Virology - parvovirus, adenovirus, poxvirus, herpesvirus Flashcards
(117 cards)
1
Q
Is parvovirus enveloped?
A
No - stable in environment
2
Q
What type of symmetry does parvovirus nucleocapsid have?
A
Icosahedral
3
Q
What is the surface of a parvovirus like?
A
Rugged
4
Q
What is the classification of parvovirus?
A
Linear single stranded DNA
Can be either positive or negative sense
Class 2
5
Q
What does parvovirus need to replicate?
A
Host cell proteins from dividing cells
6
Q
What does the open reading frame on the 3’ end of the parvovirus genome encode for?
A
Non-structural proteins (NS)- for DNA transcription and replication
7
Q
What does the open reading frame on the 5’ end of the parvovirus genome encode for?
A
Structural proteins (VP)- form the capsid
8
Q
What does parvovirus NS1 do?
A
Unzips DNA (helicase) for viral DNA replication
9
Q
What does parvovirus NS 2 do?
A
Regulates viral gene expression
10
Q
Which is less frequent out of the parvovirus structural proteins - VP1 or VP2?
A
VP1
11
Q
How is the parvovirus genome replicated?
A
ssDNA made into dsDNA
Then mRNA is made to make viral proteins
And new ssDNA is made to be packaged into virions
12
Q
Where does parvovirus DNA replication occur? In what kind of cells?
A
In the nucleus
Dividing cells
13
Q
What does parvovirus not have?
A
DNA polymerase
14
Q
What receptor does canine parvovirus use to enter cells?
A
Transferrin receptor
15
Q
What age does canine parvovirus affect?
A
All ages, less than 6 months the worst
16
Q
How is canine parvovirus transmitted/infection?
A
Ingestion or inhalation via direct or indirect contact
17
Q
Where in the body does parvovirus infect?
A
Replicates in lymph nodes via naso and oropharynx
Then to where cells rapidly divide (bone marrow and intestine crypts of villi) via blood stream
Also heart of young dogs
18
Q
What are the clinical symptoms of canine parvovirus?
A
Diarrhoea due to blunting of villi
Haemorrhage in severe cases
Immunosuppression
19
Q
How is canine parvovirus diagnosed?
A
Virus in faecal samples
Haemagglutination
PCR
Antigen ELISA
20
Q
Can you vaccinate against canine parvovirus?
A
Yes
Vaccination also provides maternal antibodies so puppies more protected
21
Q
What does porcine parvovirus infection cause in pigs?
A
Reproductive failure - stillbirths, mummification, infertility, embryo death
22
Q
Where is porcine parvovirus infection mostly found?
A
Foetuses - lots of dividing cells
Before 60 days old - no immune system
23
Q
How is porcine parvovirus infection transmitted?
A
Transplacentally
24
Q
How is porcine parvovirus infection controlled?
A
Vaccination of gilts (young female pigs)
25
What classification is adenovirus?
Single linear double stranded DNA
| Group 1
26
Is adenovirus enveloped?
No
27
What symmetry does adenovirus have?
Icosahedral
28
What is unique to the adenovirus capsid?
Has a fibre - attaches the virus to host cells and is a haemagglutinin
29
What is the adenovirus capsid made up of?
Hexons and pentons
30
What does the adenovirus genome have on each end?
An inverted terminal repeat
31
What do the adenovirus early region genes do?
Regulate transcription
32
What is the role of the adenovirus late region genes?
Structural
33
What is the promotor region for the late region of the adenovirus genome called?
Major late promoter
34
What does adenovirus use for transcription of their genome?
Its own viral DdDp - copies genome
| Host DdRp - makes mRNA to produce viral proteins
35
Where does adenovirus replication occur?
In the nucleus - needs hosts DdRp which is found in the nucleus
36
Which form of adenovirus is infectious and why?
Mature virions - contain the entire genome and have proteolytically processed capsid proteins
37
What does adenovirus E proteins do?
Cause immune evasion
38
What can you use to diagnose adenovirus infections?
Haemagglutination inhibition assay
39
What severe disease is caused by adenovirus in dogs?
Canine adenovirus 1 - causes canine hepatitis
40
How is canine adenovirus 1 transmitted?
Ingestion of infected bodily fluids eg. urine, faeces or saliva
41
What age of dogs are affected by canine adenovirus 1? What severity?
All ages
More severe in puppies
Subclinical infection is common
42
What are the three syndromes of canine adenovirus 1?
Peracute disease - dead without a sign
Acute disease
Mild disease - partial immunity, vaccine
43
What are the symptoms of acute disease?
Fever, thirst, vomiting and diarrhoea etc.
| Blue eye in 25% of affected dogs - bilateral corneal opacity
44
Why does blue eye form in canine adenovirus 1 infections?
Virus forms immune complexes with antibodies in the eye, causes inflammation
45
What milder disease is caused by adenovirus in dogs ?
Canine adenovirus 2 - localised respiratory disease, kennel cough
46
Can you vaccinate against canine adenovirus?
Yes - canine adenovirus 2 vaccine is used to vaccinate against both 1 and 2
47
What classification is poxvirus?
Linear double stranded DNA
| Group 1
48
Where does poxvirus replicate?
In the cytoplasm
49
Does poxvirus have an envelope?
No - stable in environment in dry conditions
50
What shape are poxviruses?
Brick shaped
51
How many layers does a pox virus have? What are they?
```
4 layers
Core
Core wall
Inner membrane
Outer membrane
```
52
What does poxvirus have on its outer membrane?
Short surface tubules
53
What shape is the poxvirus core?
Egg timer - lateral bodies squash middle together
54
How are poxvirus virions released from the host cell?
Budding
55
What shape is the parapoxvirus?
Ovoid shaped
56
What are found at the ends of the poxvirus genome?
Inverted terminal repeats
57
What do inverted terminal repeats do?
Join DNA strands together by crosslinking them
58
Where are the genes that code for the structural proteins found on the poxvirus genome?
In the centre
59
Where does poxvirus replicate?
In the cytoplasm - minimally dependent on host cell
60
What is the main feature of the poxvirus genome?
Very big, codes for lots of (100+) proteins eg. DdDp and immune modulating (affecting) proteins
61
What are viroreceptors?
Cell receptors that are altered by poxvirus so they are not anchored to the cell membrane, get secreted
62
What are virokines?
Secreted viral proteins made by poxvirus which resemble host cytokines but are not functional
63
How are poxviruses transmitted?
Skin abrasions
Aerosol
Contaminated environment
Biting arthropods
64
What transmits swinepox?
Pig/hog louse (haematopinis suis)
65
How can poxviruses affect a wide range of different species?
They dont rely on specific cellular receptors to enter cells, instead they use host molecules
66
How does the vaccinia poxvirus attach to cells?
Viral outer membrane proteins bind to host cell glycosaminoglycans
67
What are the 3 stages of poxvirus replication?
Early, intermediate and late
68
How are each stage of poxvirus protein encoded?
By the genes from the stage before eg. intermediate gene transcription factors are encoded by early genes
69
What is a characteristic of cells which are infected with poxvirus?
Host cell has intra-cytoplasmic inclusion bodies - stain red
70
What are the flat red spots on skin from a poxvirus infection called?
Macules
71
What are the raised red spots on skin from a poxvirus infection called?
Papules
72
What are papules that are filled with with fluid/pus called?
Vesicles/pustules (3/4 weeks to develop
73
What are examples of poxvirus?
Vaccinia virus
| Orf
74
Where is vaccinia virus found?
Not seen in Europe since smallpox vaccination ceased - vaccinia used as a human vaccine for smallpox
Outbreaks still in India
75
Where are the lesions found in cowpox and buffalopox virus?
```
Mild form - udders and teats
Severe form (only in buffalopox) - generalised lesions
```
76
How is cowpox spread?
In rodents - mice and voles
| Cows lie on grass and udder comes in contact with rodent droppings
77
What is feline cowpox like?
More severe - single lesion, necrotising dermatitis for 6-8 weeks
78
What is the other name for orf?
Contagious ecthyma
79
Where does orf affect?
Mucocutaneous junctions of the muzzle and lips
80
What does orf affect?
Young lambs and kids
81
How can you prevent orf?
Vaccination - live attenuated
| Of ewes before lambing
82
How is orf vaccine administered?
Scratch application to skin - scarification
83
What are examples of parapoxviruses?
Pseudocowpox virus
| Bovine papular stomatitis
84
What is pseudocowpox virus?
Less severe than cowpox
| Affects udder and teats of cows
85
How is pseudocowpox transmitted?
Horizontally through milking teat cups and hands, suckling and flies
86
What is papular stomatitis?
Less severe than orf
| Affects mouth, muzzle and nostrils
87
What classification is herpesvirus?
Linear double stranded DNA
| Group 1
88
Does herpesvirus have an envelope?
Yes
89
What type of herpesvirus is cold sores?
Herpes simplex virus 1 (HSV1)
90
What type of herpes virus is genital herpes?
HSV2
91
What type of herpes virus is chickenpox?
Varicella zoster
92
What are the 3 subfamilies of herpesvirus?
Alpha herpesvirinae
Beta herpesvirinae
Gamma herpesvirinae
93
What are the characteristics of alpha herpesviruses?
Short replication cycle (<24hrs)
Wide host range
Rapid destruction of cultured cells
Latent infections in neurones
94
What are the characteristics of beta herpesviruses?
Long replication cycle (>24hrs)
Narrow host range
Slow destruction of cultured cells
Infected cells contain cytoplasmic and nuclear inclusions
Latent infection in lymph and secretory cells
95
What are the characteristics of beta herpesviruses?
```
Narrow host range
Lymphotropic
Latent in lymphocytes
Linked to oncogenic transformation of lymphocytes
Cytolytic
Infects epithelial cells and fibroblasts
```
96
What are the three distinct structures of a herpes virus?
Envelope
Capsid
Tegument
97
How does herpes virus replicate its genome?
Uses a host DdRp RNA polymerase to create mRNA to make proteins for new virions
Uses a viral DdDp to copy its genome
98
What happens to herpesvirus genome when it enters the host cell nucleus?
It binds at its ends to form a circle
99
How do herpesviruses enter cells?
Most bind to glycosaminoglycans
| Some bind to receptors
100
What part of herpesviruses are released into the cytoplasm?
The tegument and nucleocapsid
101
Where does transcription of herpesvirus occur?
All in the nucleus - none in the cytoplasm
102
How are herpesviruses packaged and matured after replication?
By budding through the nuclear membrane to envelop the nucleocapsid and then be in vacuoles in the cytoplasm
103
How does herpesvirus remain latent in cells?
Stay in host cell nucleus as circular viral genome or by integrating the genome into a host chromosome
104
How does the immune system protect against herpesvirus?
Neutralising antibodies ad antibody dependent cellular cytotoxicity
IFN-a limits virus spread
Cytotoxic T cells clears active infection
105
How does herpesvirus evade the immune system?
Viral proteins not expressed on cell surface
Blocks and destroys MHC
Secretes virokines
106
What diseases does bovine herpes virus 1 cause?
Bovine rhinotracheitis and pustular vulvovaginitis
107
What are the symptoms of bovine rhinotracheitis (bovine herpes virus 1)?
Fever
Serous nasal discharge
Tissue necrosis - secondary infections, death
Conjunctivitis
108
What are the symptoms of pustular vulvovaginitis (bovine herpes virus 1)?
Affects cows uterus, oviducts, ovaries and vulva
Tail held away from vulva
Fever and depression
109
How long does pustular vulvovaginitis (bovine herpes virus 1) last?
Acute stage - 4-5 days
| Heals by 10-14 days
110
Where does bovine herpes virus 1 remain latent?
Sciatic and trigeminal ganglia
111
How is bovine herpes virus 1 diagnosed?
Swabs, ELISA, PCR
112
How is bovine herpes virus 1 prevented?
Vaccination - used extensively, reduces severity of disease
113
What diseases does bovine herpes virus 2 cause?
Mammillitus
| Pseudo-lumpy skin disease
114
Where does mammillitus affect?
Teats and udder
115
How is mammillitus transmitted?
Serous exudate from lesions
| Suckling, direct, indirect
116
How is pseudo-lumpy skin disease transmitted?
Biting insects
117
How is BHV2 infection diagnosed?
Cultured in bovine cells, electron microscope
| PCR
