Unit 8 Influenza A
What viruses did the Trivalent flu vaccine fight?
- A/Hawaii/70/2019 (H1N1) pdm09-like virus - A/HongKong/45/2019 (H3N2)-like virus - B/Washington/02/2019-like virus (B/Victoria lineage)
What are the two different forms of MHC markers in the body?
- MHC class 1 markers (MHC-1) are present on every nucleated cell of the body. This is the general "self" identification tag - MHC class 2 markers (MHC-2) are only present on the immune system cells that provide the link between the nonspecific and specific immune responses
What five characteristics do biologists use to determine if something is considered alive or not?
- process energy and material - maintain an internal environment - respond to stimuli from the environment - reproduce - adapt to changing environmental conditions
What is the effects of mutations?
A change in the nucleotide sequence of a DNA molecule can change the sequence of a DNA molecule can change the sequence of amino acids in a protein, and thus the properties of that protein
What is an alternative to a flu shot?
A nasal spray. This contains weakened versions of the influenza viruses and thus may produce some flu-like symptoms. However, concerns have been raised over the effectiveness of this form of the vaccine, specifically with regard to H1N1 (swine flu) viruses
Influenza A is followed by?
A nomenclature on the types of spikes found on the surface of the virus (H1N1 for example)
What is the purpose of Thimerosal in a flu shot?
A preservative that may be present in some multi-dose vials of the vaccine
What do the glycoproteins act as?
Act as identification tags.
What components are in a flu shot?
Aluminum salts, Antibiotics, Egg protein, Formaldehyde, Gelatin/sorbitol/or monosodium glutamate (MSG), and Thimersol
What is an Antigen?
An antigen is any substance that produces a specific immune responses by the body.
What are N spikes?
An enzyme called neuraminidase. N spikes help breakdown the mucous material surrounding host cells in the respiratory tract and initiate penetration of the virus into the host cell
What are the two types of structures in Comparative Anatomy? (1)
Analogous structures: Structures that serve the same function, and often may appear the same, but that evolved independently as adaptions to a specific environment. Wings of birds, bats, and insects are examples of analogous structures.
Why does antigenic shift occur?
Antigenic shift occurs when two different influenza viruses infect the same host cell, and a new form of the virus is manufactured
What are the two methods influenza virus changes its genetic information?
Antigentic shift and antigentic drift
What are H spikes associated with?
Associated with hemagglutinin, a type of glycoprotein that assists the virus in identifying the receptors on the host cell
what is the first stage of Lytic cycle?
Attachment: The structure of the proteins on the capsid allows it to recognize and target specific cells for infection
What are the three aspects of the viral life cycle? (1)
Attachment: Viruses are specific in the types of cells they infect. Therefore, it is possible to target either the molecules on the surface of the host cell that the virus identifies with or the proteins that the virus uses to attach to the cell
What do fossil fuels record?
Because fossil records may be dated by looking at ratios of certain radioactive compounds in the rocks, these transitional; fossils can help calibrate the fossil record
Why does the use of RNA as genetic material present problems for the virus?
Because the host cells protein synthesis processes require DNA as the starting template
What do scientists refer viruses as?
Being obligate intracellular parasites, which is really just a way of saying that viruses need a host cell in order to replicate.
What is the third stage of Lytic cycle?
Biosynthesis: At this point, the virus hijacks the host cells machinery to manufacture new capsid proteins and copies of its genetic material. Energy and materials for these processes are all provided by the host cell
What does the term evolution mean?
Changes in species or population over time
What does the genetic material contain?
Contains the instructions needed to manufacture the proteins that compose the capsid surrounding the virus
In all organisms, except RNA viruses, the flow information is from...
DNA to RNA (ribonucleic acid) to proteins
What did Darwin's observations help him figure out?
Darwin's observations of the finches and tortoises of the Galapagos provided him with his ideas on how natural selection drives evolutionary change
What do the cells Natural killer (NK) cells do in the immune system?
Destroy cells of the body that have been infected by viruses or bacteria (nonspecific)
What do the cells Macrophages, dendritic cells, and neutrophils do in the immune system?
Destroy pathogens by phagocytosis (nonspecific)
What other systems of the body are affected by the flu?
Digestive, Muscular, Nervous, and Integumentary
What 3 ways can natural selection influence the variation for a trait in a population? (2)
Directional selection: Changes in the environment direct natural selection to favor the variants at one end of the distribution. This causes a shift in the distribution of the trait over time toward one of the extremes.
What 3 ways can natural selection influence the variation for a trait in a population? (3)
Disruptive selection: Changes in the environment cause the average, or most common, form of variation to be detrimental, and favors the variants at the ends of the distribution
When are homologous structures also evident in?
During the Embryonic development of animals
What do ecologists do?
Ecologists research how organisms have evolved to fill their roles within an ecosystem
What is the purpose of Aluminum salts in a flu shot?
Enhances the ability of the immune system to detect the virus. Some vaccinations are aluminum-free.
Within the body, how are epithelial cells arranged?
Epithelial cells are arranged into a thin layer of tissue, called epithelium, that is often only one cell-layer thick
What is one of the accumulated evidence that supports that species have changed over time and that this change is the result of natural selection?
Evidence from fossil fuels and living organisms
What do Epithelial cells form?
Form the boundary between the tissues of our bodies and internal environments, such as the respiratory tract and digestive tract. Our skin is also composed of epithelial cells and serves to isolate us from our external environment
What do all viruses have in common?
Genetic material: the genetic material which may be in the form of DNA of RNA. However they contain a relatively small number of genes in comparison to a living cell. Capsid: A protein coat that surrounds the genetic material. The capsid may have proteins attached to it, such as tail fibers or spikes, that assist the virus in attaching to the target host cell.
What two forms of spikes are there on Influenza A?
H spikes and N spikes
What two forms of Influenza A contribute to the normal seasonal flu outbreak?
H1N1 and H3N2
In 2019, the national institutes of health announced the first human trials of a vaccine called,
H1ssF_3928, that was designed to provide protection against a variety of influenza viruses
What is an example of a RNA virus?
HIV virus, are called retroviruses, because they require a reverse ("retro") step before their genetic information can be expressed.
How is the genetic material of RNA shown in humans?
HIV, influenza, SARS-CoV-2
Influenza B is followed by?
Have a lineage designation (either B/Yamagata or B/Victoria) that help identify the history of the virus.
What are the two types of structures in Comparative Anatomy? (2)
Homologous structures: Structures that are similar because they have been inherited from a common ancestor. The bone structure of the limbs of a mouse, bat, and whale are all similar because these mammals all descended from a common ancestor
What is the life cycle of a virus?
In the lytic cycle, viral reproduction begins almost immediately after the virus enters the host cell. In the lysogenic cycle, reproduction is delayed and the viral DNA integrates into the host cell genome
What is the purpose of Formaldehyde in a flu shot?
Inactivates any toxins from the viruses or bacteria that may have been present during production
What series of steps does natural selection occur in? (step 3)
Individuals differ in their fitness: Individuals who have favorable traits will survive at a greater rate than those without them. When these individuals reproduce, they pass these traits on to the next generation. The term fitness is often used to describe this reproductive success
What series of steps does natural selection occur in? (step 2)
Individuals struggle to exist: Populations produce more offspring than can survive, which creates competition for available resources
What series of steps does natural selection occur in? (step 1)
Individuals vary in their traits: Variation exists in a population for heritable traits. This does not just include physical characteristics, such as beak shape, but also physiology and behavior
What are the two most prevalent forms of influenza that infect humans?
Influenza A and B
What several forms of influenza are there?
Influenza A, B, C, and D
What is the most common method of producing a flu vaccine?
Injecting the viruses into fertilized chicken eggs and allow them to incubate for a few days, during which time the viruses begin to replicate
What is one of the biggest problems with antigenic drift?
It can make the annual flu vaccine less effective if the virus mutates after the vaccine has been developed
What is the problem with antigenic shift?
It causes a more rapid change in the virus, and because our immune system has not been exposed to this form of the virus before, it takes longer to respond to it, and thus an outbreak in population may more easily result
Why is this protein added to the virus?
Its added to a virus that infects insect cells and is then cultured to produce large amounts of the H spike protein
How is the lymphatic system involved in the immune system?
Its involved in returning fluids (called lymph) from the tissues of the body back to the circulatory system
What is the most common pathway for all viruses?
Lytic cycle
What pathway is used in Influenza A?
Lytic cycle
What do geneticists investigate?
Many geneticists investigate how genetic material changes over
What is the fourth stage of lytic cycle?
Maturation: Also known as assembly, this is when the pieces of the virus are assembled
What does natural selection act on?
Natural selection acts on the variation within the population by favoring some variants over others.
What research is currently being down on a Universal flu vaccine?
Newer vaccines are being designed to use other proteins within the capsid of the virus as the basis for programming the adaptive responses. These proteins, sometimes called core proteins, do not change at the same rate as the H and N spikes on the virus and are more similar between influenza viruses
Do all organisms form fossils?
No, other organisms such as bacteria, jellyfish, plants, and other organisms lack skeletons and shells may form impressions on the sediments.
What is Antigenic Drift?
Occurs when there are small changes in the surface spikes of the influenza virus
What are two possible ways this new version of the flu will appear?
Often new forms of the influenza virus originate in animal hosts, such as pigs and chickens. Due to humans close proximity to these animals on farms, it is possible for the viruses to undergo an antigenic shift and produce new forms of the virus, which may then infect humans.
Where are the forms from that antigenic shift forms?
Often these forms are from different hosts, such as pigs, and birds, although the process can occur in humans too
What is one the roles of the immune system?
One of the roles of the immune system is to monitor these fluids (from lymphatic system) for the presence of pathogens. This is mainly done in the lymph nodes of the body.
What is the second stage of Lytic cycle?
Penetration: Once the virus has identified the host, its genetic material enters the cell. This can occur by injecting the genetic material directly into the host cell (leaving the capsid outside), or by convincing the host cell to engulf the entire virus (a process called endocytosis) In the case of influenza, the latter process occurs, and once in the cell, the virus releases its genetic material into the host cell.
What series of steps does natural selection occur in? (step 4)
Populations become adapted to the environment: Over time, natural selection increases the frequency of the advantageous trait in the population and decreases the frequency of detrimental traits. Over multiple generations, the population becomes adapted to the new environment
What is the purpose of Antibiotics in a flu shot?
Prevents bacterial growth during the preparation and storage of the vaccine
What do the cells B lymphocytes do in the immune system?
Produce antibodies to target specific antigens in the fluids of the body (specific)
What to proteins often have in viruses?
Proteins often have complex, three-dimensional shapes, and in the case of capsid proteins, these complex shapes allow the virus to target specific molecules on the surface of the target cell.
Antigens are usually...
Proteins or large carbohydrates that are specific to pathogens such as bacteria and viruses
What is the life cycle of an RNA Virus ?
RNA viruses, such as influenza, must convert their genetic information into DNA to form viral proteins. Influenza provides an enzyme called RNA polymerase to convert viral RNA to mRNA. Once done, biosynthesis of new viral proteins can begin
What do white blood cells release in the immune system?
Release proteins called cytokines. Cytokines act as an alarm to the organ systems of the body, altering them that a pathogen is present
What is the last/fifth stage of lytic cycle?
Release: Finally the new viruses are ready to leave cell. This is possible by either causing the host cell to burst (called lysis) or by exiting through the plasma membrane (exocytosis). Viruses that possess an outer envelope leave by exocytosis. As they exit, they often create an envelope about themselves by acquiring pieces of the host cell's plasma membrane
What are the three aspects of the viral life cycle? (3)
Release: Many viruses provide an enzyme that interacts with specific molecules in the host cells membrane to allow the newly formed viruses to escape the host cell
What is the purpose of Egg protein in a flu shot?
Remnants from the production of the vaccine. Newer vaccines that do not use eggs during production will not have these proteins present.
How are the flu viruses selected to make a vaccine? (part 2)
Scientists review data to determine each flu virus's potential to cause a worldwide pandemic, what is known about the strain of the virus, and the ability to produce an effective vaccine against the strain
How does embryonic development used as evidence of evolution?
Similarities in embryonic development, as well as the appearance of homologous structures such as pharyngeal pouches, is evidence of evolution.
How is the genetic material of DNA shown in humans?
Smallpox, chickenpox, herpes
What is interesting about giant viruses?
Some of them possess the ability to manufacture their own proteins, a characteristic that has traditionally reserved for organisms classified as alive.
What is the purpose of MSG in a flu shot?
Stabilize the vaccine and protect it from temperature variations during storage
What 3 ways can natural selection influence the variation for a trait in a population? (1)
Stabilizing selection: Selection favors the most common form of variant for the trait, and selects against the extreme variants. In this case, the average individual is most adapted to the environment
What are the symptoms and cytokine action of the Nervous system?
Symptoms: Headache, fever Cytokine action: Presence of cytokines tells the hypothalamus in the brain to increase the body temperature
What are the symptoms and cytokine action of the Muscular system?
Symptoms: Joint and muscle aches Cytokine Action: Breakdown of muscle fibers and accumulation of fluid
What are the symptoms and cytokine action of the Digestive system?
Symptoms: Loss of appetite, nausea, vomiting Cytokine action: Reduces the action of appetite centers in the brain
What are the symptoms and cytokine action of the Integumentary system?
Symptoms: chills Cytokine Action: Restriction of blood vessels in the skin to conserve heat
What are one of the more commonly known antivirals for influenza?
Tamiflu
What does tamiflu target?
Tamiflu targets the release stage of the influenza life cycle by inhibiting a viral enzyme, called neurminidase, that allows the virus to leave the host cell. The antiviral drugs Rapivab (peramivir) and Relenza (zanamivir) have similar functions
What do the cells T lymphocytes do in the immune system?
Target cells that have been infected by a specific pathogen (specific)
Once the virus is in the respiratory track,...(part 5)
The alveoli are thin-walled structures, lined with a single layer of epithelial cells. This structure greatly increases the surface area of the lungs and makes gas exchange more efficient
What other method has been created to produce a flu vaccine?
The cell-based method. It is similar to the process with chicken eggs, except that the viruses are placed into mammalian cell cultures to replicate. As with the egg-based process, the harvested viruses are then inactivated and developed into vaccines.
Is the complete virus produced after this process?
The complete virus is not produced, and the extracted H spike protein is used to make the vaccine. This is the most rapid method of producing a vaccine, and also allows for the production of egg-free vaccines.
What is the product of the long evolutionary process?
The diversity of life on our planet, currently estimated to be millions of species is the product of that long evolutionary process
What is the primary cell that is targets in the influenza virus?
The epithelial cells lining the respiratory system
What does the genetic material do for evidence?
The genetic material is not just a set of instructions for our various traits, it is a history of our evolutionary past
What is one of the most important pieces of evidence of evolution?
The genetic material of all living organisms
Once the virus is in the respiratory track,...(part 3)
The initial infection may occur at any point along the respiratory tract, from the nasal cavity to the lungs
What happens to the liquid portion of the infected egg?
The liquid portion of the infected egg is then extracted and the viruses in it are killed
What two pathways happen once the virus has entered the target cell?
The lytic cycle: It can either immediately begin using the resources of the host cell to manufacture new viruses The lysogenic cycle: It can integrate directly into the host cell genome and delay its own reproduction until a later time
Where is the majority of the immune system work performed in?
The majority of its work is performed by cells that interact with all of the tissues and organs of the body
What the membrane of the plasma membrane made of itself?
The membrane itself is made of phospholipids. Within the membrane are a variety of proteins. One of these proteins types is called a glycoprotein because it has a large sugar group attached to it
What does the number of genes define?
The number of genes in a virus is often only a fraction of what is found in living organisms
What is Thymus?
The organ where T lymphocytes mature
What is the Spleen?
The organ where blood is filtered and cleaned by the action of white blood macrophages
What does the plasma membrane act as?
The plasma membrane acts as the barrier between the interior of the cell and the exterior environment
What portion from the virus is used in the flu vaccine?
The portion of the virus used is protein associated with the H spikes because that is what is identified by our immune systems
How are the flu viruses selected to make a vaccine?
The process almost begins a year in advance when a global network of over 100 worldwide influenza monitoring stations send clinical samples to influenza centers in five countries.
What is the newest method used to produce a flu vaccine?
The recombinant process, it only uses a small portion of the influenza virus
Are all spikes the same in all Influenza A viruses?
The spikes are not all the same in all influenza A viruses. There are currently 17 different known forms of H spikes and 10 different variations of N spikes. These variations are what gives the Influenza A viruses their instinct name.
What is an example of biological sciences focusing on understanding the importance of evolution to life?
The study of systematics is an area of biology that studies the evolutionary relationships of organisms
What happens to the virus particles after extracting the virus?
The virus particles are then isolated, purified, and used to make the vaccines
What is the genetic material of a virus?
Their genome may use either DNA or RNA as their genetic material
Why do epithelial cells play an important role in the body?
These cells play an important role in regulating the activities of the body because any substances that enter or leave the body must pass through them before entering the blood stream and other body tissues. Influenza disrupts these functions, which accounts for many flu symptoms
What do the scientists studies show in documenting the history of life on our planet?
These studies show a progression of change starting with the origins of the simplest single-celled prokaryotes (such as bacteria)
What are giant viruses?
These viruses are much larger than a typical virus with some almost half the size of a bacteria
What are scientists suggesting to consider viruses living organisms?
They are suggesting the tree of life to be reorganized to include the viruses as living organisms
What are Hox genes?
They control the early embryonic development of all animals. Analysis of these genes suggests that the closer two organisms are to each other, the more similar their genes
What have geneticists discovered in embryonic development?
They have discovered the similarity in embryonic development is due to the action of a series of developmental genes, called Hox genes
How is retrovirus performed?
This is performed by an enzyme, supplied by the virus, called reverse transcriptase, which converts the viral RNA to DNA. This DNA can then be transcribed and translated into the polypeptides and proteins needed for the biosynthesis stage.
What specificity do viruses have in the type of cells they infect?
This specificity is the function of the proteins located on the capsid of the virus
What are Lymph nodes?
Tissue where the interstitial fluid is filtered and cleansed by white blood cells called macrophages
What is Red bone marrow?
Tissue where the lymphocyte cells of the body are produced. The location where B lymphocytes mature
How does the immune system recognize self from nonself? (step 1)
To do that, the cells of the immune system must be able to distinguish "self" from "nonself". This is accomplished by a series of markers present on the plasma membrane of each cell
What is the purpose of a virus?
To find a host cell and then hijack the metabolic machinery of that cell to produce more copies of itself
How do transitional fossil fuels help as evidence?
Transitional fossils not only help us understand how species have changed over time, but they can also provide an indication of the timeline of these changes.
What are the three aspects of the viral life cycle? (2)
Uncoating: Once inside the cell, some viruses provide an enzyme to remove their genetic material from the capsid
What is a Virus?
Viruses are parasites of our cells
Does evolution relate to the influenza virus?
Viruses, specifically the influenza virus, are an excellent example of how evolution occurs over time
What does the most common method of producing a flu vaccine require?
While this process is effective in producing vaccines (and has been used for decades), it requires the longest development time.
Once the virus is in the respiratory track,...(part 4)
Withing the lungs are millions of tiny air sacs, called alveoli, where gas exchange occurs.
Who are the Influenza viruses typically named by?
World Health Organization (WHO)
Can the impression still be counted as evidence for evolution?
Yes because these impressions can provide evidence of how life has changed for these species over time, as well as provide an indication of what climate and environment were like in that region while they were alive.
As the infection progresses, the immune system sends...
a host of cells to the respiratory system
The replication cycle of the influenza virus begins,....
almost immediately, and the production of new viruses can start within just a few hours
Once inside the cell, the virus not only hijacks the cellular machinery to make new viruses but...
also produces proteins that interfere with the normal function of the epithelial cell
Human influenza viruses originate in...
animal hosts, such as the pig and bird
Because epithelial cells are involved in regulating the movement of materials into and out of the tissues of the body,...
any disruption of this function will have an adverse effect on the tissue or organ-in this case, the lungs
As the epithelial cells lose their function, they may also undergo...
apoptosis or programmed cell death. When this occurs, it may cause inflammation of the tissue, which in turn activates the immune system
Initially these viruses (influenza) are rarely dangerous to humans...however,
as the viruses exchange genetic material, they evolve into new forms, which can then be transmitted to humans, causing flu outbreaks
What do the chemical signals do?
chemical signals increase blood flow to these tissues. Combined, this causes tissues to swell and inflammation to increase. As a result, large amounts of mucus are produced, which caused the congestion and cough associated with the flu
Influenza viruses enter the respiratory system through...
either the nose or mouth.
Often viruses are picked up on the...
hands and introduced to the body when we touch our faces or mouth, or handle food. From there, they quickly enter into the respiratory system and travel down the pharynx into the trachea and lungs
As the RNA genetic material is the influenza virus mutates....
it develops methods to avoid our immune system
Historically, biologists have not classified viruses as....
living organisms
The glycoproteins involved in identifying self are collectively called,
major histocompatibility complexes, or MHCs
What is the term antigenic often used?
often used to describe organisms that can evade our immune defenses
Viruses are not capable of....
processing energy or materials by themselves, and instead rely on a host cell for those processes
These molecules may be other proteins,....
receptors on the surface of the cell, or other molecules integrated into the membrane of the host cell
What does the term antigen refer to?
refers to any substance that prompts an immune system response, such as viruses and bacteria
The lympathic system consists of...
several organs and tissues that are involved in either filling and cleaning the blood and interictal fluids of the body, or in the production and maturation of immune system cells called lymphocytes.
Once the virus is in the respiratory track,...
the H spikes of the influenza A virus identify host epithelial cells by detecting the presence of specific glycoproteins on the surface of the cells
Once the virus is in the respiratory track,...(part 2)
the N spikes then act to break down the membrane and initiate the entry of the virus into the target cell
What is the basic philosophy behind genetic comparisons?
the closer the genetic information is between two species, the closer their evolutionary relationship
What levels of biology does evolution play a role in?
the evolution of cells, to the internal physiology of individual organisms, to the complex interactions of ecosystems such as rain forests and coral reefs
What is the Immune System?
the immune system is responsible for protecting our bodies from foreign pathogens, such as viruses and bacteria, and works very closely with the lymphatic system.
When pathogens are ingested by the macrophages and dendritic cells of the immune system...
they are digested, and a small portion of the pathogen is attached to the surface of the macrophage
And the flu virus that a vaccine contains?
two different forms of vaccine are used each year. The most common vaccine contains three viruses. This is called a trivalent vaccine.
In an antigenic shift...
two different forms of virus infect the same cell
On the surface of an influenza A virus there are...
two different types of spikes. These spikes are a type of glycoproteins (a protein with a sugar attached) that assist the virus in identifying and entering its host cell
All viruses have similar structure, but...
vary in their shape and form of genetic material
The evolution of a species only occurs...
when heritable changes in the genetic information (DNA or RNA) of an organism are passed on from generation to generation. As a result the species is able to become more adapted to its environment
