Lecture 6A & B Flashcards
What is a Passive vector
agent does not
replicate within the vector.
What is active vector
agent does replicate
within the vector.
What are the route of transmission
- Vector-borne transmission
- Airborne transmission
- Faeco-oral transmission
- Direct transmission
- Indirect / fomite transmission
- Common vehicle transmission
- Iatrogenic transmission
- Zoonotic transmission
What are the types of transmission
Horizontal and Vertical transmission
What is horizontal transmission
- Vector-borne transmission
- Airborne transmission
- Faeco-oral transmission
- Direct transmission
- Indirect / fomite transmission
- Common vehicle transmission
- Iatrogenic transmission
- Zoonotic transmission
What is Vertical transmission
Mother to offspring transmission in utero
or in ovo (early post-partum period)
Transmission across placenta, in birth
canal, in colostrum/milk
What can vertical transmission do
Cause embryonic death, mummification,
resorption (time of gestation) or congenital
defects
What is Disease control
strategy based on
Vaccination
Movement restrictions
Stamping out
Quarantine
When does the disease happen
when a non-vector animal(reservoir animal) infect a vector animal
What are some passive vector disease
• Equine infectious anaemia: biting flies
• Myxomatosis: fleas, mites, mosquitos
• HIV/AIDS: injecting drug use
(not primary route of transmission)
How to prevent passive transmission
Prevent contamination of vector Prevent access of vector to susceptible new host Immunological protection of susceptible new host
What disease is Equine infectious anaemia
Retrovirus disease
How is Equine infectious anaemia transmitted
Transmitted by biting flies:
tabanid flies and stable flies
(stomoxys spp.).
How does Equine infectious anaemia spread
Iatrogenic spread (non-sterile needles and syringes) Blood containing EIAV is transmitted when fly bites next host
What does Equine infectious anaemia do
White cells attacking red blood cells Sub-acute EIA: continued moderate fever followed by recovery. Some recurrent episodes of fever/disease Chronic EIA: mild illness, fever, anaemia, oedema
Life-long persistent infection
How to control Equine infectious anaemia
Prevent insect bites
Remove life-long carriers
(Coggins test)
Use sterile needles and syringes
What is myxomatosis
Poxvirus disease of rabbits: Causes benign fibromas in wild rabbits in Americas Severe generalised disease in European rabbits
What are the vectors for myxoma virus
Mosquito, fleas
What is Arboviruses
Arthropod borne viruses
replicate in their haematophagous arthropod hosts and
transmitted to vertebrate host by biting
What does haematophagous mean
blood sucking
What are the usual virus reservoir for mosquito
birds
What is ornithophilic mosquito?
bird attracted mosquito
What is enzootic cycle
also enzootic or sylvatic transmission cycle, is a portion of the natural transmission cycle of a pathogen
What is epizootic cycle
An epidemic outbreak of disease in an animal population, often with the implication that it may extend to humans
What is the pathogenesis of genus flavivirus
Bite from infected arthropod Local virus replication Viraemia Dissemination to target organs (endothelium, liver, foetus, CNS) Family Flaviviridae Mature virions quite labile: sensitive to heat, detergents, common disinfectants
Where did west nile virus start?
USA bronc zoo in queens
Why was the virus so successful?
there were a lot of birds present in the city
What is the distinct clinical syndromes in NSW 2011 of the arbovirus
- Myalgia and arthralgia
* Neurological signs and encephalitis
How do you monitor the arbovirus outbreak
Monitoring: Disease in vertebrate host Antibody in vertebrate host Presence of vector Presence of virus in vector
What is a good indicator whether a place is safe
Presence of vector
Presence of virus in vector
before arriving
What causes Bluetongue
African Horse Sickness
Equine Encephalosis
Genus
Orbivirus
What does blue tongue infect
Disease of sheep, cattle and goats
What are the clinical signs of blue tongue
Hyperaemia of oral and buccal cavities (salivation / frothy mouth)
Nasal discharge (serous – mucopurulent – blood flecked)
Cyanosis of the tongue
Hyperaemia of the coronary bands
Oedema (head and neck)
Why was it hard to cure blue tongue
there are 25 setypes of bluetongue, and are different virulence
What are the control for bluetongue
Vaccination programmes
Monitoring schemes: Vector and host surveillance
Live attenuated vaccines are available and used overseas
What are the reservoir host of african horse sickness
horses
What are African Horse Sickness
Peracute pulmonary form:
Nasal discharge progressing to respiratory distress and often 100% mortality
difficult to breath due to oedema
What is the definition of infection
entry and development or
multiplication of an infectious agent in the
body.
What is the definition of disease(infectious)
clinical and/or
pathological manifestation of infection
What is anthroponosis
from infected humans [farmers, owners, veterinarians…] to
animals
What is the Basis of host specificity
• Presence/absence of Host receptors for
colonisation; presence/absence of Pathogen
adhesion systems or other virulence factors
• Persistence within tissues, macrophages, and
translocation
• Frequency of contact between different host
species or mode of contamination
• Host-specific immune responses
What is the difference between Salmonella Gallinarum vs. Salmonella Dublin in
experimentally infected calves
– Dublin and Gallinarum are both able to colonize
and invade bovine intestines, BUT…
– Dublin persists within the mucosa and tranlocates
in lymph more than other serovars
Major cause of antibiotic resistance in human pathogens
is the (over) use of antibiotics in humans rather than animals.
Where does Enterotoxinogenic E. coli (ETEC) fimbriae colonise
– Colonise the intestine and cause diarrhoea
toxins
Is virtually all animal-derived human pathogens arose from
pathogens of other warm-blooded vertebrates
yes
What increases the Probability of cross-species infection
- abundance of the existing donor host
- frequency of encounters with donor host
- phylogenetic distance between the hosts
- pathogen variability
How many percent of the zoonotic pathogen do not persist
• approx. 25% do not persist in humans without
repeated reintroductions from animals
What is 1: agent
only in
animals type of transmissibility
Not zoonotic
2: primary
infection
None, only from
animals
3: limited
outbreak
From animals or
humans (few
cycles)
4: long
outbreak
From animals or
humans (many
cycles)
5: exclusive
human
agent
Only from
humans
What evolution does Yesinia pestis have
- Lost genes encoding urease, toxic for fleas
* Gained genes helping flea gut colonisation
What is one disease that is anthroponotic
S. aureus infection in broiler
chickens
What does ELISA detect
antibodies
What can serum component do
• Neutralize toxins • Agglutinate bacteria • Precipitate toxins • Lyse bacteria (with assistance of complement)
What are antibodies produced by
B cells
What does antibodies recognise
recognise antigens in a specific way
What is the basic structure of antibody
2 heavy chains and 2 light chains
What is an epitope
An epitope is a part of an antigen that is recognised by
immune system
What is a paratope
A paratope is the part of the antibody binding the antigen
√ The paratopes is defined by a combination of the variable
region of the heavy and light chains of the antibody
Where can B cell epitopes be accessed?
B cell epitopes are
accessible from the outside
Where are B cell epitope located
– Exposed on the surface of the cell • Antibodies are hydrophilic and water soluble • Antibodies can not pass through the plasma membrane
What does the choice of isotype depend on
– Depends on cytokine environment
– Depends on type of T cell help provided
What is the full name for ELISA
ELISA = Enzyme-Liked Immuno-Sorbent Assay
What is are the steps for indirect
- Antigen - coated well
- Add specific antibody to be measured
- add enzyme-conjugated secondary antibody
- Add substrate (S) and measure color
What are the steps for sandwich ELISA
- Antibody-coated well
- Add antigen
- Add enzyme-conjugated secondary antibody
- Add substrate and measure color
What is the meaning indirect of captured antigen
– Often using a detection antibody and an antibody to the
detection antibody (i.e. indirect detection)
– Amplification (several enzyme linked antibodies bind to 1
detection antibody)
– Capture antibody and detection antibody MUST be different
• Different species
• Different isotypes
Why is indirect detection flexible
– Increased flexibility (only needs one enzyme linked reagent
What is streptavidin
– Very strong binding to biotin
– Increased flexibility
• Can be bound to fluorescent molecule (FITC)
• Can be bound to enzyme for ELISA
– One streptavidin molecule can bind 4 biotin molecules and
several enzymes can be bound to one stretavidin molecule
• Amplification
What is sandwich ELISA
• Epitope recognised by the capture and detection Ab
needs to be different
• Capture Ab needs to be relatively pure as the binding
to the ELISA plate is by adsorption and this non-specific
What is the difference between IgG and IgM
IgM is the first stage of the antibody, or the first time it was affected
What is class switch
changing from IgM to IgG
Is class reversible
Class switch is irreversible
How many antibodies does one be cell produce
one, epitope
How to immortalise b cells
Thymidine Kinase (TK)
mutant method
Thydmidine: rescue of nucleotide synthesis pathway
Why cancer cell can never die
Cancer cell has a mutation in the Thymidine Kinase gene (TK-) to achieve this.
What does aminopterin do
blocks pathways for synthesis of nucleotides
How help to cancer cell survive in HAT
In the presence of hypoxanthine
and thymidine a rescue pathway exists provided that thymidine kinase (TK) and HGPRT enzymes are present.
How to select TK- myeloma cells
– Myeloma cells are naturally TK+
– To make TK- myeloma cells culture in presence of
bromodeoxyuridine
– The bromodeoxyuridine gets incorporated into the
DNA and kills the cells only TK- cells survive
How to select Ab negative myelomas
Myeloma cells used for fusion are derived from B
cells and normally make their own antibodies
– This would result in mixed Ab secretion (native Ab of
fusion partner, native Ab of spleen cells and mixed
Ab with different specificity)
– Need to select for H and L chain negative mutants so
that only native Ab of spleen cells are remaining
What is the diagnostic application of monoclonal antibodies
Detection of specific proteins
• Detection of specific small molecule (i.e. competitive dip-stick test)
– Detection of antibiotic in milk
what is the use of PCR
It’s a quick, easy way to create copies
of DNA from a small starting input
What is the annealing temperature
5 degree different from the melting temperature oh primer(lower)
What is the effect of MgCl2 in PCR
• Cofactor of DNA polymerase
what can high Mg2 concentration cause
increase PCR yield but
decrease the specificity of the reaction
What can low Mg2 concentration cause
Lower Mg2+ concentrations increase specificity, but
decrease yield.
What differs Conventional PCR vs qPCR
qPCR Uses non-specific DNA binding dyes (SYBR GREEN) 2. Uses labelled probe that binds between forward and reverse primers (Taqman)
What is Cycle threshold (CT
)
– The cycle number at which the
signal crosses the threshold line.
