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(4) VMCB > (RNA VIRUSES) Lesson 15: Togaviridae > Flashcards

(RNA VIRUSES) Lesson 15: Togaviridae Flashcards

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1
Q

General description of Togaviridae

A
  1. 60–70 nm in diameter
  2. Enveloped, RNA viruses with icosahedral symmetry
  3. Replicate in cell cytoplasm
  4. Labile in the environment
  5. Two genera, Alphavirus and Rubivirus
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2
Q

The family name Togaviridae e is taken from the Latin word ______.

A

toga

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3
Q

toga meaning

A

cloak or mantle

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4
Q

is a reference to the viral envelope of Togaviridae

A

cloak or mantle

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5
Q

Togaviridae: Enveloped or Non-enveloped

A

Enveloped

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6
Q

Togaviridae Replicate in

A

cytoplasm

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7
Q

Two genera of Togaviridae

A

Alphavirus and Rubivirus

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7
Q

in common with certain members of the Flaviviridae, Reoviridae, Rhabdoviridae and Bunyaviridae

A

Alphaviruses

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8
Q

Alphaviruses, in common with certain members of the Flaviviridae, Reoviridae, Rhabdoviridae and Bunyaviridae, are termed _________ indicating that they are arthropod- borne.

A

arboviruses

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9
Q

Alphaviruses / Genus Alphavirus cause what diseases

A

a. eastern equine encephalitis (EEE)
b. western equine encephalitis (WEE)
c. Venezuelan equine encephalitis (VEE)

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10
Q

major cause of zoonotic infections under Togaviridae

A

Alphaviruses / Genus Alphavirus

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11
Q

The majority of these viruses are found in tropical developing countries and have a
distinct geographical distribution.

A

arboviruses

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12
Q

The majority of arboviruses are found in ______ developing countries and have a
distinct geographical distribution.

A

tropical

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13
Q

Togaviridae
Ecological factors limiting the distribution of particular arboviruses include:

A

✓ temperature
✓ rainfall
✓ distribution of both vertebrate reservoir host and of the
arthropod vector

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14
Q

Togaviridae
The most important arthropod vectors.
The vector remains infected for life.

A

mosquitoes
midges
ticks
sandflies

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15
Q

Togaviruses of veterinary importance

A

1) Venezuelan
equine
encephalitis virus
(VEEV)
2) Eastern equine
encephalitis virus
(EEEV)
3) Western equine
encephalitis virus
4) Getah virus

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16
Q

Common arthropod vector of Togaviruses

A

Mosquito

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17
Q

Present in Central and South America with
occasional outbreaks in southern USA.

A

Venezuelan
equine
encephalitis virus
(VEEV)

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18
Q

Geographical distribution of Venezuelan
equine
encephalitis virus
(VEEV)

A

Central and South America w/
occasional outbreaks in southern USA

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19
Q

Venezuelan
equine
encephalitis virus
(VEEV) causes disease in

A

horses, donkeys and
man

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20
Q

Present in eastern USA, Caribbean and
South America

A

Eastern equine
encephalitis virus (EEEV)

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21
Q

Eastern equine
encephalitis virus
(EEEV) causes disease in

A

pheasants, horses and
man

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22
Q

Present throughout much of the Americas.

A

Western equine
encephalitis virus
(WEEV)

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23
Q

Western equine
encephalitis virus
(WEEV) causes disease in

A

horses and man

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24
Milder disease than EEEV
Western equine encephalitis virus (WEEV)
25
Sporadic cause of disease in horses; fever, urticaria and hind-limb oedema.
Getah virus
26
Getah virus: Sporadic cause of disease in these animals; fever, urticaria and hind-limb oedema.
horses
27
Infection common in pigs but significance unclear.
Getah virus
28
Present in Australia and southeast Asia
Getah virus
29
are important causes of nervous disease in horses in the New World which produce similar clinical signs
✓ Venezuelan equine encephalitis viruses (VEEV) ✓ Eastern equine encephalitis viruses (EEEV) ✓ Western equine encephalitis viruses (WEEV)
30
Several epidemiological features are common to the three diseases.
✓ Venezuelan equine encephalitis viruses (VEEV) ✓ Eastern equine encephalitis viruses (EEEV) ✓ Western equine encephalitis viruses (WEEV)
31
Togaviruses: The peak of disease incidence coincides with the time of maximum vector numbers in late summer or following the rains
32
The Venezuelan equine encephalitis (VEE) complex comprises several viral species, divided into six subtypes I to VI ENUMERATE
1) Subtype 1: have 5 serotypes (AB -F) 2) Subtype II : Everglades virus 3) Subtype III: Mucambo virus 4) Subtype IV: Pixuna virus 5-6) The viruses are maintained in sylvatic cycles involving rodents such as spiny rats (Proechimys chrysaeolus) and mosquitoes of the Culex (Melanoconion) and Aedes (Ochlerotatus) taeniorhynchus subgenus
33
Subtype 1 of Venezuelan equine encephalitis (VEE) complex
have 5 serotypes (AB - F)
34
Subtype II of Venezuelan equine encephalitis (VEE) complex
Everglades virus
35
Subtype III of Venezuelan equine encephalitis (VEE) complex
Mucambo virus
36
Subtype IV of Venezuelan equine encephalitis (VEE) complex
Pixuna virus
37
The viruses (Everglades virus, Mucambo virus, Pixuna virus) are maintained in what cycles?
sylvatic cycles
38
The viruses (Everglades virus, Mucambo virus, Pixuna virus) are maintained involving rodents such as spiny rats (Proechimys chrysaeolus) and mosquitoes of the Culex (Melanoconion) and Aedes (Ochlerotatus) taeniorhynchus subgenus
sylvatic cycles
39
The viruses are maintained in sylvatic cycles involving the two organisms
✓ rodents such as spiny rats ✓ mosquitoes
40
SN of spiny rats
Proechimys chrysaeolus
41
SN of Culex
Melanoconion
42
SN and subgeus of Aedes
✓ Ochlerotatus ✓ taeniorhynchus
43
is found principally in Atlantic coastal areas of the USA, Canada, Michigan, the Caribbean Basin and South America.
Eastern equine encephalitis virus (EEEV)
44
Two distinct lineages of EEEV
✓ North American (pathogenic group I) ✓ South American (Groups IIA, IIB and III)
45
Lineage of EEEV pathogenic group I
North American
46
Lineage of EEEV under Groups IIA, IIB and III
South American
47
The virus is maintained in cycles of infection involving passerine birds and the irrigation ditch mosquito Culiseta melanura
Eastern equine encephalitis virus (EEEV)
48
SN of irrigation ditch mosquito
Culiseta melanura
49
Western equine encephalitis virus (WEEV) cycle of infection involves _______
✓ mosquitoes, mainly Culex tarsalis ✓ wild birds
50
cycle of infection involves mosquitoes, mainly Culex tarsalis, and wild birds
Western equine encephalitis virus (WEEV)
51
Western equine encephalitis virus (WEEV) cycle of infection involves mosquitoes, mainly __________, and wild birds.
Culex tarsalis
52
these animals are infected by WEEV incidentally and are dead-end hosts, developing only low titres of virus in the blood.
Horses
53
A related virus of WEEV, occurs in the eastern United States and causes encephalitis in horses rarely.
Highlands J virus
54
A related virus of WEEV, Highlands J virus, causes what?
encephalitis in horses rarely
55
A related virus of WEEV, Highlands J virus, causes encephalitis rarely in what animals?
horses
56
incubation period of Togaviruses
1-9 days
57
clinical signs of Togaviruses usually last for how many days?
4-9 days
58
Replication of Togaviruses occurs where
✓ near the site of inoculation by a feeding mosquito ✓ local draining lymph nodes
59
TOGAVIRUSES Viraemia ranging from barely detectable to an exceedingly high titre follows. This is accompanied by fever.
60
In severe cases the Togavirus invades the _______ resulting in neuronal necrosis, perivascular cuffing and interstitial mononuclear inflammatory infiltration.
central nervous system
61
In severe cases the Togaviruses invades the central nervous system resulting in
✓ neuronal necrosis ✓ perivascular cuffing ✓ interstitial mononuclear inflammatory infiltration (IMII)
62
Clinically, the diseases caused by the three togaviruses are very similar
63
The 3 togaviruses vary in severity from mild signs of fever and depression to a fatal febrile encephalomyelitis.
64
The case fatality rate is highest for EEE at ____%.
90%
65
case fatality rate is ___% for VEE
50–80%
66
case fatality rate is ___% for WEE
20–40%
67
The case fatality rate is highest for this togavirus at 90%
EEE
68
Recovered horses (affected by togaviruses) are usually normal but a few may have residual nervous signs.
69
Laboratory work with these viruses (VEEV, EEEV, WEEV) should only be carried out by ________ in ________ following containment level ____ procedures.
immunized personnel biosafety cabinets level 3
70
definitive diagnostic technique if togaviruses is
virus isolation (lab animal inoculation, embryo inoculation, cell culture)
71
TOGAVIRUSES Specimens to be collected:
✓ whole blood ✓ brain tissue ✓ cerebrospinal fluid (CSF)
72
TOGAVIRUSES Specimens to be collected: whole blood during what stage?
pyrexic stage
73
TOGAVIRUSES Specimens to be collected for horses which died following nervous disease
brain tissue or CSF
74
Diagnosis of Togaviruses
✓ RT-PCR ✓ Serology • ELISA • plaque reduction neutralization assay • complement fixation • haemagglutination inhibition

(4) VMCB (15 decks)

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