Virology Flashcards
What are Koch’s postulates?
- microrganism found in diseased but not healthy individuals
- microorganism must be cultured from the diseased individual
- inoculation of healthy individual with culutred microorganism must recapitulated the disease
4.microorganism must be reisolated from inoculated, diseased indiviual and matched to original microorganism
What is the point of Koch’s postulates?
criteria designed to assess whether a microorganism causes a disease
What is propagation of a virus?
To multiply, a virus has to enter a living cell. Thereafter, the viral genome is released from the capsid, and interacts with the host cell in order to replicate and to produce viral proteins.
Why propagate a virus in a chicken egg?
-specific pathogen free
- isolate the virus
-inoculate membrane that best supports specific virus
- convinient for growing high titre stocks of viruses
What are the requirments for culturing cells?
culutre flasks
tissue culture medium
cell culture incubator
sterile technique
safe working environment
What is passaging cells?
Passaging cells (or splitting cells) involves taking a
fraction of cells from a cell culture and diluting those
cells in fresh medium in new dish. The passage number
of a cell line is used to keep track of how long a cell
line has been cultured for, and each passaging event
will represent a number of cell divisions
What is the cytopathic effect?
Morphological chances induced by viral infection
Dependant on:
- the virus
- cell type
- multiplicity of infection
- time point
- isolate
-mutations
WHat can plaque assays be used for?
– Quantify virus stock (pfu).
– Purify a virus stock (make clonal).
– Assay attenuation of virus stocks.
– Determine particle-to-pfu ratio.
– Generate/select recombinant viruses
Parvoviridae properties
ssSND
non eneloped
small
icosahedral
RESISTANT (heat, disinfectants. pH)
only replicate in nucleus of dividing cells
(parvovirus)
Signif parvoviruses
Canine parvovirus (highly contagious/ in utero)
feline panleucopaenia virus (abortions)
porcine parvovirus (SMEDI)
bovine parvovirus
goose/chicken/ duck parvovirus
Patho of parvo
nasal or oral
- needs dividing cells
replicates in nucelus leaving intranuclear inclusion body
*big impacts on newborns and foetus as have lots of cell division
- bone marrow and interstinal crypts
-continous rep
highly suseptible to infection
Immunity to parvo
annual booster
killed and live attenuated vaccines
(6-8 weeks of age, continue monthly)
3 shots enough
maternal antibody via colostrum protects newborn
Parvo diagnosis
antigen in faecal, blood or tissue sample
haemagglutination assays
ELIZA or RIM
PCR
Immunohistochemistry
Porcine parvo charactersitics
repro failure in pigs
Stillbirth Mummification Embryonic Death Infertility (SMEDI)
very resistant (70-73* for 30-60 mins to deactivatea)
endemic in herds
infected pig (viremia) –> sheds oral and feacal secretions
carrier boars (screen semen used for AI)
Porcine parvo patho
infected pigs –> viremia –> without clinical disease or obvious lesions
strong humoral response
seroneg sows exposed during gestation cause repro issues
Virus loves foetal tissue
Porcine parvo treament
no treatment
endemic
vaccinate breeding gilts and suseptible sows prior mating
vaccine (2-4 weeks prior mating)
boosters 6-12 months
Porcine parvo prevention
biosecurity
quarantine nd screen
antibody or antigen testing
control human movement
allin-allout
Canine parvo prevention
dogs secrete 3-4 days before clinical signs
isolation
footbaths
disposable clothing, bedding
disinfecting
puppy vaccines
Papillomaviridae properties
dsDNA
non enveloped
icosahedral
stable in ennviro
RESISTANT (heat, lipid solvents, disinfectants)
loves epitheliol cells
hst specific
*unable to grow in cell culture
very species specific
WARTS (cell mass into papilloma)
Signif Papillomaviridae
Bovine
- type 1&2 (young cattle - head, neck, penis)
(equine)
- type 3 (cutaneous pap)
- type 4 (alimentry tract)
- type 5 &6 (teat)
Equine (young, lips and muzzle)
Canine oral (young)
Ovine(sheep)
Papillomavirus diagnosis
clinical apperance
histopathology
EM to look for virus in tissue
PCR
CANT CULTURE
Equine sarcoids
– Locally invasive dermal fibroblastic skin
tumour
– Locally aggressive but not metastatic
– Benign skin tumour
– Most often on ventral abdomen, limbs,
head and sites of previous trauma
– Occur as a single or multiple lesions
– DO NOT REGRESS !!
* EPV regress in 4 - 8 weeks
Caused by BPV types 1 or 2
Equine sarcoid risk factors
age (2-6)
breed (quater>throurough>standard)
genetic suseptibility
absense of immune recog
Transmission (cattle –> horse/horse–>horse
SKin abrasions
equine sarcoid diagnosis
PCR
qPCR
Biopsy
histopathology
equine sarcoid treatment
surgical excision
cryotherapy
immunotherapy
radiofrequency hyperthermia
laser surgery
siRNA
Poxviridae properties
large
complex structure
dsDNA
enveloped
BREAKS A LOT OF RULES
can survive in environemnt (yearsvin dried scabs)
sensitive (heat/detergent)
ONLY REPLICATE IN CYTOPLASM (inclusion bodies)
predilection liking) for epidermal cells
SIgnnif pox viruses
Smallpox
Vaccinia
Cowpox
Camel and mouse pox
Parapoxvirus (ORF) –> scabby mouth)
Pseudocowpox
Bovine papular stomatitis virus
Croc and caiman pox
Capriopox (sheep and goat)
Suipoxvirus (swine pox)
Leporipoxvirus (myxoa)
avipoxvirus(fowlpox)
MANY ZOONOTIC-> localised skin lesions
Pox path
contagious
small abrasions (between animals) –> direct and indirect
Vectors
Aerosols
ALL CAUSE SKIN LESIONS
like epiderml cells
cell associated viremia
viral rep and assembly in cytplasm
virions releasrd (budding)
LIVE VIRAL VACCINES NEEDED
Pox diagnosis
clinical apperance
histopathologgy
isolation of irus in cell culture
EM
PCR
Pox prevention
Vaccine (only commercial and lab rabbits)
live modified
not permitted for pet rabbits (vaccine)
ectoparasite control
pet rabbits in rural areas
Scabby mouth properties
ORF
sheep and goats
pustular dermititis
zoonotic
muzzle nd lips
scabs
eyes, lower legs, teats
Scabby mouth spread
direct or indirect
dry stable environ
epitheliotropic
What are diagnostic methods to detect the virus itself?
- growth in culture
- Nucleic acids (PT-PCR, PCR)
- Antigens (ELIZA, IFA, IB/WB, LFT/RAT)
- Activities (HA)
What are diagnostic methods to detect the immune response to a virus?
- Antibiodies (ELIZA, HAI, virues
- neutralisation (IGA< IB/WB)
What are Prions?
– Infectious proteinaceous particles
– “Infectious proteins”
– Lack nucleic acid
– Non-immunogenic
– Extremely resistant to:
– Heat
– Chemicals
– Irradiation
– Cause Transmissible Spongiform
Encephalopathies (TSEs)
