Arteriviruses Flashcards
Viral Resp Diseases II
Structure ?
(+) ssRNA viruses
enveloped
produce single nucleocapsid proteins (x6)
How do arteriviruses show cell tropism ?
some cells in the body have heparin-like molecule shaped receptors
the virus has the matching counterpart to these receptors
cell targets include macrophages, monocytes, dendritic cells, lymphocytes and endothelial cells
some have a wide tropism, others are very restricted
Pathogenesis ?
induce necrosis or apoptosis directly and suppress type-1 IFNs through dendritic cells and macrophages
also immune-suppression and persistent infection
Replication cycle ?
attachment to host receptors
fusion of virus membrane with endosomal membrane
ssRNA(+) genome is released into the cytoplasm
synthesis and proteolysis of replicase polyproteins
synthesis of structural proteins
assembly of new virion
release of new virions
Name the most important arteriviruses
Equine viral arteritis (EAV)
Porcine Reproductive and Respiratory Syndrome (PRRS)
EAV clinical signs
death
abortion
oedema of legs/brisket/mammary/jaw
skin plaques
conjunctivitis
decreased stallion fertility
flu-like symptoms
[ some asymptomatic! ]
EAV histology findings
fibrinoid necrosis of the tunica media and perivascular oedema with lymphocytic infiltrate
interstitial pneumonia
choroiallantois
EAV transmission ?
aerosols
venereal infection
transplacental
fomites
What samples do you collect to diagnose ?
nasal secretions
blood
semen
tissues and fluids
whole blood (EDTA)
lung fluid
mummified or aborted piglets
How do you diagnose arteriviruses ?
antigen detection (IHC)
antibody detection
serology (ELISA, IFA, LAMPs)
–
isolate virus through immunofluorescence and CPE
Prevention of EAV
separate pregnant mares from other horses and breed carrier stallions only to well-vaccinated or sero-positive mares
Are there vaccines available for EAV ?
yes - available to protect uninfected stallions before breeding season
PRRS transmission
done by close contact - virus is shed in resp tract secretions, saliva, semen, mammary secretions, urine and faeces.
transplacental, venereal, fomite and mosquitoes all possible transmission factors
PRRS clinical signs
also called “Blue-Ear Pig Disease”
in young –> dyspnoea, slow growth, reddening of the skin, loss of appetite, lethargy
in pregnant –> dyspnoea, lethargy, loss of appetite, SMEDI
in boars –> fever, mild resp. distress, can become persistently infected and shed for life
Control of PRRS
main aim to stop the introduction of the virus into seronegative herds
biosecurity !!A
