Micro 1 Flashcards
(110 cards)
1
Q
Eukaryotes size, metabolism, cell organisation, replication, maintenance of shape, nucleic acid handling, ribosomal structure, genome
A
Size - vary Metabolism - generally aerobic Cell organisation - compartmentalise, enclosed nucleus Replication - sexual repro Maintenance of shape - intracellular skeleton Nucleic acid - all within the nucleus Ribosomal - same origins Genome - divided into chromosomes
2
Q
Prokaryotes size, metabolism, cell organisation, replication, maintenance of shape, nucleic acid handling, ribosomal structure, genome
A
Size - vary
Metabolism - variety
Cell organisation - all metabolic activity in same space
replication - binary fission
maintenance of shape - extracellular skeletal structure cell wall
nucleic acid - occurs at the same time, transcription and translation
ribosomal - same origins
genome - single circular chromosome within cytoplasm
3
Q
taxonomy when useful and what used for
A
- Can be useful in parasites and most viruses
- Organisms in the same group tend to share habitats and life cycles
- Similar epidemiologies and pathogeneses
- Not helpful with bacteria as they have been evolving since the beginning and they are very diverse
4
Q
Light microscopy what occurs, when sensitive and what are the 2 mechanisms
A
1) Unstained wet preparations - generally fungi and some bacteria
2) Oil immersion - fixed, stained specimens - allows us to have high magnification - bacteria
○ Refracted light around the organism so not so sensitive and generally only detected when in large numbers
5
Q
Culture how does it work, how are most cultured
A
- Success depends on the quality of the sample as well as how it is stored and transported
- Some pathogens cannot be cultured
Most are cultured on cell free media - range of nutrients in a liquid (broth generally in 5ml bottles) or agar form
○ Agar allow single colonies from a single cell - pure so can identify based on colour, shape, consistency, smell - Additives, temperature and atmosphere
○ Generally 37 for mammals, fish 15-10 degrees, fungi about 25 degrees
6
Q
What only grows in animals cells and what type of cultured cells are there
A
- Only grow in animal cells - viruses
- Cultured cells
○ Primary cell culture - cells directly from the animal, foetal cells used generally as generally unlikely that it has other viruses within
○ Established lines - transformed cells that replicate and grow on different media, stop natural cell death, limited in species that can get them from
○ Grown in complex media, often containing serum - cell factors that cells need to grow in vitro
7
Q
What are the 5 ways to identify microbes
A
1) Microscopy
2) Culture
3) Organ culture
4) chick embryo
5) Animal inoculation
8
Q
Chick embryo features
A
- Next step if won’t grow in an organ culture, many vaccinations such as the influenza and Q fever has to be grown within a chick embryo
- Specific ages
- Specific sites
○ Amniotic cavity
○ Allantoic cavity
○ Yolk sac
○ Chorioallantoic membrane
9
Q
List 6 tests that detect microbial proteins or carbohydrates and describe
A
1) Toxin-Antitoxin Tests - animal is inoculated with tissue from clinical case and second animal is inoculated with sample and specific antitoxin. If animal inoculated with sample along is affected and animal with antitoxin is not than positive test
2) Labelled Antibody Tests - Antibodies specific for proteins are labelled and applied to sample, the sample then can have a fluorescein stain applied and examined microscopically.
3) ELISAs - antibody bound to plate is used to capture pathogen proteins from solution and a second labelled antibody then detect whole organism or bound protein
4) Neutralisation or Inhibition Assays - the growth of some bacteria or viruses can be blocked by specific antibodies
5) Hemagglutination - some microorganisms agglutinate certain RBCs such as parvo virus
6) Latex Agglutination - within latex beads mix has an antibody that is specific to a carbohydrate that will agglutinate (clump beads together) if present
10
Q
List the 4 methods of detection of nucleic acids
A
1) genome itself
2) hybridisation - single stranded DNA will bind to complementary DNA
3) PCR - polymerase chain reaction
4) High throughput sequencing
11
Q
Polymerase chain reaction what occurs and advantages
A
○ Segments of DNA are separated and compared to reference range to identify
○ Can determine different strains where the lines are just slightly off where the reference range is, if same strain than identical banding will be shown
○ Real time PCR - every cycle measure how much DNA product is produced, once amount of DNA reaches threshold then say positive and compare to other dilutions to determine amount of DNA in the first place - determine amount of disease present
§ If RNA need to add a reverse transcriptase
○ Can overestimate the likelihood of the animal being infectious as DNA can still be present
○ A lot quicker turnaround time for result than culture and more sensitive
12
Q
High throughput sequencing how does it work and compare to PCR
A
○ Collecting nucleic acid from sample and putting into DNA sequencing team
○ Search through nucleic acid to find certain pathogens
○ Costs about $1000 and can just plug into the laptop - easily accessible
○ Not as sensitive as PCR as looking at everything that is there unlike PCR that zones in on exact sequence you are after, this could also be a positive as it may identify novel pathogens that weren’t expected to be identified
13
Q
Mechanism of detection of specific immune responses
A
Acute and convalescent test
- Produces an antibody response
- If antibody is present than get clumping/agglutination
- At some time in this patient it was exposed to the pathogen - not necessarily recent
- Generally take initially (Acute) and 2 weeks later and look for difference in antibody level - if recent infection than the antibody levels would have risen in this time
14
Q
List 8 ways specific immune responses or antibodies can be detected
A
- Agglutination
- ELISAs
- Neutralisation
- Western blots
- Immunoprecipitation
- Complement fixation
- Immunofluorescence
- Haemagglutination inhibition
15
Q
Cell mediates responses how determined
A
- Lymphocyte stimulation test and detection of cytokine release (especially interferon gamma and/or interleukin 2)
- Will generate mild inflammatory response - slight lump and Redding
○ Used with the Q fever vaccination pre-test
Again doesn’t tell you what is happening now just a few weeks ago and beyond
16
Q
what is the difference between infection and disease
A
Infections (entry into the body) occur frequently
• Disease (loss of function) does not
17
Q
Normal flora features and roles
A
• Always present
• Variation
• Role in health
○ Digestive process and Vitamins (K and B)
• Protective role - prevent growth
○ Detoxify toxic substances, competition for other microbes
• Source of opportunists
○ If in other parts of the body like deeper tissues
• Significance in diagnosis
Complicates the diagnosis - identify strains and characteristics
18
Q
Koch’s postulates what does it do and list them
A
- Determinants that need to be passes in order to determine between normal flora and infectious agents
• regularly found in lesions of the disease
• Isolated in pure culture on artificial media
• Experimental reproduction
• Recovered from experimental disease
19
Q
List 4 problems of Koch’s postulates
A
- Most pathogens cannot be grown in culture
- Synergistic infection - needs another disease - sometimes normal flora opportunistic
- Environment may play a role in disease
- Some organisms may lose virulence when cultured on artificial media
20
Q
Questions asked when making a microbiological diagnosis if detect an organism, if don’t detect an organism
A
If I detect an organism:
• Is it from the animal? - need to take the sample carefully, if it is the surface of the skin
• Is it the one causing disease?
• Is it the only one causing disease? - synergistic is common
If I don’t detect an organism:
• Is it because there wasn’t one there?
• Is it because it didn’t survive the trip?
• Did I look for the right one?
21
Q
List the 5 important features when collecting samples for diagnosis
A
1) History - everything you know
2) Site of sampling - an active or fresh lesion and preferable not one that is open to the surface of the body
○ try to avoid sampling a dead animal due to bacterial overgrowth and the agent generally has declines in numbers
○ Best site is the medulla of the long bone (bone marrow) if dead sample
3) Method of sampling and transport - generally cool (chilled but not frozen) it and send it off to the laboratory as soon as possible
4) Consultation - Consult laboratory if necessary and maintain a relationship
5) Handle with Caution - zoonotic disease potential, can be dangerous to the health of other animals seen that day
22
Q
What are the 4 classes of containment facilities
A
Class I
• Class II - what we are working in - 80% laboratory infections from exposure to aerosols
• Class III - completely change clothing before and after you go in
• Class IV - positive pressure suits - protects the person within or negative pressure within the chamber so if any break the organisms can’t get out because sucked back in
23
Q
sterilisation and disinfection definition
A
- Sterilisation - absolute - no infectious risk, no infectious spores or organisms
- Disinfection - selective process - taking out the riskiest organisms, may be better at killing some organisms than others
24
Q
Antisepsis, bacteriostatic agents, bacteriocidal agents define
A
Antisepsis - lower level, removal of majority of surface organisms - used when cleaning skin surface before surgery
- Application of chemicals to a body surface to kill or inhibit pathogens
• Bacteriostatic agents - used as treatments, stop the growth of the organism but rely on animals immune system to destroy the agent
• Bacteriocidal agents - kill the organisms - quite toxic for animals
25
How is heat used to destroy microbes
most efficient and generally the quickest and most available - Most would be inactivated 50-70degrees spores at 100 degrees
- Pasteurisation - doesn't completely sterilise but important in milk in terms of public health and zoonosis spread
- Moist Heat - not as good on metal as may rust but better than just heat as the water makes bonds with separated molecules so lower temperatures are necessary to sterilise wet rather than dry material
○ Boiling - not efficient at destroying the spores
○ Autoclaving - steam sterilisation and under pressure - complete sterilisation besides mad cow disease
- Dry Heat - need to be used higher temp and longer as explained above
26
How is radiation used to destroy microbes
- Ultraviolet Light - cannot penetrate through glass or objects
- Ionising Radiation - gama rays, effective sterilisation and generally not much damage to the material itself
27
What are 7 features of chemicals agents that needs to be considered
* Activity spectrum - few disinfectants are effective against spores and viruses are generally more resistant than bacteria
* Inhibition vs Inactivation - need inactivation
* Rate of action - can take extended period of time to act
* Compatability
* Effect of organic material
* Side effects - on yourself, staff, animals and materials
* Price and stability - can have a short lifespan of efficacy
28
List some major groups of chemicals used as disinfectants
```
Soluble Alcohols
- Ethanol, isopropylalcohol
• Alkylating Agents
- Ethylene Oxide, Formaldehyde
• Halogens
- Chlorines, Iodines
• Phenolics (Creosol, semi-synthetic phenols)
• Quarternary Ammonium Compounds (cationic detergents)
• Anionic Detergents (soaps)
• Biguanide Compounds (chlorhexidine)
• Dialdehydes (gluteraldehyde)
• Alkalis (sodium hydroxide, lime) and Acids
```
29
Preservation of microorganisms
- Chilling and freezing typically used to preserve microorganisms
- Killing effect of freezing due to crystallisation of the water together with salt solutions damages the cell or viral envelope
- Effect of multiple freeze-thaw cycles will kill most of the organisms
- Cryoprotectants
- Low temperature storage within liquid nitrogen, solid carbon dioxide or low temperatures refrigerators
- Freeze drying or lyophilisation organisms can be stored at room temperature
30
List the 4 features that virus taxonomy is based on
1. Type of nucleic acid
2. Strategy of viral replication
3. Morphology of the virion
4. Sequence analysis of the viral genome
31
how do you get chains and clumps of bacteria
Divide in same planes = chains
| Divide in different planes = clumps
32
What are the steps in the gram stain and the result
1) gentiane violet -> rinse
3) iodine -> rinse
4) alcohol acetone -> rinse
5) dilute carbol fuschine
Gram positive is purple
Gram negative is pink
33
what are the characteristics of gram positive and gram negative bacteria
Gram positive
- Thicker capsule
- Large peptidoglycan layer
- Harder for stain to leave so retains the gentiane violet
Gram negative
- Instead of large peptidoglycan layer only small broken layer
- Also have lipopolysaccharides
34
What are some components of the bacterial capsule and function
- Extracellular material not always present
- Usually polysaccharide (sometimes polypeptide)
- Mucoid colonies (makes the colonies look this way)
- Capsular antigen associated with pathogenicity (E.coli)
Function
- Protects from desiccation
- Facilitates adherence to surfaces
Interferes with phagocytosis
35
At what phase of bacterial growth do you want for control methods
Want bacteria in the exponential phase
- When they are metabolising and growing
- Actively replicating
Using biochemical pathways that are used as identification
36
List 3 types of special media
1. Enrichment media
2. Selective media
3. Indicator or differential media
37
Virus structure what are the two common structures
Nucleocapsid: nucleic acid surrounded by protein coat (capsid)
- Icosahedral or helical shape of capsid
Envelope: acquired by budding through cellular membranes
- Glycoproteins on surface of envelope
- Susceptible to environment
38
Enveloped viruses components, properties, treatment and how released
```
Components: lipids, proteins, glycoproteins
Properties/Treatment:
• Labile in the environment
• Sensitive to acid, detergent,
• drying and heat
• Modifies cell membrane
Released by budding and cell lysis
```
39
Non-enveloped virus components, properties, treatment and how released
```
Components: proteins
Properties/Treatment
• Stable in the environment
• Insensitive to acid, detergent,
• drying and heat
Released by cell lysis
```
40
Enveloped virus what conditions, how spread, environment, immunoprotection
• Must be in moist conditions
• Spread in large droplets, secretions, transfusions etc
• Do not survive adverse conditions (GIT)
• Do not need lysis to spread within host
Antibody alone may not provide immunoprotection (CMI)
41
Non-Enveloped virus what conditions, how spread, environment, immunoprotection
* Can be spread easily
* Infective after drying
* Survive adverse conditions (inside gastrointestinal tract)
* Resistant to detergents
* Antibody may provide immunoprotection
42
what are the bad components of embryonated egg inoculation
1) time consuming
2) labor intensive
3) technically difficult
4) need infectious virus
43
what are the bad components of cell culture
1) Time consuming
2) Labour intensive
3) Technically difficult
4) need Infectious virus
- Cytopathic effect (CPE)
44
PCR advantages, disadvantages and what need
- Rapid diagnosis
- Specialised equipment
- (May be) Quantitative
- Doesn’t need infectious virus
- Don't need to have a viable organism arrive at the lab
45
What are the 4 features of culturing fungi
* Room temperature, frequently prolonged
* Aerobically
* Selective media
* Identification often morphological or cultural (colour, fruiting bodies)
46
What are the 3 main areas that you find microbes
1. Environment
2. Other animals
3. The animal itself
47
List and describe the 4 types of microbes found in the environment
1) soil saprophyte - predisposed if immunocompromised, broad spectrum antibiotics, loss of epithelial integrity
2) non-enveloped virus - resistance
3) endospores - resistant. no metabolic activity
4) nosocomial infections - within hospital (herd immunity not present)
eg - parvovirus, MRSA
48
What are 3 features need to consider with microbes from other animals
1) species of animal
2) host range - implications for control/eradication - FMD
3) sub-clinical infections - carrier for other animals, mastitis and strangles
49
List 4 ways the animal itself can be a source of infection
1) previously infected but not completely resolved
2) reactivation of latent infection - herpes
3) persistent infection
4) opportunistic pathogens
50
What are the 6 steps in virus replication and differences between enveloped and non-enveloped viruses
1)Attachment: viral proteins bind to cell surface receptors
2) Uptake of virus: by receptor mediated endocytosis or by fusion with the plasma membrane
3) Uncoating: makes viral genes available for transcription
4) Early viral genes: shut down cellular protein synthesis, regulate expression of viral genome and production of enzymes (polymerase)
5) Late viral genes: express structural proteins for virus assembly
6) Release
Enveloped viruses acquire their envelope by budding through the plasma membrane, the cytoplasmic membranes or the nuclear membranes
• Non‐enveloped viruses accumulate in cytoplasm and are released when the cell lyses
51
List 3 different molecules that lead to increase virulence in bacteria and function
1) Exotoxins: damage cell membrane, disrupt intracellular processes allowing bacteria to colonise further into the tissue
- Toxins can also break down neutrophils or tissues
2) Enzymes: elastase, collagenase, proteinase, coagulase
3) Leucotoxins: disrupt the phago‐lysosome
52
List 4 different ways virus disseminate within the host
1) local spread
2) haematogenous spread
3) tissue invasion
4) neural spread
53
Describe local and haematogenous spread of virus within host
Local
○ from cell to cell in close proximity to the site of entry and primary replication
○ Contiguous infection of adjacent cells
Haematogenous
Introduced through bite, needle, migration
can get primary (low titre) and secondary replication (high titre) occurs
free in plasma or cell associated
54
Describe tissue invasion and neural spread of viruses within hosts
Tissue
○ Mechanisms that promote movement from vascular space to tissues is poorly understood
Often associated with infection of endothelial cells and/or passive transport across the endothelial cells
Neural
○ Virus moves to the nerve supplying the site of primary replication
○ Immune evasion strategy
○ Rabies an example
55
What are the two main modes of transmission and examples within
1) vertical
2) horizontal
1. direct contact
2. indirect contact
3. vehicle transmission
4. airborne
5. iatrogenic
6. nosocomial
7. zoonotic
56
Describe vertical transmission
- Mother to offspring transmission in utero or in ovo (early post‐partum period)
○ Transmission across placenta, in birth canal, in colostrum/milk
- Cause embryonic death, mummification, resorption (depends on time of gestation) or congenital defects
57
What are important environmental issues that help determine health
1) housing - overcrowding, ventilation, waste management, bedding, noise
2) nutrition - starvation, toxins, trace elements
3) age - old age, newborn, unborn animals
58
List 3 main features in the hsot that determine health and examples
1) physical defences - epidermal integrity, oils in skin, tears, gastric acid, mucus
2) innate immunity - complement, mononuclear cells, natural killer cells
2) acquired immunity - antigen specific, CMI, humoral immunity
59
List 7 sites of entry into host
1) skin
2) respiratory tract
3) gastrointestinal tract
4) genitourinary tract
5) conjunctiva
6) umbilicus
7) oropharynx
60
List 5 defences of the respiratory tract
1. Goblet cells secrete mucus
2. Mucocilliary clearance: mucus propelled and impinging particles propelled orad by ciliated columnar epithelial cells
3. Humoral and cellular immune mechanisms operate locally
4. IgA – in mucus (local immunity)
5. tonsillar lymphoid tissue alveolar macrophages other phagocytes
61
How do viruses enter the respiratory tract and what determines their distrubution
- Viruses enter as aerosolised droplets or saliva
○ Size of the droplet determines the distribution of the particle in the respiratory tract
§ > 5μm – filtered by turbinates
§ < 5μm – lower respiratory tract
62
List the 4 main host defences in the gastrointestinal system and how bacteria evade thsi
1) gastric pH 2-3 -> acid stable
2) proteases secreted by gastric and pancreatic cells -> resist proteoytic inactivation
3) bile salt - resist degradtin by bile salts
4) mucos containing IgA
63
Give examples of viruses present within the gastrointestinal tract and what they lead to
1) rotaviruse - outer protein coat is digested by trypsin
2) coronavirus - enveloped
LEADS TO SECRETORY AND OSMOTIC DIARRHOEA
64
Give examples of diseases that enter from the genitourinary tract, mammary gland and umbilicus
genitourinary - HIV, HSV-2, HPV, bacterial cystitis
mammary - mastitis
umbilicus - neonatal sepsis
65
Conjunctiva how enter and how does it spread
- Direct inoculation - mechanical damage, foreign bodies
- Usually local infection
- Very rarely spreads to systemic (unless from another site)
66
what disease doesn't require entry
Most important toxicoses:
- Botulism / Tetanus Cyanobacterial blooms
Toxins survive passage through intestine
• Direct effect on intestine or Systemic effect
67
What are 4 actions if IgA
- Blocking Adherence
- Export of Invading Organisms
- Intracellular Neutralisation
- Opsonisation
68
what makes a dead end host
don't develop a high enough titre in order to remain contagious
69
describe clinical signs vs symptoms
- Clinical signs are abnormalities detected during a physical examination (Objective observations)
- Symptoms are a feature that indicates a condition of disease, particularly a feature that is apparent to the patient - about how the patient is feeling - NOT IN VETERINARY MEDICINE
70
define infection vs disease vs contagious disease
- Infection is the growth (detection) of infectious agents in the body
- Disease refers to organ or body system dysfunction
- Contagious disease is an infectious disease that can spread from one animal to another animal
71
define specificity and sensitivity
Specificity - rate of true negative
| Sensitivity - rate of true positives
72
Interpretation oh Haemaglutination assays
Dilute red - antibody positive as enough antigen to bind all the RBCs
Red dot - antibody -ve, not enough antibody to bind to RBCs - sink to the bottom
73
How do you calculate the Haemagglutination titre of the antiserum
Expressed as the reciprocal of the highest diluation of serum causing HA
The last concentration where there is haemagluttination
74
Describe how virus neutralisation tests work
POSITIVE SAMPLE - anti-viral Ab's present, add viral Ab's to cultured cells -> anti-viral Ab's inhibit viral attachment and replication, no damage to cells
NEGATIVE SAMPLE
anti-viral Ab's absent, add viral Ab's to cultured cells where the virus can replication -> causes visible damage
75
What are 3 features of immunohistochemistry
- Labelled antibody
- Binds to antigen
- Localises site of replication or expression within the tissue
76
What are the 3 steps of PCR
1. Melting: denaturing of the DNA duplex at a high temperature to yield single stranded DNA.
2. Annealing: primers anneal to the single stranded target DNA sequence.
3. Elongation: DNA polymerase extends the primers by adding dNTPs to the phosphate backbone.
77
What are 4 steps in quantitative (real time PCR)
Uses fluorescent dyes or probes to detect DNA amplification
Detect fluorescence after each cycle
Fluorescence exceeds background threshold
Allows quantification of target in original sample
78
What are 5 features of sample collection and storage
* Collect from lesions on live animals (dead animals undergo autolysis – early after death is better)
* Minimise contamination
* Collect samples before antimicrobial administration
* Refrigeration
* Appropriate identification and OHS approved container / media
79
List 6 steps in controlling an outbreak
1) history - presentation, duration
2) generic control measures - movement control, PPE, quaratine
3) sample collection
4) agtent specific control measures
5) communication
6) prevention
80
List 7 characteristics that make an ideal vaccine
* Easy to administer - not injectable
* Highly efficacious - ideal would stop infection or would provide 100%
* One vaccination would provide life-long protection
* Minimal side effects
* Safe to administer to all animals (young, old, pregnant)
* DIVA capacity - ability to differentiate between infected and vaccinated individuals
81
What are two main types of vaccines
1) Non-replicating vaccine
| 2) replication vaccine
82
List 5 different types of non-replicating vaccines
* Inactivated viral vaccines (whole)
* Bacterins (whole)
* Toxoids (sub‐unit)
* Recombinant proteins - that activate the immune system
* Direct DNA - replication and express the protein of interest
83
List 3 different types of replicating vaccine
* Attenuated viral vaccines
* Recombinant vector vaccines
* Lower virulent strains
84
Live attenuated viruses what are the 3 types and describe
1) culture attenuated - single nucleotide mutation - unsure on change therefore how individuals will react
2) genetically attenuated - know what is removed therefore reaction
3) recombination virus - remove certain genes from pathogenic virus and place into another non-pathogenic virus
85
List 3 main features of live/attenuated vaccines and disadvantages
1) booster not required - replicates in host
2) longer duration of immunity
3) antibody and CTL response (TH1)
Safety issues
1) immunocompromised/pregnant animals - may cross the placenta
2) Reversion to virulence (vaccine associated disease)
3) Deletion mutants
86
Why was the equine influenza vaccine used
* Rapid onset of immunity
* Immunity after one dose
* Used in South Africa - anecdotal
* D.I.V.A.
* Epidemiologically relevant EI strains
87
Toxoid vaccine features
“Detoxified” bacterial exotoxins
Highly immunogenic
Tetanus and botulinum toxins
Circulating IgG is protective
88
List the advantages and disadvantages of non-replicating vaccines
```
Advantages:
Safe and successful technology
Disadvantages:
Reduced immunogenicity
Boosters required
Adjuvants required
```
89
what is the equine influenza vaccine and how is it safe
Canarypox
Non-replicating within mammals
No production of infectious virions within the mammalian host
- Avian cell get the production of the virions
90
What are 5 features of sample collection and storage
* Collect from lesions on live animals (dead animals undergo autolysis – early after death is better)
* Minimise contamination
* Collect samples before antimicrobial administration
* Refrigeration
* Appropriate identification and OHS approved container / media
91
What is the important protein with Hendra Virus and function
G protein:
- Viruses uses to binds to host cell receptors
- Initiates infection
92
What are 4 main features of herd immunity
* Sufficient immune animals in herd to reduce the spread of infection
* All about reducing the risk of infection and disease
* Fewer susceptible animals
* Reduced excretion
93
What are the two main vaccination strategies
1) blanket vaccination -> vaccinate everyone
2) ring vaccination
Outbreak and put a ring around - doom of the donut larger and smaller based on spread of disease as well as contagious time
Anticipate the stop of the spread of the outbreak
Size of internal ring depends on characteristics of the virus
94
List the 4 main control strategies for disease oubreak
1. Test and slaughter
2. Movement controls
3. Zoning, Regionalisation, Compartmentalisation
4. Vaccination
95
What is an emergency animal disease and what are the 3 roles of the Chief Veterinary Officer
```
- Exotic and foreign disease
Chief Veterinary Officer (CVO unit)
1. Sampling and Testing
2. Control and vaccination
3. Eradication (+/- slaughter)
```
96
AUSVETPLAN what is it, main goal and advantage
- Contain, control, eradicate
- Main goal is to go back to disease free
- Very generic guidelines to respond and control an outbreak for specific diseases
- Advantage - everyone following the same general guidelines
97
What were the 3 main features of AUSVETPLAN for equine influenza and how did that work
- •Movement restrictions
- •+/‐ vaccination
- •+/‐ regionalisation / zoning
After the horse movement restrictions the disease was contained into the same areas
STOPPED THE SPREAD OF THE DISASE
98
What occurred after the equine influenza stop of movement
Next step Ease of movement dependant on zone
- Low risk
- Medium risk - stand still
- High risk - can move within high risk areas if they wanted to as there were lots of breeding studs which in order for horse racing to continue the following year needed to get mares serviced if they wanted to take the risk
99
What occurred with the distribution of equine influenza vaccine
- Based on infection rates, horse density, geographical terrain
- Ring vaccination strategy - multiple rings used around different areas of outbreaks
○ start vaccinating into the centre of the ring
- Help mop up the disease - preventing the disease spread
- If people didn't want to vaccinate their horse then move them into the red - high risk area
100
Family and genus of Rabies virus how does transmission occur and where does virus replicate
Family Rhabdoviridae
Genus Lyssavirus: Rabies
Transmission - usually occurs through bites (scratching and licking)
Virus replicates
- Virus replicates in muscle cells
- Very little virus replication in nerve cells
- Variable incubation period (weeks – years) (between infection and clinical signs) - needs to go up the nerves
- Bites around face, deep bites = shorter incubation period
101
What are the two main cycles rabies is maintained within
1. Sylvatic (wildlife) rabies - very hard to control - selective baiting - dose issues, catch vaccination big issue
- Need to use live-virus vaccination so they don't need more than one dose, stronger more durable immune response
2. Dogs - easier one to control - dog control vaccination programs (bring dogs in and vaccinate for free)
- 95% of all humans cases relate to dog bites, majority children under 15
102
Foot and Mouth Disease family, genus and features
Family Picornaviridae, Genus Aphthovirus
- highly contagious
- very high morbidity / low mortality
- dramatic reduction in production (especially cattle)
- disease of economic importance (direct and trade)
- Animal welfare issue - very painful
103
List 6 reasons why Foot and Mouth Disease is hard to control
1) multiple host species (pigs are amplifier hosts)
2) multiple serotypes
3) small infective dose
4) rapid replication
5) highly contagious
6) multiple modes of transmission
104
Why wasn't vaccine used with Foot and Mouth disease and what are the options for countries in terms of status
- Vaccinated animals can be carriers, serologically indistinguishable from exposed animals
- Major issue with trade - why vaccine wasn't used
What are the options
1. FMD free without vaccination
- Serological test & slaughter (positive and in contact animals)
- Australia is an example of this and this is the UK name
2. FMD free with vaccination
- Ring vaccination, +/- slaughter, blanket vaccination
3. Endemic FMD
- Eradication campaign with blanket vaccination
105
Virus have been classified according to list to 5
1) disease or syndrome they cause
2) physical properties of the virus
3) morphology of the virion
4) sequence analysis of the viral genome
5) based on virus tropisms and modes of transmission
106
What are the 4 main groups of virus modes of transmission and examples
1) Enteroviruses - acquired by ingestion (faecal-oral transmission)
Families Coronaviridae, Adenoviridae
2) Respiratory viruses acquired by inhalation
- Families Picornaviridae, Caliciviridae, Paramyxoviridae, Orthomyxoviridae,
3) Arboviruses replicate in their haematophagous arthropod hosts and transmitted to vertebrate host by biting
Families Togaviridae, Flaviridae, Rhabdoviridae
4) Oncogenic viruses – acquired by close contact, injection and other means. Target specific tissues, become persistent and evoke host cellular transformation (neoplasia)
Families Retroviridae, Adenoviridae, Herpesvirida
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What is virus taxonomy based on
1. Type of nucleic acid
- Strategy of viral replication
- Family of viruses generally replicate in certain ways
2. Morphology of the virion
- Enveloped or non-enveloped
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What are the 3 ways in which penetration occurs
1. Translocation across cytoplasmic membrane
2. Endocytosis into intracellular vacuoles
3. Fusion of envelope to cell membrane
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Antiviral chemotherapy why not really used but give an example
- Viruses depend on host enzymes and metabolic pathways of host cell to replicate.
○ Therefore, to interfere with virus replication is to interfere with host cell function - lots of toxic side effects on the host
- Hasn't been any proper clinical trials
Examples
Nucleoside analogues
- Phosphorylated and substituted for nucleosides within the transcription of DNA and stops the transcription of the virus
Eg - Acyclovir
○ Viral infected cells are targeted as those cells activate the drug
- Very expensive drugs
Best results when give before being infected
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Give 2 examples of Anti-influenza agents and function
1) Amantadine and Rimantadine
- Inhibit uncoating of virus during entry into cells and release of virus from infected cells
2) Zanamivir and Oseltamivir sialic acid analogues
- Competes to bind to neuraminidase, inhibits virus release
