Microbiology MCQs with Answer and Explnation | Chapter 13

Answer: Both Detection of antigens and Detection of antibodies

Serological reactions are laboratory techniques that use the interactions between antibodies and antigens. These reactions are useful for both the detection of antigens and the detection of antibodies. Examples include ELISA (Enzyme-Linked Immunosorbent Assay), agglutination tests, and Western blotting.

The other options are incorrect:

• Detection of antigens: Serological reactions are indeed used for the detection of antigens. These reactions rely on the binding of antibodies to specific antigens.
• Detection of antibodies: Serological reactions are also used for the detection of antibodies. These reactions can reveal the presence of specific antibodies in a sample.

Answer: Immunoelectrophoresis

Immunoelectrophoresis is a method used for the separation and identification of proteins, including antigens. In this technique, an electric field is applied to a gel containing proteins, and the proteins migrate based on their charge and size. Antibodies are then added to the gel, allowing the identification of specific antigens by the formation of precipitation lines.

The other options are incorrect:

• Flocculation is a technique that is used to detect the presence of antigens by observing the formation of visible aggregates or complexes when they interact with their corresponding antibodies. It is not used for the separation of antigens.
• Agglutination is a similar technique to flocculation, but it is used to detect the presence of antibodies by observing the agglutination (clumping together) of red blood cells that have been coated with antigens. It is also not used for the separation of antigens.

Answer: Agglutination

When a particular antigen is mixed with its corresponding antibody in the presence of an electrolyte at a suitable temperature and pH, and the particles form visible clumps or aggregates, this is referred to as agglutination. Agglutination reactions are commonly used in various laboratory tests, such as blood typing and serological assays.

The other options are incorrect:

• Precipitation: Precipitation involves the formation of a visible insoluble complex when an antigen and antibody react, but it typically refers to the settling of the complex rather than clumping.
• Electrophoresis: Electrophoresis is a technique for separating particles based on their charge and size under the influence of an electric field. It is not specifically related to the clumping of particles.
• CIE (Counterimmunoelectrophoresis): Counterimmunoelectrophoresis involves the migration of antigens or antibodies in an electric field through a gel medium and is not specifically related to the clumping of particles.

Answer: Neutralisation

Toxins and viruses can be detected by neutralization assays. Neutralization involves the inactivation of toxins or viruses by specific antibodies. If antibodies are present in a sample, they can neutralize the biological activity of toxins or prevent the infectivity of viruses. This is a crucial mechanism in the immune response to toxins and viral infections.

The other options are incorrect:

• Precipitation: Precipitation reactions involve the formation of visible insoluble complexes when antigens and antibodies react. While it can be used in some assays, it is not the primary method for detecting toxins or viruses.
• Agglutination: Agglutination reactions involve the clumping together of particles, such as cells or bacteria, in the presence of antibodies. While agglutination can be used in some diagnostic tests, it is not the primary method for detecting toxins or viruses.

Answer: Exotoxins

Exotoxins are generally more antigenic than endotoxins. Exotoxins are proteins released by some bacteria as part of their growth and metabolism. They are highly immunogenic and can elicit a strong immune response, leading to the production of antibodies.

The other options are incorrect:

• Endotoxins: Endotoxins are components of the outer membrane of Gram-negative bacteria. While they can induce an immune response, they are generally less antigenic than exotoxins.
• Viruses: Viruses can be highly antigenic, but their antigenicity depends on various factors, including the specific viral proteins and the host immune response. It’s not universally true that viruses are more antigenic than exotoxins.

Answer: Diphtheria

The Schick test is used for the detection of immunity against diphtheria. It is an intradermal skin test that helps determine whether an individual is susceptible to diphtheria toxin. The test involves injecting a small amount of diphtheria toxin under the skin. If the person is immune, there will be no reaction; if not immune, a local reaction will occur.

The other options are incorrect:

• T.B. (Tuberculosis): The Schick test is not used for the detection of tuberculosis.
• Cholera: The Schick test is not used for the detection of cholera.
• Typhoid: The Schick test is not used for the detection of typhoid. It is specifically employed for assessing immunity to diphtheria.

Answer: Both Haemolysis and Phagocytosis

The secondary functions of complement are both haemolysis and phagocytosis.

• Haemolysis is the process of lysing red blood cells. Complement can cause haemolysis by creating pores in the cell membrane, which allows the cell to lyse. This is an important part of the immune response, as it helps to destroy pathogens that have invaded red blood cells.
• Phagocytosis is the process of engulfing and destroying foreign particles. Complement can promote phagocytosis by opsonizing particles, which means that it coats them with complement proteins that make them more recognizable to phagocytes. This makes it easier for phagocytes to engulf and destroy the particles.

Answer: ELISA

ELISA is a highly effective and efficient immunological assay that can detect the presence of antibodies or antigens in a sample. It is characterized by its speed, sensitivity, and the ability to analyze multiple samples simultaneously. ELISA is widely used in diagnostic laboratories for various purposes, including the detection of infectious diseases, hormones, and other biomolecules.

The other options are incorrect:

• CFT (Complement Fixation Test): The complement fixation test is a traditional serological test but is not as widely used or as high-throughput as ELISA.
• Neutralization: Neutralization assays are specific for assessing the ability of antibodies to neutralize the activity of toxins or viruses. They may not be as high-throughput as ELISA.
• Agglutination: Agglutination assays involve the clumping of particles in the presence of antibodies. While they are useful, they may not be as high-throughput as ELISA for large-scale testing.

Answer: Humoral immunity

β-cells, also known as B-cells, are involved in humoral immunity. Humoral immunity is a component of the immune system that involves the production of antibodies by B-cells. These antibodies circulate in bodily fluids (humors), such as blood and lymph, and play a crucial role in defending against pathogens and toxins.

The other options are incorrect:

• Cell-mediated immunity: Cell-mediated immunity is primarily associated with T-cells, not β-cells (B-cells). T-cells play a central role in cell-mediated immune responses.
• Active immunity: Active immunity involves the production of an immune response by the host’s immune system, either through natural infection or vaccination. The term “β-cells” is not specifically associated with active immunity.
• Passive immunity: Passive immunity involves the transfer of pre-formed antibodies or immune cells from one individual to another. β-cells are not directly associated with passive immunity.

Answer: Non-specific

Innate immunity refers to the non-specific defense mechanisms that an organism possesses from birth. It provides a rapid but general response to a wide range of pathogens without the need for prior exposure. Innate immunity includes physical barriers (such as the skin), cellular components (like phagocytes), and soluble factors (such as complement proteins).

The other options are incorrect:

• Specific immunity is the type of immunity that is directed against a specific pathogen. Specific immunity is acquired through exposure to a pathogen or through vaccination.
• Active immunity is the type of immunity that is acquired when an individual’s immune system mounts a response to a pathogen. Active immunity can be acquired through natural infection or through vaccination.
• Passive immunity is the type of immunity that is transferred from one individual to another, such as from a mother to her infant through breast milk. Passive immunity is temporary and does not provide long-lasting protection against a pathogen.

Answer: Both Mechanical barriers and Chemical barriers

Innate immunity is developed through various mechanisms, including both mechanical and chemical barriers.

• Mechanical barriers: Examples include the skin and mucous membranes, which act as physical barriers preventing the entry of pathogens.
• Chemical barriers: Examples include substances such as antimicrobial peptides, enzymes, and mucus that create an environment hostile to pathogens, preventing their colonization and growth.

The other options are incorrect:

• Mechanical barriers: Mechanical barriers are indeed part of innate immunity, but the complete innate immune response involves a combination of mechanical and chemical barriers.
• Chemical barriers: Chemical barriers are also part of innate immunity. The innate immune system uses a range of chemical substances to defend against pathogens.

Answer: All of these

• Natural acquired immunity is the type of immunity that develops after an individual is exposed to a pathogen and their immune system mounts a response against it. This can occur through natural infection, such as getting the chickenpox or the measles. The body’s immune system produces antibodies specifically designed to fight off the invading pathogen. Once the infection is cleared, the body retains the memory of the pathogen, allowing it to quickly mount a strong defense against future infections.
• Artificial acquired immunity is the type of immunity that is induced through vaccination. Vaccination involves introducing a weakened or inactive form of a pathogen, or a part of a pathogen, into the body. This triggers the immune system to produce antibodies without causing the disease. As a result, the body is prepared to fight off the actual pathogen if it encounters it in the future.

In addition to being classified as natural or artificial, acquired immunity can also be categorized as active or passive.

• Active acquired immunity is the type of immunity that develops when an individual’s immune system produces its own antibodies in response to a pathogen. This can occur through natural infection or through vaccination.
• Passive acquired immunity is the type of immunity that is transferred from one individual to another. For example, a mother passes on antibodies to her baby through breast milk, providing the baby with protection against certain infections. Passive immunity is temporary and does not provide long-lasting protection against a pathogen.

Answer: Both Natural means and Artificial means

Natural acquired immunity is the type of immunity that develops after an individual is exposed to a pathogen and their immune system mounts a response against it. This can occur through natural infection, such as getting the chickenpox or the measles. The body’s immune system produces antibodies specifically designed to fight off the invading pathogen. Once the infection is cleared, the body retains the memory of the pathogen, allowing it to quickly mount a strong defense against future infections.

Artificial acquired immunity is the type of immunity that is induced through vaccination. Vaccination involves introducing a weakened or inactive form of a pathogen, or a part of a pathogen, into the body. This triggers the immune system to produce antibodies without causing the disease. As a result, the body is prepared to fight off the actual pathogen if it encounters it in the future.

Answer: Type-I

Immediate type hypersensitivity reactions are classified as Type-I hypersensitivity reactions. These reactions are characterized by an immediate onset of symptoms upon exposure to an allergen. Type-I hypersensitivity involves the activation of mast cells and basophils, leading to the release of histamine and other mediators, resulting in symptoms like itching, redness, and swelling. Common examples include allergic rhinitis, asthma, and anaphylaxis.

The other options are incorrect:

• Type-II hypersensitivity reactions are also known as cytotoxic reactions. They are mediated by IgG and IgM antibodies and are characterized by the destruction of cells.
• Type-III hypersensitivity reactions are also known as immune complex reactions. They are mediated by IgG, IgM, and sometimes IgA antibodies and are characterized by the deposition of immune complexes in tissues.

Answer: Mast cells

Immediate type of hypersensitivity reactions are mediated by mast cells. Mast cells are a type of white blood cell that is found in connective tissues throughout the body. They are responsible for releasing histamine and other inflammatory mediators, which are responsible for the symptoms of immediate type hypersensitivity reactions.

The other options are incorrect:

• T-cells are a type of white blood cell that is involved in cell-mediated immunity. They are not involved in immediate type hypersensitivity reactions.
• B-cells are a type of white blood cell that produces antibodies. Antibodies are involved in humoral immunity, but they are not directly involved in immediate type hypersensitivity reactions.
• Macrophages are a type of white blood cell that is involved in phagocytosis, which is the process of engulfing and destroying foreign particles. Macrophages are not directly involved in immediate type hypersensitivity reactions.

Answer: All of these

All the examples provided—Tuberculin-type hypersensitivity, contact dermatitis, and granulomatous reactions—are instances of cell-mediated immunity:

Tuberculin-type hypersensitivity: This is a delayed-type hypersensitivity reaction commonly seen in response to tuberculosis (TB) infection.
Contact dermatitis: Contact dermatitis is an inflammatory skin condition resulting from exposure to allergens or irritants. It involves a delayed-type hypersensitivity reaction.
Granulomatous reactions: Granulomas are organized collections of immune cells, often forming in response to persistent infections or foreign substances. Granulomatous reactions involve cell-mediated immunity.

Answer: T.B

The Mantoux test, also known as the tuberculin skin test, is used for the detection of tuberculosis (T.B.). It involves the intradermal injection of purified protein derivative (PPD) derived from Mycobacterium tuberculosis. The reaction is observed after 48 to 72 hours, and the presence of a raised, red bump at the injection site indicates a positive reaction, suggesting exposure to the tuberculosis bacterium.

The other options are incorrect:

• Diphtheria: is a bacterial infection that affects the respiratory system. It is diagnosed by a different skin test called the Schick test.
• Cholera: is a bacterial infection that causes severe diarrhea. It is diagnosed by testing a stool sample for the presence of the cholera bacterium.

Answer: Similar specificity

Antibodies produced by a single B-cell, also known as a β-cell, have similar specificity. This is because each B-cell is specific to a particular antigen, and the antibodies it produces will recognize and bind to that specific antigen. The antibodies from a single B-cell will have the same antigen-binding specificity but may vary in other characteristics, such as their isotype or subclass.

The other options are incorrect:

Different specificities: Antibodies from a single B-cell have the same specificity, as they are designed to recognize a particular antigen.
Similar size: While antibodies from a single B-cell may have similar specificity, their sizes can vary based on factors such as glycosylation and subclass differences.

Answer: Spleen cell – Myeloma cell

In the hybridoma technique, hybridoma formation involves fusing a spleen cell (antibody-producing B-cell) with a myeloma cell (a cancerous B-cell). The resulting hybridoma cell line possesses the ability to produce antibodies like the original B-cell and the immortalized characteristics of the myeloma cell.

The other options are incorrect:

• Spleen cell – Spleen cell: The correct combination for hybridoma formation in the hybridoma technique is a spleen cell fused with a myeloma cell, not with another spleen cell.
• Myeloma cell – Myeloma cell: Hybridoma formation involves the fusion of a normal B-cell (spleen cell) with a myeloma cell to create a hybrid cell line with the desired characteristics.

Answer: Attenuated bacilli

The anthrax vaccine is prepared using a strain of the bacterium Bacillus anthracis that has been weakened or attenuated. This attenuated strain of bacteria is no longer able to cause disease in humans, but it can still stimulate the immune system to produce antibodies against anthrax.

The attenuated strain of bacteria is grown in a culture medium, and the bacteria are then killed. The killed bacteria are then purified and concentrated, and the resulting vaccine is formulated with an adjuvant to increase its effectiveness.

The other options are incorrect:

• Killing the bacilli does not provide protection against anthrax, as the killed bacteria are not able to stimulate the immune system to produce antibodies.
• Live bacilli are too dangerous to use in a vaccine, as they can cause disease in humans.

Answer: Sabin vaccine

The attenuated, oral poliomyelitis vaccine is commonly known as the Sabin vaccine. This vaccine was developed by Dr. Albert Sabin and is an oral polio vaccine (OPV). It contains live, weakened forms of the poliovirus strains and is administered orally to induce an immune response without causing the disease.

The other options are incorrect:

• BCG vaccine is a vaccine that is used to protect against tuberculosis (TB).
• Measles vaccine is a vaccine that is used to protect against measles.
• TAB vaccine is a vaccine that is used to protect against typhoid fever, cholera, and botulism.

Answer: Salk

The killed, or inactivated, polio vaccine is commonly known as the Salk vaccine. Developed by Dr. Jonas Salk, the Salk vaccine contains inactivated poliovirus and is administered through injection. It is an effective method of polio immunization and is part of global efforts to eradicate the disease.

The other options are incorrect:

• Sabin vaccine: The Sabin vaccine is the oral polio vaccine (OPV), which contains live, attenuated poliovirus strains. It is not a killed vaccine.
• BCG: BCG (Bacillus Calmette-Guérin) is a vaccine primarily used for tuberculosis and is not related to polio vaccination.
• TAB: TAB (Typhoid-Paratyphoid A-B) vaccine is used for typhoid fever and is not a polio vaccine.

Answer: between 9 months and 10 years

The measles vaccine is typically given to children between the ages of 9 months and 10 years. In the United States, the Centers for Disease Control and Prevention (CDC) recommends that children receive the first dose of the measles, mumps, and rubella (MMR) vaccine at 12 to 15 months of age and the second dose at 4 to 6 years of age.

The other options are incorrect:

• 1 year is too late to give the first dose of the MMR vaccine.
• 7 months is too early to give the first dose of the MMR vaccine.

Answer: Formalin killed

Pertussis vaccine is formalin killed. This means that the bacteria that cause pertussis are killed with formaldehyde, a preservative. The killed bacteria are then injected into the body, where they trigger the immune system to produce antibodies against pertussis.

The other options are incorrect:

• Heat-killed bacteria are not as effective at stimulating the immune system as formalin-killed bacteria.
• Attenuated bacteria are still alive, but they have been weakened so that they cannot cause disease. Attenuated pertussis vaccines are not used in the United States because they have been associated with rare side effects.
• Live pertussis vaccines are not used in the United States because they can cause serious side effects, such as seizures.

Answer: Triple vaccine

DPT stands for Diphtheria, Pertussis (whooping cough), and Tetanus. It is a combination vaccine that includes antigens against these three diseases. The DPT vaccine is commonly administered to protect against diphtheria, pertussis, and tetanus. In some regions, it has been replaced by the DTaP vaccine, which is an acellular pertussis vaccine.

The other options are incorrect

• Double vaccine: DPT is a triple vaccine, not a double vaccine. It includes protection against diphtheria, pertussis, and tetanus.
• Tetanus toxoid: While tetanus toxoid is a component of the DPT vaccine, DPT itself includes protection against diphtheria, pertussis, and tetanus.

Answer: All of these

DPT is a vaccine that is used to protect against diphtheria, pertussis, and tetanus.

• Diphtheria is a serious bacterial infection that can cause breathing problems, heart failure, paralysis, and death.
• Pertussis, also known as whooping cough, is a highly contagious respiratory illness that can cause severe coughing fits and other complications, especially in young children.
• Tetanus, also known as lockjaw, is a serious bacterial infection that causes muscle stiffness and spasms.

DPT is one of the most important vaccines for children, and it is recommended that all children receive five doses of the DPT vaccine between the ages of 2 months and 6 years of age.

Answer: Both 0.5 ml at intervals of 4 weeks and A booster dose of 0.5 ml

DPT (Diphtheria, Pertussis, Tetanus) vaccine is typically administered to children in a series of doses. The primary series is usually given at the age of 6 weeks, 10 weeks, and 14 weeks. In some cases, a booster dose is given at 16-24 months.

So, the correct statement is that DPT is given as 0.5 ml doses at intervals of 4 weeks as part of the primary series, and a booster dose of 0.5 ml may be given later.

Answer: Mixed vaccine

If a vaccine contains more than one kind of immunizing agent, it is referred to as a mixed vaccine. Mixed vaccines are designed to provide protection against multiple diseases by incorporating various antigens or components. For example, combination vaccines may include antigens for different bacterial or viral infections.

The other options are incorrect:

• Cellular vaccine: Cellular vaccines typically involve the use of live, attenuated cells or cellular components to induce an immune response.
• Recombinant vaccine: Recombinant vaccines are developed using genetic engineering techniques to produce antigens for specific diseases.
• Toxoid vaccine: Toxoid vaccines are those that use inactivated toxins to induce an immune response, often against bacterial diseases.

Answer: Inactivated (killed) vaccine

Inactivated vaccines are prepared from microbes that have been killed using heat, chemicals, or radiation. The killing process destroys the microbes’ ability to replicate, but it preserves their antigens, which are the substances that trigger the immune system to produce antibodies. Inactivated vaccines are generally safe and effective, but they may not provide lifelong immunity.

The other options are incorrect:

• Attenuated vaccines are prepared from live microbes that have been weakened in the laboratory so that they cannot cause disease. Attenuated vaccines are generally more effective than inactivated vaccines at providing lifelong immunity, but they may carry a small risk of causing disease in people with weakened immune systems.
• Autogenous vaccines are prepared from microbes that have been taken from the patient themselves. Autogenous vaccines are typically used to treat specific infections that are not responding to other treatments.

Answer: Measles and Mumps vaccine

Vaccines used against viral infections include the Measles and Mumps vaccine. These vaccines are designed to provide immunity against specific viral infections:

• Measles vaccine: Protects against the measles virus.
• Mumps vaccine: Protects against the mumps virus.

The other options are incorrect:

• Cholera vaccine is a vaccine that is used to protect against cholera, a bacterial infection.
• Typhoid vaccine is a vaccine that is used to protect against typhoid fever, a bacterial infection.
• Anti-rickettsial vaccine is a vaccine that is used to protect against rickettsial diseases, which are a group of bacterial infections.

Answer: Autogenous vaccines

If the microbes used in a vaccine are obtained from the patient who will receive the vaccine, it is referred to as an autogenous vaccine. Autogenous vaccines are customized vaccines prepared from the specific pathogens causing infection in an individual or a small group. These vaccines are tailored to the patient’s own microbial isolates.

The other options are incorrect:

• Anti-viral vaccines: Anti-viral vaccines are designed to provide immunity against viral infections, not necessarily personalized to an individual.
• Anti-bacterial vaccines: Anti-bacterial vaccines are vaccines targeting bacterial pathogens, not necessarily personalized to an individual.

Answer: Sub-cellular vaccines

Vaccines prepared from toxins and chemicals, particularly those derived from bacterial toxins, are classified as sub-cellular vaccines. These vaccines often use inactivated toxins or toxoids, which are modified forms of toxins that have lost their toxic properties but retain their ability to stimulate an immune response.

The other options are incorrect:

• Cellular vaccines: Cellular vaccines typically involve live, attenuated cells or cellular components to induce an immune response.
• Attenuated vaccines: Attenuated vaccines use live but weakened forms of microbes to induce an immune response.
• Heterologous vaccines: Heterologous vaccines are those developed from a different species or strain and may include a variety of vaccine types.

Answer: Rubella & BCG

Examples of live vaccines include Rubella (German measles) and BCG (Bacillus Calmette-Guérin):

• Rubella vaccine: It contains a live attenuated (weakened) form of the rubella virus.
• BCG vaccine: It is a live attenuated vaccine derived from a strain of Mycobacterium bovis.

Live vaccines typically involve the use of weakened but live forms of the infectious agent to induce an immune response.

The other options are incorrect:

• Polio & TAB: The oral polio vaccine (OPV) is a live vaccine, but TAB (Typhoid-Paratyphoid A-B) vaccine is not.
• Diphtheria & Tetanus: Diphtheria and Tetanus vaccines are typically inactivated or subunit vaccines, not live vaccines.
• Hepatitis A & Rabies: Hepatitis A and Rabies vaccines are typically inactivated or subunit vaccines, not live vaccines.

Answer: Diphtheria, Tetanus & pertusis

DPT stands for Diphtheria, Pertussis (whooping cough), and Tetanus. Therefore, DPT vaccine is given for the prevention of all three diseases: Diphtheria, Tetanus, and Pertussis.

The other options are incorrect:

• Diphtheria, Tetanus: DPT includes protection against Pertussis as well, not just Diphtheria and Tetanus.
• Diphtheria, Pertussis: DPT includes protection against Tetanus as well, not just Diphtheria and Pertussis.

Answer: Influenza

The correct answer is influenza.

Influenza is a viral infection that causes fever, cough, sore throat, muscle aches, and fatigue. It is a highly contagious disease that can spread from person to person through the air or by touching an infected person or surface.

There are two types of influenza vaccines: inactivated and live attenuated. Inactivated influenza vaccines are made from killed influenza viruses. They are safe and effective for most people, but they may not provide lifelong immunity. Live attenuated influenza vaccines are made from weakened influenza viruses. They are more effective than inactivated vaccines at providing lifelong immunity, but they may carry a small risk of causing mild side effects, such as fever and runny nose.

The other options are incorrect:

• Measles is a viral infection that causes fever, cough, runny nose, rash, and conjunctivitis. It is a highly contagious disease that can spread from person to person through the air or by touching an infected person or surface.
• Rabies is a viral infection that affects the central nervous system. It is transmitted through the bite of an infected animal, such as a dog, cat, or bat. Rabies is almost always fatal if not treated.
• Polio is a viral infection that causes paralysis. It is transmitted through the fecal-oral route, meaning that it can spread from person to person through contact with contaminated feces. Polio is a highly contagious disease, but it can be prevented with vaccination.

Answer: All of these

IV can be transmitted through blood, semen, vaginal fluid, breast milk, and rectal fluids.

HIV is most commonly transmitted through sexual contact, including vaginal, anal, and oral sex. It can also be transmitted through sharing needles or syringes with an infected person, from an infected mother to her child during pregnancy, childbirth, or breastfeeding, and through blood transfusions or tissue transplants.

The risk of HIV transmission is highest when the person who is transmitting the virus has a high viral load. The viral load is the amount of virus in the person’s blood or other bodily fluids. People with HIV who are taking antiretroviral medication can lower their viral load to very low levels, which can make it much less likely that they will transmit the virus to others.

There is no cure for HIV, but there are effective antiretroviral medications that can help people with HIV live long and healthy lives. These medications can also reduce the risk of transmitting HIV to others.

Answer: Both V. Cholera and S.typhosa

Animals are often naturally immune to infections caused by certain bacteria, including Vibrio cholerae (which causes cholera) and Salmonella typhi (which causes typhoid fever). Many bacteria have specific host ranges, and the factors that make a human susceptible to these bacteria may not be present in animals.

• V. Cholera: Animals are generally naturally immune to Vibrio cholerae.
• S.typhosa: Animals are generally naturally immune to Salmonella typhi.

Answer: Artificial active immunity

Artificial active immunity is a type of immunity that is acquired by introducing an attenuated (weakened) form of a pathogen into the body. This triggers the immune system to produce antibodies against the pathogen, without causing the disease. Examples of vaccines that provide artificial active immunity include the measles, mumps, and rubella (MMR) vaccine, the polio vaccine, and the hepatitis A vaccine.

The other options are incorrect:

• Passive immunity: is a type of immunity that is acquired by receiving antibodies from another source, such as from a mother to her infant through breast milk. Passive immunity is temporary and does not last as long as active immunity.
• Natural active immunity: is a type of immunity that is acquired by getting a disease and recovering from it. Natural active immunity is often lifelong.
• Local immunity: is a type of immunity that is limited to the site of infection. For example, if you get a cut on your finger and it becomes infected, the area around the cut may become immune to the bacteria that caused the infection. However, the rest of your body will not be immune.

Answer: Any one of the above

Organisms can be attenuated (weakened) for inoculation through various methods. Some common approaches include.

• Growing it at a temperature higher than optimum: This method, known as temperature attenuation, can weaken the organism.
• Passage through animals of different species which are less susceptible to it: Serial passage through animals can result in the adaptation of the organism to the new host, potentially reducing its virulence for the original host.
• Continuous cultivation in the presence of antagonistic substances: Exposure to substances that inhibit growth can lead to the attenuation of the organism.

Answer: 2 – 3 months

Passive immunity, which is acquired by receiving pre-formed antibodies, typically lasts for a relatively short period. The duration of passive immunity is generally in the range of 2 to 3 months. This is because the antibodies transferred to the individual gradually decline over time as they are metabolized and cleared from the body.

The other options are incorrect:

• 10 days: 10 days is a relatively short duration and may not cover the typical duration of passive immunity.
• 10 years: 10 years is a longer duration and is not characteristic of the typical duration of passive immunity.

Answer: All of these

Markers helpful in detecting an immune response (antiimmunity) include various indicators:

• Hyper gamma globulinemia: Elevated levels of gamma globulins, which include antibodies, can indicate an immune response.
• Circulating antibodies: The presence of specific antibodies circulating in the blood is a key marker of an immune response.
• Response to cortisone: Cortisone is a corticosteroid that can suppress the immune response. Monitoring the response to cortisone can provide information about the immune system’s activity.
• Lymphoid hyperplasia: Enlargement of lymphoid tissues, such as lymph nodes, can be a sign of an immune response.

Answer: Both Motile organ & Non-motile organ

H antigens are present in both motile and non-motile organs. The H antigen is a precursor structure that can be modified to form the A and B antigens on the surface of red blood cells. These antigens are part of the ABO blood group system.

Answer: Passive

Antitoxin is used for passive immunization. Passive immunization involves the direct administration of pre-formed antibodies to provide immediate protection against a specific pathogen or toxin. Antitoxins are antibodies that neutralize toxins produced by bacteria. Passive immunization is temporary, as the transferred antibodies have a limited lifespan in the recipient’s body.

The other options are incorrect:

• Active: Active immunization involves stimulating the immune system to produce its own antibodies. Antitoxin administration is not a form of active immunization.
• Both Active and Passive: Antitoxin is specifically used for passive immunization, not active immunization.

Answer: All of these

The agglutinin test, commonly known as agglutination test, is used for various purposes in microbiology.

• Identification of isolated bacteria: Agglutination tests can be employed to identify specific bacterial strains based on their reaction with antibodies or agglutinins.
• Typing of bacterial species: The agglutination test is used for typing bacterial species, helping to differentiate between different strains or serotypes.
• Study of antigenic structure of bacteria: Agglutination reactions provide information about the antigenic structure of bacteria, helping in the characterization of their surface antigens.

Answer: Both Blood of hologous group should always be same & Direct matching between patient’s serum and donor’s corpuscles be performed

In blood transfusion, it is essential to ensure compatibility between the donor’s blood and the recipient’s blood to prevent adverse reactions. This involves.

Blood of homologous group should always be the same: Matching the blood group of the donor and the recipient is crucial to avoid immune reactions. The ABO blood group system and the Rh factor are considered during this matching.

Direct matching between patient’s serum and donor’s corpuscles be performed: Crossmatching is done to check for compatibility by mixing a sample of the recipient’s serum with the donor’s red blood cells. This helps identify any potential reactions.

Answer: All of the above

To be anaphylactic, the sensitizing substance should be a protein in nature, should have a large molecular weight, and should be soluble in tissue fluids. This is because these characteristics make it more likely that the substance will be able to bind to IgE antibodies, which are responsible for mediating anaphylaxis.

Proteins are complex molecules that are made up of amino acids. They are the building blocks of cells and tissues, and they play a variety of roles in the body, such as enzymes, hormones, and antibodies.

Large molecular weight substances are more likely to be recognized by the immune system as foreign and to trigger an allergic response.

Soluble substances can easily move through the body and bind to IgE antibodies, which are located on the surface of mast cells and basophils.

Answer: All of these

The basics of pathology in asthma, allergic rhinitis, and urticaria involve multiple factors:

• Local vasodilation: Inflammatory responses in conditions like asthma, allergic rhinitis, and urticaria can lead to local vasodilation, causing increased blood flow to the affected area.
• Increased capillary secretion: Inflammatory processes can stimulate capillaries to release fluids, leading to increased capillary secretion in tissues.
• Excess eosinophils in tissue secretion and blood: Eosinophils, a type of white blood cell, are often involved in allergic reactions and inflammatory conditions. An excess of eosinophils may be present in both tissue secretions and blood.

Answer: Schick tests

The Schick test is a skin test that is used to determine whether or not a person is susceptible to diphtheria. It is performed by injecting a small amount of diluted diphtheria toxin into the skin of the forearm. If the person is immune to diphtheria, there will be no reaction at the injection site. However, if the person is susceptible to diphtheria, there will be a red, swollen bump at the injection site.

The other options are incorrect:

• Dick test is a skin test that is used to determine whether or not a person is infected with scarlet fever.
• V-P test is a blood test that is used to diagnose primary syphilis.
• Precipitin test is a serological test that is used to detect antibodies to a specific antigen.

Answer: All of these

There are several different methods that can be used to prepare plague and tularemia vaccines. These methods include.

• Using a chemical fraction of the causative bacteria: This method involves extracting a specific antigen from the bacteria and then using this antigen to prepare the vaccine. This method is often used to prepare vaccines that are more purified and less likely to cause side effects.
• Using a heat-killed suspension of virulent bacteria: This method involves killing the bacteria with heat and then using the dead bacteria to prepare the vaccine. This method is often used to prepare vaccines that are more effective at stimulating an immune response.
• Using a formalin-inactivated suspension of virulent bacteria: This method is similar to the heat-killed method, but it uses formalin instead of heat to kill the bacteria. Formalin is a chemical that can kill bacteria without damaging them too much, which can make them more effective at stimulating an immune response.
• Using avirulent live bacteria: This method involves using a live strain of the bacteria that has been weakened so that it is no longer able to cause disease. This method is often used to prepare vaccines that are more effective at stimulating an immune response.

Answer: Display cytotoxic effect on tumour cell

Natural killer (NK) cells are part of the innate immune system and are known for their ability to recognize and kill virus-infected cells and cancer cells without prior exposure to the specific antigen. NK cells do not belong to the B-cell or T-cell lineages, as they are a distinct subset of lymphocytes.

The other options are incorrect:

• Belongs to B-cell lineage: NK cells do not belong to the B-cell lineage. B cells are responsible for antibody production.
• Belongs to T-cell lineage: NK cells do not belong to the T-cell lineage. T cells are involved in cell-mediated immunity.
• Require previous antigen exposure for activation: Unlike adaptive immune cells, NK cells do not require previous antigen exposure for activation. They can recognize and respond to infected or transformed cells without prior sensitization.