Term
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Definition
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Term
| 2 main geni of flaviridae= |
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Definition
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Term
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Definition
+ssRNA
with 5'cap, no poly A tail and short hair pin loop protecting RNA from degradation |
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Term
| nucelocapsid of flaviridae = |
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Definition
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Term
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Definition
| yes! tightly fitting with small peplomers |
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Term
| replication of flaviridae is similar to... |
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Definition
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Term
| flaviridae infection of host cell = |
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Definition
| endocytosis after binding to sialic acid, derc endosome pH = fusion of virus ENV and endosome mb = release + ssRNA into cytoplasm |
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Term
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Definition
| single polycistronic ORF translated inot one large polyprotein thats then cleaved into lots of diff proteins |
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Term
| structural genes in flaviridae virus grouped at ____ end |
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Definition
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Term
| translation of flaviridae mRNA is via... |
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Definition
| ...host cells ribosomes of the RER |
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Term
| leader sequence of flaviridae acts as a secretory signal to... |
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Definition
| ...ensure proteins become inserted onto ER mb |
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Term
| structural flaviridae proteins are processed by... |
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Definition
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Term
| NSP are at ____ end and = |
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Definition
3'end
protease and RNA pol |
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Term
| virus assmebles and buds from... |
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Definition
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Term
| flaviridae exits the cell bia... |
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Definition
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Term
| flavivirus main example = |
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Definition
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Term
| Rs of louping ill virus = |
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Definition
| sialic acid/gangliosides (found on variety of cells including nerves) |
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Term
| louping ill virus has dsRNA intermediates = |
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Definition
| potentially gd IFN inducers |
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Term
| louping ill virus is a member of the.... |
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Definition
| ...tick borne encephalitis group of flavirus |
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Term
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Definition
| ixodes ricinus tick (found upland areas where sheep graze) |
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Term
| what kind of transmission of loupig ill virus do you get between ticks? |
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Definition
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Term
| motality of red grouse infected with louping ill virus = |
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Definition
80%
this is imp as red grouse is an economically imp gaming bird |
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Term
| louping ill virus infects what sp? |
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Definition
| not sp restricted. Infects a variety of mammals and birds |
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Term
| louping ill virus is mainly seen in... |
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Definition
| ...sheep in spring or autumn (when you have peak levels of ticks) |
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Term
| louping ill virus replicates in... |
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Definition
...leucocytes
macro
dendritic cells
endothelial cells 9therefore can infect BBB and get into brain!) |
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Term
| tick saliva helps viral infection by... |
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Definition
| ...supressing hosts immunity |
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Term
| get primary fever with louping ill virus associated with... |
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Definition
| ...IFN response and viraemia spread of virus |
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Term
| viraemia of louping ill virus is... |
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Definition
| ...prolonged and can allow spread to CNS = neuro signs |
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Term
| neuro signs seen with louping ill virus infection = |
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Definition
ataxia
mm tremors and spasms
louping (abnormal gait)
paralysis
death |
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Term
| neurone louping ill virus infection = |
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Definition
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Term
| reservoir hosts of louping ill virus = |
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Definition
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Term
| route of louping ill virus infection in red grouse = |
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Definition
| red grouse eat infected ticks |
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Term
| more severe dz with louping ill virus is asociated with... |
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Definition
...immunosupression due to coinfection with ehrlicia phagocytophillia (a small bacteria = IC parasite)
ehrlichia phagocytophillia is ynergistic with louping ill virus |
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Term
| after infection with louping ill virus and recovered = |
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Definition
| immune (rise in Ab titre) |
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Term
| if ewes properly immunised will you see louping ill virus in lambs? |
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Definition
| no as lambs protected by maternal Abs |
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Term
| vacc of louping ill virus ? |
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Definition
| inactivated cell culture derived vacc and used to protect breeding ewes - annual boosters |
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Term
| mst sheep with louping ill virus ten to be between the gae of... |
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Definition
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Term
| dx of louping ill virus = |
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Definition
1. virus isolation
2. serology - IgM rise = infection is now, IgG rise = may be infection now, last wk or incr IgG due to sheep being vacc, therefore need to to serology quickly)
3. immunohistology |
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Term
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Definition
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Term
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Definition
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Term
| one of the most imp pathogenic viruses of cattle in UK = |
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Definition
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Term
| do all cattle with BVDV show signs of dz? |
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Definition
| only a proportion of cows in herd (the runts) show signs of dz |
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Term
| does BVDV cause diarrhoea? |
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Definition
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Term
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Definition
+ssRNA
like FMD has IRES (Internal Ribosomal entry site) to initiate transcription |
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Term
| structural genes of BVDV at ____ end of +ssRNA |
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Definition
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Term
| structural genes of BVDV are translocated to... |
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Definition
| ...ER mb whre theyre cleaved into their seperate parts by host signal peptodase/host proteases |
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Term
| viral NSP2/3 of BVDV do what? |
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Definition
| cleave key proteins that cause pathogenesis |
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Term
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Definition
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Term
| dz seen with BVDV is due to... |
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Definition
| ...conversion to cytopathic strain due to NSP3 mutation, in chronic infection Usually mutation into 80kD NSP3 ( a bigger NSP3) |
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Term
| normal activity of NSP3 of BVDV= |
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Definition
| proteolytic action restricted to at ER = not much damage to host cell |
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Term
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Definition
| proteolytic activity of NSP3 isnt restricted to around ER so it drifts around host cell breaking proteins up! |
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Term
| does BVDV cause an IFN response? |
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Definition
| normal BVDV blocks IFN response, however cytopathic mutated BVDV does induce IFN response |
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Term
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Definition
CD46 (C' control protein)
protein on the surface of many cells |
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Term
| why is BVDV only seen in cattle? |
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Definition
| CD46 (R BVDV binds to) are diff in diff sp |
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Term
| 2 biotypes of BVDV. which one is most common in UK? |
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Definition
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Term
| conversion of BVDV biotype 1 to ctopathic form causes... |
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Definition
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Term
| conversion of BVDV biotype 2 to cytopathic form cuases... |
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Definition
| ...thrombocytopaenia (decr platelets) and haemorrhagic dz - haemorrhagic diarrhea or haemorrhage of mucous mb |
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Term
| BVDV can cause many dzs, such as... |
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Definition
1. acute infection of susceptible cattle with non-cytopathic BVDV
2.moderate/severe outbreaks with cytopathic BVDV
3. infection of preg cow with non-cytopathic BVDV
4. endemic herds
5. mucosal dz (cytopathic biotype 1) |
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Term
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Definition
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Term
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Definition
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Term
| BVDV spreads in body via... |
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Definition
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Term
| BVDV is found in what cells? |
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Definition
| T and Bcells and also causes a decr in the no of t and b cells, BVDV is immunosupressive = get secondary infection = exacerbate resp dz |
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Term
| dz is usually mild woth non-cytopathic virus. morbidity is... |
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Definition
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Term
| clinical signs of non-cytopathic BVDV = |
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Definition
few if any!
transient fever, then Ab response to birus and recover) |
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Term
| why dont you ever find cytopathic BVDV on its own in cattle? |
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Definition
| as cytopathic BVDV has mutated from non-cytopathic BVDV |
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Term
| clincial signs of cytopathic BVDV = |
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Definition
fever
depression
diarrrhoea
erosions in mouth and coronary band (petechiae)
some deaths
immunosupressive = secondary infection = exacerbate resp dz |
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Term
| animals that recover from BVDV ... |
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Definition
| ...seroconvert (have gd immunity/high Ab levels against BVDV) |
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Term
| infection of preg cow in 1st 30days of gestation = |
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Definition
transplacental infection of fetus =
-early embryonic death :(
-cow mounts an immune response and wont get BVDV again - 2nd preg fine :) |
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Term
| BVDV infection of preg cow 30-90 days into gestation = |
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Definition
transplacental infection of fetus =
-embryonic death/fetal death = abortion or mummification :(
-cow mounts immune response-2nd preg will be fine :) |
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Term
| BVDV infection of preg cow 90-120 days into gestation = |
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Definition
transplacental infection of fetus =
-infection during critical period of calves immune system develoment. Calf survives but is immunotolerant to BVDV = lifelong persistance of BVDV infection in calf with no immune respnse and may not have clincial signs = carrier
-cow mounts immune response, clears virus and becomes immune |
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Term
| infection of preg cow >125days into gestation= |
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Definition
transplacental infection of fetus =
cow and claf develop immune response as calf has a developed immune system.
calf will reach full term but can get some fetal defects:
-retinal dysplasia
-cerebellar hypoplasia
-cerebral cavitation
-low birth weight
-neonatal death :( |
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Term
| once got endemic of BVD in herd = |
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Definition
| hard to eradicate :( (due to persistant infections) |
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Term
| how common in BVDV infection in adults? |
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Definition
| rare as got high immunity once been infected once |
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Term
| what age of cow most likely to become infected with BVDV? |
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Definition
| heifers when first joining the herd (ie during 2nd preg) |
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Term
| how mainy animals in endemic herd are perisitantly infected? |
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Definition
| approx 1% - maintains infection and low fertility levels |
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Term
| mutation of biotype 1 BVDV NSP3 to... |
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Definition
| ...80kD NSP3 that has tropism for mucosal immune system eg peyers patches, lamina propria, mesenteric LNs |
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Term
| onset of mucosal BVDV dz = |
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Definition
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Term
| BVDV mucosal dz can be seen at any age but most commonly seen... |
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Definition
| ...between 6months and 2yrs |
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Term
| clinical signs of BVDV mucosal dz = |
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Definition
1. pyrexia
2. anorexia
3. profuse watery diarrhoea (DDx = johnes) - wont go away = progressive dz
4. nasal discharge
5. erosive stomatitis- inflam of mouth mucous mb and ulcers around mouth, nose, oesoph and forestomachs
6. dehydration
7. emaciation
8. foot lesions
9. hyperaemia
10. intestinal necrosis of peyers patches and lymphoid tissue = kills all lymphocytes in peyers patch |
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Term
| mortality of BVDV mucosal dz = |
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Definition
100%
usually takes several wks and then die |
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Term
| mortality of BVDV mucosal dz = |
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Definition
100%
usually takes several wks and then die |
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Term
| how can you differentiate between BVDV and FMD? |
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Definition
FMD will have a few cows affected
BVDV will have one cow affected with chronic onset |
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Term
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Definition
approx 80%
most likely to be healthy and maintained immunity from previous infection |
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Term
| immunotolerant persistantly infected cows Ab levels = |
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Definition
NO Abs = sero-
therefore serology ELISA of individual cows Ab levels is of limited us for dx of BVDV |
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Term
| how can you ID infected herd? |
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Definition
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Term
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Definition
-tissue culture + immunofluorescence
-detection of BVDV RNA by RT-PCR
-Ag capture ELISA = coat plate with Abs that capture the virus, + virus, + another Ab with marker that detects virus. Use to find persistant immunotolerant carriers |
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Term
| control of BVDV to get BVDV free herd = |
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Definition
| test and cull (use Ag capturee ELISA test) |
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Term
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Definition
| big impact on productivity and fertlitly of the herd :( |
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Term
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Definition
yes, live attenuated and inactivated vacc but...
-not all totally effective
-may not protect against all strains of BVDV
-not certain to prevent fetal infection
-some evidence may contribute to dz onset in tolerant animals (as how can you have a live attenuated virus of a non-cytopathic virus???) - better now as engineered virus to remove what causes IFN block from virus
-can spread virus by using same dirty needles (need to wash inbetween, can get self washing needles!) |
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Term
| can kill ENV virus with... |
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Definition
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Term
| 2 step BVDV Vacc of remaining animals after test and cull = |
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Definition
| 1st admin inactivated vacc, then 2nd booster dose admin live attenuated vacc |
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Term
| replacemtn animals need to be vacc against BVDV at... |
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Definition
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Term
| biosecurity is v imp and effective in control of BVDV as... |
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Definition
| ...BVDV is an ENV virus and Env viurses are so easily destroyed with detergent! |
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