Assignment Code: BZYET-141/TMA/2023

Course Code: BZYET-141

Assignment Name: Immunology

Year: 2023

Verification Status: Verified by Professor

Note: Attempt all questions. The marks for each question are indicated against it.

Part-A

Q1i) Define the following terms: (8)

a) Tolerance

Ans) The capacity of T and B cells to either ignore self-antigens or tolerate their presence is what is meant when we talk about immunological tolerance. In order to reach a state of tolerance, it is necessary to first destroy self-reactive cells in a targeted manner throughout development. The thymus is responsible for the elimination of T-cells that bind to self-antigens, whereas the bone marrow is responsible for the elimination of B-cells that do the same thing. The phrase "central tolerance" is used to characterise the tolerance that can be achieved using procedures such as these. The immune system is able to develop cells that are highly specific to a given antigen through the processes of tolerance and somatic recombination. These are the two processes that make this possible.

b) Autoimmunity

Ans) Autoimmunity is a disorder in which the immune system of the body assaults healthy cells and tissues within the body, thinking that they are harmful intruders from the outside. Autoimmunity is characterised by the immune system's inability to differentiate between self and non-self-antigens. Under normal circumstances, the immune system is programmed to identify and eliminate foreign entities, such as viruses or bacteria. This can result in the development of a number of autoimmune conditions, including but not limited to lupus, rheumatoid arthritis, multiple sclerosis, and type 1 diabetes, to name a few. It is not completely understood what causes autoimmunity; nonetheless, it is believed to involve a complicated interaction between a person's genes and the environment in which they were raised.

c) Phagocytic barriers of innate immunity

Ans) Pathogens are first stopped by the phagocytic barrier, part of the innate immune system. Phagocytic cells, like neutrophils, macrophages, and dendritic cells, consume bacteria, viruses, and fungus. Phagocytic cells eliminate infections in several ways. Pattern recognition receptors find pathogen-associated molecular patterns (PAMPs) on microorganisms (PRRs). Toll-like receptors (TLRs) and scavenger receptors bind to PAMPs and initiate phagocytosis and inflammation.  Phagocytic cells wrap pathogens with antibodies and complement proteins. Opsonization enhances phagocytic activity.

Phagocytic cells engulf pathogens in phagosomes. These phagosomes then form phagolysosomes with digesting enzyme-containing lysosomes. Phagolysosomes digest pathogens.

Phagocytic barriers enable adaptive immunity and infection control. Pathogens can evade phagocytic cells by producing virulence factors like capsules or biofilms. Thus, understanding phagocytic barriers helps fight viral diseases.

d) Inflammation

Ans) Tissue damage, infection, or toxins can induce inflammation, a complex biological reaction. It protects the body's natural immune system from infections. Neutrophils, macrophages, and mast cells release cytokines, chemokines, and prostaglandins during inflammation. These chemicals enlarge blood arteries, bringing extra blood to the location. They make blood arteries more permeable, allowing immune cells to enter tissue and trigger an immunological response. The stimulation determines how long inflammation lasts.

Acute inflammation is a brief response to remove damaging stimuli and start tissue healing. Chronic inflammation persists. It can harm tissues and cause disease, including autoimmune, cardiac, and cancer. Inflammation protects the body, but too much or too often can harm it. Chronic inflammation damages tissues, fibrosis, and organs. Uncontrolled acute inflammation can cause sepsis, which can kill.

Q1ii) Give an example of each of the following in the space provided: (2)

Q2) Write a comparative note on the role of Thymus and Bone marrow with respect to immune response. (10)

Ans) The thymus and bone marrow are two important parts of the immune system that help make immune responses and keep them going. Both organs help make various kinds of immune cells, but they are in various places, have different functions, and make different kinds of cells.

The thymus is a small gland in the middle of the upper chest. It is important for the development and maturation of T cells, which are an important type of immune cell in the cellular immune response. T cells are made in the bone marrow, but the thymus gland is where they mature before they move to other parts of the body.

The thymus gland is most active when a person is a child or adolescent, and its function slowly goes down as a person gets older. During T cell maturation in the thymus, a process called "thymic selection" takes place in which T cells are exposed to different self-antigens to test their ability to recognise and respond to foreign antigens. Negative selection is the process by which this process gets rid of T cells that could attack the body's own tissues. The T cells that make it through this process are then put into the bloodstream so they can go to other parts of the body and help the immune system.

In contrast, the bone marrow is a soft tissue inside bones that makes red blood cells, white blood cells, and platelets, among other types of blood cells. Haematopoiesis, the process of making blood cells, takes place in the bone marrow. It is also the main place where B cells, another type of immune cell that is important to the humoral immune response, grow and divide.

B cells are made in the bone marrow and mature in the lymphoid organs around the body, such as the lymph nodes, spleen, and mucosa-associated lymphoid tissues. Somatic hypermutation is a process that happens when B cells mature. During this process, the B cells' genes change, which makes it easier for them to recognise antigens and respond to them. The mature B cells then move to other parts of the body where they can make antibodies in response to foreign antigens.

The thymus and bone marrow work together to protect the body from pathogens by making different types of immune cells that work together. The thymus makes T cells, which find and kill infected cells. The bone marrow makes B cells, which make antibodies that neutralise pathogens and stop them from spreading.

Q3i) How does the protein structure influence the capacity of antigens to form antibodies? (5)

Ans) The structure of proteins is one of the most important things that determines whether or not they can act as antigens and cause the body to make antibodies. Antigens are molecules that the immune system can recognise as foreign, and their shape is a key part of whether or not they are immunogenic.

Proteins are made up of long chains of amino acids that fold into complicated three-dimensional structures. The primary structure of a protein is made up of the order of its amino acids. The secondary, tertiary, and quaternary structures are made up of how the amino acids interact with each other. These structures are especially important for figuring out if a protein is antigenic and if it can cause an immune response.

In general, proteins with complicated three-dimensional structures and many epitopes, or antigenic determinants, are more likely to be immunogenic than proteins with simple structures and fewer epitopes. An antibody can recognise a specific part of an antigen called an epitope. The number and location of epitopes on a protein can have a big effect on its ability to trigger an immune response.

Antigenicity is also affected by how the epitopes on a protein are shaped and how big they are. Epitopes that are on the surface of a protein and have a unique shape that an antibody can recognise are more likely to be immunogenic than epitopes that are inside the protein or have the same shape as other self-antigens.

Antigenicity can also be affected by how stable the structure of the protein is. Proteins that are stable and hard to break down are more likely to keep their antigenic properties and make the immune system react strongly.

The link between the structure of a protein and its ability to cause an immune response is important for making vaccines and diagnostic tests. When making vaccines, antigens are often proteins that are highly immunogenic and have multiple epitopes. These proteins cause the body to make protective antibodies. In the same way, proteins with specific epitopes can be used as antigens in diagnostic tests to look for antibodies against a certain pathogen.

ii) Write down the differences between alloantigen and autoantigen. (5)

Ans) The difference between alloantigen and autoantigen is as follows: 

4) Fill in the blanks: (10)

i) The isotypes have similar ………………… regions of ………………… and ………………… chains but different ………………… regions of ………………… chains.

Ans) The isotypes have similar constant regions of heavy and light chains but different variable regions of heavy chains.

ii) The allotypes may have different amino acids in CDR regions of the ………………… chain or the ………………… chain.

Ans) The allotypes may have different amino acids in CDR regions of the heavy chain or the light chain.

iii) The idiotype provides ………………… antibodies to interact with different ………………… in one’s own body.

Ans) The idiotype provides unique variable antibodies to interact with different epitopes in one's own body.

iv) The foetus acquires immunity from the mother as ………………… can cross ………………….

Ans) The foetus acquires immunity from the mother as antibodies can cross the placenta.

Q5i) Explain, Antigen processing and Antigen presentation? (5)

Ans) Antigen processing and antigen presentation are important parts of the immune system because they allow immune cells to recognise and get rid of foreign antigens. Antigen processing is the process of breaking down antigens into smaller pieces called peptides. Antigen presentation is when these peptide pieces are put on the surface of antigen-presenting cells (APCs) so that T cells can recognise them.

There are two main ways that antigens can be processed: the endogenous pathway and the exogenous pathway. The proteasome, a large protein complex that breaks down proteins into smaller peptide fragments, processes intracellular antigens like viral or tumour antigens. This is part of the endogenous pathway. Then, these peptide fragments are sent to the endoplasmic reticulum (ER), where they bind to major histocompatibility complex (MHC) class I molecules. The MHC class I-peptide complexes are then moved to the surface of the cell so that CD8+ T cells can recognise them.

The exogenous pathway, on the other hand, is made up of phagocytic cells like dendritic cells, macrophages, and B cells that process antigens that are outside of cells, like bacterial or fungal antigens. These cells take in the antigens and break them up into smaller pieces called peptide fragments, which are then loaded onto MHC class II molecules. The MHC class II-peptide complexes are then moved to the surface of the cell so that CD4+ T cells can recognise them.

Once the peptide-MHC complexes are on the surface of the APCs, T cells can use their T cell receptors to find them (TCRs). Peptide-MHC class I complexes are known to CD8+ T cells, while peptide-MHC class II complexes are known to CD4+ T cells. T cells become active when they recognise peptide-MHC complexes. Activated T cells then perform effector functions like releasing cytokines and killing infected or cancerous cells.

Several things can affect how well antigens are processed and presented. These include the type of antigen, the type of APC, and the presence of co-stimulatory signals. Some antigens may be harder to deal with and show than others, and some APCs may be better at dealing with and showing antigens than others. T cells must also have co-stimulatory signals, such as those sent by CD80/CD86 on APCs, in order to be activated.

Q5ii) What are the differences between class I and class II MHC molecules? (5)

Ans) The difference between class I and class II MHC molecules is as follows:

Part-B

Q6i) What is BCR? What are its functions? Which 2 Igs make up the BCRs? (5)

Ans) BCR stands for B cell receptor, which is a type of membrane-bound immunoglobulin (Ig) molecule found on the surface of B cells. The BCR is a complex consisting of two identical heavy chains and two identical light chains, each with a variable region that can bind to a specific antigen.

The primary function of the BCR is to recognize and bind to antigens, which are typically proteins or other large molecules that are foreign to the body. When an antigen binds to the BCR, it triggers a series of intracellular signaling events that lead to the activation and proliferation of the B cell. This activation can lead to the production of large amounts of antigen-specific antibodies that can help to eliminate the foreign antigen.

In addition to their role in recognizing and binding to antigens, BCRs also play a crucial role in the development and maturation of B cells. During the early stages of B cell development, B cells undergo a process called V(D)J recombination, in which the genes that encode the variable regions of the heavy and light chains are rearranged to create a diverse repertoire of BCRs. B cells that generate BCRs that recognize self-antigens are typically eliminated through a process called negative selection, which helps to prevent the development of autoimmune diseases.

The two Igs that make up the BCRs are IgM and IgD. IgM is the first Ig isotype produced during the development of B cells and is found on the surface of immature and mature B cells. IgD is produced later in B cell development and is found on the surface of mature B cells. Both IgM and IgD are capable of binding to antigens, although IgM has a higher binding affinity and is typically the first Ig produced in response to an antigen.

In addition to their roles in antigen recognition and B cell development, BCRs also play a role in immune memory. B cells that are activated by an antigen can differentiate into memory B cells, which are long-lived cells that can quickly generate large amounts of antigen-specific antibodies upon re-exposure to the same antigen. This memory response is the basis for the effectiveness of many vaccines, which rely on the generation of a memory response to provide long-lasting protection against infectious diseases.

Q6ii) Describe the major events of the B-Cell maturation briefly. (5)

Ans) B-cell maturation is a complicated process that happens in the bone marrow. It leads to the growth of mature, functional B cells that can make antibodies that are specific to antigens. Here are the main things that happen when B cells grow up:

1.  Hematopoietic stem cells (HSCs) in the bone marrow change into common lymphoid progenitor (CLP) cells, which give rise to both B and T lymphocytes.

2. Early pro-B cells are made from CLP cells. These cells express a certain set of genes that are needed for B-cell development.

3. Early pro-B cells go through a process called V(D)J recombination, in which the genes that code for the variable regions of the heavy and light chains are rearranged to make a variety of B-cell receptors (BCRs).

4. If the newly generated BCR does not recognize self-antigens, the pro-B cell undergoes further maturation into late pro-B cells, which begin to express both heavy and light chains

5. Late pro-B cells continue to undergo V(D)J recombination until they produce a functional BCR.

6. Pre-B cells, which are characterized by the expression of a complete BCR that has not yet been tested for self-reactivity, undergo a process called allelic exclusion, in which one of the two heavy-chain genes and one of the two light-chain genes is silenced.

7. Pre-B cells then undergo a process of selection, in which cells that recognize self-antigens with high affinity are eliminated through a process called negative selection.

8. Pre-B cells that survive negative selection continue to differentiate into immature B cells, which migrate from the bone marrow to secondary lymphoid tissues such as the spleen and lymph nodes.

9. Immature B cells continue to undergo selection in the secondary lymphoid tissues, in which cells that recognize self-antigens with high affinity are again eliminated through a process called receptor editing.

10. Immature B cells that survive selection and encounter antigens undergo activation and differentiation into mature B cells, which are capable of producing antigen-specific antibodies.

Q7i) Choose whether following sentence are true (T) or False (F): (6)

a) T helper cells possess CD8+ surface markers.

Ans) False.

b) Cytotoxic T -cells kills the antigen infected cells.

Ans) True.

c) MHC molecule requires to present antigen peptide on the surface of APCs.

Ans) True.

d) CD8+ marker recognizes MHC II complex.

Ans) False.

e) CD4+ marker recognizes MHC I complex.

Ans) False.

f) All nucleated cells possess MHC I molecule.

Ans) True.

Q7ii) Define the CD and MHC molecules. (2)

Ans) Cluster of Differentiation: CD molecules, which stand for "cluster of differentiation," are found on the outside of immune cells and are used to tell them apart. They are proteins that are on the outside of immune cells and help them do things like communicate with other cells, stick together, and recognise antigens. CD molecules get their names based on how they show up on different types of immune cells, and they can be used to tell T cells, B cells, and other immune cells apart.

Major Histocompatibility Complex: MHC molecules, which stand for "major histocompatibility complex," are a group of proteins on the surface of cells that help present and recognise antigens. They are found on the outside of immune cells and oversee showing T cells peptides made from proteins inside the cell. MHC molecules are highly polymorphic, which means that they are different for each person. They are a key factor in figuring out whether two tissues can be transplanted together.

Q7iii) Which type of antigen-presenting molecule is found only on macrophages, dendritic cells, and B cells? (1)

Ans) MHC class II is the only antigen-presenting molecule that is only found on macrophages, dendritic cells, and B cells. MHC class II molecules are proteins on the outside of cells that help present peptides made from proteins outside of cells to CD4+ T cells. This starts the adaptive immune response.

MHC class II molecules are made up of two chains called and. These chains are coded for by different genes. The endoplasmic reticulum makes these chains, which then link up with a protein called the invariant chain. This keeps the MHC class II molecule from binding to intracellular peptides. The MHC class II-invariant chain complex then moves to a special place in the cell called the endocytic pathway. There, the invariant chain is broken down and the MHC class II molecule is loaded with peptides made from proteins outside of the cell.

Once the MHC class II molecule is full of peptides, it is moved to the cell surface. There, it shows the peptide to CD4+ T cells. A co-receptor called CD4, which is found on the surface of helper T cells, makes the link between the MHC class II molecule and the T cell receptor even stronger. This interaction turns on the CD4+ T cell, which then releases cytokines that help the adaptive immune response work together.

Q7iv) Which type of antigen-presenting molecule is found on all nucleated cells? (1)

Ans) MHC class I is the type of antigen-presenting molecule that is found on all cells with nuclei. MHC class I molecules are proteins on the outside of cells that help present peptides made from proteins inside the cell to CD8+ T cells. This allows CD8+ T cells to start the adaptive immune response against infected or abnormal cells.

MHC class I molecules are made up of a chain, which is coded by the MHC gene, and a smaller protein called 2-microglobulin, which is not coded by the MHC gene. The endoplasmic reticulum makes the chain, which then joins up with the 2-microglobulin. The MHC class I molecule then binds to peptides made from intracellular proteins. The proteasome makes the peptides, and a special transporter called TAP moves them into the endoplasmic reticulum.

Once the MHC class I molecule is full of peptide, it moves to the cell surface and shows the peptide to CD8+ T cells. A co-receptor called CD8, which is found on the surface of cytotoxic T cells, makes the connection between the MHC class I molecule and the T cell receptor even stronger. This interaction turns on the CD8+ T cell, which then kills the infected or abnormal cell showing the antigen.

Q8i) Match the following with the correct option of Column I with Column II. (5)

Q8ii) State whether the following statement are ‘True’ or ‘False’: (5)

a) The removal of self-reactive cells within our body immune system is Tolerance.

Ans) True.

b) The deposition of antigen-antibody complexes in tissues or blood vessels causes the activation of complement system along with recruitment of neutrophils.

Ans) True.

c) Type-I hypersensitivity is accompanied by clinical symptoms like: anaphylaxis, angioedema, bronchospasm, hypotension etc.

Ans) True.

d) Myasthenia Gravis is a condition of muscular dysfunction arising from acetylcholine inadequacy not auto-immunity.

Ans) False.

e) Type-IV hypersensitivity is clinically associated with haemolytic anaemia, thrombocytopenia, neutropenia.

Ans) False.

Q9i) What is immunosuppressive therapy. Explain the two major types of the same. (5)

Ans) Immunosuppressive therapy (IST) is a medical treatment used to stop the immune system from attacking the body's own cells or tissues, which is what causes many autoimmune diseases. IST is also used to keep organs from being rejected after a transplant, when the body's immune system might see the new organ as foreign and attack it. Immunosuppressive therapy comes in two main forms:

Non-specific immunosuppressants: These drugs turn down the immune system as a whole and are mostly used to keep organs from rejecting transplants. Non-specific immunosuppressants come in two main types:

1. Calcineurin Inhibitors: Drugs like cyclosporine and tacrolimus belong to this group. They work by stopping T cells from doing their job, which is to get rid of foreign tissues. They work well to keep organ transplants from being rejected, but they can also cause side effects like high blood pressure, damage to the kidneys, and a higher risk of infection.

2. Anti-proliferative Agents: Some of these drugs are azathioprine, mycophenolate mofetil, and methotrexate. They work by stopping new T and B cells, which are part of the immune response, from being made. They are also used to treat lupus and rheumatoid arthritis, which are autoimmune diseases. These drugs can make you feel sick, make you throw up, and make you more likely to get an infection.

Targeted immunosuppressants: These drugs target parts of the immune system that are involved in the autoimmune response. They are mostly used to treat diseases that are caused by the immune system. Targeted immunosuppressants come in two main types

1. Biologics: These are proteins that have been changed genetically to target specific immune molecules or receptors. TNF-alpha inhibitors (like adalimumab and infliximab), interleukin inhibitors (like tocilizumab and anakinra), and B-cell inhibitors are all examples of biologics (rituximab). Biologics are particularly good at treating autoimmune diseases, but they can also cause serious side effects like an increased risk of infection, allergic reactions, and cancer.

2. Janus Kinase (JAK) Inhibitors: The immune response is part of the JAK-STAT signalling pathway, which is what these drugs go after. Tofacitinib and baricitinib are both examples of JAK inhibitors. They are used to treat autoimmune diseases like rheumatoid arthritis and psoriasis. They are generally well-tolerated, but they can cause side effects like an increased risk of infection, liver damage, and blood clots.

Q9ii) Define the immunological tolerance highlighting the central and peripheral tolerance. (5)

Ans) Immunological tolerance is when the immune system can tell the difference between self-antigens and foreign antigens, so it doesn't attack its own cells and tissues. Immunological tolerance is especially important for preventing autoimmune diseases, which happen when the immune system attacks self-tissues by mistake. Immunological tolerance is made possible by two parts of the immune system: central tolerance and peripheral tolerance.

Central tolerance happens in the first lymphoid organs, like the thymus and bone marrow, during the early stages of lymphocyte development. Positive and negative selection happen in the thymus to make sure that only T cells that can recognise foreign antigens but not self-antigens can mature and leave the thymus. T cells that have a high affinity for self-antigens go through negative selection and die by apoptosis. Specialized cells in the thymus called thymic epithelial cells and dendritic cells help this process along by showing developing T cells self-antigens.

In the bone marrow, B cells that make antibodies against self-antigens go through a process of receptor editing and clonal deletion to get rid of them. Immature B cells that strongly bind to self-antigens go through a process called receptor editing, in which the B cell receptor is changed to make it less sensitive to self-antigens. If receptor editing doesn't work, these B cells are killed by clonal deletion and apoptosis.

Peripheral tolerance is the second way that immunological tolerance is kept up. It happens in tissues outside of primary lymphoid organs. It involves getting rid of self-reactive lymphocytes that get past central mechanisms of tolerance. Several things keep peripheral tolerance going, such as anergy, suppression by regulatory T cells, and the removal of self-reactive B cells.  Anergy is a state in which lymphocytes stop responding to their specific antigen. This is called functional inactivation. This happens when self-reactive lymphocytes meet self-antigens without co-stimulatory signals. These cells do not do anything, so they stay in the lymphoid tissues of the body's edges.

Regulatory T cells, or Tregs, are a type of T cell that stops the immune system from attacking self-antigens. They stop autoimmunity by stopping self-reactive T cells from becoming active and multiplying. Tregs are made in the thymus when T cells develop or in other parts of the body when self-antigens come into contact with naive T cells.

In peripheral lymphoid tissues, autoreactive B cells are killed off. Autoreactive B cells that have gotten past the central mechanisms of tolerance go through a process called receptor editing, receptor revision, or apoptosis to stop them from making antibodies that attack themselves.

Q10i) Explain DNA vaccine. (5)

Ans) A DNA vaccine is a type of vaccine that uses genetic material (DNA) that codes for antigenic proteins to stimulate the immune system to make an immune response against a specific pathogen. DNA vaccines are different from traditional vaccines, which contain weakened or inactive versions of the pathogen or its proteins. Instead, DNA vaccines only contain the genetic material that codes for the antigen.

The DNA vaccine works by putting into the host cells the DNA sequence that codes for the antigen. Then, the host cells use their own machinery to make the antigenic protein, which is then given to the immune system. This triggers a response from the immune system, which makes antibodies and other parts of the immune system that can recognise and attack the pathogen.

Using DNA vaccines is better in many ways than using traditional vaccines. One benefit is that they are easy to make and design because they are made with recombinant DNA technology, which is a simple and cheap process. Also, DNA vaccines might be able to cause both cellular and humoral immunity, which can protect against the pathogen for a long time.

Most of the time, the following steps are needed to make a DNA vaccine:

1. Identifying the Antigen: In order to make a DNA vaccine, the first step is to find the antigenic protein that can cause an immune response. This can be done by looking at the pathogen's DNA sequence or by using other methods to find proteins that are known to make the immune system react.

2. Cloning the Antigen: After the antigenic protein has been found, its gene is copied into a plasmid vector. Plasmids are small, circular DNA molecules that are often used in genetic engineering to put foreign DNA into cells.

3. Inserting the Plasmid into Host Cells: The plasmid with the gene that makes the antigen is then usually injected into the host cells. The plasmid is taken up by the host cells, which then start to make the antigenic protein.

4. Expression of the Antigen: Once the plasmid is inside the host cell, it starts to make the antigenic protein. This protein is then shown to the immune system.

5. Immune Response: When the antigenic protein is shown to the immune system, the immune system responds by making antibodies and other parts of the immune system that can recognise and attack the pathogen.

There are two main types of DNA vaccines: those made from "naked" DNA and those made from "vectors." In naked DNA vaccines, the DNA that codes for the antigen is injected directly into the host cells. Vector-based DNA vaccines, on the other hand, use a virus or bacteria that has been changed to carry the antigen-coding DNA into the host cells.

Q10ii) Based on formulation how many types of vaccines are there and give the example of major preventable diseases of each? (5)

Ans) There are several types of vaccines available, based on the formulation used to create them. Some of the major types of vaccines and examples of preventable diseases they can be used for including:

1. Inactivated or Killed Vaccines: The virus or bacteria in an inactivated vaccine has been killed, so it can't make you sick. The polio vaccine, the hepatitis A vaccine, and the flu vaccine are all good examples.

2. Live Attenuated Vaccines: Attenuated forms of the virus or bacteria are used to make live attenuated vaccines. They are still alive, but they can't make healthy people sick. Some examples are the vaccines for measles, mumps, and rubella (MMR), chickenpox, and yellow fever.

3. Subunit, Recombinant, or Conjugate Vaccines: Some parts of the virus or bacteria are used in these vaccines to make the immune system react. Some examples are the vaccines for hepatitis B, human papillomavirus (HPV), and pneumococcal conjugate.

4. mRNA Vaccines: Messenger RNA (mRNA) is used in these vaccines to tell cells to make a viral protein that can trigger an immune response. For example, the COVID-19 vaccines made by Pfizer-BioNTech and Moderna are good examples.

5. DNA Vaccines: DNA vaccines send a small piece of DNA that has the gene for a viral or bacterial protein on it. This causes the immune system to react. The experimental DNA vaccine for the Zika virus is a good example of this.

6. Vector Vaccines: Vector vaccines use a harmless virus or bacteria to carry a piece of the virus or bacteria that the vaccine is meant to protect against. As an example, the Ebola vaccine uses an adenovirus from chimpanzees as the "vector." With these vaccines, you can protect yourself from diseases like:

a) Polio (inactivated vaccine)

b) Hepatoviral A (inactivated vaccine)

c) Influenza (inactivated vaccine)

d) Rubella, measles, and mumps (live attenuated vaccine)

e) Pox (live attenuated vaccine)

f) Yellow fever means: (live attenuated vaccine)

g) Hepatoviral B (subunit vaccine)

h) Human papillomavirus (subunit vaccine)

i) Pneumococcal disease (conjugate vaccine)

j) COVID-19 (mRNA vaccine)

k) Zika virus (DNA vaccine)

l) Ebola virus (vector vaccine)

It is important to keep in mind that different types of vaccines can have different effects, side effects, and storage needs. Healthcare professionals can recommend the best type of vaccine for an individual or group of people based on things like age, health, and how common the disease being targeted is.