Exam 2 Flashcards
What are the three complement pathway modes of activation?
Classical
Alternative
Lectin
What is the common product that will lead into the terminal part of the complement pathway
C3b product
What activates the complement pathway in innate immunity?
C-reactive protein on a pathogen is bound by C1
C1 cleaves C4
Through the classical complement pathway, what is the initial activator in the adaptive immune response?
An antibody binds to the antigen. C1 binds to the antibody and cleaves C4
In the classical pathway, explain the process from initiation to formation of the C3b product of the complement pathway
Antibody binds C1 -> activates C1 -> C4 to C4a and C4b C4b -> C2 to C2a and C2b C4b+C2b=C3 convertase C3 convertase -> C3a and C3b
Explain the terminal process of the complement pathways.
C3b+C2b+C4b= C5convertase (lectin and classical)
C3bBbC3b=C5convertase (alternative)
C5 convertase -> C5a and C5b
C5b+C6+C7+C8 ->associate with C9 in membrane
Form membrane attack complex
What is the activator of the Lectin pathway?
Mannan binding lectin (MBL)
MBL-associated serine protease-2 (MASP-2)
What is the activator of the alternative pathway?
C3 in contact with microbial cell wall
What is the initial complement component of the lectin pathway?
C4 and C2
To C4b and C2b
Form C3 convertase = C3b+C4b+C2b
What is the initial complement component of the alternative pathway?
C3, Factor B, Factor D, and properdin
Form C3 convertase = C3bBbC3b
What are the 4 consequences of complement activation?
Lysis
Opsonization
Activation of Inflammatory response
Clearance of immune complexes
How does the complement pathway cause cell lysis?
Formation of membrane attack complex -> pore into the cell
How does the complement pathways cause opsonization?
C3b binds to pathogen and to monocytes
Marks pathogen for phagocytosis
How does the complement pathway activate immune responses
C3a and C5a are chemoattractants Cause - smooth muscle contraction -mast cell degranulation - local oedema -neutrophil activation
How does the complement pathway aid in clearance of immune complexes?
C3b binds with antibody-antigen complexes ->phagocytosis by macrophage or neutrophils
What is humoral immunity?
Immunity mediated by antibodies secreted by antigen-activated Bcells and their plasma cells
What are the 3 main differences between primary and secondary humoral responses?
Primary- lag phase, which is shorter in secondary Secondary has a greater magnitude of antibody Major antibody class is IgG in secondary response
What is the main structure of immunoglobulin?
Y-shaped molecule
4 chains connected by disulfide bonds
Hypervariable region (for specific binding of antigen)
Define epitope
Protein domain on antigen that is recognized by an antibody.
Antigens can be have multitalented (multiple) epitope that are repeated (all the same) or different
Define Paratope
Part of antibody that recognizes an antigen (antigen-binding site)
Aka hypervariable region = Small region of 15-20aa on Fab region of antibody
What 3 cells types have paratopes with specificity for a single antigenic epitope?
Antibody
Bcell receptors
Tcell receptors
What do Tcells require to recognize a pathogen?
Denatured peptide fragment to be presented on a MHC
What cells can you find MHC I on and what cells do they interact with?
Nucleated cells
Present antigen fragment to CD8+ Tcell
On what cells can you find MHC II and what is its function?
Only on APC (Bcell, macrophages, and dendritic cells)
Present antigen to CD4+ Tcell
What is processing occurs in an endogenous infection in a Tcell adaptive immune response?
Endogenous antigen infects cell -> viral proteins are synthesized by cell in cytoplasm -> peptide fragments are bound by MHC I in ER -> MHC I takes fragment to surface -> CD8+ Tcell binds-> cytotoxic Tcell effect
In an exogenous infection, what is the process following macrophage phagocytosis?
Within vesicle degradation of bacteria ->bacterial peptides are bound by MHCII ->MHCII brings bacterial peptide to surface -> Th1 recognizes and binds to complex (Cd4+) -> activates macrophages
How are antigens bound by Bcell immunoglobulins processed?
Cell surface immunoglobulin bound to antigen is engulfed by Bcell -> Degradation of antigen in vesicle -> MHC II binds peptide fragment and brings it to the surface -> Th2 cell receptor binds to antigen and activates Bcells
What MHC molecule is found on antigen presenting cells?
MHC II
CD8+ Tcells are ____________ restricted
MHC I
CD4+ Tcells are _______________ restricted
MHC II
What cells bridge the innate and adaptive immune response
Dendritic cells
Take antigen from site of infection through the lymph to the lymph node where it presents the antigen to Tcells and Bcells for specific immune response
What is antibody dependent cell-mediated cytotoxicity?
A cell-mediated immune response where an effector cell actively lyses a target cell, whose membrane-surface antigens have been bound by specific antibodies
(NK cells, Macrophages, Neutrophils, and Eosinophils)
An infection that is interstitial, in blood, or lymph activates what type of immune reaction?
Antibody
Complement
Phagocytosis
CD4+ Th2
Humoral response
A pathogen on epithelial surfaces activates what immune response?
IgA
Antimicrobial peptide
CD4+ Th2
Humoral response
An intracellular, cytoplasmic infection causes what immune response?
Cytotoxic Tcell
NK cells
CD8+ cytotoxic Tcell
A intracellular Vesicular infection activates what immune response?
Macrophage
CD4+ Th1
Cell mediated response
What is a virus made up of?
Nucleic acid (RNa or DNA)
Protein capsule
Sometimes -lipid envelope
Virology
Study of viruses and viral diseases
Virologist
Someone who studies viruses
Zoonotic disease
Disease that can be transferred from animal to human
Why do viruses require a host cell?
They are non living organisms, with no cell organelles
Cannot produce their own energy or proteins
All viruses are __________________, requiring a host cell to replicate
Intracellular obligate parasites
Dormant outside of the host
The virus protein shell is called ___________
Capsid
The capsid is made of of many ______________________
Capsomeres
The capsid = nucleic acid together is called _______________
Nucelocaspid
Describe a viral lipid envelope
Covers the capsid
Lipid bilayer derived from host cell
Glycoproteins often appearing as spikes
What is pleomorphism?
Ability of some virus to alter their shape/size
What 4 forms of nucleic acid can viruses carry?
Double stranded DNA
Single stranded DNA
Double stranded RNA
Single stranded RNA
What 4 impacts can a virus have on host
Cell death
Fusion of cells
Transformation to malignant cell
No apparent change
How are viruses classified and what organization is responsible for virus classifications?
Nature of genome and its genetic diversity
Replication strategies
Morphology
International committee on viral taxonomy
What are the modes of transmission
Direct contact Indirect contact Common vehicle Airborne Vector born Vertical Zoonotic
Direct- contact transmission
Contact of infected host/reservoir species with a susceptible individual
Indirect-contact transmission
Contaminated inanimate object
Common vehicle transmission
Fecal contamination of water or food
Airborne transmission
Aerosols, sneeze, cough, usually short lived
Vector bone transmission
Arthropod carrying disease
-mosquito or tick
Vertical transmission
Mother to embryo, fetus, or newborn
Zoonotic transmission
Animal/bird to human
How can viruses be diagnosed/detected?
Clinical signs of disease Histopathology Necropsy Cultivation and isolation in tissue culture Electron microscopy ELIZA PCR /RT-PCR Virus genome sequencing
What three ways can you treat a virus?
Antiviral drugs
Immune system stimulation
Antibody synthesis/ administration of natural antiserum
What is the mode of action of antiviral drugs?
Interfere with the ability of a virus to infiltrate a target cell or target different stages of replication/synthesis of viral components
What is the mode of action of immune system stimulation as a viral treatment?
Interferons - class of protein that has an antiviral effect and modulates immune system function
How can viruses be controlled or prevented?
Vaccination
Proper hygiene and sanitation
Eliminating arthropod vectors
Quarantine/ culling
What are the three types of vaccines?
Live-attenuated virus
Non-replicating virus
Recombinant DNA virus
Live -attenuated viruses
Naturally occurring
Serial passage in culture or host
Cold-selected mutant
Non replicating virus vaccines
Inactivated whole virions
Viral proteins
Recombinant DNA vaccinations
Subunit expression of protein in eukaryotes
Gene deletion/mutation of virus genome
Pathologenicity
Ability of virus to cause disease in host
Pathogenesis
Mechanism of development of disease
Pathogenic or non-pathogenic
Virulence
Quantitative or relative measure of the degree of pathogenicity of infecting virus
Intensity of disease
Avirulent
Not virulent (not harmful to hosT)
How is virulence measured?
Lethal dose 50 (LD50)
Define lethal dose 50
The dose of the virus required to case death in 50% of animals
What are the steps of viral infection?
Entry of virus Primary replication Spread Infection of target organs Virus-cell interaction Tissue and organ injury Shedding
Viremia
Spread of virus in blood stream
Disseminated infection
Spread beyond primary site of infection
Systemic infection
Many organs and tissues infected
What is the difference between primary and secondary viremia
Primary entry from subepithelial, lymphatic, or injection into blood stream.
Secondary entry from replication in major organs and is re-entering the blood stream
How can viruses spread to the CNS
Peripheral nerves
Receptor neurons in nasal olfactory epithelium
Cross the Blood brain barrier
Neurotrophic virus
Viruses that can infect neural cells
Neuroinvasive cells
Enter CNS after peripheral nerves
What are neurovirulent viruses
Cause disease of nervous tissue, manifested by neurological symptoms
How can viruses cross the blood brain barrier?
Trafficking monocytes - virus enter monocytes, monocytes enters brain , virus leaves monocytes
Tropsim
The specificity/affinity of a virus for a particular host tissue
Pantropic virus
Replicate in more than one host/organ
What are the outcomes of viral injury?
Cell lysis Apoptosis Oncoviruses Persistent infection Immunosuppression
How can viruses can disease and injury in a cell?
Inhibit -host nucleic acid synthesis -host cell RNA transcription -host protein synthesis Produce -toxic viral proteins Interference with cellular membrane function
How can viruses cause persistent infection in the host?
Can be latent or dormant in host cell for long periods avoid immune system
Chronic stimulation of immune system -> immunopathy
How can viruses cause immunosupression?
Destroy immune system cells
Make body susceptible to other infections
Describe viral shedding in an acute infection
Intense shedding of virus over a short period of time
Describe viral shedding in a persistent infection
Shed at lower titers over months to years
Infectious disease prevention
Inhibiting the introduction or establishment of a disease into an area, herd, or individual
Disease eradication
Complete elimination of pathogen or disease agent from a geographic area
What is primary disease prevention?
Maintaining health of a population
Avoid occurrence-> eliminate pathogen/ eliminate increasing resistance
What is secondary disease prevention?
Halt the progress of disease at its early strange and prevents complications
- early diagnosis, prompt treatment, control and quarantine
- intervention at individual level and preventing disease spread
What is tertiary disease prevention ?
Rehabilitation and elimination of a long -term impairment (established parasite)
How can you prevent and control disease within a farm
Purchasing policy-closed herd
Dirty and clean road
Vehicles leaving farm- clean and log book
People and workers- cleanliness and few visitors as possible
Fodder and water- clean, no animal byproducts
Equipment - clean and dedicated tools
Housing and Management - density, all in all out,
Vermin and bird control
Animal health - individual health (quarantine and testing of unhealthy)
Disposal of carcasses- burying, compost, and incineration
What is the best method of disposal of dead animals when an infectious disease is suspected
Incineration/ burning
What should you consider when burying carcasses of animals?
Away from farm
Depth - not able to be uncovered by other animals/scavenging
Water- not going to infect water lines or sources
(Same concerns in composting)
Decontamination
Process or treatment that makes an item safe to handle
Sterilization
Process or treatment that eliminates all forms of microbial life, pathogens
Disinfection
Eliminates all or many pathogenic microorganisms except bacterial spores, inanimate object
Antisepsis
Application of liquid antimicrobial chemical to skin or living tissue to inhibit or destroy microorganisms
Incubation period
Microbe is replicating but the host is not symptomatic yet
Infectious disease
Disease caused by the invasion and multiplication of a living agent in/on a host
Infestation
Invasion, but not multiplication in/on a host (eg fleas, ticks, sometimes parasites)
Contagious
Disease transmissible form one human/animal to another iva direct or airborne routes
Communicable disease
Disease caused by an agent capable of transmission by direct, airborne, or indirect routes from an infected person, animal, plant, or a contaminated inanimate reservoir
Reservoir
Habitat in which an infectious disease agent lives, grows, and multiplies
Maintains a pathogen over a long period of time
What are the three characteristics of a reservoir
Naturally infected
Maintain pathogen over time
Transmit pathogen to a susceptible host
How can pathogens survive in a reservoir for a long periods of time
Mutate to escape immunity
Immune evasion
Chronic infection with minimal symptoms (balanced pathogenicity)
Incubatory carriers
Animal that is able to transmit disease before symptoms appear
Convalescent carriers
Host that is clinically recovered but can still spread disease
Latent carriers
Host that harbors infection without clinical disease
Vertical transmission
From reservoir host to its offspring
- congenital
- perinatal
Horizontal transmission
From reservoir to a new host
Congenital transmission
Type of vertical transmission
Across the placenta, infect eggs
Perinatal transmission
Type of vertical transmission
Partition, via colostrum
Direct transmission
Reservoir to susceptible host
Indirect transmission
Any sort of intermediary between reservoir and host
Types of direct transmission
Direct-contact: skin-skin, mucous membranes, soil reservoir, bite/scratch
Direct propulsion (droplet spread): wet, large, and short ranging aerosols
Airborne
What are vehicles of transmission?
Inanimate object that serves to communicate disease
Common vehicle- food, water, and contaminated IV drugs
Fromites- object that can be contaminated and transmit disease
What are vectors?
Live organisms that transmit disease
What are the two types of vectors?
Mechanical- a pathogen does not multiply or undergo any life cycle on the arthropod
Biological- pathogen undergoes changes or multiplies while on vector (required for transmission)
What is an emerging disease
PREVIOUSLY UNKNOWN disease that appears in a population
KNOWN disease that appears in a new population (species/area)
What is a re-emerging disease?
KNOWN disease that was previously on decline but is becoming more common
What are the determinants of pathogen emergence?
Pathogen- mutation or change (new pathogens originate from old pathogens)
Reservoir- phylogenetic disease
Transmission-reservoir size, pathogen prevalence, contact frequency
Host-susceptibility
How can a pathogen adapt/change?
Increase antibiotic resistance
Increased virulence
Evasion of host immunity
What does phylogenetic distance mean for disease transmission?
Within species- viruses can travel easily
Closely related species (eg ruminants)- transmission more difficult
Distantly related species- transmission is difficult, but when it occurs the disease is often very different and more severe
What factors can increase the rate of transmission?
Increase reservoir abundance
Increase pathogen prevalence
Increase contact between reservoir and new host
Anthroponoses
Disease that is transmitted person to person
In what scenarios are people likely to be exposed to a zoonotic disease
Agriculture Animal product processing and manufacturing Forestry Recreation Clinics/ labs Epidemiology Emergency
What are the costs of a zoonotic disease on the population
Cost of human health- loss of productivity/ loss of life
Economic cost- treatment, import/export restrictions, lost trade and tourism
What social changes can affect zoonoses
Change in animal ownership (domestic and exotic), status, food animal production, global trade
Increased _______________of farm animals leads to changes can affect zoonotic diseases, due to increased reservoir size and higher contact frequency
Density
What is a veterinarians role in preventing zoonoses
Surveillance
Prevention and control - decrease animal reservoirs and owner education
Occupational safety
Tania sodium is a ________________disease
Parasitic
Giardia is a _________________ disease
Parasitic
What is the reservoir and intermediate host of taenia solium
Primary host:human
Intermediate host: pigs
What does Taenia solium cause in its pig host?
Porcine cysticercosis
What two disease outcomes occur when a human is infected with Taenia solium
Human Taeniasis - GI tapeworm
Neurocysteicercosis - larvae encyst in brain
How is taenia solium transmitted?
Consumption of food/water contaminated with human feces (untreated sewage
How can taenia solium be prevented?
Block transmission- hygiene
Target vehicle- sewage management
Target reservoir - treatment
What animals can be hosts to Giardia ?
Humans and animals
How is giardia transmitted?
Mainly through contaminated water
Surface contaminated food
Consuming cysts
How can Giardia be prevented?
Water treatment
Sewage treatment
Wash/peel fruits and veggies
What are the disease outcomes of giardia
Trophozite form produces cysts
Chronic diarrhea
Rabies is a _____________ disease
Viral
What is the species name and virus type of Rabies?
Rhabdoviridae Lyssavirus
RNA virus
What are the hosts of rabies
Basically all the mammals
True or false: all vectors are reservoirs, but not all reservoirs are vectors
False
All reservoirs are vectors, but not all vectors are reservoirs
What are the reservoirs of rabies virus ?
Carnivores and bats
How is the rabies transmitted?
In the saliva of infected animals -> bite
What is the progression of the rabies virus?
Bite- neuroinvasive -> peripheral nervous system to CNS
Dumb form and Furious form (Old Yeller)
What is the distribution of the rabies virus?
Worldwide, except some islands in Pacific Oceana
How is rabies prevented
Surveillance -human and animal
Reduce animal reservoir - vaccination and control of populations
Reduce human risk- post-exposure procedures, vaccinate those at risk, and education.
What is the distribution of hantavirus ?
Worldwide
What is the reservoir of hantavirus
Rodents (sylvatic)
How is hantavirus transmitted?
Shed in saliva, urine, and feces.
Direct and indirect contact
Usually inhalation of aerosol
Secondary - bite
What are the clinical signs of hantavirus?
Hantavirus pulmonary syndrome “new world” disease . Chills fever, myalgia, headache
Hemorrhagic fever. “Old world” disease. Petechial hemorrhange and renal damage.
What are the risk factors associated with human-rodent contact?
Human rodent contact ->Increased rodent density and living in barns/buildings
How can hantavirus be prevented?
Decrease exposure to rodents
Anthrax is a ______________disease
Bacterial
Brucellosis is a _________________ disease
Bacterial
What is the scientific name for anthrax?
Bacillus anthracis
How do different species come into contact with anthrax?
Herbivores- consume soil spores
Carnivores - eat infected herbivores
All species - inhalation of spores
What are the manifestations of human anthrax?
Cutaneous
GI
Pulmonary
What is the manifestation of anthrax in cattle??
Bleeding from all offices
Swelling
Sudden death
What are the postmortem signs of anthrax in cattle?
Blood not clotted Spores in blood microscopy Rapid bloating Lack of rigor mortis Blood from offices
How is brucellosis transmitted?
Ingestion, mucous membrane exposure, and percutaneous (through skin)
How is brucellosis controlled?
Eliminate animal reservoir
Swine monitored
Reduce public exposure -> pasteurization of milk
What are the two most common strains of brucellosis
Brucellosis melitensis
Brucellosis abortus
Why is brucellosis hard to diagnose?
Symptoms of undulating fever
Abortions if pregnant
Pleiomorphic symptoms
Name two vector borne diseases
Borreliosis and west nile virus
What is the vector for borreliosis
Ticks
Hard tick (Ixodes)- lyme disease
Soft tick- relapsing fever
What is the reservoir for Lyme disease
Rodents and some lizards
How can Borrelia be prevented?
Decrease contact
Repellants
Tick removal
What is the vector and reservoir of west nile virus
Mosquito-bird-mosquito
Humans and horses are ___________________ hosts of west nile virus.
Dead end hosts
What is the primary and secondary transmission of west nile virus?
Primary- mosquito bite
Secondary- bloodborne, lab exposure, and breast milk
What are the main broad categories of preventative care strategies?
Reservoir neutralization Reducing contact potential. (interruption of transmission) Protection of portal of entry Increasing host resistance Immune treatment
What are the three methods of reservoir neutralization?
Removing infected individuals
Mass therapy
Environmental manipulation
What is mass therapy?
Method of reservoir neutralization
Treat all potentially infected animals without first testing
Control
Risk-development of resistant strains and side effects of therapy
How can environmental manipulation prevent disease?
Method of reservoir neutralization to break transmission between hosts
Decrease vehicles and vectors
What are the three methods of vector control?
Source Reduction
Biological Control
Chemical control
Explain biological control of vector populations
Use of natural enemies to manage mosquito populations such as predatory fish that feed on mosquito larvae
Explain chemical control against vector populations
Larvicides: Insecticides that specifically targets the larval life stage of mosquitoes
Adulticide: Insecticides against adult mosquitoes
What are common methods to reduce contact potential in preventative care strategies
Isolation
Quarantine
Population control programs
What is the difference between isolation and quarantine ?
Isolation: applies to animals that are KNOWN to be ill with a contagious disease
Quarantine: Applies to those who have been exposed to a contagious disease, but not confirmed to have the disease. (For the longest incubation period of that disease)
How can portals of entry be protected from disease?
Clothing
Repellant
Nets on doors/windows
Mosquito nets
How can host resistance be increased to prevent disease?
Chomoprophylaxis
Immunization
What is chemoprophylaxis?
Use of antimicrobial drugs
- attempts to prevent infection, or reduce severity of disease
- only is useful as long as the drug is in the system
What are the 4W’s of immunization?
Where: where is the disease prevalent
When: in season
Who: those at risk
Why: justifiable, the loss caused by disease must be greater than cost of immunization
What are the features of a safe vaccine
Safe to use Effective against diverse strains of same pathogen Few side effects Long lasting Low cost Stable and long shelf life Easy to administer Inexpensive Benefits outweighs the cost
What is herd immunity
Form of immunity that occurs when the vaccination of a significant/large portion of a population provides a measure of protection for the small number of individuals who have not developed immunity
Infected premises
Where a positive case is (clinical or lab confirmation )
Infected zone
Contains infected premises
Contact premises
With susceptible animals that may have been exposed to animals or products, fromite, or people
Zone infected+buffer
Contact premises
Infected zone
Immediately surrounds infected premises
Buffer zone
Zone immediate surrounds infected zone
Control area
Infected + buffer zone
Surveillance zone
Outside and along boarder of control area
Free area
Area not included in any control area
Vaccination zones
Emergency vaccination zone - containment vaccination (in control area)
Protection vaccination zone - outside a control area (may also be a secondary zone designation)