Vaccine and Vaccination Practice Questions

Q: Which of the following is NOT a vaccine-preventable disease?

Measles. **Explanation** The correct answer is **D. Gonorrhea**. (Note: The prompt incorrectly marked Measles as the correct option; however, medically and for NEET-PG purposes, Gonorrhea is the only disease listed for which no vaccine currently exists.) **1. Why Gonorrhea is the Correct Answer:** *Neisseria gonorrhoeae* possesses high **antigenic variation**, particularly in its pili and Opa proteins. This genetic instability allows the bacteria to constantly change its surface antigens, making it difficult for the immune system to develop lasting immunity and complicating the development of an effective vaccine. Currently, prevention relies on barrier methods and prompt antibiotic treatment. **2. Why the Other Options are Incorrect:** * **Measles (A):** Prevented by the **Live Attenuated** vaccine (Edmonston-Zagreb strain in India). It is a part of the National Immunization Schedule (MR/MMR). * **Typhoid (B):** Multiple vaccines exist, including the **Vi polysaccharide** vaccine, the live oral **Ty21a** vaccine, and the newer **Typhoid Conjugate Vaccine (TCV)**, which provides longer-lasting immunity. * **Hepatitis B (C):** Prevented by a **Recombinant DNA vaccine** (using HBsAg). It is the first "anti-cancer" vaccine as it prevents hepatocellular carcinoma. **Clinical Pearls for NEET-PG:** * **Antigenic Variation:** This is the primary reason why vaccines are unavailable for Gonorrhea, Malaria, and HIV. * **Hepatitis B Vaccine:** Administered at 0, 1, and 6 months. It is the most common vaccine to cause an anaphylactic reaction (due to yeast components). * **Measles Vaccine:** Given at 9 completed months. It must be used within 4 hours of reconstitution to avoid **Toxic Shock Syndrome** caused by *Staph. aureus* contamination.

Q: All of the following are true about the BCG vaccine except?

The site of injection should be cleaned with spirit.. **Explanation:** The BCG (Bacillus Calmette-Guérin) vaccine is a **live attenuated vaccine** derived from *Mycobacterium bovis*. The correct answer is **Option D** because the site of injection should **never** be cleaned with spirit or any antiseptic. Antiseptics like alcohol/spirit can kill the live bacilli in the vaccine, rendering it ineffective. Instead, the site should be cleaned only with sterile water if necessary and allowed to dry before injection. **Analysis of other options:** * **Option A:** The WHO recommends the **Danish 1331 strain** for global production to ensure uniformity and potency. * **Option B:** It is strictly administered **intradermally** (usually over the left deltoid). This route is essential for the slow release of the antigen and the formation of the characteristic permanent scar. * **Option C:** **Normal Saline (0.9% NaCl)** is the recommended diluent. Distilled water is avoided as it causes irritation and pain due to its hypotonicity. **High-Yield Clinical Pearls for NEET-PG:** * **Dose:** 0.05 ml for neonates (under 1 month) and 0.1 ml for infants above 1 month. * **Reconstitution:** Once reconstituted, the vaccine must be used within **3–6 hours** or discarded to prevent contamination (usually by *Staphylococcus aureus*). * **The "BCG Evolution":** Papule (2-3 weeks) → Vesicle → Pustule → Shallow Ulcer (6-8 weeks) → **Permanent Scar** (12 weeks). * **Protective Effect:** It provides high protection against **Tubercular Meningitis** and **Miliary TB** in children, but its efficacy against adult pulmonary TB varies significantly (0-80%). * **Direct BCG:** BCG given without a prior Mantoux test (standard practice in India).

Q: Identify the scientist shown in the image below:

Robert Koch. ***Robert Koch*** - The image shows **Robert Koch**, a renowned German physician and microbiologist, often recognized for his pioneering work in bacteriology. - He is famous for establishing **Koch's postulates**, a set of four criteria designed to establish a causal relationship between a causative micro-organism and an infectious disease. *John Snow* - **John Snow** was a British physician who is considered one of the fathers of modern epidemiology, particularly for his work identifying the source of a cholera outbreak in London. - He is known for using a **spot map** to demonstrate the cluster of cholera cases around a public water pump. *Edward Jenner* - **Edward Jenner** was an English physician and scientist who pioneered the concept of vaccines, creating the world's first vaccine for **smallpox**. - He is often referred to as "the father of immunology" for his groundbreaking work. *James Lind* - **James Lind** was a Scottish surgeon in the Royal Navy who is celebrated for conducting one of the first recorded clinical trials to discover the cause of **scurvy**. - He demonstrated that **citrus fruits** could cure and prevent scurvy, a debilitating disease prevalent among sailors.

Q: Which of the following diseases is caused by the virus shown below?

Aplastic crisis. ***Aplastic crisis*** - The image depicts a **bun-shaped, non-enveloped virus** with a **single-stranded DNA genome**, characteristic of **Parvovirus B19**. - **Parvovirus B19** has a strong tropism for **erythroid progenitor cells** in the bone marrow, leading to their lysis and subsequent inhibition of erythropoiesis, which can cause **aplastic crisis**, especially in individuals with underlying hemolytic disorders like sickle cell anemia. *Burkitt lymphoma* - This lymphoma is caused by **Epstein-Barr virus (EBV)**, a **double-stranded DNA herpesvirus**, which has a different morphology than the virus depicted. - EBV is associated with B-cell proliferation, not direct destruction of erythroid precursors which leads to aplastic crises. *Primary effusion lymphoma* - This is a rare B-cell lymphoma associated with **Human Herpesvirus 8 (HHV-8)**, also known as Kaposi's sarcoma-associated herpesvirus. - HHV-8 is a **double-stranded DNA virus** with a different structure and tropism than the parvovirus shown in the image. *Vesicular vaccination lesion* - Vesicular vaccination lesions are typically caused by the **Vaccinia virus**, a **large, complex DNA virus** belonging to the Poxviridae family. - The Vaccinia virus has a distinct brick-shaped morphology and replicates in the cytoplasm, unlike the small, non-enveloped parvovirus shown.

Q: The addition of killed Bordetella pertussis microorganisms to diphtheria toxoid enhances the antibody response of the latter because of

endotoxin of the Bordetella organism. ***endotoxin of the Bordetella organism*** - The **endotoxin** (specifically **lipopolysaccharide** or LPS) of *Bordetella pertussis* acts as an **adjuvant**, stimulating the immune system non-specifically. - This adjuvant effect enhances the antigen presentation and lymphocyte activation, leading to a stronger and more sustained **antibody response** against the diphtheria toxoid. *formation of local granuloma* - While some adjuvants can induce granuloma formation to *sustain* antigen presentation, the primary mechanism of *Bordetella pertussis* *killed organisms* as an adjuvant is not solely due to granuloma formation. - Granuloma formation is more typical of adjuvants like **aluminum salts**, which create a depot effect rather than directly stimulating immune cells via endotoxin. *exotoxin of the Bordetella organism* - **Exotoxins** are typically highly potent toxins produced and secreted by bacteria that can cause specific clinical effects. - The adjuvant effect of killed *Bordetella pertussis* is primarily due to its **cell wall components** (endotoxin), not isolated exotoxins, which would likely be neutralized or removed during vaccine preparation. *additive action of the two antigens* - The enhancement is not merely an "additive action" of two antigens generating separate immune responses. - Instead, the *Bordetella pertussis* components (specifically endotoxin) *potentiate* the immune response to the diphtheria toxoid, acting as an **adjuvant** rather than just another antigen.

Q: Vaccines prepared in embryonated hen's eggs are:

Measles. ***Measles*** - The **measles vaccine** is produced using live attenuated virus grown in **chick embryo fibroblast (CEF) cultures** derived from embryonated hen's eggs. - This egg-based production method requires caution in individuals with **severe egg allergies**, though the risk is minimal with modern formulations. - Among the given options, measles is the **classic example** of an egg-substrate vaccine. *Rabies* - Most modern **rabies vaccines** are produced in **human diploid cells (HDCV)** or **purified chick embryo cell (PCEC)** cultures. - While PCEC uses chicken-derived cells, it represents a **cell culture system** rather than direct embryonated egg production. - Not the primary example of egg-based vaccine production. *Rubella* - The **rubella vaccine** component is manufactured using live attenuated virus grown in **human diploid cell cultures** (WI-38 or MRC-5). - **Does not involve** embryonated hen's eggs in its production process. *Varicella* - The **varicella (chickenpox) vaccine** is produced from live attenuated virus grown in **human diploid cell cultures** (MRC-5). - **Does not utilize** embryonated hen's eggs in manufacturing.

Q: The process of attenuation can be achieved by all except:

Serial passage in an experimental host. ***Serial passage in an experimental host*** - This option is **too vague and non-specific** to reliably achieve attenuation. The term "experimental host" could refer to *any host used in laboratory settings*, including the **natural host** of the pathogen. - Serial passage in the **natural/susceptible host** may actually **maintain or increase virulence** rather than attenuate, as the pathogen continues to adapt to its preferred environment. - **Attenuation requires passage in *unnatural* or *unfavorable* conditions** - not just "an experimental host." *Repeated cultures in artificial media* - This method attenuates pathogens by forcing adaptation to an **in vitro environment**, leading to loss of virulence factors unnecessary for artificial growth but crucial for host infection. - **Examples:** *BCG vaccine* (attenuated *M. bovis* after 230 passages), *Sabin polio vaccine* (passage in monkey kidney cells). - Virulence genes become non-functional over many passages in cell-free media. *Growing bacteria in unconventional host* - Passage in a **non-natural host** (different species) causes loss of virulence factors specific to the original host. - **Example:** *Yellow fever 17D vaccine* (passage in chicken embryos), *measles vaccine* (passage in chicken embryo fibroblasts). - This is a **specific application** of serial passage that reliably achieves attenuation. *Growing bacteria in adverse environment* - Exposure to **suboptimal conditions** (unfavorable temperatures, pH, oxygen tension) causes genetic mutations or loss of virulence plasmids. - **Example:** *Live attenuated influenza vaccine* (cold-adapted strains grown at 25°C instead of 37°C). - Selects for strains prioritizing survival over pathogenesis.

Q: Nakayama strain used for which vaccine?

Japanese encephalitis. **Correct Answer: Japanese encephalitis** - The **Nakayama strain** is a well-known strain of the **Japanese Encephalitis Virus (JEV)** and was historically used in the development of some of the earliest inactivated JEV vaccines. - While newer vaccine strains like Beijing-1 and SA14-14-2 are more common today, the Nakayama strain played a crucial role in vaccine history and is still referenced in the context of Japanese encephalitis. *Incorrect: Chicken pox* - The vaccine for chickenpox (varicella) typically uses the **Oka strain** of the **Varicella-Zoster Virus (VZV)**, not the Nakayama strain. - Chickenpox is caused by VZV, a herpesvirus, which is distinct from the flavivirus causing Japanese encephalitis. *Incorrect: Typhoid* - Typhoid vaccines are designed to protect against **Salmonella Typhi**, a bacterium, not a virus. - Common typhoid vaccines include inactivated whole-cell vaccines or the Vi polysaccharide vaccine, none of which involve the Nakayama strain. *Incorrect: Yellow fever* - The yellow fever vaccine uses a live-attenuated virus derived from the **17D strain** of the **Yellow Fever Virus (YFV)**. - While both JEV and YFV are flaviviruses, they are distinct, and the Nakayama strain is specific to Japanese encephalitis.

Q: Type of immunity conferred on an individual by vaccination is -

Artificial active. ***Artificial active*** - Vaccination introduces **antigens** to the body (artificial means) without causing disease, stimulating the immune system to produce its own antibodies and memory cells. - This type of immunity is considered **active** because the individual's immune system actively participates in generating the protective response, leading to long-lasting immunity. *Artificial passive* - This involves the direct transfer of **pre-formed antibodies** from an external source into an individual to provide immediate, short-term protection. - Examples include antitoxins for tetanus or rabies, where the recipient's immune system does not actively participate in antibody production. *Natural passive* - This occurs when antibodies are transferred naturally from one individual to another, such as from a mother to her fetus across the **placenta (IgG)** or through **breast milk (IgA)**. - It provides temporary protection to the infant without requiring the infant's immune system to produce its own antibodies. *Natural active* - This type of immunity develops when an individual is naturally exposed to a **pathogen** and the immune system responds by producing its own antibodies and memory cells. - This occurs after recovering from an infection, providing long-lasting protection against subsequent encounters with the same pathogen.

Q: Which of the following is a cell-fraction derived vaccine?

Hepatitis-B. ***Hepatitis-B*** - The Hepatitis B vaccine is a **recombinant vaccine**, produced by inserting the gene for the Hepatitis B surface antigen (HBsAg) into yeast cells. - These yeast cells then produce large amounts of HBsAg, which is purified and used as the vaccine, making it a **cell-fraction derived** or subunit vaccine. *Measles* - The measles vaccine is a **live-attenuated virus vaccine**, meaning it contains a weakened form of the measles virus. - It induces a robust immune response by mimicking natural infection without causing severe disease. *Mumps* - Similar to measles, the mumps vaccine is also a **live-attenuated virus vaccine**, containing a weakened form of the mumps virus. - This type of vaccine provides long-lasting immunity with a single dose. *Rubella* - The rubella vaccine is another example of a **live-attenuated virus vaccine**, using a weakened rubella virus strain. - It is often administered as part of the MMR (Measles, Mumps, Rubella) combination vaccine.

Question 1

Which of the following is NOT a vaccine-preventable disease?

Accepted Answer

Measles

Answer

Typhoid

Answer

Hepatitis B

Answer

Gonorrhea

Question 2

All of the following are true about the BCG vaccine except?

Accepted Answer

The site of injection should be cleaned with spirit.

Answer

WHO recommends the Danish 1331 strain of M. bovis.

Answer

It is given intradermally.

Answer

Normal saline is used as a diluent.

Question 3

Identify the scientist shown in the image below:

Accepted Answer

Robert Koch

Answer

John Snow

Answer

Edward Jenner

Answer

James Lind

Question 4

Which of the following diseases is caused by the virus shown below?

Accepted Answer

Aplastic crisis

Answer

Burkitt lymphoma

Answer

Primary effusion lymphoma

Answer

Vesicular vaccination lesion

Question 5

The addition of killed Bordetella pertussis microorganisms to diphtheria toxoid enhances the antibody response of the latter because of

Accepted Answer

endotoxin of the Bordetella organism

Answer

formation of local granuloma

Answer

exotoxin of the Bordetella organism

Answer

additive action of the two antigens

Question 6

Vaccines prepared in embryonated hen's eggs are:

Accepted Answer

Measles

Answer

Rabies

Answer

Rubella

Answer

Varicella

Question 7

The process of attenuation can be achieved by all except:

Accepted Answer

Serial passage in an experimental host

Answer

Repeated cultures in artificial media

Answer

Growing bacteria in unconventional host

Answer

Growing bacteria in adverse environment

Question 8

Nakayama strain used for which vaccine?

Accepted Answer

Japanese encephalitis

Answer

Chicken pox

Answer

Typhoid

Answer

Yellow fever

Question 9

Type of immunity conferred on an individual by vaccination is -

Accepted Answer

Artificial active

Answer

Artificial passive

Answer

Natural passive

Answer

Natural active

Question 10

Which of the following is a cell-fraction derived vaccine?

Accepted Answer

Hepatitis-B

Answer

Measles

Answer

Mumps

Answer

Rubella

Vaccine and Vaccination — MCQs

Vaccine and Vaccination — MCQs

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