Lesson 12: Poxviridae

Question 1

Lesson 12: Poxviridae
General description:
 ______ DNA viruses
 ________ symmetry
 The virions in this family are either ________ (220 to 450nm×140 to 260 nm)
with a surface membrane composed of
tubular or globular proteins or ovoid (250
to 300nm × 160 to 190 nm) with a surface
membrane composed of a regular spiral
filament
 Replicate in _______ (viral factories)
 Stable in the environment
 _______ a prominent feature
 Individual poxviruses tend to infect
particular host species; some poxviruses
are not species-specific
 The family is divided into two subfamilies,
______________,____________________

Answer 1

*Enveloped
*Complex
*brickshaped
*cytoplasm
*Skin lesions
*Chordopoxvirinae, the poxviruses of
vertebrates, and Entomopoxvirinae, the
poxviruses of insects

Question 2

POXVIRIDAE
They contain more than 100
proteins including several virusencoded enzymes. A biconcave
core or nucleoid contains linear
double-stranded DNA and one
or two lateral bodies within a
surface membrane.
 A cell-derived envelope
encloses some of the mature

Question 3

pg. 62-64

Question 4

FOWL POX
 Associated with _______ infection of domestic poultry, particularly
chickens and turkeys
 Infection spreads slowly through contact and on the _________________________
 Disease is characterized by __________
 Contributing factors to the development of the disease includes malnutrition,
debilitation and stress
 Diagnosis: demonstration of inclusion bodies (Bollinger bodies) which
contain smaller elementary bodies (Borrel bodies) in the cytoplasm of
infected cells during histology is confirmatory

Answer 4

*poxvirus
*mouthparts of arthropods such as mosquitoes
*Diagnose: proliferative cutaneous lesions (dry pox) and diphtheritic lesions (wet pox) in the upper digestive and respiratory tracts

Question 5

SHEEP POX/GOAT POX
 The virus replicates locally in the ______ depending on the route of
infection and appear as macules around 7 days post-infection, then
macules turn into papules within 24 hours and persists for a week before it
becomes necrotic
 Diagnosis:
 Material intended for virus isolation or antigen detection
should be collected early in the clinical course prior to the
development of neutralizing antibodies
 Skin biopsies from live animals or necropsy specimens can be
submitted for laboratory confirmation
 Papules may be present at many sites internally including
tongue, oesophagus, rumen, abomasum and large intestine
 Histopathological examination of acute-stage skin lesions
typically reveals a large cellular infiltration, vasculitis, oedema
and the presence of eosinophilic intracytoplasmic inclusions in
cells in the dermis

Answer 5

*skin or lungs

Question 6

ORF VIRUS
 also called contagious pustular dermatitis or contagious ecthyma virus,
infects sheep, goats, camels and man that is worldwide in distribution
 affects young animals and may be so mild as to go unnoticed or so
severe as to result in significant mortality
 Lesions are most commonly seen on the commissures of the lips and
muzzle but may also appear on the feet, genitalia and teats
 The incubation period is about four to seven days.
 The virus is highly epitheliotropic producing proliferative wart-like
lesions in affected animals following entry into the host through
abrasions of the skin.
 Lesions progress through a series of characteristic phases. Initially
papules develop but rapidly give way to a vesicular and then pustular
stage. Scabs form within a few days while proliferation of the
underlying dermis produces a verrucose mass. The lesions usually
heal within four weeks leaving no scar.
 Secondary bacterial infection may prolong the course. The virus is
readily transmissible to humans
 Diagnosis: based of the characteristic clinical presentation. If
necessary, electron microscopy can be performed on active scab
material to confirm the diagnosis