Vaccine and Vaccination Practice Questions

Q: The presence of which of the following factors in viruses makes protective vaccines a possibility?

Protein coat. ***Protein coat*** - The **protein coat** (capsid) of viruses contains **antigenic proteins** that can be recognized by the host immune system. - Vaccines work by exposing the immune system to these viral proteins, stimulating the production of **antibodies** and memory cells for future protection. *Lipids* - While some viruses have a **lipid envelope**, lipids themselves are generally **poor antigens** and do not effectively stimulate a protective immune response on their own. - The immune response against enveloped viruses is primarily directed at the **glycoproteins** embedded within the lipid envelope, not the lipids themselves. *Enzymes* - Viruses contain various enzymes (e.g., reverse transcriptase, RNA polymerase) essential for their replication, but these are typically **intracellular targets**. - **Enzymes** are not usually present on the viral surface in an exposed manner that would consistently trigger a protective antibody response. *Polysaccharide* - **Polysaccharides** are common components of bacterial capsules but are generally **not significant components** of viral structure. - Viruses are primarily composed of nucleic acids and proteins, and the immune response to viruses rarely involves polysaccharides.

Q: A microbiologist wants to develop a vaccine for prevention of attachment of diarrhoeagenic E.coli to the specific receptors in the gastro-intestinal tract. All of the following fimbrial adhesions would be appropriate vaccine candidates except -

P1-Pili. ***P1-Pili*** - **P1-pili** (also known as P-fimbriae or Pap-pili) are primarily associated with **uropathogenic *E. coli*** causing **urinary tract infections**, not diarrhoeagenic *E. coli* in the gastrointestinal tract. - A vaccine targeting P1-pili would therefore not be relevant for preventing gastrointestinal attachment. *K 88* - **K88 fimbriae** are well-known **adhesins** found in certain strains of **enterotoxigenic *E. coli*** (ETEC) that colonize the gut and cause diarrhoea, especially in piglets. - Targeting K88 would be an appropriate strategy for a vaccine against diarrhoeagenic *E. coli*. *CFA-1* - **Colonization Factor Antigen I (CFA/I)** is a major **fimbrial adhesin** expressed by human **enterotoxigenic *E. coli*** (ETEC) strains. - CFA/I mediates bacterial attachment to intestinal epithelial cells and is a critical virulence factor, making it a suitable vaccine candidate. *CS-2* - **Colonization Factor Antigen II (CFA/II)**, which includes subunits like **CS-2** (CS for "coli surface"), is another important **fimbrial adhesin** found in human **enterotoxigenic *E. coli*** (ETEC). - CS-2 contributes significantly to ETEC's ability to colonize the small intestine and cause diarrhoea, making it a strong vaccine candidate.

Q: Adjuvants given along with antigens are going to

increase antigenicity. ***increase antigenicity*** - Adjuvants are substances added to vaccines to **enhance the immune response** to the co-administered antigen. - They work by various mechanisms, such as forming an antigen depot, activating antigen-presenting cells, and stimulating cytokine production, all leading to a **stronger and more prolonged immune response**. *reduce the antigenicity* - This statement is incorrect as adjuvants are specifically designed to **potentiate, not diminish**, the immune response to an antigen. - Reducing antigenicity would counteract the primary purpose of vaccination, which is to induce protective immunity. *reduce the toxigenicity* - Adjuvants generally do not directly impact the **toxigenicity** of an antigen, which refers to its ability to produce toxins. - While some vaccines detoxify bacterial toxins (e.g., toxoids), this is a separate process from the action of adjuvants that boost immune recognition. *increase toxigenicity* - This is incorrect; adjuvants are not intended to make an antigen more toxic. - Their role is to enhance immunogenicity safely, and increasing toxicity would be counterproductive and harmful.

Q: Conjugate vaccines are available for the prevention of invasive disease caused by all of the following except

N. Meningitidis (group B). ***N. Meningitidis (group B)*** - While conjugate vaccines are available for several serogroups of *N. meningitidis*, a **polysaccharide-protein conjugate vaccine** for **serogroup B** has been challenging to develop due to its **less immunogenic capsule** and antigenic mimicry with human tissues. - Currently, available vaccines against **meningococcal serogroup B** are **recombinant protein-based vaccines** (e.g., Bexsero, Trumenba), not traditional polysaccharide-protein conjugate vaccines. *Strep pneumoniae* - **Pneumococcal conjugate vaccines (PCVs)**, such as PCV13 and PCV15, effectively prevent invasive disease caused by *Streptococcus pneumoniae* in both children and adults. - These vaccines conjugate **polysaccharide capsular antigens** to carrier proteins, enhancing immunogenicity, especially in young children. *H influenzae* - The **Haemophilus influenzae type b (Hib) conjugate vaccine** is highly effective in preventing invasive Hib disease, including meningitis and epiglottitis. - This vaccine links the **Hib polysaccharide capsule** to a protein carrier, eliciting a T-cell-dependent immune response. *N. Meningitidis (group C)* - **Meningococcal conjugate vaccines** are widely available and routinely used to prevent invasive disease caused by *Neisseria meningitidis* serogroup C. - These vaccines include **monovalent (e.g., MenC)** and **quadrivalent (e.g., MenACWY)** formulations that target serogroup C.

Q: MW vaccine is prepared from:

Mycobacterium indicus pranii. ***Mycobacterium indicus pranii*** - The MW vaccine, also known as the **M. indicus pranii (MIP) vaccine**, is derived from heat-killed *M. indicus pranii* cells. - It is currently being explored as an immunomodulator and vaccine candidate for **leprosy** and **tuberculosis**. *Mycobacterium welchii* - This is an incorrect name; the correct species is *Clostridium perfringens*, previously known as *Bacillus welchii*. - *Clostridium perfringens* is a **gram-positive, anaerobic bacterium** that causes gas gangrene and food poisoning, and is not used in vaccine production for tuberculosis or leprosy. *Mycobacterium bovis* - *Mycobacterium bovis* is the bacterium used to produce the **BCG vaccine** (Bacillus Calmette-Guérin). - The BCG vaccine is primarily used to prevent **tuberculosis**, particularly severe forms in children. *Mycobacterium tuberculosis* - This is the primary causative agent of **tuberculosis** in humans. - A vaccine derived directly from live, virulent *M. tuberculosis* is not used due to its pathogenicity and the risk of causing disease.

Q: What is the primary advantage of using live attenuated vaccines?

They provide stronger, longer-lasting immunity. ***They provide stronger, longer-lasting immunity*** - Live attenuated vaccines mimic natural infection, leading to a robust immune response involving both **humoral** and **cell-mediated immunity**. - This comprehensive immune activation often results in **lifelong protection** with fewer doses, similar to immunity gained from natural infection. *They are cheaper to produce* - The production of live attenuated vaccines can be complex due to the need for careful **attenuation** and strict quality control, which can be costly. - While some attenuated vaccines might be cost-effective in the long run due to fewer doses, initial production costs are not their primary advantage. *They are effective with single doses* - While many live attenuated vaccines are highly effective with a single dose, not all are; some, like MMR, still require a second dose for optimal protection. - The effectiveness with fewer doses is rather a consequence of the strong immune response, not a standalone advantage over the quality of immunity. *They require fewer booster shots* - This is a direct benefit stemming from the **strong, long-lasting immunity** conferred by live attenuated vaccines. - However, the primary advantage is the quality and duration of the immune response itself, which in turn reduces the need for frequent boosters.

Q: In the context of viral diseases, which of the following is a key advantage of live attenuated vaccines over inactivated vaccines?

Induces long-term immunity with a single dose.. ***Induces long-term immunity with a single dose*** - **Live attenuated vaccines** stimulate a more comprehensive immune response, mimicking natural infection, leading to stronger and **longer-lasting immunity** often with a single dose. - This robust response typically involves both **humoral and cellular immunity**, providing excellent protection. *Safe for use in immunocompromised patients* - **Live attenuated vaccines** are generally **contraindicated in immunocompromised individuals** due to the risk of the attenuated virus replicating and causing disease. - **Inactivated vaccines**, which do not contain live virus, are safer for this population. *Elicits a robust antibody response without risk of reversion* - While live attenuated vaccines do elicit a robust immune response, there is a **small risk of the attenuated virus reverting to a virulent form**, especially in populations with low vaccine coverage. - **Inactivated vaccines** do not carry this risk as the virus is killed and cannot replicate or revert. *Preferred for mass vaccination during an outbreak* - While sometimes used, **live attenuated vaccines** require careful handling, cold chain maintenance, and may have contraindications that complicate mass vaccination efforts during an outbreak. - **Inactivated vaccines** can sometimes be easier to administer during a large-scale outbreak due to their stability and perceived safety profile in diverse populations.

Q: Which type of vaccine contains live, attenuated organisms?

MMR vaccine. ***MMR vaccine*** - The **MMR (Measles, Mumps, Rubella) vaccine** is a classic example of a **live-attenuated vaccine**, using weakened forms of the viruses. - Live-attenuated vaccines generally provide long-lasting immunity with a strong immune response, often after just one or two doses. *Hepatitis B vaccine* - The **Hepatitis B vaccine** is a **recombinant vaccine**, meaning it contains only a specific antigenic component (the surface antigen) of the virus. - It does not contain the whole live or inactivated virus, but rather a manufactured protein that elicits immunity. *Polysaccharide vaccine* - **Polysaccharide vaccines**, such as the pneumococcal polysaccharide vaccine, consist of **purified capsular polysaccharides** from bacteria. - These are **subunit vaccines** that target specific components of the pathogen but do not contain live organisms. *Inactivated influenza vaccine* - The **inactivated influenza vaccine** contains **killed influenza viruses** or viral components that have been chemically or physically inactivated. - Since the viruses are inactivated, they cannot replicate or cause disease, distinguishing them from live-attenuated vaccines.

Q: What is the specific protein content of the malaria vaccine RTS,S/AS01?

Sporozoite protein (Circumsporozoite protein). ***Sporozoite protein*** - The RTS,S/AS01 vaccine specifically targets the **circumsporozoite protein (CSP)** from the *Plasmodium falciparum* sporozoite stage. - This design aims to prevent **malaria infection** by blocking the parasite before it can infect liver cells. *Gametocytic protein* - Vaccines targeting gametocytic proteins are in development but are designed to block **transmission** of malaria, not prevent initial infection. - They aim to induce antibodies that neutralize gametes within the mosquito, preventing the parasite's sexual reproduction. *Polysaccharide sheath* - **Polysaccharide components** are common in bacterial vaccines (e.g., pneumococcal), but not the primary immunogen in RTS,S, which is a protein-based vaccine. - *Plasmodium* parasites do not possess a significant polysaccharide sheath that serves as a primary vaccine target in this context. *Lipoprotein envelope* - **Lipoprotein envelopes** are characteristic of some viruses (e.g., influenza, HIV), not typically the primary antigen of interest for *Plasmodium falciparum* sporozoites. - While there are lipid components in the parasite, the specific targeted antigen for RTS,S is a **protein**.

Q: What is the serum marker after Hepatitis B vaccination?

Anti-HBs. **Anti-HBs** - The Hepatitis B vaccine contains **HBsAg** (Hepatitis B surface antigen), which stimulates the immune system to produce **antibodies against HBsAg (Anti-HBs)**. - The presence of **Anti-HBs** indicates successful vaccination and immunity to Hepatitis B infection. *Anti-HBe* - **Anti-HBe** antibodies develop during an acute or chronic Hepatitis B infection and indicate a decrease in viral replication and infectivity. - This marker is not associated with vaccination. *Anti-HBc* - **Anti-HBc** (antibodies against Hepatitis B core antigen) is produced during an active or past Hepatitis B infection, but not as a result of vaccination. - It signifies exposure to the **core protein** of the virus. *HBs antigen* - **HBs antigen (HBsAg)** is a surface protein of the Hepatitis B virus that indicates active acute or chronic infection. - It is the antigen used in the vaccine to stimulate an immune response, but it is not a marker of immunity after vaccination.

Question 1

The presence of which of the following factors in
viruses makes protective vaccines a possibility?

Accepted Answer

Protein coat

Answer

Lipids

Answer

Enzymes

Answer

Polysaccharide

Question 2

A microbiologist wants to develop a vaccine for prevention of attachment of diarrhoeagenic E.coli to the specific receptors in the gastro-intestinal tract. All of the following fimbrial adhesions would be appropriate vaccine candidates except -

Accepted Answer

P1-Pili

Answer

K 88

Answer

CFA-1

Answer

CS-2

Question 3

Adjuvants given along with antigens are going to

Accepted Answer

increase antigenicity

Answer

reduce the antigenicity

Answer

reduce the toxigenicity

Answer

increase toxigenicity

Question 4

Conjugate vaccines are available for the prevention of invasive disease caused by all of the following except

Accepted Answer

N. Meningitidis (group B)

Answer

Strep pneumoniae

Answer

H influenzae

Answer

N. Meningitidis (group C)

Question 5

MW vaccine is prepared from:

Accepted Answer

Mycobacterium indicus pranii

Answer

Mycobacterium welchii

Answer

Mycobacterium bovis

Answer

Mycobacterium tuberculosis

Question 6

What is the primary advantage of using live attenuated vaccines?

Accepted Answer

They provide stronger, longer-lasting immunity

Answer

They are effective with single doses

Answer

They are cheaper to produce

Answer

They require fewer booster shots

Question 7

In the context of viral diseases, which of the following is a key advantage of live attenuated vaccines over inactivated vaccines?

Accepted Answer

Induces long-term immunity with a single dose.

Answer

Safe for use in immunocompromised patients.

Answer

Elicits a robust antibody response without risk of reversion.

Answer

Preferred for mass vaccination during an outbreak.

Question 8

Which type of vaccine contains live, attenuated organisms?

Accepted Answer

MMR vaccine

Answer

Hepatitis B vaccine

Answer

Polysaccharide vaccine

Answer

Inactivated influenza vaccine

Question 9

What is the specific protein content of the malaria vaccine RTS,S/AS01?

Accepted Answer

Sporozoite protein (Circumsporozoite protein)

Answer

Gametocytic protein

Answer

Polysaccharide sheath

Answer

Lipoprotein envelope

Question 10

What is the serum marker after Hepatitis B vaccination?

Accepted Answer

Anti-HBs

Answer

Anti-HBe

Answer

Anti-HBc

Answer

HBs antigen

Vaccine and Vaccination — MCQs

Vaccine and Vaccination — MCQs

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