Arteriviruses

Question 1

What is the order and family of arteriviruses?

Answer 1

• Order- Nidovirales
• Family-Arteriviridae

Question 2

What is the genome organisation of arteriviruses?

Answer 2

• Single-Stranded RNA
• Positive Sense

Question 3

What is the arterivirus virion structure?

Answer 3

• Singular nucleocapsid protein
• 6 different enveloped proteins

Question 4

What are the two cellular receptors of arteriviruses?

Answer 4

• Heparin-like molecules
• CD163 and sialoadhesins

Question 5

What are the virus counterparts of arterivirus?

Answer 5

Sialic acid in glycan chains of GP5/M and GP2/3/4 trimers

Question 6

What cell types do arteriviruses target?

Answer 6

• Macrophages, Monocytes, lymphocytes, endothelial cells

Question 7

What effects do arterivirus have on the infected cells?

Answer 7

• Necrosis or apoptosis directly
• Supression of type-I interferons

Question 8

How do arteriviruses replicate?

Answer 8

• Attach to the host receptors
• Fusion of virus membrane with the host membrane
• ssRNA genome is released into the cytoplasm
• Synthesis and proteolysis of replicase polyproteins
• assembly of new virions via exocytosis

Question 9

What are the three most important things surrounding arterivirus pathogenesis?

Answer 9

• Dysregulation of cytokine production via macrophages
• Immuno-supression
• Persistent Infection

Question 10

What does equine Arterivirus cause?

Answer 10

Equine Viral Arteritis

Question 11

What are the Clinical Symptoms of Equine Arterivirus?

Answer 11

• Death- in old young or immunocomprimised horses
• Abortion rate of between 10-60%
• Influenza-like symptoms in adult horses (lethargy and stiff movement)

Question 12

How does EAV transmit horizontally?

Answer 12

Aerolisation of respiratory tract secretions

Question 13

How does EAV transmit venereally?

Answer 13

• Acutely infected mares
• Acutely and chronically infected stallions
• Natural service and artificial insemination

Question 14

How does EAV transmit vertically?

Answer 14

• Transplacental transmission, especially when mares get infected late
• results in abortion, fatal interstitial pneumonia,
• Fibronecrotic enteritis

Question 15

When do the viruses become inactivated?

Answer 15

• 20-30 mins at 56-58ºC
• 2 to 3 days at 37-38ºC
• Up to 75 days at 4-8ºC

Question 16

What happens when EAV infects monocytes/ macrophages?

Answer 16

release of pro-inflammatory cytokines and TNF-alpha
dysfunction of the vascular endothelium and systemic pathology, pyrexia, cachexia, lipolysis

Question 17

What effects the severity of the EAV virus?

Answer 17

• Virus Strain
• Horse Breed
• Donkey species

Question 18

What are the clinical signs of EAV in stallions

Answer 18

• Decreased Fertility
• Reduced sperm quality
• Caused by increased scrotal temp and edema
• Decreased libido

Question 19

What samples may you take for EAV?

Answer 19

• Nasal secretions
• Blood
• Semen

Question 20

How would you detect antigens?

Answer 20

• Virus isolation
• Nucleic acid detection
• Immunohistochemistry

Question 21

How would you detect antibodies?

Answer 21

Serology
Virus neutralisation
ELISA
fluorescent antibody
Fluorescent microsphere immunoassay

Question 22

How would you manage the venereal transmission?

Answer 22

• Separate pregnant mares from other horses
• Isolate new arrivals
• Breed carrier stallions only to well vaccinated or seropositive mares

Question 23

How would you prevent/ control transmission in carrier stallions?

Answer 23

• Physically isolate from uninfected horses
• Clean and disinfect fomites
• Testing and identification
• there is no specific treatment other than surgical castration

Question 24

What is the genus of PRRS?

Answer 24

Single stranded positive RNA (arterivirus)

Question 25

How many proteins does the PRRS genome encode?

Answer 25

7 proteins

Question 26

What are the two distinct PRRS genotypes?

Answer 26

• European
• American

Question 27

What are the three PRRS subtypes?

Answer 27

• Attenuated strain
• Immuno-Supressive (type I)
• Inflammatory (type II)

Question 28

What are the primary target cells for PRRSV tropism?

Answer 28

• Monocyte/ Macrophage lineage
• infects different subsets of differentiated macrophages in the lungs, lymphoid tissue and placenta

Question 29

How is PRRSV transmitted?

Answer 29

* Horizontal transmission
* From contaminated food
* Vertical transmission
* Through transplacental transmission
* Venereal transmission
* During breeding with semen from PI boars
* lateral transmission
* Through fomites or personnel
* Mechanical vectors.
* Flies and mosquitoes might serve as mechanical vectors

Question 30

What is the pathogenesis of PRRS?

Answer 30

• Infection via aerosols/ fomites
• Mucousal surfaces or lung macrophages
• Draining regional lymph nodes
• Target organs are the lung, thymus, uterus, placenta and testis

Question 31

What are the clinical signs of PRRS in young pigs?

Answer 31

• Dyspnoea, nasal exudate
• Slow growth
• Reddening of the skin
• Loss of appetite and lethargy

Question 32

What are the clinical signs of PRRS in pregnant sows?

Answer 32

• Dyspnoea
• Lethargy
• Loss of appetite
• Abortion, stillborn pigs, mummified foetus, weak pigs

Question 33

What are the clinical symptoms of PRRS?

Answer 33

• Fever
• Mild respiratory distress

Question 34

What samples would you take to determine PRRS?

Answer 34

• Whole blood EDTA
• Serum
• Lung/ Respiratory tract
• Spleen and tonsils

Question 35

What are the three subtypes of PRRS virus?

Answer 35

• Attenuated
• Immuno-suppressive
• Inflammatory