies that cross the placenta, and an **antitoxin** injection against tetanus or snake venom. ## Vaccine Platforms, ACE2 and HIV ## Vaccines and the COVID-19 platforms The principle of vaccination rests on immunological **memory**: a harmless preparation of antigens, or a weakened or inactivated pathogen, makes the body produce antibodies and memory B and T cells that overwhelm the real pathogen quickly later (Mains 2022). Recombinant DNA technology lets antigens be made in bacteria or yeast, as in the **hepatitis B vaccine made from yeast**. | **Platform** | **Idea** | **COVID-19 and other examples** | | Live attenuated | Weakened live pathogen | BCG, oral polio, measles | | Inactivated | Killed whole pathogen | Covaxin (Bharat Biotech) is an inactivated-virus vaccine (2022 PYQ) | | Subunit or recombinant protein | A purified or engineered antigen | Hepatitis B (yeast), Corbevax (spike protein fragment) | | Toxoid and conjugate | Inactivated toxin; sugar coat joined to a carrier protein | Tetanus and diphtheria; pneumococcal conjugate vaccine | | Viral vector (recombinant vector) | A harmless virus or bacterium carries a gene from the pathogen; made by genetic engineering (2021 PYQ) | Covishield (Serum Institute, not an mRNA vaccine) and Sputnik V are vector-based (2022 PYQ) | | mRNA | Messenger RNA in lipid nanoparticles makes cells produce the antigen | Pfizer-BioNTech and Moderna COVID-19 vaccines | | DNA | A plasmid carries the gene for the antigen | ZyCoV-D (Zydus Cadila) | - **Pneumococcal conjugate vaccines** protect against pneumonia, meningitis and sepsis, and by preventing infection they cut the use of antibiotics and so help against drug resistance. No vaccine has zero side effects (2020 PYQ). - **ACE2** is the receptor on human cells that the spike protein of SARS-CoV-2 binds to in order to enter (2021 PYQ). - **Adenoviruses** have double-stranded DNA genomes and can cause the common cold; **retroviruses** such as HIV have RNA genomes and use reverse transcriptase to make DNA (2021 PYQ). - **HIV and AIDS:** HIV, a retrovirus with an RNA genome, damages the immune system; it spreads through sexual contact, contaminated blood and needles and from mother to child, not by touch. Symptoms may take 5 to 10 years to appear. ## Antibodies as Drugs, the 2025 Pipeline and How UPSC Could Ask Next ## Antibodies as drugs and the 2025 pipeline - **Monoclonal antibodies** are laboratory-made proteins (identical copies from one cell line) that bind to one specific antigen; binding helps the immune system attack the target. They are used for cancers, autoimmune diseases and some viral infections, including Nipah virus (2025 PYQ: all three statements correct). - **National Biopharma Mission:** in about seven years it delivered two COVID-19 vaccines, **ZyCoV-D and Corbevax**, among other products. Under the Department of Biotechnology, early-stage vaccine candidates for chikungunya, coronavirus and monkeypox are being developed, and a shared vaccine-development facility with a BSL-3 laboratory exists at BRIC-THSTI. - **CSIR-CDRI** has developed a whole-parasite malaria vaccine that deletes two genes (*SCD* and *SCOT1*) so the parasite can infect the liver but cannot enter the bloodstream; it showed 100 per cent efficacy in preclinical trials. An indigenous **mRNA-based chikungunya vaccine** from the CSIR-CCMB Atal Incubation Centre is set for large-scale trials. ## How UPSC Could Ask This Next - **Platform-to-vaccine matching:** viral vector, mRNA, DNA, inactivated, subunit. - **Immunity types:** which cells or antibodies do what, and what counts as passive immunity. - **Pathogen features:** RNA versus DNA viruses, the receptor a virus uses, and why a retrovirus needs reverse transcriptase. - **Programmes:** National Biopharma Mission, indigenous vaccines, antibody drugs. ## Further Reading - NCERT Biology (Class 12) and Geography textbooks, the India State of Forest Report, the MoEFCC Annual Report, the Economic Survey and the official lists cited in this note β€” the primary sources behind every figure above. ## Test Yourself: Practice Questions and PYQs Twelve practice questions on immunity, vaccines and antibodies, followed by the real UPSC Prelims questions and exact Mains questions. ## Practice Questions **Q1.** Interferons, proteins secreted by virus-infected cells that protect neighbouring cells, are an example of which innate barrier? - (a) Cytokine barrier - (b) Physiological barrier - (c) Physical barrier - (d) Cellular barrier **Answer: (a)** β€” The four innate barriers are physical, physiological, cellular and cytokine. **Q2.** An antibody molecule is made of - (a) four peptide chains: two heavy and two light - (b) two chains of DNA - (c) one long chain - (d) three light chains **Answer: (a)** β€” It is represented as H2L2. **Q3.** Which of the following is an example of passive immunity? 1. Colostrum given to a newborn 2. Antibodies passing from mother to foetus through the placenta 3. Antitoxin injected after a snake bite - (a) 3 only - (b) 1 and 2 only - (c) 1, 2 and 3 - (d) 2 and 3 only **Answer: (c)** β€” Ready-made antibodies are supplied in all three. **Q4.** The principle of vaccination is based on - (a) innate immunity - (b) allergic reaction - (c) immunological memory - (d) antibiotic action **Answer: (c)** β€” Memory B and T cells recognise the pathogen quickly on later exposure. **Q5.** Which of the following COVID-19 vaccines is made of inactivated whole virus? - (a) Covishield - (b) Covaxin - (c) Pfizer-BioNTech - (d) Sputnik V **Answer: (b)** β€” Covishield and Sputnik V are viral-vector vaccines; Pfizer-BioNTech uses mRNA. **Q6.** Consider the following statements about recombinant vector vaccines: 1. Genetic engineering is used in developing them. 2. Bacteria and viruses can be used as vectors. Which of the statements given above is/are correct? - (a) Neither 1 nor 2 - (b) 2 only - (c) Both 1 and 2 - (d) 1 only **Answer: (c)** β€” UPSC's 2021 key. **Q7.** HIV is a retrovirus. This means that - (a) it can be cultured on agar - (b) it has a DNA genome and no envelope - (c) it infects only bacteria - (d) its RNA genome is copied into DNA by reverse transcriptase **Answer: (d)** β€” The viral DNA is then integrated into the host genome. **Q8.** The term ACE2 is associated with - (a) genes in genetically modified plants - (b) radio collars for wildlife - (c) India's satellite navigation system - (d) the entry of the SARS-CoV-2 virus into human cells **Answer: (d)** β€” ACE2 is the receptor that the spike protein binds. **Q9.** Which of the following statements about B cells and T cells is correct? - (a) They alleviate pain and inflammation - (b) They protect the body from diseases caused by pathogens - (c) They act as immunosuppressants - (d) They protect the body from environmental allergens **Answer: (b)** β€” UPSC's 2022 key. **Q10.** Monoclonal antibodies are - (a) laboratory-made proteins that bind to a specific antigen - (b) hormones made by T cells - (c) mixtures of all antibodies in a person's blood - (d) viruses used as vaccines **Answer: (a)** β€” They have been used against cancers and some viral infections. **Q11.** The hepatitis B vaccine is produced using - (a) killed whole bacteria - (b) mRNA in lipid nanoparticles - (c) a recombinant antigen made in yeast - (d) live weakened virus **Answer: (c)** β€” It is a recombinant subunit vaccine. **Q12.** The two COVID-19 vaccines delivered under the National Biopharma Mission were - (a) Sputnik V and Covaxin - (b) ZyCoV-D and Corbevax - (c) Moderna and Pfizer - (d) Covaxin and Covishield **Answer: (b)** β€” ZyCoV-D is a DNA vaccine and Corbevax a protein-subunit vaccine. ### UPSC Previous Year Questions (PYQs) *Real UPSC Prelims questions, checked against the official paper and answer key.* **Q1.** (2020) What is the importance of using Pneumococcal Conjugate Vaccines in India? 1. These vaccines are effective against pneumonia as well as meningitis and sepsis. 2. Dependence on antibiotics that are not effective against drug resistant bacteria can be reduced. 3. These vaccines have no side effects and cause no allergic reactions. Select the correct answer using the code given below. - (a) 3 only - (b) 1 only - (c) 1, 2 and 3 - (d) 1 and 2 only **Answer: (d)** β€” Pneumococcal conjugate vaccines prevent pneumonia, meningitis and sepsis, and by preventing infection they reduce the use of antibiotics and so help against drug resistance. No vaccine is free of side effects and allergic reactions, so statement 3 is wrong. **Q2.** (2021) With reference to recent developments regarding 'Recombinant Vector Vaccine', consider the following statements: 1. Genetic engineering is applied in the development of these vaccines. 2. Bacteria and viruses are used as vectors. Which of the statements given above is/are correct? - (a) Both 1 and 2 - (b) 1 only - (c) Neither 1 nor 2 - (d) 2 only **Answer: (a)** β€” Recombinant vector vaccines are made by genetic engineering: a gene from the pathogen is inserted into a harmless virus or bacterium that acts as the vector. Both statements are right. **Q3.** (2021) Consider the following statements: 1. Adenoviruses have single-stranded DNA genomes whereas retroviruses have double- stranded DNA genomes. 2. Common cold is sometime caused by an adenovirus whereas AIDS is caused by a retrovirus. Which of the statements given above is/are correct? - (a) Neither 1 nor 2 - (b) 1 only - (c) Both 1 and 2 - (d) 2 only **Answer: (d)** β€” Adenoviruses have double-stranded DNA genomes and retroviruses have RNA genomes, so statement 1 is wrong. Adenoviruses can cause the common cold and the retrovirus HIV causes AIDS, so statement 2 is right. **Q4.** (2021) The term 'ACE2' is talked about in the context of - (a) spread of viral diseases - (b) development of India's own satellite navigation system - (c) genes introduced in the genetically modified plants - (d) radio collars for wildlife tracking **Answer: (a)** β€” ACE2 is the receptor on human cells that the spike protein of the SARS-CoV-2 virus binds to in order to enter them, so the term is used for the spread of a viral disease. **Q5.** (2022) In the context of vaccines manufactured to prevent COVID-19 pandemic, consider the following statements: 1. The Serum Institute of India produced COVID-19 vaccine named Covishield using mRNA platform. 2. Sputnik V vaccine is manufactured using vector based platform. 3. COVAXIN is an inactivated pathogen based vaccine. Which of the statements given above are correct? - (a) 1, 2 and 3 - (b) 2 and 3 only - (c) 1 and 3 only - (d) 1 and 2 only **Answer: (b)** β€” Covishield is a viral-vector vaccine, not an mRNA vaccine, so statement 1 is wrong. Sputnik V is vector-based and Covaxin is made from an inactivated virus, so statements 2 and 3 are right. **Q6.** (2022) Which one of the following statements best describes the role of B cells and T cells in the human body? - (a) They protect the body from environmental allergens. - (b) They act as immunosuppressants in the body. - (c) They protect the body from the diseases caused by pathogens. - (d) They alleviate the body's pain and inflammation. **Answer: (c)** β€” B cells make antibodies and T cells destroy infected cells and coordinate the immune response, so together they defend the body against disease-causing pathogens. **Q7.** (2025) With reference to monoclonal antibodies, often mentioned in news, consider the following statements : 1. They are man-made proteins. 2. They stimulate immunological function due to their ability to bind to specific antigens. 3. They are used in treating viral infections like that of Nipah virus. Which of the statements given above are correct? - (a) 1 and 2 only - (b) 1 and 3 only - (c) 2 and 3 only - (d) 1, 2 and 3 **Answer: (d)** β€” Monoclonal antibodies are laboratory-made proteins that bind to one specific antigen; by binding they help the immune system attack it, and they are used against some viral infections, including Nipah. All three statements are correct. ### Mains Practice Questions Use these to frame full-length answers. You don't have to answer one exactly β€” they show the angles UPSC tests, so let them guide which points you cover. - What is the basic principle behind vaccine development? How do vaccines work? What approaches did Indian vaccine manufacturers adopt to produce COVID-19 vaccines? - Compare innate and acquired immunity, and active and passive immunity, with examples. - Explain how a viral-vector vaccine and an mRNA vaccine differ in design and storage needs. - How has India's National Biopharma Mission contributed to vaccine self-reliance, and what gaps remain? - Discuss the role of monoclonal antibodies in treating viral diseases. ### UPSC Mains β€” Previous Years’ Questions on this topic (last 10 years) These are the **actual GS Mains questions** UPSC has asked on this theme β€” real proof of how, and when, it is tested. Try to write a full answer to each. - 2022 (GS-III): What is the basic principle behind vaccine development ? How do vaccines work? What approaches were adopted by the Indian vaccine manufacturers to produce COVID-19 vaccines? - 2020 (GS-III): COVID-19 pandemic has caused unprecedented devastation worldwide. However, technological advancements are being availed readily to win over the crisis. Give an account of how technology was sought to aid management of the pandemic.