PID Exam 2 Flashcards
What are the 3 main complement pathways?
Classical, Alternative, Lectin.
Do all 3 complement pathways have the same terminal pathway?
Yes.
What are the 4 end effects of the Complement Pathways?
- Cell Lysis
- Inflammation
- Opsonization
- Clearance of Immune Complexes
When a complement is cleaved which segment is labeled ‘B’ and which is labeled ‘A’?
The larger segment is named ‘B’ and the smaller is named ‘A’.
Older literature may not be clear on this distinction. This is fairly recent.
What 2 things activate the Classical Complement Pathway? Which is innate and which is adaptive?
The binding of C1q to an antibody (IgM or IgG) complexed with antigens (ADAPTIVE - binding of Ab to Ag) or when C1q binds directly to the surface of a pathogen (INNATE - C1 reactive protein binding)
What is the Initial Complement Component in the Classical Pathway?
C1-Complex is composed of 1 molecule of C1q, 2 molecules of C1r and 2 molecules of C1s.
C4 and C2 are also present.
For the Classical Complement Pathway what is C3-convertase and C5-convertase composed of?
C3-Convertase: C4bC2b
C5-Convertase: C4bC2bC3b
What is the function of C3-Convertase and C5-Convertase in any of the 3 complement pathways?
C3-Convertase acts to cleave C3 into a and b
C5-Convertase acts to cleave C5 into a and b
What activates the Lectin Complement Pathway?
The binding of Mannose-Binding Lectin (MBL) to mannose residues on the pathogen surface. This binding activates the MBL-Associated Serine Proteases: MASP-1 and MASP-2.
What is the Initial Complement Component of the Lectin Complement Pathway?
C4 and C2
What is C3-Convertase and C5-Convertase composed of in the Lectin Complement Pathway?
C3-Convertase: C4bC2b
C5-Convertase: C4bC2bC3b
What activates the Alternative Complement Pathway?
The contact of microbial cell wall with C3.
Does not rely on pathogen-binding antibodies like the other pathways.
The internal thioester bond of C3 undergoes spontaneous hydrolysis and this reacts with hydroxyl or amino group of a molecule on the surface of a cell or pathogen. Constantly activated at a low level (think car idling)
What is the Initial Complement Component of the Alternative Complement Pathway?
C3, Factor B, Factor D, Properdin (Factor P)
What is C3-Convertase and C5-Convertase composed of in the Alternative Complement Pathway?
C3-Convertase: C3bBb
C5-Convertase: C3bBbC3b
Note: C3-Convertase is stabilized by Factor P (Properdin) C3bBbP
What complements make up the Membrane Attack Complex (MAC)? What is its function?
C5b, C6, C7, C8, and polymeric C9
Functions to create holes in the membrane and can kill/damage pathogen/cell
What is the order of complements coming in in the Classical/Lectin Complement Pathways? Just up until C5-convertase.
C4 then C2 then C3
What complements are primarily responsible for: Cell Lysis, Opsonization and the Activation of Inflammatory Response?
Cell Lysis: MAC (Membrane Attack Complex)
Opsonization: C3b
Activation of Inflammatory Response: C3a and C5a
What is an opsonizing agent/opsonin?
A molecule that enhances phagocytosis by marking an antigen for an immune response or dead cells for recycling.
What are C3a and C5a also known as? What is their job?
They are also known as chemoattractants.
They activate inflammatory response by: smooth muscle contraction, mast cell degranulation, vasodilation (local edema, local influx of antibody and complement), neutrophil activation.
How are particulate antigens removed?
Antigens are percolated with IgG and C3b (opsonization). Then the circulating red blood cells (with C3b receptors) recognize the antigens. They are then removed in the spleen/liver.
Are the complement pathways part of the innate or adaptive immune system?
Innate primarily but can be innate or adaptive depending on the activator.
What is humoral adaptive immunity mediated by?
Mediated by antibodies secreted by antigen-activated B Cells and their progeny plasma cells.
What are the 2 types of humoral immune responses and explain the difference between the 2.
- Primary Humoral Immune Response - has never been exposed to the antigen before.
- Secondary Humoral Immune Response - has had exposure to the antigen previously.
How does secondary humoral immune response differ from primary humoral immune response?
- Shorter lag phase
- Greater magnitude
- Class-switched IgG (IgG has stronger, longer reaction than IgM (opposite is true in primary))
What are Paratopes?
Part of an antibody which recognizes an antigen; the antigen-binding site of an antibody.
It is a small region (15-22 amino acids) in the FAB (Variable region) of the antibody
What is an Epitope? Where is it found?
Epitope are antigen determinants.
They are found on antigens.
Antigens may be multitalented (have more than one epitope). If they are multivalent, they may have multiple different epitope or one repeated epitope.
What are Paratopes found on?
Antibodies
B-Cell Receptors (BCRs)
T-Cell Receptors (TCRs)
(Antigen Presenting Cells)
Which antigen presenting cells can recognize native antigen proteins without any processing or Major Histocompatibility Complex (MHC)?
B-Cell Receptors and Antibodies are capable of this. T-Cell Receptors are not.
What must antigens have in order for T-Cell Receptors to recognize them?
The antigen must be processed and on Major Histocompatibility Complex (MHC). T-Cell Receptors are unable to recognize a native protein antigen (B-Cell Receptors and Antibodies can).
Briefly describe the structure of an antibody?
~ Y-shaped
Has 2 heavy and 2 light chains.
The top of the Y tends is the light chain (Fab) and the stem is the heavy chain (Fc).
What does Ig stand for? What is it?
Immunoglobulin.
An antibody.
What are Papain and Pepsin? What is their purpose?
They are proteases.
They cleave antibodies in different regions. Where they cleave can have different clinical applications.
Why is veterinary virology important?
Because viruses cause high rates of mortality and morbidity in animals and birds.
Viral diseases in animals and birds cause tremendous financial losses to the livestock and poultry industries –> can hamper the economic development of a country.
Some viruses are zoonotic.
Describe the structure of a virus.
Nucleic acid genome (DNA or RNA - single or double-stranded) surrounded by a protein coat (Capsid) and in some cases also surrounded by an additional layer (Lipid Envelope)
Do viruses possess cellular organelles? Can viruses create their own energy or make proteins by themselves?
No. Viruses contain no standard cellular organelles.
No. Viruses cannot make energy or proteins by themselves and have to rely on a host cell.
What type of parasites are all viruses?
Obligate Intracellular Parasites.
Outside of a living cell, viruses are inert, dormant particles. Inside the cell the virus hijacks and utilizes cell machinery to produce proteins and nucleic acid for the next generation of virus.
How do viruses replicate?
They do not have the genetic capability to replicate by division.
Virus reproduction resembles an assembly line in which various parts of the virus come together from different parts of the host cell to form new virus particles.
What is a capsid of a virus? What is composed of?
A capsid is the protein shell of a virus that encases the viral nucleic acid/genome.
A capsid is composed of capsomeres held together by non-covalent bonds.
The capsid and the virus nuclei acid (DNA or RNA)/genome is referred to as what?
Nucleocapsid.
What is the lipid envelope of a virus? What is it composed of? What is often present at the surface of the envelope?
Additional layer in some viruses that covers the capsid.
It is usually made from lipid belayer derived from the host cell.
Glycoproteins are present on the surface of the envelope and often appear as spikes.
What is a naked virus?
A non-enveloped virus.
It only has a capsid enclosing the nucleic acid.
What is an enveloped virus?
Viruses that contain the additional layer (lipid envelope) enclosing the protein capsid which then encloses the nucleic acid.
Define Pleomorphism.
The ability of some viruses to alter their shape or size.
What are the steps of virus replication?
- Attachment
- Penetration
- Uncoating (injects nucleic acid into the cell)
- Synthesis of Viral Nucleic Acid and Protein (replicates using host cell machinery)
- Assembly and Maturation (New viral nuclei acid are packaged into viral particles)
- Release in large numbers (host cell may be damages in process)
What are the potential impacts that virus replication in a host cell can have on that host cell?
- Cell Death - lysis, alteration of cell membrane, apoptosis (cell suicide)
- Fusion of Cells, Mulinucleated (hybrids via mitosis)
- Transformation of a cell into a Malignant one
- No apparent changes to infected cell. Latent, persistent or chronic infection.
What are the steps of Apoptosis?
Normal Cell –> Condensation –> Fragmentation –> Apoptic Bodies
What is the organization responsible for viral taxonomy (classification of viruses)?
ICTV - International Committee on Taxonomy of Viruses
Their classification system is followed worldwide.
They are the only body charged by the International Union of Microbiological Societies with the task of developing, refining, and maintaining a universal virus taxonomy.
What are the 5 main ways that viruses are transmitted?
- Direct Contact Transmission - direct physical contact with infected/susceptible host
- Indirect Contact Transmission - contaminated inanimate object (fomites)
- Common Vehicle Transmission - fecal contamination of water/food, viral contamination or meat/meat products.
- Airborne Transmission
- Vector (Arthropod)-Borne Transmission - mosquitoes, ticks
What is vertical transmission?
Infection that is transferred from mother to embryo or fetus or newborn before, during or after parturition.
What are the main ways that one can diagnose/detect a virus/viral disease?
- Diagnosis by gross evaluation and histopathology (clinical signs, necropsy, histopathology)
- Detection via cultivation/isolation (cell/tissue culture, inoculation in eggs)
- Electron Microscopy
- Serology (ELISA, Fluorescent Antibody Staining, Immunohistochemical Staining)
- Detection of Viral Nucleic Acids (RT-PCR, PCR, Virus Genome Sequencing)
What is serology?
Detection of viral antigen or host antibody against virus.
What are the 3 main ways of doing serology?
ELISA
Fluorescent Antibody Staining
Immunohistochemical Staining
What is ELISA? What does it stand for?
Enzyme-Linked ImmunoSorbent Assay
Means of serology.
What are the main methods for detection of viral nucleic acids?
RT-PCR (Reverse Transcription (RT); Polymerase Chain Reaction (PCR)) - only for RNA viruses
PCR
Quantitative PCR
Virus Genome Sequencing (reading virus genes)
What are the main treatments for viruses?
- Antiviral Drugs
- Immune System Stimulation (interferons)
- Synthesize antibodies or administration of natural antiserum (antibodies)
How do antiviral drugs treat viruses?
They interfere with the ability of a virus to infiltrate a target cell or target different stages of replication/synthesis of components required for replication of the virus.
What are interferons?
A class of proteins that has antiviral effects and modulate functions of the immune system.
What are the 3 main types of virus vaccinations? Which is most effective and why?
- Live-attenuated Virus Vaccines
- Non-Replicating Virus Vaccines
- Vaccines produced by recombinant DNA and related technologies.
Live-attenuated virus vaccines are the most effective because they stimulate cell-mediated immunity (T-cells) whereas the others only stimulate humoral response.
What are the 4 main ways to prevent/control viruses?
- Vaccination
- Proper Hygiene and Sanitation
- Eliminate Arthropod Vectors
- Quarantine and Culling
What are the 2 main ways to eliminate arthropod vectors?
- Biological control - eg predatory fish that eat mosquito larvae
- Chemical Control - eg insecticides
Define Pathogenicity.
The ability of a virus to cause disease in the host
Define Pathogenesis
The manner/mechanism of development of a disease
Define Virulence
Quantitative or relative measure of the degree of pathogenicity of the infecting virus
Define avirulent
Not virulent (not harmful to the host)
Is virulence an absolute property of a virus? Explain.
No, virulence depends on many variables:
Factors related to virus: genetic variation, route entry into host, affinity of virus or host organs, dose of infection, immune-evasion
Factors related to host: species, host immunity, physiological factors (age, hormones, nutrition status, stage of cell differentiation), fever
Other factors: Environment, Dual Infections
What is LD50?
Lethal Dose 50.
It is the dose of virus required to cause death in 50% of animals.
If the LD50 of one virus is LOWER than another this means that it is __________ virulent.
MORE
What are the 4 main routes of entry of viruses into a host?
- The skin - needs cut/breach, transcutaneous injection (bite of Arthropods, bite of infected animal, contaminated objects (needle))
- Mucous Membrane - conjunctiva (eye), oropharynx (throat), genitourinary tract, rectum
- Gastrointestinal Tract - virus in contaminated food/water
- Respiratory Tract
Describe the spread of a virus in the host beginning with the epithelium. Think layers..
- Local spread of virus of epithelial surfaces - causes localized infection, may or may not proceed to subepithelial layer, if they proceed viruses should overcome local host defense
- Subepithelial Invasion and Lympatic Spread - in subepithelial tissues, viruses get access to lymphatic, phagocytic cells and tissue fluids - may help carry virus to bloodstream.
- Bloodstream and Spread of virus via Bloodstream - viremia
- Spread via Nerves
Define Viremia. What are the 2 types of viremia.
The presence of virus in the blood.
Two types:
1. Primary Viremia
2. Secondary Viremia
What is primary viremia? What are the 2 ways that it can happen.
Primary Viremia is the initial entry of the virus into the blood.
It can happen via:
1. Spread of virus infection to blood from the subepithelial layer/lymphatics
2. Directly injected into the blood, through bite of mosquitoes, syringes
What is secondary viremia?
Virus has replicated/multiplied in major organs and once again entered circulation
What is a disseminated infection? What is a systemic infection?
Disseminated infection is an infection that spreads beyond the primary state of infection.
Systemic infection is if a number of organs/tissues are infected.
What are the 3 ways that viruses spread via nerves?
- Through peripheral nerves
- Through receptor neurons in the nasal olfactory epithelium
- Can cross blood-brain barrier and infect CNS
What is a neurotropic virus?
Viruses that can infect neural cells.
What is a neuroinvasive virus?
Viruses that can enter the CNS (brain and spinal cord) after infection of a peripheral site
What is a neurovirulent virus?
Viruses that cause disease of nervous tissue, manifested by neurological symptoms and often death.
What is Tropism?
The specificity/affinity of a virus for a particular host.
What is a pantropic virus?
A virus that can replicate in more than one host organ/tissue.
List some virus-cell interactions (mechanisms of viral injury and disease).
Inhibition of host-cell nucleic acid synthesis
Inhibition of host-cell RNA synthesis (transcription)
Inhibition of host-cell protein synthesis
Cytopathic effects of “toxic” viral proteins
Interference with cellular membrane function
List the possible outcomes of viral injury.
- Cell lysis/bursting (following release of new viruses, after viral replication is complete)
- Apoptosis (mechanism of cell suicide that the host activates as a last resort to eliminate viral factories before new virus production is complete)
- Oncoviruses - cause cancer
- Persistent Infection - don’t cause immediate death of infected host cells but cause persistent infection. Viruses remain latent of dormant in host cell for long periods escaping detection by the host immune system
- Immunosuppression.
Describe the difference in virus shedding between acute and persistent infections.
Acute Infection - intensive shedding over a short time period
Persistent Infection - shed at lower titles for months to years
List and define the different skin injuries that a virus can produce.
- Vesicles - fluid filled sac
- Ulcers - opening in the skin, caused by sloughing of necrotic tissue, extending past the epidermis
- Nodules - solid tumorous mass
- Warts - benign skin growths that appear when a virus infects the top layer of skin
- Erythema - reddening of skin
Describe how viruses “injure” the GI tract.
Ingestion or from blood (systemic infection) –> destruction of intestinal enterocytes –> malabsorption, diarrhea –> dehydration, acidosis, hemoconcentration
List some ways viruses can cause damage to the central nervous system.
Lytic (destruction/bursting) infections of neurons. Neuronal necrosis (necrosis is death of body tissue) Neuronophagia (killing/devouring or neuronal cells by phagocytic cells) Perivascular Cuffing (inflammatory cells around blood vessels in CNS).
List the 2 ways viruses cause damage to the hemopoietic system?
- Damage to endothelium - hemorrhages.
2. Disseminated intravascular coagulation (DIC) - clots form throughout the body followed by hemorrhages
What type of viruses cause developmental defects of the embryo of fetus after in utero infection?
Teratogenic Viruses.
Define contagious and communicable and note their differences.
Contagious - disease transmissible from one human/animal to another via direct or airborne routes
Communicable - disease caused by an agent capable of transmission by direct, airborne or indirect routes from an infected person, animal or a contaminated inanimate reservoir.
List the chain of events for disease transmission
Pathogenic Microorganisms (bacteria, virus, fungi, parasite, prion) –> reservoir –> means of escape (portal of exit) –> mode of transmission –> means of entry (exposure) –> host susceptibility
Define a reservoir.
Habitat in which an infectious agent normally lives, grows and multiplies (humans, animals or the environment).
What are the 3 things that must be true for a reservoir to be a reservoir.
- It needs to be naturally infected by the pathogen.
- The species of animal (etc.) must be able to maintain the pathogen over time.
- The source must be able to transmit the disease to a new susceptible host.
What are the 2 types of vertical transmission and define them.
- Congenital - some pathogens can cross the placenta, infect eggs, etc.
- Perinatal - during parturition, via colostrum
What are the 2 types of horizontal transmission?
- Direct - directly from reservoir to susceptible host
2. Indirect - via any sort of intermediary, animate or inanimate
What are the 3 types of direct transmission?
- Direct Contact - skin-skin contact, mucous membrane contact (including sexual transmission), direct contact with a soil reservoir, bite, scratch, etc.
- Direct Projection - droplet spread - wet, large and short range aerosol (sneezing, coughing, talking)
- Airborne
What are the 2 types of indirect transmission?
- Vehicle - inanimate object which serves to communicate a disease
- Vector - living organism that serves to communicate a disease
What are the 2 types of vehicles for transmission?
- Common Vehicle - food, water, contaminated IV drugs
2. Fomites - object that can b e contaminated and transmit disease on a limited scale (door knob, knife)
What are the 2 types of vectors for transmission of disease?
- Mechanical - agent DOES NOT multiply or undergo part of its lifecycle while in/on the arthropod
- Biological - agent undergoes changes or multiplies while int he vector; these activities are required for transmission.
What is an emerging disease?
Any previously UNKNOWN disease that suddenly appears (emerges) in a population.
Any KNOWN disease that appears (emerges) in a NEW population.
What is a re-emerging disease?
A known disease, previously on the decline that is becoming more common and will likely continue to do so.
What are the main determinants of emergence?
- Pathogen - type of agent, mutation/change (increased antibiotic resistance, increased virulence (enhances transmissibility), evasion of host immunity)
- Reservoir - phylogenetic distance (same or closer related species easier to cross between)
- Transmission - reservoir size (more abundant), pathogen prevalence, contact frequency between host and reservoir
- New Host - susceptibility
What is prevention vs. control of an infectious disease?
Prevention is defined as inhibiting the introduction or establishment of a disease into an area, herd or individual.
Control is used when an infectious disease is already present and pertains to containment of the disease.
What is the only animal disease that has been eradicated?
Rinderpest.
What is primary prevention?
Aimed at maintaining a healthy population by adopting measures to avoid occurrence of disease either through eliminating the pathogen or increasing resistance to disease.
What are the 2 main divisions of primary prevention and list examples of each.
- Health Promotion - education, training, awareness, good hygiene, nutrition, epigenetics
- Specific Protection - immunization, seroprophylaxis, chemoprophylaxis, specific nutrients/supplementation, protection against occupational hazards.
What is secondary prevention?
Action which halts the progress of a disease at its incipient/early stage and prevents complications.
Relies of early diagnosis, prompt treatment and control such as quarantine.
Intervene at individual level and prevent spread.
What is tertiary prevention?
Consists of rehabilitation, elimination of long-term impairment.
What are the 2 main divisions of farm biosecurity and define them.
- External Biosecurity - measures taken to prevent an infectious disease from entering or leaving the farm
- Internal Biosecurity - measures taken to combat spread of an infectious disease within the farm
List some important Biosecurity Measures that farms should take.
- Purchasing Policy - purchase from least amount of farms, reduce number of new animals, quarantine, new animals should be in good health and vaccinated
- Principle of Dirty and Clean Road - clean road = supply animals in clean trucks, staff; dirty road = courier for semen drop off, manure, feed, visitors, dead animals, deportation of animals
- Vehicles entering/leaving the farm - disinfect, log
- People (Visitors, Farm Workers) - minimum visitors, log, discourage entering housing/feeding area, clean boot/coveralls, disinfectant foot bath, washing hands, working line (oldest animals last, then sick, young first)
- Fodder/Water - don’t feed animal byproducts/waste, purchase feed with quality assurance/monitoring, store properly,
- Equipment - sanitize, do not share equipment with other farms, use different sets of equipment in different areas of farm (color code)
- Housing and Management - minimize contact between young and old animals, maintain optimal stocking density, all-in all-out housing
- Vermin and Bird Control - prevent contact with free-roaming animals, minimize birds, pests, etc.
- Monitoring Animal Health - ID every individual animal, health records, review/update vx and treatment protocols 2x a year, isolate sick, promptly euthanize animals that won’t recover, monitor and inspect animals daily for signs of illness, necropsy
- Disposal of Cadavers/Bodies of Dead Animals - remove cadaver ASAP, store in insulated and cool place, dispose within 48 hrs of death, disinfect.
What are the 3 main methods of disposal of dead bodies and what are the main considerations for each?
- Burying - far from farms/inhabited areas, dig deep (no scavengers gaining access), avoid areas with drainage systems nearby, don’t add disinfectants like lime
- Composting - use as fertilizer, use of substrates in pile (sawdust, straw, hay) to obtain proper moisture and C:N ratio (6:1), pile should be away from farm/inhabited areas/drainage areas, avoid scavenging
- Incineration/Burning
List general considerations for the prevention and control of infectious disease transmission in pets.
Avoid overcrowding
Maintain temp, humidity, ventilation
Separate enclosures (for new arrivals, pups/kittens, known exposure to disease)
Designated isolation and quarantine wards
Disinfection, sanitation and pest control
Reduce stress
Ecto- and endo-parasite control
Good nutrition
Vaccination
Behavioral Wellness/Enrichment
Routine health monitoring and record keeping
Define Decontamination.
Process of treatment that renders a medical device, instrument or environmental surface sage to handle
Can range from sterilization to cleaning with soap & water
Sterilization, Disinfection and Antisepsis are all forms of what?
Decontamination.
What is sterilization?
Process that destroys or eliminates all forms of microbial life/pathogens, including highly resistant pathogens such as bacteria with spores.
Are there degrees of sterilization?
No, it is an all or none process
Define Disinfection.
Process that eliminates many or all pathogenic micro organisms except bacterial spores or inanimate objects.
Less effective than sterilization, does not necessarily kill all microorganisms.
Define Antisepsis.
Application of a liquid antimicrobial chemical to skin or living tissue to inhibit or destroy microorganisms,
List the 5 main sterilization methods and describe each.
- Moist Heat - steam, Autoclave (steam heated to 121C for at least 15 minutes in 15psi)
- Dry Heat - hot air oven, 2 hrs at 160C
- Chemical Methods - gases like ethylene oxide, ozone; chemicals like hydrogen peroxide at high concentrations
- Radiation - non-ionizing: UV; Ionizing: Gamma rays, x rays
- Sterile Filtration - microfiltration using membrane filters (pore size very small removes most microbes)
List innate immune responses.
Constitutional Factors Natural barriers and normal flora Cytokines/interferons Phagocytosis Complement
List adaptive immune responses.
Humoral
Cell-mediated
What is cell-mediated immunity mediate by?
Antigen-activated T-cells and the cytokines they secrete.
Where would you find MHC Class I?
On all nucleated cells including APCs
Where would you find MHC Class II?
B Cells, Macrophages, and Dendritic Cells (APCs)
What is the function of MHC Class I?
To present antigen to cytotoxic T (CD8+) Cells
What is the functions of MHC Class II?
To present antigen to T (CD4+) helper cells.
Describe the steps of MHC action for an endogenous antigen.
- Virus Infects Cell
- Viral proteins are synthesized in cytoplasm
- Peptide fragments of viral proteins bound by MHC Class I in ER
- Bound peptides are transported by MHC Class I to the cell surface
- Cytotoxic T Cells (CD8+) recognizes complex of viral peptide with MHC Class I and kills infected cell.
Describe the MHC action for an exogenous antigen processed in endosomes. DTH response.
- Macrophage engulfs and degrades bacterium, producing peptides
- Bacterial peptides bound by MHC Class II in vesicles
- Bacterial peptides transported by MHC Class II to cell surface
- TH1 cell (CD4+ TH1) recognizes complex of peptide antigen with MHC Class II and activates macrophage for DTH (Delayed Type Hypersensitivity) Response
Describe the MHC action for an exogenous antigen processed in endosomes. Antibody Response.
- Cell surface immunoglobulin of B cell binds bacteria and engulfs and degrades them, producing peptides.
- Bacterial peptides bound by MHC Class II in vesicles
- Bound peptides transported by MHC Class II to cell surface
- TH2 cell (CD4+ TH2) recognizes complex of peptide antigen with MHC Class II and activated B cell for antibody response.
What makes up the peptide binding groove for MHC Class I?
Alpha 1 and Alpha 2
What makes up the peptide binding groove for MHC Class II?
Alpha I and Beta I
How many transmembrane domains does MHC Class I have? How many does MHC Class II have?
MHC Class I has 1 transmembrane domain.
MHC Class II has 2 transmembrane domains.
What aspect of the CD8+ T Cell and CD4+ T Cell recognize the peptide on MHC Class I and MHC Class II respectively?
CD8 for CD8+ T Cell is needed to recognize peptide on MHC I
CD4 for CD4+ T Cell is needed to recognize peptide on MHC II
TH1 cells elicit what kind of a response? TH2 cells?
TH1 cells elicit a cell-mediated response
TH2 cells elicit a humoral response
When a pathogen does penetrate the epithelium, how long does it take for the innate response? How long for the adaptive response?
Innate response in minutes to hours - acute inflammatory response
Adaptive response in 7-10 days.
Dendritic cells will take the infection to the lymph node and do what? Why are they important?
They stimulate the adaptive immune system.
Dendritic cells are the best APC to activate naive T Cells and they serve as a critical bridge between innate and adaptive immunity.
What does ADCC stand for and what is it?
Antibody Dependent Cell-mediated Cytotoxicity
-it is a cell mediated immune defenses whereby an effector cell actively lyses a target cell whose membrane-surface antigens have been bound by specific antibodies
What are the 4 cells involved in ADCC?
Natural Killer (NK) Cells
Macrophages
Neutrophils
Eosinophils
If the site of infection is extracellular and in interstitial spaces, blood or lymph what type of T cell would be active? What type of protective immunity?
CD4+ TH2
Antibodies, complement, phagocytosis
If the site of infection is intracellular and cytoplasmic what type of T cell would be active? What is the protective immunity for these infections?
CD8+ CTL
Cytotoxic T Cells, NK Cells
If the infection is extracellular and on the epithelial surface what type of T Cell would be active? What type of protective immunity?
CD4+ TH2
IgA antibodies, Antimicrobial peptides
If the infection is intracellular and vesicular what type of T Cell would be active? What protective immunity?
CD4+ TH1 for DTH
Activated macrophages.
What is the immune response to a viral infection?
Virus –> APC –> TH1, TH2, CD8+ –> TH2 stimulates B cells –> antibodies
What is the antibacterial immune response?
Bacteria –> APC –> TH2 –> B Cells –> antibodies
Bacteria is mainly CD4+ TH2 cells (humoral response)
What is the anti-protozoan immune response?
Need an increase in TH1 response
What is the immune response to intestinal helminths?
ADCC is most important in helminth response.
Increase in eosinophils!
What is anthroponoses?
Diseases that people get from other people.
What is zoonoses?
Infectious disease that people get from animals, either directly or indirectly
If you are envenomated from a snake, is that zoonoses?
If you are scratched and bit by a dog, is that zoonoses?
If you are allergic to a cat, is that zoonoses?
If you are bit by a dog that has rabies and you contract rabies, is that zoonoses?
No
No
No
Yes
What are some social changes that are affecting zoonoses?
Changes in small animal ownership (Increase)
Changes in the status of animals (human-animal bond, pets are family)
Changes in exotic animal ownership (Increase)
Changes in food animal production (Decrease in # of farms, Increase in # of animals per farm)
Changes in global trade and travel (decreased transit time, increased trade in animals and animal products, exotic animal trade (increase exotic animal/multi-species shipments)
Which animal species are associated with zoonotic diseases?
EVERY SINGLE ONE
Which taxonomic groups do zoonotic diseases come from?
ALL OF THEM - bacteria, fungi, viruses, prions, protozoa, helminths, ectoparasites
How do you break the chain of infection at the host reservoir?
Naturalization
How do you break the chain of infection at the Mode of Transmission?
Interruption
How do you break the chain of infection at the route/portal of exit?
Protection
How do you break the chain of infection at the New Susceptible Host?
Immunization
List and describe some methods of reservoir naturalization?
Remove Infected Individuals - testing and slaughtering those found to be infected
Mass Therapy - All potentially infected animals/people are treated without first testing to identify infected individuals. Treatment must eliminate infection in carriers not just cure clinical illness.
Environmental Manipulation - Designed to break chain of transmission between portal of exit of the infected host and the susceptible host by reducing survival of the agent in vector or vehicles. Extensively used when immediate source of infection is inanimate
What are the 3 main ways of vector control?
- Source Reduction
- Biological Control (predatory fish, feed on mosquito larvae)
- Chemical Control (larvicides, adulticide)
What are the 3 methods of Reducing Contact Potential (Interruption of Mode of Transmission)?
Isolation
Quarantine
Population Control Programs - population reduction to control spread of zoonosis within a reservoir population; biological control of wildlife reservoirs.
Define Isolation vs. Quarantine.
Isolation - applies to animals/persons who are known to be ill with a contagious disease (shows symptoms or tests positive)
Quarantine - applies to those who have been exposed to a contagious disease (enforced for longest incubation period of the disease)
What are the ways that we increase host resistance?
Chemoprophylaxis
Immunization
What is Chemoprophylaxis?
Use of antimicrobial drugs.
Attempts to prevent infection of at least reduce the severity of the disease.
Passive means, effect lasting only as long as the drug lasts.
Pathogens may be resistant to the antimicrobial.
List the 4 W’s of Immunization and define them.
Where? Primarily populations in endemic areas
When? If disease has a distinct “season”, such as seen with a vector borne agents, immunization just before the season will provide maximum efficiency. When outbreak of a non endemic disease occurs.
Who? The population at risk.
Why? For a vaccination program to be justifiable the loss caused by the disease must be greater than the cost of the immunization.
List some features of a good vaccine.
Safe to use Effect against diverse strains of the same pathogen Few side effects Gives long lasting, appropriate protection Low in cost Stable with long shelf life Easy to administer Inexpensive to manufacture Benefit outweighs the risk.
What is herd immunity?
Form of immunity that occurs when the vaccination of a significant portion of the population provides a measure of protection for the small number of individuals who have not developed immunity.
What is oie?
The World Organization for Animal Health
What is WAHID?
World Animal Health Information Database
What are national labs, reference labs and sentinel labs?
National Labs - unique resources to handle highly infectious agents and the ability to identify specific agent strains.
Reference Labs - can perform tests to detect and confirm the presence of a threat agent. These labs ensure a timely local response in the event of a threat incident.
Sentinel Labs - represent the thousands of hospital based labs that are on the front lines. Have direct contact with patients.
What are Infected Premises (IP) what zone are they located in?
Premises where a presumptive positive case or confirmed positive case exists based on laboratory results, compatible clinical signs, case definition and international standards.
Found in Infected Zone (IZ)
What are contact premises (CP)? What zone(s) are they located in?
Premises with a susceptible animal that may have been exposed to the FAD agent, either directly, indirectly, including but not limited to exposure to animals, animal products, fomites, or people from infected premises.
Found in infected zone and buffer zone.
What does FAD standard for?
Foreign Animal Disease
Define the Infected Zone
The zone that immediately surrounds an infected premises.
Define the buffer zone.
Zone that immediately surrounds an infected zone.
Define Control Area.
Consists of infected zone and buffer zone
Define the Surveillance Zone.
Zone outside and along the border of the control area.
Define the Free Area
Area not included in any control area
Define the Vaccination Zone.
Emergency vaccination zone classified as either a containment vaccination zone (typically inside a control area) or a protection vaccination zone (typically outside a control area). THis may be a secondary zone designation.
What are the 3 aspects of the One Health Triad?
Healthy People, Healthy Animals, Healthy Environment
What does GLEWS stand for
Global Early Warning System for Major Animal Diseases Including Zoonoses.
What are the 3 groups that are in collaboration with GLEWS?
FAO - Food and Agriculture Organization of the United Nations
OIE - World Organization for Animal Health
WHO - World Health Organization
What type of infectious agent is Taenia Solium?
Parasitic (trematode)
What are the methods of transmission to humans for Taenia Solium?
Taeniasis - eating under cooked, infected pork (infected with cysts)
Neurocysticercosis - ingest eggs (not washing hands, fecal contamination from another person with T. Solium tapeworm intestinal infection, consuming food/water contaminated with T. Solium eggs (untreated sewage, fecal), contamination of drinking/irrigation water)
What are the methods of control and prevention for Taenia Solium?
Prevention of Taeniasis - meat inspection, proper cooking of pork, proper handling of raw pork (education, washing hands)
Prevention of Neurocysticercosis- Block Transmission (hygiene), target vehicle (human feces - sewage management - don’t use untreated sewage for fertilizer, irrigation), Target the Reservoir (treat people with tapeworms (education))
Does Taenia Solium produce flu like symptoms?
No - headaches, confusion, seizures, etc.
What type of infectious agent is Giardiasis?
Protozoan Parasite
What are the methods of transmission to humans for Giardiasis?
Consuming cysts - usually contaminated water, contaminated surface of food
What are the control and prevention methods for Giardiasis?
Water treatment (filtering), sewage treatment (prevent contamination of irrigation water), wash or peel vegetables and fruit
Does Giardiasis produce flu-like symptoms in humans?
Yes. Chronic diarrhea.
What is the family and genus of Rabies?
Family - Rhabdoviridae
Genus - Lyssavirus
What is the method of transmission to humans for Rabies?
Usually obtained from a bite - virus travels to salivary glands of reservoir animals.
Dog is the most important global animal reservoir - although USA has eliminated Rabies in the dog
What are the prevention/control methods for Rabies?
Surveillance - both animal and human
Reduce Animal Reservoir - vaccination of domestic animals, vaccination of wildlife, control feral animal populations
Reduce Human Risk - post-exposure procedures, vaccinate at-risk individuals (eg veterinarians), education to reduce exposure risk
What type of infectious agent is Hantavirus?
Virus
What is the typical reservoir for Hantavirus?
Rodents - they are usually asymptomatic
What is the mode of transmission to humans for Hantavirus?
Rodents shed virus in saliva, urine and feces.
Transmission is primarily aerosol - inhalation of viruses in urine or feces (virus can survive for weeks in cool conditions)
Transmission can be direct or indirect.
Secondary transmission via bite.
What are the prevention/control methods for Hantavirus?
Reduce human exposure.
Face masks, gloves when appropriate.
Reduce contact with rodents.
Does Hantavirus produce flu-like symptoms in humans?
Yes.
Hantavirus Pulmonary Syndrome (HPS) - New World - fever, chills, muscle pain, headache (40% die)
Hemorrhagic Fever with Renal Syndrome (HFRS) - Old World
What is the common name for Bacillus anthracis?
Anthrax
What is the common reservoir for Bacillus anthracis (Anthrax)?
Soil
What type of infectious agent is Bacillus anthracis?
Bacterial.
What is the mode of transmission to humans for Bacillus anthracis?
Aerosol or percutaneous exposure to blood from infected animals (gets in through micro-wounds that we can’t see).
Skin, breathing, eating meat of a contaminated animal.
How do herbivores vs. carnivores get Bacillus anthracis?
Herbivores - ingest spores while grazing
Carnivores - eat infected herbivores
All Species - inhale spores in aerosolized soil or other contaminated fomites
What are the prevention/control methods for Bacillus anthracis?
Vets: NO NECROPSY on suspected cases (anthrax is in a vegetative form in the body but comes spores if the body is opened up), Animal vaccination (in endemic areas), burn infected carcasses or bury in quick lime, inform health officials.
Doctors/Public Health Workers: work with vets to control disease, evaluate exposed people for post exposure prophylaxis, advise people exposed to spores to wash hands with soap and water and then iodine solution immersion.
What are the symptoms of Bacillus anthracis in animals?
Bleeding from orifices (blood not clotted), sudden death, lack of rigor mortis, bloating
Does Bacillus Anthracis produce flu-like symptoms in humans?
Yes. Sore throat, mild fever, fatigue, muscle aches.
What are the 2 most common types of Brucellosis? Which is most pathogenic? What animals are they most commonly found in?
Brucella melitensis - most pathogenic for people; goats, sheep
Brucellosis abortus - cattle
What type of infectious agent is Brucellosis?
Bacterial
What is the mode of transmission to humans for Brucellosis?
Ingestion, mucous membrane exposure or percutaneous inoculation with aborted placenta, fetus, fetal fluids, unpasteurized milk, can also be found in blood, urine, semen, feces and uterine/vaginal secretions, food/water contaminated with these materials.
What are the prevention/control methods for Brucellosis?
Eliminate Animal Reservoir - eradication program in USA, swine also monitored (abattoir-based)
Reduce public exposure through pasteurization of milk and milk used to make soft cheeses
Does Brucellosis produce flu-like symptoms in humans?
Yes. Recurring fever, can last for months. Abortions in pregnant animals/people. Symptoms are pleiomorphic - difficult to diagnose.
What is the common name fore Borreliosis?
Lyme Disease
What type of infectious agent is Borreliosis?
Vector-Borne Disease.
Tick-transmitted spirochetes.
What is the mode of transmission to humans for Borreliosis?
Exposure to Ixodes ticks.
Outdoor activities in tick infested areas (hiking, camping, etc.)
Tick must be attached for more than 48 hours to transmit disease (not true for all tick-borne illnesses).
Infected dogs can serve as domestic sources if left untreated.
What are the prevention/control methods for Borreliosis?
Avoid direct contact with ticks (avoid brushy areas, walk in center of paths).
Apply tick repellants (DEET or permethrin).
Remove ticks from your body, pets, clothes
Does Borreliosis cause flu-like symptoms in humans?
Yes. Acute febrile illness, muscle pain, joint pain.
What type of infectious agent is West Nile Disease?
Vector-Borne Disease. Transmitted by Mosquitoes.
What is the primary reservoir for West Nile Disease?
Birds - birds get the virus from mosquitoes as well
Mosquitoes that bite the reservoir birds pick up and carry West Nile.
Humans/Horses are dead-end hosts, so they are not reservoirs because a healthy mosquito that bites an infected human/horse will not pick up the disease.
What is the mode of transmission for West Nile Disease?
Bite of infected mosquitoes.
Secondary transmission through blood borne infection, laboratory exposure, breast milk.
No evidence that human infection occurs through handling dead/ill birds.
What are the control/prevention methods for West Nile Disease?
Dead birds are monitored.
Reduce exposure to mosquitoes.
Does West Nile Disease cause flu-like symptoms in humans?
Yes. Fever, joint pain in 20% of cases. 80% are asymptomatic.
<1% are neuroinvasive - 10% of these are fatal.
