Biological Therapeutics Exam 1
What is the most commonly used DNA vector?
-Bacterial plasmid vector -A circular and double stranded DNA molecule that occurs naturally and replicates extra chromosomally in bacteria -It contains multicloning sites, replication origin, antibiotics selection gene and capable of hosting up to 10 kb DNA fragment -Capable of generating high copy number in bacteria.
What are the outcomes of innate immune response?
-Antigen elimination and restore homeostasis -Induce inflammation, helps wound repair
What are dendritic cells?
-Antigen presenting cells -Express receptors that enable response to antigens -Migrate from epithelia via lymphatics
What are the 4 different types of vaccine development?
-Attenuated Vaccine -Toxoid -Recombinant -Peptide
What are common problems in vaccine development?
-Attenuated organisms revert to wild type -Contamination by animal viruses -Autoimmunity -Local inflammatory reactions -Hypersensitivity -Interferences with vaccines given together
What are the molecular components (humoral) of the immune system?
-Basic antibody structure -Five immunoglobulin (Ig) classes -Complement components
What are the two types of immunity?
- Humoral Immunity: Humoral immunity is the process of adaptive immunity manifested by the production of antibodies by B lymphocytes against an antigen. -Cell-mediated Immunity: Cell-mediated immunity is the activation of phagocytes, antigen-specific cytotoxic T cells and the release of various cytokines in response to an antigen.
Name two differences between the SARS-CoV-2 virus and the influenza virus.
- SARS CoV-2 is a single-stranded, non-segmented, (+) RNA virus, whereas the influenza virus is comprised of 8 single-stranded (-) mRNA gene segments. - The virulence factors of the two viruses are dependent on their unique surface proteins. SARS-CoV-2 virus contains spike proteins which bind to ACE2 receptors, whereas the influenza virus relies on the hemagglutinin and neuraminidase proteins to enter and exit host cells.
Would you recommend administering a new COVID-19 vaccine each year, as is recommended for the flu? Why or why not?
- The average mutation rate of SARS-CoV-2 is relatively low and steady compared to other RNA viruses like the influenza virus. RNA viruses tend to mutate quickly because enzymes that replicate RNA are error-prone. However, data has shown that the typical SARS-CoV-2 virus accumulates only two single-letter mutations per month in its genome — a rate of change about half that of influenza. - The influenza virus contains 8 segments of the RNA genome and undergoes antigenic drift, in which there are point mutations in HA and NA genes, and antigenic shift, in which two different strains can infect the same host and genetic reassortment produces a new strain containing genetic information from both previous strains. Since SARS-CoV-2 is a non-segmented virus, it is not prone to antigenic drift or antigenic shift like the influenza virus is. Since the genetic information of the SARS-CoV-2 virus is not changing dramatically, the COVID-19 vaccines are effective at producing an immune response against the current existing variants. However, it is recommended to get a flu shot each year because the influenza virus rapidly mutates and new strains are produced through genetic reassortment, so each flu vaccine is only effective against four specific strains, the ones that are most likely to appear that season.
Explain how the Moderna and Pfizer/BioNtech mRNA vaccines elicit cellular immune responses via (a) muscle cells and (b) professional antigen presenting cells.
- The mRNA vaccines against SARS-CoV-2 contain non-replicating mRNA encoding the spike protein antigen, which is responsible for recognizing and binding to the ACE2 receptors in the body. The mRNA vaccine is injected in the muscle of the upper arm and contains encoded mRNA encased in a lipid nanoparticle delivery system which protects the mRNA from being degraded before entering the cell. Once the mRNA enters the cell, it utilizes the host cell translational machinery to produce antigenic spike proteins. Host ribosomes translate the mRNA into proteins, which may undergo post-translational modification and either function in the cell or be secreted. - Proteins that remain in the muscle cell are degraded by proteasomes. This produces the antigenic peptide epitopes of the spike protein. These spike protein fragments are transported to the endoplasmic reticulum and loaded onto MHC class I molecules. MHC class I molecules present these spike peptides on the surface of muscle cells (or other nucleated cells that contain MHC class I molecules) for specific cytotoxic T cells which have the CD8 receptor. Cytotoxic T cells have T cell receptors and CD8 receptors which recognize the specific spike protein antigen presented by the MHC class I molecule of the infected muscle cell. The activated cytotoxic T cell will release perforin molecules to make holes in the infected cell membrane so granzyme molecules which promote apoptosis can center the cell, thus destroying the infected muscle cell. - The secreted S proteins can be taken up by professional antigen presenting cells in the tissue. Antigen presenting cells include B cells, monocytes, macrophages, and dendritic cells, which express MHC class II molecules. The S protein enters the APC via endocytic vesicles and is degraded by endosomal proteases into smaller antigenic fragments. MHC class II molecules are assembled in the endoplasmic reticulum and transported to endosomes, where the processed peptides can associate with the MHC class II molecules. The peptide-MHC class II complex is presented on the surface of the APC and can be recognized by helper T cells containing T cell receptors and CD4. The activated helper T cells then proliferate and differentiate, and have many important functions in the immune response, including activation of B cells to differentiate into plasma cells for antibody production and memory cells, macrophages to destroy invading pathogens, and cytotoxic T cells to kill infected cells.
What is a vaccine adjuvant and the advantages of using a vaccine adjuvant?
-A substance that is added to the vaccine in order to increase the body's immune response to the vaccine -Advantages: allow for lesser quantitates of the vaccine and fewer doses
What is an epitope?
-AKA antigenic determinant -Part of an antigen that is recognized by an antibody.
What are tumor vaccines?
-Agent used for cancer therapy or cancer prevention that elicits an immune response and induces protective immunity against specific molecules (antigens) expressed on tumor cells. -Currently no vaccines that can prevent cancer from developing, but some therapeutic tumor vaccines have shown promise in patients with selected cancers.
How was anthrax used during the war?
-Biological war weapon -Contaminated mail
What are tumor cell vaccines?
-Cancer cells removed from a patient are killed and altered to increase potential immune response against them -Autologous: removed tumor cells from patient's own body. -Allogenic: removed tumor cells from someone other than the patient.
What are the challenges of recombinant vaccines?
-Delivery of DNA to cells is not optimal -Extended immunostimulation can lead to inflammation and or autoantibodu production
What are the steps in PCR?
-Denaturation by Heat: double-stranded DNA is separated into two single strands, by a process called denaturation which occurs at temperatures higher than 90 degrees Celsius. Heat breaks hydrogen bonds between the base pairs, while the stronger bonds between deoxyribose and phosphates, remain intact. -Annealing Primers to Target Sequence: before the target sequence is replicated, it must be targeted using primers that target the ends of the target DNA sequence by annealing (binding) to the complementary sequence. Annealing occurs at lower temperature (between 40 and 65 degrees Celsius) which depends on the length and base sequence of the primers. -Extension: after annealing, the temperature is increased to 72 degrees Celsius and the Taq DNA polymerase enzyme is used for replicating the DNA strands. During synthesis (or extension), two identical double stranded DNA molecules are synthesized. -Amplification: after extension the process is repeated generally between 25 and 35 times.
What are the 5 types of cancer vaccines?
-Dendritic cell vaccines -Antigen vaccines -Anti idiotype vaccines -DNA and mRNA vaccine -Tumor cell vaccine
What are the primary reasons for a lack of effective cancer vaccines?
-Difficulty to identify tumor specific antigens capable of inducing antibody and Tc cells against tumor -Cancers have a unique way of shutting down immune system for self protection
What are virus-like particles (VLP)?
-Extract individual structural genes that are unique to the virus -These genes are put into a plant or cell system which is designed to make virus like particles that contain these identifying surface features, such as spike proteins -Trigger an immune response that makes more cells so that these surface proteins will be recognized if the true virus actually invades the body. -Do not contain viral material that can infect the patient
How is the flu virus unique compared to most viruses?
-Flu virus can enter the cells by binding to sugar polymers (carbohydrates) so there is no specific proteins that it binds to -All the surfaces in it's pathway are covered by mucus -Takes advantage of the abundant mucus surface which enhances the success rate of the virus
What are applications of recombinant DNA technology?
-Gene functional studies -Engineering E. coli to produce a foreign protein
What host cells are commonly used for producing protein antigens?
-Genetically engineered microorganisms (yeast) -Cultured animal cells (CHO) -Transgenic plants -Insect larvae
What are the different ways flu viruses can be inactivated?
-Inactivated by heat at 50 degrees Celsius for 30 minutes. -Survive only 1 week at 0-4 degrees Celsius --Survive 2 weeks in a blanket -Destroyed by ether, formaldehyde, and phenol.
What are the major differences between inactivated vaccines and live attenuated vaccines?
-Inactivated vaccines can be split virus vaccines or a subunit vaccine with purified HA and NA -Inactivated vaccines can be injected via subcutaneous or intramuscular injection. -Live attenuated vaccines have flu strains that replicate at 25 degrees Celsius but poorly at body temperature. -Live attenuated vaccines are administered primarily via intranasal injection.
What is a recombinant vaccine?
-Instead of whole microorganism, the DNA, mRNA, and proteins from the pathogen can be formulated and used for immunization -The protein that is both immunogenic and critical for pathogen is identified and the gene encoding the protein is isolated -Gene is put in a vector and can be used to produce the mRNA to make the protein which then is used to induce an immune response -This works as the mRNA is injected the host cells take it to produce the antigenic protein and present it on the surface.
What are dendritic cell vaccines?
-Isolated dendritic cells are exposed to tumor antigens under the experimental condition to maximize antigen presentation. -The mixture of dendritic cells and antigens is then infused to patients to generate activated T and B cells and long-term memory cells.
What are the goals of recombinant DNA technology?
-Isolation and characterization of a DNA fragment (e.g. gene) -Make desired modification in isolated DNA sequence -Artificial synthesis of new genes -Modification of organisms' genome -Produce gene product (RNA and protein)
List 2 features of the influenza virus structure.
-Lipid bilayer -Spherical in shape -RNA genome that exists in 8-10 segments and codes for 9-11 types of proteins -Membrane surface contains spike-like proteins (hemagglutinin, neuraminidase, and M2 proton channel protein) -Exhibits polymorphism.
What are methods used for attenuation?
-Use of a related virus from another animal species -Administration of pathogenic or partially attenuated virus by an unnatural route -Passage of the virus in an "unnatural host" or host cells -Development of temperature sensitive mutants
What are the organelles in the lymphatic system?
-Lymph: Fluid and cells (lymphocytes) in lymphatic vessels -Lymphatic vessels: Collect and return interstitial fluid to blood, transport immune cells throughout body, transport lipid from intestine to blood -Lymph nodes: Kidney shaped organs at intervals along lymphatic vessels -Naïve lymphocytes circulate between blood, lymphatic vessel and lymph nodes. -Pathogens from infected tissue sites are picked up by lymphatic vessels and arrive at closest lymph node.
What are the organs of the immune system?
-Lymphoid organs: Lymph nodes and lymphatic vessel. -Bone marrow: Source of immune cells -Thymus: Site for T cell maturation -Spleen: Store various immune cells; breaking down red blood cells and platelets -Tonsils: Checking point for entrance of germs from mouth or nose -Skin and mucous membranes in intestine, lungs, urinary tracks, and linings of the vagina: Provide a physical barrier to prevent germ entry
Binding of antibodies to antigens inactivates antigens by what?
-Neutralization -Agglutination of microbes -Precipitation of dissolved antigens -Activation of complement system: leads to cell lysis
How does the COVID vaccine work and explain the body's response?
-Our immune system uses several tools to fight infection. Blood contains red cells, which carry oxygen to tissues and organs, and white or immune cells, which fight infection. Different types of white blood cells fight infection in different ways: -Macrophages are white blood cells that swallow up and digest germs and dead or dying cells. The macrophages leave behind parts of the invading germs, called "antigens". The body identifies antigens as dangerous and stimulates antibodies to attack them. -B-lymphocytes are defensive white blood cells. They produce antibodies that attack the pieces of the virus left behind by the macrophages. -T-lymphocytes are another type of defensive white blood cell. They attack cells in the body that have already been infected. - The first time a person is infected with the virus that causes COVID-19, it can take several days or weeks for their body to make and use all the germ-fighting tools needed to get over the infection. After the infection, the person's immune system remembers what it learned about how to protect the body against that pathogen. - The body keeps special type T-lymphocytes, called "memory cells," that go into action quickly if the body encounters the same virus again. When the familiar antigens are detected, B-lymphocytes produce antibodies to attack them. But with all types of vaccines, the body is left with a supply of "memory" T-lymphocytes as well as B-lymphocytes that will remember how to fight that virus in the future. - It typically takes a few weeks after vaccination for the body to produce T-lymphocytes and B-lymphocytes. Therefore, it is possible that a person could be infected with the virus that causes COVID-19 just before or just after vaccination and then get sick because the vaccine did not have enough time to provide protection. Sometimes after vaccination, the process of building immunity can cause symptoms, such as fever. These symptoms are normal and are signs that the body is building immunity. A booster shot is for people who built enough protection after completing their primary vaccine series, but then that protection decreased over time.
What specific kind of molecule do cytotoxic T cells contain that aid in destruction of infected cells? What function does this molecule help Tc cells to perform?
-Perforin -Helps to make holes in the infected cells membranes -Enzyme (apoptotic promoter enzyme) can enter infected cells and induce cell death.
What is an attenuated vaccine?
-Prepared from attenuated strains of a virus that are almost completely devoid of pathogenicity but still immunogenic -Can multiply in the host and provide antigenic stimulation over a period of time.
What is the difference between primary and secondary antibody responses?
-Primary: antibody concentration gradually rises, peaks after 2 weeks of vaccination -Secondary: antibody concentration rises quickly, response is more intense, concentration remains higher for longer
What are advantages of mammalian cell systems?
-Proteins are correctly folded and properly function -Wide range of plasmics and viral vectors
Describe 5 characteristics of an ideal vaccine.
-Rapid induced immunity -Give life-long protection -Broadly protective against all variants of organism -Prevent disease transmission -Effective in all patient types
Describe the steps of the modern-day procedure employed in vaccine development.
-Recognize the disease and identify the etiologic agent -Grow the agent in laboratory -Obtain genome sequence -Establish animal model for disease -Choose antigen in laboratory -Prepare candidate vaccine following cGMP's -Evaluate the candidate vaccine for ability to stimulate immune response and protect animals against the pathogen
What does vaccine development focus on?
-Safety -Efficacy -Generating memory cells
What are pathogen entry sites?
-Skin -GI tract -Respiratory tract -Urological tract -Eyes and ears
What is a peptide/conjugate vaccine?
-Small peptide sequences corresponding to important epitopes on a microbial antigenic can be synthesized economically. -Can be highly immunogenic in their free form -T cell epitope must be linked to B cell epitope
What are the routes of vaccine administration?
-Subcutaneous/intramuscular injection -Oral route -Transdermal route -Scarification -Intranasal route
What are advantages of peptides?
-The antigens are precisely defined and free from unnecessary components which may be associated with side effects -Stable and relatively cheap to manufacture -Less quality assurance is required -Feasible even if the pathogen cannot be cultivated -Changes due to natural variation of the virus can be readily accommodated.
Name the most common adjuvant in vaccines and an example of a vaccine that adjuvant is used in today.
-The most common vaccine adjuvant is Aluminum, and it is used in Hepatitis A and B vaccines today. -Others: AS04, saponins
What are the currect focuses for cancer vaccines?
-To find tumor specific antigens. -To understand the immune surveillance of tumors. -To develop strategies gaining enhanced immune response against tumors.
What are the 3 types of influenza viruses?
-Type A viruses are the source of seasonal influenza epidemics and all pandemics. -Type B viruses infect humans (& seals) and do not cause pandemics. -Type C viruses infect human and pigs causing mild disease.
What are DNA and mRNA vaccines?
-Vectors carrying tumor specific DNA sequence are injected into the patients, which instructs the cells to continuously produce tumor antigens. -DNA vaccine increases production of antigens, which forces the immune system to respond by activating and producing more T cells. -Constant supply of antigens to allow the immune response against the tumor cells.
Explain the recombinant DNA process and how you may get a purified recombinant plasmid DNA.
1) A First a DNA vector is chosen which is typically a bacterial plasmid. The plasmid you want needs to be purified 2) Restriction enzymes then cut the plasmid at specific sites creating 3' and 5' overhangs. Once you have the cut plasmid you want to extract them using a DNA extraction technique from the agarose gel. 3) As that is done in another experiment the DNA that you want to add to the cut plasmid should be replicated using polymerase chain reaction (PCR). Or you could synthesize the desired insert strand from an mRNA using reverse transcriptase. 4) Next you should mix the desirable strands and add DNA ligase to combine the fragment with the cut plasmid. Essentially this makes your new recombinant DNA. 5) To take it a step further, you could insert that recombinant DNA into E. coli through a process called transformation and the cell will now uptake and replicate that recombinant plasmid. You could isolate the plasmid from the cells in large amounts.
How do Tc cells work?
1. Cytotoxic T cell binds to infected cell 2. Perforin makes holes in infected cell membrane and enzyme enters 3. Infected cell is destroyed
How is microinjection used to generate transgenic animals?
1. Direct microinjection of exogenous DNA into an embryonic cells 2. Stable integration of the target DNA into the genome of the cell 3. Cells are implanted into a surrogate mother 4. Transgenic animal harbors a copy of the transferred DNA
How do killed/inactivated vaccines work?
1. Following injection, the inactivated organism is phagocytosed by immature dendritic cells. 2. Processed peptides will be presented on the cell surface as MHC IIantigenic fragment complexes. 3. Th cells with T cell receptor (TCR) will be activated. 4. B cells with a B cell receptor (BCR) for a specific antigen will bind antigens that drain along lymph vessels. The antigens are processed and presented as MHC II -antigen complex. 5. Activated Th will release IL2, IL4, IL5 and IL6 to induce B cell activation, differentiation and proliferation with subsequent isotype switch (IgM to IgG) and memory Bcell formation.
How does a viral vector-mediated immune response work for COVID-19?
1. Gene that encodes for COVID spike protein is inserted into the virus' genetic material 2. Altered virus is injected into muscle and heads towards cells 3. Virus tells cells to make COVID spike protein 4. Spike protein moves to cell surface 5. Immune response begins
Explain the process of making a recombinant vaccine?
1. Identify a protein that is immunogenic and critical for the pathogen 2. Gene encoding for specific protein is identified and isolated 3. Gene is cloned into a suitable expression vector 4. mRNA or protein is prepared 5. Gene, mRNA, or proteins are formulated
How does an mRNA vaccine work?
1. Scientists generate an mRNA sequence that codes for the spike protein 2. The RNA sequence is wrapped in a liquid coating for delivery 3. Cells read the information and produce millions of spike protein copies 4. The protein fragments produce antibodies that protect when a virus enters the body
How do viruses work?
1. Virus enters the body through the mouth or nose 2. Virus moves into airways and lungs 3. Virus attacks respiratory track, replicates, and releases more virus into the body 4. Immune system starts to hunt and clear virus 5. Recovery unless too many lung cells are destroyed
What is a toxoid vaccine?
A chemically or physically modified toxin from a pathogenic microorganism, which is no longer toxic but remains antigenic and can be used as a vaccine. These molecules take advantage of the immature dendritic cells and MHC II pathway to present the toxoid to provide an adaptive immune response.
What is cancer?
A collection of diseases caused by unlimited cell division (growth) and spread into surrounding tissues (metastasis).
What is recombinant DNA technology?
A series of procedure to join together (recombine) the DNA segments to make a new and different DNA molecule.
Distinguish 4 differences in antigenic shift and antigenic drift.
Antigenic Shift: - Major changes in HA and NA - Occurs in influenza A - Two different influenza viruses enter cell and combine resulting in a new influenza strain - Cause major epidemic about every 10 years Antigenic Drift: - Minor changes in HA and NA - Occurs in influenza A and B - Antibodies are not effective against new mutation - Causes a minor epidemic about every two years
What are advantages and concerns about attenuated vaccines?
Advantage: -Sufficiently immunogenic -Vaccine failure is uncommon Concerns: -Under attenuation -Preparation instability -Mutations may lead to reversion to virulence -Heat liability
What are advantages and disadvantages of transgenic plant systems?
Advantages: -Low cost of plant cultivation -Harvest equipment/methodologies are inexpensive -Ease to scale-up -Proteins expressed in seeds are generally stable -Plant-based systems are free of human pathogens Disadvantages: -Variable/low expression levels of proteins -Potential post-translational gene silencing -Seasonal/geographical nature of plant growth
What are the advantages and disadvantages of killed/inactivated vaccines?
Advantages: -Safer since they cannot cause the disease, and there is no possibility of reversion to virulence. -Cannot spread the disease to unimmunized people since the vaccine antigens are not actively multiplying. -More stable and last longer since they are less susceptible to changes in temperature, humidity, and light. Disadvantages: -Contaminations cause allergic reactions and autoimmunity -Protective immunity is not always induced -Induce humoral immunity rather than cell mediated immunity
What are the advantages and disadvantages of toxoids?
Advantages: -Safer: do not cause disease they prevent -Cannot spread to nonimmunized people -Stable and long lasting Disadvantages: -Need several doses -Local inflammatory reactions
What are restriction enzymes?
An enzyme isolated from bacteria that cuts DNA molecules at specific sequences. The isolation of these enzymes was critical to the development of recombinant DNA (rDNA) technology and genetic engineering
How is antigen presented?
By major histocompatability complex (MHC), a group of cell surface protein expressed on all nucleated cells of vertebrates
What are the structures of COVID-19 and Influenza?
COVID-19 Structure: - Membrane Virus, 80 -120 nm in size - 4 structural proteins: spike, membrane, envelop, nucleocapsid - 29.7 kb RNA genome with structural genes and nonstructural genes - Positive sense RNA strand, directly translated Influenza Structure: - Membrane virus with a lipid bilayer - Spherical in shape and 80 - 120 mm in size - RNA genome existing in 8 - 10 segments coding for about 9 - 11 protein types - Membrane surface containing H, N, and M2 proton channel proteins.
What are the differences between the two types of dendritic cells?
Classical dendritic cells: -Most common dendritic cells -Constantly sample environment -Produce inflammatory cytokines Plasmacytoid dendritic cells: -Rare type of immune cells -Do not sample environment -Secrete type I interferon
Explain the differences between DNA and mRNA vaccines regarding how they produce antigen proteins after injection.
Composition: - DNA: promotor/enhancer region, coding sequence, & poly A sequence - mRNA: 5' cap, un-translational regions, coding sequence, & poly A sequence Mechanism to produce antigen protein - DNA: transcription (in nucleus) THEN translation (cytosol) - mRNA: ONLY translation (cytosol)
What are anti-idiotype vaccines?
Comprise of antibodies that have 3D immunogenic regions, termed idiotopes, that consist of protein sequences that bind to cell receptors
To what extent must a variant be different from the original virus for the existing COVID-19 vaccines to be ineffective?
Current COVID-19 vaccines induce the immune system to produce antibodies and induce the T cell response against the SARS-CoV-2 spike protein. Mutations in the spike protein can affect the efficacy of COVID-19 vaccines by altering the structure of the spike protein. A mutation can change the structure of the spike protein slightly so that the virus is not fully neutralized by antibodies, or a mutation can change the spike protein so significantly that the antibodies produced by vaccination do not recognize the specific antigenic epitopes, and the variant evades the immune response induced by vaccination. Thus, mutations in the viral spike protein pose the biggest threat to rendering current COVID-19 vaccine therapies ineffective.
How were vaccines discovered?
Edward Jenner injected cowpox into a boy and noticed that the boy did not get smallpox
What is DNA ligase?
Enzyme that helps to join the ends of DNA and re-establishes phosphodiester bond in the DNA molecule
Your brother has had a stuffy nose and congestion for two days. Two months ago, he had COVID-19 as confirmed by a RT-PCR test. Today, he chooses to take a rapid antibody test to see if he has COVID-19. After taking the tests, two lines appear. When you consult the instructions, you understand there are three possible lines IgM, IgG, and a control line. His IgM test was negative while both the IgG and control line were positive. Do you believe he currently has COVID-19?
He most likely does not have COVID-19. This is due to the fact that there are no IgM antibodies for the disease in his system, which would be prevalent since he just recently had symptoms. The IgG antibodies are most likely from the previous time he had COVID-19, and are remaining in his system.
What is the difference between cell-mediated immunity and humoral immunity?
Humoral: -Antibody mediated -Controls extracellular pathogens -Major role involves B cells Cellular: -Cellular is cell mediated -Cellular controls intracellular pathogens -Cellular: major role is T cells
What is the immune system?
Immune system is made of organs, cells, and molecules that provide non-specific and specific protection against microorganisms, microbial toxins, and tumor cells
List the differences between an innate immune response and an adaptive/acquired immune response.
Innate Immune Response: - First line defense - Fast - No memory - Primarily involve physical barriers, complement components, and immune cells like macrophages, neutrophils, natural killer cells, and dendritic cells - Releasing proinflammation cytokines - Release soluble antigens Adaptive Immune Response: - Acquired by responding to a specific pathogen - Involve antigen presentation, T cells and B cells - Produce antibodies, cytotoxic T cells and memory T and B cells - Results in long term protection
What was the second generation of vaccines?
Louis Pasteur developed the vaccine for chicken chloral and anthrax by cultivating a microbe in a broth made of chicken meat
What are the differences between MHC I and MHC II?
MHC I: -Composed of an α (or heavy) chain in a non-covalent complex with a β2- microglobulin -Recognized by CD8+Tcells (Tc) -Accommodate peptides that are 6 to 16 amino acid residues in length -Expressed on all nucleated cells -Cytosolic proteins are proteolytically degraded in the proteasome MHC II: -Contain two MHC-encoded polymorphic chains, an α chain and a β chain. -Recognized by CD4+Tcells (Th) -Allows larger peptides (up to 30 amino acid residues in length or more) to bind -Expressed mainly on specialized APCs -Extracellular proteins are internalized into endosomes
A pharmaceutical company, Medicago, is carrying out clinical trials on a new COVID vaccine that uses plant-based technology to insert genes from the virus that code for the identifying protein features on the outside of the virus particles and inserting these into a plant system. As a result, this produces molecules that mimic the appearance of the virus's identifiers, such as a spike protein on the surface, to trigger an immune response that can then produce memory cells for this structure without the possibility of infecting the patient. Based on this information, what type of vaccine does it appear that Medicago is developing? Defend your answer with your knowledge of vaccine types.
Medicago is developing a virus-like particle vaccine. Because virus-like particle vaccines do not contain any of the viral material that can infect the patient because it only contains genes for these structural identifiers, this also matches the provided description, defending the choice of virus-like particle vaccines as the one being used by Medicago.
What is an antigen?
Molecule which stimulates production of and binds specifically to an antibody
What is an immunogen?
Molecules which can stimulate immune response
What type of immune response does a vaccine mimic?
Natural immune response
Based on what you know about the mechanisms of the human immune system, explain which step(s) in the immune response process you think may be limiting to the development of an influenza vaccine that will protect against all possible combinations of the flu (a "forever flu vaccine"/injecting all possible influenza H#/N# types in one vaccine).
Possible Answers: 1) In the innate immune response, neutrophils are mainly involved in attacking the original invasion of foreign invaders. However, with over 100 possible versions included in one vaccine, neutrophils may become overwhelmed with the amount of antigens present. This is because in order to include that many H#N# types that will protect against all versions of the flu that would be transmissible by humans, the vaccine would have to dramatically increase in volume, injecting high amounts of protein so encompass some that are specific to each type. As a result, it is clear that the number of antigens being introduced may outnumber the resources in this first line of defense. 2) i. In the adaptive immune response, dendritic cells may begin to capture these antigens, but again they may be overwhelmed by the high volume of antigens that have invaded the system, only being able take up so much. This leaves free antigens, which will directly activate B cells. However, those B cells will also be stimulated by the helper T cells that are responding to the antigen-presenting cells. This is also true of cytotoxic T cells, which are responding to antigen presentation and will be stimulated by helper T cells. Because the antigen volume is so high, this extra stimulation of these B cells due to so many free antigens along with the use of the MHC I and/or MHC II pathways may create an overactive immune response that could stress the patient. Additionally, this would overload the stream of B cells and cytotoxic T cells that would need to then be made into memory B cells and memory T cells, creating a long and heavy immune response.
How is a tumor different from cancer?
Rapidly dividing cells do not invade and spread to surrounding tissues
What is a hapten?
Small (low MW) molecule unable to elicit immune response unless linked to a larger carrier
How does the agent in a vaccine stimulate the body's immune response?
The immune system recognizes the agent as foreign, destroys it, and keeps a record to detect and destroy these microorganisms in future encounters more easily
In 2009, there was a major breakout of H1N1. Explain what the name "H1N1" means, and which virus it refers to.
The nomenclature in the format H#N# is used to name different strains of the influenza virus. H1N1 means that that strain of flu has the proteins hemagglutinin type 1 and neuraminidase type 1.
Both the Pfizer and Moderna COVID vaccines require two shots that must be taken 3-4 weeks apart. Explain why there is a waiting period between the two doses, and why it is important to receive both doses for optimal immunity.
The purpose of a second shot is to initiate a secondary immune response. For a true secondary response, it will generally take about month after the first exposure for memory cells fully developed. A secondary response boosts immunity because it allows for a faster response from memory cells and results in a higher level of IgG antibodies.
Suppose two companies designed vaccines for a novel coronavirus named CoV-03. Company A, utilizing modern methods, designed a mRNA vaccine, encoding a spike protein (protein S) responsible for entry into the host cell. Company B decided to go a more traditional route, and used an attenuated CoV-03 (cold preferential strain) virus that does not replicate well at 37°C. Both vaccines are shown to prevent disease in 80% of healthy adults which receive the vaccine. Suppose a mutation occurred in which the S protein changed sequence due to amino acid substitutions, though retained the ability to bind to the host cell. What effect would this have on both vaccines? Would one vaccine become less efficacious than the other? Why or why not?
The substitution in the amino acid sequence of the S protein could lower the efficacy of both vaccines, though it most likely would affect the mRNA vaccine more than the traditional attenuated virus vaccine. This is due to the mRNA vaccine using only the S protein as an antigen, while the attenuated virus vaccine contains all viral proteins, allowing for other antigens to be presented, and for a possibility of antibodies for epitopes other than that on the S protein.
What is the difference between killed and inactived?
The term "killed" generally refers to bacterial vaccines whereas "inactivated" relates to viral vaccines.
What is a unique feature about a live/attenuated virus?
They are almost or completely devoid of pathogenicity but still elicit an immune response
What is the naming process of the influenza virus?
Type/geographic origin/strain #/year isolated/virus subtype
What are antigen vaccines?
Use tumor-specific antigens to stimulate the immune system to produce an increased number of antibodies to attack cancer cells
Place the steps of the innate immune response in order from 1 to 8: _____ Neutrophils secrete factors that kill and degrade pathogens. _____ Platelets from blood release blood-clotting proteins at wound site. _____ Inflammatory response continues until the foreign material is eliminated and the wound is repaired. _____ Bacteria and other pathogens enter the wound. _____ Neutrophils and macrophages remove pathogens by phagocytosis. _____ Dendritic cells capture antigen. _____ Mast cells secrete factors that mediate vasodilation and vascular constriction. Delivery of blood, plasma, and cells to injured area increases. _____ Macrophages secrete hormones called cytokines that attract immune system cells to the site and activate cells involved in tissue repair.
__4__ Neutrophils secrete factors that kill and degrade pathogens. __2__ Platelets from blood release blood-clotting proteins at wound site. __7__ Inflammatory response continues until the foreign material is eliminated and the wound is repaired. __1__ Bacteria and other pathogens enter the wound. __5__ Neutrophils and macrophages remove pathogens by phagocytosis. __8__ Dendritic cells capture antigen. __3__ Mast cells secrete factors that mediate vasodilation and vascular constriction. Delivery of blood, plasma, and cells to injured area increases. __6__ Macrophages secrete hormones called cytokines that attract immune system cells to the site and activate cells involved in tissue repair. Lecture 8 slide 5
