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Virology - Poxviridae
viruses
63
Veterinary Medicine
Undergraduate 3
06/01/2012

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Term
siz eof pox virus =
Definition
v large - genome = 130-280kbp(with complex structure)

can encode over 200 proteins of which 100 are contained within the virion
Term
ENV?
Definition
yes
Term
genome =
Definition
dsDNA link/loop
Term
what does pox virus have that no other virus has?
Definition
-looped dsDNA
-lateral bodies
-surface microtubules
-replicates in cytoplasm (unlike other DNA viruses)
Term
what do we think is involved in binding and fusion of poxvirus and host cell?
Definition
microtubules
Term
what is in poxvirus core?
Definition
-RNA pol (DNA to mRNA)
-transcription factors
-poly (A) polymerase
-capping enzymes

(everything needed to replicate DNA and make mRNA)
Term
early genes =
Definition
activates within minutes of infection:
-mRNA synth
-transcriptiion factors
-virokine (competitive inhibitors of cell cytokine = subvert/inhibitu immune response)
-GFs
-soluble IFN Rs = block IFN on way to naughbouring cell by binding to IFN
Term
intermediate genes =
Definition
-mRNA and DNA synth
-late gene transcritpion factors= activate host cell division = virus division
Term
late genes =
Definition
processing of viral DNA structural proteins eg lateral bodies
Term
concatamer resolution =
Definition
concatamer is a long continous loop of DNA molecule that contains multiple copies of the same DNA seq
Term
2 types of intracytoplasmic inclusion bosies of poxvirus =
Definition
type A
type B
Term
type A inclusion bosy =
Definition
contain virus particles compacted together in mass of protein to protect virus.

Acidic inclusion dosies
Term
type B inclusion bodies =
Definition
blue-brown

appear b4 type A

contains replicating virus = lots of DNA and nucleic acid

basic
Term
stomatitis =
Definition
inflam of mucous mb of mouth
Term
pathogenesis of pox =
Definition
1. macule (red flat spot sue to incr BF/inflam response)
2. papule (raised red spot 1-2cm wide) due to oedema, cellular swelling and cellular prolif
3. formation of vesicles as cells loose adhesion between eachother (as cells are dieing) and inclusion bosies in cells
4. pustular lesions (small pimple/blister on epi surface containing pus)
5. vesicules/pustules rupture and ooze serum, attempt to clot = scab
6. resolution with scarring (pox mark) in 2-3wks
Term
how long to pox survive in enviro?
Definition
yrs, espec in dessicated scab material

virus is v hardy
Term
how is pox transmitted/spread?
Definition
-skin (surface inoculation)
-mucosal route/aerosol
-mechanical vectors - biting insects eg haematopinus suis (louse) transmits swine pox
Term
why do most pox viruses have a restricted range?
Definition
virokine and GFs have to match hosts
Term
vaccinia =
Definition
strain of pox virus used to vaccinate against small pox
Term
origin of vaccina =
Definition
unclear. Not cowpox, but will grow on cow and cause pox lesions on teats and udder
Term
Buffalo pox causes =
Definition
outbreaks of pox lesions on teats and udders of water buffalo in India and egypt
Term
cow pox is actually a
Definition
rodent virus, which may spread to cows or cats (but rare to see in cat), humans or zoo animals
Term
reservoir of cowpox in UK =
Definition
voles and wood mice
Term
prevelance of cowpox =
Definition
higher in autumn when population of young susceptible animals reaches its peak, and theres lots of mice around

young more susceptible to pox
Term
infection of cowpox in cows =
Definition
localised to teat and udder
Term
how is cowpox spread between cows?
Definition
during milking
Term
cowpox seen in what aged cats?
Definition
young cats only. A sonce recovered = life long immunity
Term
why do cats become infected with cowpox?
Definition
hunt voles and wood mice
Term
primary lesion sof cowpox in ctas =
Definition
on face or paws
Term
cowpox in cats causes =
Definition
1.often goes unreported and reaolves in a few days
2. can become generalised with widespread skin lesions - recovery takes 6-8wks
3. can get pulm spread and pneumonia = usually fatal :( often associated with immunosupression, eg cats with FIV or FeLV
Term
why does the pulmonary form of cowpox often occur in cheetahs?
Definition
cheetahs have inadequate MHC 1 = not much variation in Tcell epitpoe capacity = limited capacity to defend against different pathogens
Term
myxomatosis virus is a virus from...
Definition
...wild S American rabbits causing benign fibroma
Term
in EU rabbits myxomatosis causes...
Definition
...severe highly fatal dz
Term
is myxo highly infectious and contagious?
Definition
highly infectious but NOT highly contagious (wont get myxo by standing next to another rabbit)
Term
virulent myxo strains cause
Definition
-blepharoconjunctivitis (inflam of eye and conjunctiva)
-swelling around muzzle and anogenital region)
-fever, depression
-rapid detah in 48-72hrs
Term
les virulent myxo strains =
Definition
-slower progression of dz
-development of gelatinous subcut swelling over entire body
-death in 7-12days
Term
myxo spread by...
Definition
...fleas mechanically in rabbit burrow

substantial evidence for mosquito spread in UK as dz can occur in domestic rabbits where theres been no contact with wild rabbits
Term
dx of myxo =
Definition
-clinical signs
-EM (can see lateral bodies)
-virus isolation on rabbit cell culture or embryonated eggs
Term
vacc's available for domestic pet rabbits against myxo =
Definition
-attenuated
-related shope fibroma virus
Term
avipoxvirus is found in...
Definition
...chickens (fowlpox)
...turkeys and ducks (turkeypox)
Term
avipox is spread by....
Definition
...mosquitos and lice mechanically
...or aerosol
Term
canarypox is used as...
Definition
...a vacc vector
Term
avipox infection is localised to...
Definition
...comb and wattle or legs
Term
aerosol spread of avipox virus causes
Definition
pulm form of dz = diptheritic fowlpox

mortality up to 50% in severe outbreaks
Term
dx of fowlpox =
Definition
-clinical signs
-EM (can see lateral bodies)
-virus isolation
Term
vacc of fowlpox?
Definition
live attenuated skin prick vacc given to pullets (hens <1yr old) at 7wks old
Term
pigeonpox dz occurs in
Definition
racing or show pigeons presumably acquired from wild/feral flocks
Term
vacc against pigeon pox?
Definition
attenuated live vacc
-admin by brushing into open follicles after plucking out 6-8feathers from loew leg or breast
-admin to birds over 5wks old (can be used to control an outbreak in birds over 5wks of age)
Term
EM of parapox virus =
Definition
crisscross pattern (a ball of twine)
Term
name a parapoxvirus
Definition
orf - contagious pustular dermatitis
Term
orf prevelance =
Definition
worldwide condition in sheep
Term
infection of orf occurs where on body?
Definition
face
lips
poll
teats
udder
Term
lesions of orf virus =
Definition
-more proliferative than orthopox virus (eg cowpox = an ot=rthopox virus)
-following minor trauma lesions bleed (due to virus producing an endothelial GF (virokine) that activates bv prolif)
Term
infection of orf is more severe in...
Definition
...lambs - infect gums, tongue and buccal mucosa = prevent suckling = weight loss

also lesions on ewes teat can stop lambs suckling as painful for ewes AND can transmit orf to lambs face if lamb allowed to suckle by ewe
Term
mortality with orf =
Definition
rare
Term
endemic orf flock =
Definition
problems yr after yr affecting susceptible lambs
Term
orf infection on humans =
Definition
nodular lesions that last for several wks
Term
orf vacc?
Definition
1. live attenuated
-still qu virulent
-only use in endemic flocks (can be used to control outbreaks)
-scratch application onto skin on ewes axilla/front leg as less risk to lamb cf back leg
-give no less/no closer than 7wks b4 lambing
-12 months protection
-no colostral immunity = protection NOT transferred to lambs
-can vacc lamb on axilla if neccessary
Term
bovine parapoxvirus/pseudocowpox is more or less severe than cowpox?
Definition
less severe
Term
what shape lesion does bovine parapoxvirus/pseudocowpox cause?
Definition
horse shoe shaped lesion
Term
bovine parapoxvirus/pseudocowpox causes what in humans?
Definition
milkers nodule
Term
bovine parapoxvirus/pseudocowpox is v similar to...
Definition
...orf lesions
Term
bovine papular stomatitis is seen in...
Definition
...calves and cause proliferative lesions in mouth and on muzzle

generally less severe than orf in sheep
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