M and Cs
Which of the following describes a type of probiotic mechanism where the probiotic shifts the microbial profile in the gastrointestinal tract increasing the abundance of certain species or groups of species. These newly promoted species subsequently reduce the ability of pathogens to colonize or infect.
Indirect mechanism of action
aggregated mechanisms
Prebiotic
Direct mechanism of action
Indirect mechanisms of action
The process by which innate immune cells move to the site of infection once they exit the capillaries is known as:
Opsinization
Complementation
Diapedesis
Chemotaxis
Chemotaxis
List FOUR mechanisms of action which could explain health benefits associated with probiotic consumption in animals. Provide detail describing ONE of the FOUR mechanisms listed
Competitive exclusions: space - Adhesion to epithelium is necessary for pathogens to become established and cause infection, preoccupation of site by probiotics prevent pathogen attachement
competitive exclusions; nutrients - Probiotics utilize available nutrients competing with pathogens = all microorganisms require iron for growth (some probiotics are able to bind to iron at the cell surface, exclude it from pathogens), Spore forming probiotics/yeasts may use up oxygen (Less oxygen available for pathogens many of which can use oxygen)
Competitive exclusions: anti-microbial effects - many species produce antibiotic compounds for sample bacteriocins are secreted proteins which may limit growth of competitive bacteria, some bacteria deconjugate bile acids which are bacteriostatic and this also could decrease the cholesterol level, others produce hydrogen peroxide and nitric oxide
aggregation - Probiotic microorganisms may coat pathogens preventing their attachment and facilitating removal by peristalsis, Coaggregate - more than one probiotic bacterial species could be involved
immune stimulation - Activate immune cells and enhance acquired immune response & Activate "innate" immune mechanisms - increased mucin secretion by goblet cells, increase expression of antimicrobial peptides, decrease epithelial permeability
Direct and Indirect measures
Vaccines have been extremely successful in controlling infectious disease in humans and animals. In general, what are the objectives of vaccination?
Safe for all individuals, induces protective response, long lasting, overcomes maternal immunity, easily administered, single dose, inexpensive to produce, stable
Acts like an infection without giving clinical signs in order to provide you protection against a real infection later - A vaccine introduces a vaccine into your system to provide your immune system with a baseline for what that specific infection can look like. This provides time for your immune system to make cells (T cells and B cells) to fight future infections.
(idk if i did that right)
Describe the steps required to activate naïve T and B cells resulting in antibodies that bind an invading bacterial antigen and provide immunological memory.
T cells:
- the antigen is engulfed by an antigen-presenting cell, degraded, and presented on the cell's surface via MHC CLass II
- An activated T helper cell from the thymus binds to this antigen using its T cell receptor
- once the "handshake" via CD4 confirms that the binding is correct, the APC sends a costimulatory signal of cytokines to the T helper cell
- the T helper cell binds to these cytokines and proliferates via clonal expansion, making many daughter cells
- some of the daughter cells continue this process, some activate B cells, and some remain in the animal as memory T helper cells for the next infection
B cells:
- the naive B cell finds an antigen that matches its coding for a specific antibody in the environment and engulfs it, degrades it, and presents it via its transmembrane antibodies. This is done through the endocytose antigen via their transmembrane antibodies. This makes it so they only bind to antigens they should bind to
- the T helper cell finds a naive B cell with the specificity for the same antigen, and binds to the B cell
- once the "handshake" via CD4 confirms that the antigens are correct, the T helper cell signals to the B cell to propagate and begin clonal expansion, creating many daughter cells
- Some of the clones will produce and secrete antibodies for the antigen, and some of the B cells will remain as memory B cells for the next infection
A non-living (non-viable) feed additive which promotes growth of beneficial organisms when ingested.
Prebiotic
Microbiota
Probiotic
Organic acid
The process by which certain immune cells engulf and kill pathogens that invade beyond the first line of immune defenses
Opsinization
Complement
Chemotaxis
Phagocytosis
Phagocytosis
Probiotic organisms used in livestock species are commonly spore- forming bacteria such as Bacillus subtilis. Give TWO reasons why spore-forming bacteria are commonly sold as feed additives relative to non-spore formers.
Spore forming probiotics may use up the available oxygen - which means there is less available oxygen for pathogens to use (pathogens like E. coli and salmonella)
They are also very hardy and easily survive processing, storing, feeding and a variety of temps (i don't actually know this its just an answer on the exam)
What normally happens to naïve B cells that bind self-antigens? Why?
Naive B cells require T helper cells to activate them. T helper cells are exposed to self-antigens in the thymus and are destroyed if they bind to self-antigens. B cells can only be activated by matching T cells. This means that there is a very low chance that a naive, self-antigen-binding B cell would be activated. Since B cells have a short lifespan after presentation, these B cells would die. This is called B cell anergy.
The mammalian immune system generally has five different kinds of antibodies (5 different isotypes). Name THREE isotypes AND give ONE function or characteristic at which each excels.
IgD - Transmembrane on surface = Looks like a y
IgM - transmembrane, complement activation, opsinization = Looks like a 5 pointed star
IgG - Serum Ig, complement activation, opsinization = Looks like a y
IgA - Helps stop pathogens from binding to your epithelium, mucosal secreted antibody, resistant to degradation in lung and gut = looks like a double ended y
IgE - provides allergy and parasite protection = Looks like a y
Which of the following best describes the competition between beneficial bacteria and pathogens for gastrointestinal space, attachment sites and nutrients?
aggregation
Competitive Exclusion
Phagocytosis
Antigen presentation
Competitive exclusion
Many innate immune proteins attach to the surface of a bacterium and provide an anchor for attachment by cells that can subsequently engulf and kill the organisms. This coating process is known as:
Complementation
chemotaxis
Opsinization
Diapedesis
Opsinization
Organic acids are being added to pig feed as an alternative to prophylactic antibiotics to promote gut health. What is the PRIMARY mechanism, occurring in the stomach, by which organic acids added to feed promotes gut health?
Organic acids are weak acids, and thus are non-dissociated in the stomach, as it has a pH of 2-5 (no charge). They move into the bacteria present in the stomach, and dissociate here due to the more neutral pH of 7 (loss of H+). This causes the bacteria to be acidic, requiring the bacteria to waste energy to pump the H+ back out or die. The mechanism of organic acids in the stomach is bacteriostatic, as they slow the growth of bacteria. When paired with a proper feeding strategy retention time in the stomach can be increased allowing the organic acids to be more effective
Why are killed and subunit vaccines generally considered less effective in inducing cytotoxic T cells?
Killed and subunit vaccines propagate a poor cell-mediated immunity response because they are non-viable. Cytotoxic T cells only see the antigens presented on MHC Class 1, and if the pathogen introduced is dead, the cell won't synthesize it via transcription and translation. The pathogen would instead be internalized via phagocytosis and presented on MHC Class II, which would not help cytotoxic T cells to kill the pathogen. While this makes them relatively safe, they are not as effective at priming cytotoxic T cells.
Give THREE characteristics that define the Innate Immune system?
First line of defense, Acts within hours/days of infection, Broad protection, Activates the acquired immune system
Uses physical barriers, physiological barriers and cells as protection
Has danger detection in the form of pattern recognition receptors
Cells of the body capable of internalizing antigens, hydrolyzing them into small pieces and placing them on their surface in association with Major Histocompatibility Class (MHC) II are known as:
Naive cells
phagocytes
Leukocytes
Antigen Presenting Cells
Antigen presenting cells
Several families of receptors on the surface of macrophages, dendritic cells and epithelial cells that bind to microbiota-associated molecular patterns are called:
Chemokines
LPS receptors
Microbial receptors
Pattern Recognition Receptors
Pattern Recognition receptors
Why is its sometimes difficult to immunize (vaccinate) very young animals?
Young animals receive passive maternal immunity from their mothers via the placenta or colostrum. This immunity declines with age as the animal's immune system develops. Maternal immunity must be cleared from the young animal's immune system before it is vaccinated. Otherwise, the antibodies from the mother will clear the vaccine from the animal's system without the animal's own immune system learning how to respond to the new pathogen. If the maternal antibodies are not out of the system then the vaccine needs to be able to overcome maternal immunity in order to work effectively
Given ONE example of a type of live vaccine and ONE example of a type of non-living vaccine. Give ONE advantage and ONE disadvantage for each example.
Live vaccines = heterologous - smallpox Don't use this one
= live attenuated = advantages = rapid onset or single dose, disadvantage = risk of reversion to virulence or shedding of organism into environments
= live recombinants = advantage - effective humoral and cell mediated immune response or single inoculation, disadvantage = potential reversion or pre-existing immunity to the vaccine carrier or vector
Dead vaccines
= Killed vaccines - Advantage = Relatively safe or longer shelf life, Disadvantage = Poor cell-mediated immunity or usually require an adjuvant
= DNA/RNA vaccines - advantage = no anti vector response or rapid synthesis and testing, Disadvantage = expensive or need to identify protective antigen
= Subunit vaccines - advantage = safe or longer shelf life, disadvantage = multiple administrations or poor cell mediated immunity or requires and adjuvant
From the perspective a developer of animal vaccines, briefly outline THREE vaccine characteristics that your customer (livestock owners or pet owners) would value highly. These could be considered characteristics of an ideal vaccine.
safe for all individuals - lacks side effects, non toxic, is a non-living vaccine
induces protective response - Right antigen/right conformation, broad cross protection against variants, cellular vs humoral immune response
long lasting - has lifetime protection
Overcomes maternal immunity
easily administered - preferably without a needle
single dose = not needing extra boosters
inexpensive to produce
Stable - avoids requirements for cold storage, avoids necessity for reconstitution
Activation of receptors that bind microbiota-associated molecular
patterns on resident macrophages and dendritic cells, results in the release of "hormones" of the immune system that activate inflammatory responses. These "hormones" of the immune system are called:
Acute phase proteins
Bacteriocins and organic acids
Cytokines and Eicosanoids
chemokines and phagocytes
Cytokines and eicosanoids
The cells of the body that carry Major Histocompatibility Complex (MHC) II on their surface are:
All cells of the body
Phagocytic cells
Macrophages, Dendritic Cells and B cells
B cells and T cells
Macrophages, Dendritic cells and B cells
What is meant by the term "Common Mucosal Immune System"?
The Common Mucosal Immune System refers to the fact that immune cells can move between different mucosal sites. This has strong implications for vaccines. For example, when a Peyer's Patch detects an antigen and the M cells begin the process of activating and releasing T and B cells, the cells travel to the lymph nodes, then to the heart, then into general circulation. These immune cells have specialized receptors to return to the endothelium of the small intestine and proliferate there. But some of these T and B cells will go to other mucosal sites, such as the respiratory tract, the oral cavity, and the nasal cavity, to provide antibodies to the mucosa in those regions, propagating the Common Mucosal Immune System.
What is meant when we describe a vaccine as producing a PROTECTIVE immune response? Give ONE reason why a vaccine might NOT be protective.
Provides a cellular versus humoral immune response depending on what is needed. The type of immune response will depend on what type of vaccine you make
immune responses against those antigens must contribute to either preventing infection or clearing infection (e.g. an antibody that binds a protein inside a virus particle or bacterium cytosol is likely not be protective). This means the vaccine antigens, the antigens must be formulated to induce an immune response, the antigens must retain very similar properties of structure to the antigens observed the native pathogen so that the antibodies and t cells induced bind to the native pathogen,
Provides broad cross protection against variants
Is the right antigen to the right conformation
Name a vaccine type which is inherently poor at inducing cellular immunity? Why?
Subunit vaccines, Killed vaccines
propagate a poor cell-mediated immunity response because they are non-viable. Cytotoxic T cells only see the antigens presented on MHC Class 1, and if the pathogen introduced is dead, the cell won't synthesize it via transcription and translation. The pathogen would instead be internalized via phagocytosis and presented on MHC Class II, which would not help cytotoxic T cells to kill the pathogen. While this makes them relatively safe, they are not as effective at priming cytotoxic T cells.