Diseases Caused by Arteriviruses

Question 1

What is the order of arteriviruses?

Answer 1

Nidovarales

Question 2

What are the characteristics of genome organisation?

Answer 2

• Single stranded RNA, positive sense, nested set of subgenomic mRNA
• Monocistronic mRNA produces multiple proteins through ribosmal frame s

Question 3

What is the meaning of Monocistronic?

Answer 3

the Mrna only has one cistron within the transcriptional unit

Question 4

What is the structure of the virion?

Answer 4

Single nucleocapsid protein- 6 different enveloped proteins

Question 5

What cellular receptors are found on arteriviruses?

Answer 5

• Heparin-Like receptors
• CD163 and sialoadhesins

Question 6

What types of cell would an arterivirus target?

Answer 6

• Macrophages, Monocytes, dendritic cells and lymphocytes

Question 7

What effect may an arterivirus have on the infected cells?

Answer 7

Necrosis or apoptosis directly
* Supression of type I AFN’S by DC and macrophages

Question 8

What is the arterivirus replication cycle?

Answer 8

• Attaches to host receptors
• Fusion of the virus membrane with the endosomal membrane
• ssRNA genome is then released into the cytoplasm
• Synthesis and proteolysis of replicase polyproteins
• Assembly
• release of new virions by exocytosis

Question 9

What are the three bases of arterivirus pathogenesis?

Answer 9

• Dysregulation of cytokine production via macrophages
• Immuno-suppression
• Persistent infection

Question 10

What is Equine Viral Arteritis?

Answer 10

an economically important, contagious, viral disease
of equids caused by equine arterivirus

Question 11

How many recognised serotypes of EAV are there?

Answer 11

Only one recognised serotype

Question 12

What is the incubation period of EAV?

Answer 12

Between 2 days and 2 weeks

Question 13

What are the three clinical symptoms seen in horses with EAV?

Answer 13

• Death- in old/ immunocompromised animals
• Abortion rate of between 10% and 60%
• influenza-like symptoms in adult horses (fever, runny nose)

Question 14

What are the four main ways EAV can be transmitted?

Answer 14

• Horizontal
• Venereal
• Vertical
• Mechanical

Question 15

How may EAV cause edema?

Answer 15

• Virus begins at the mucousal surface of the respiratory or genital tracts
• effects the endothelial cells of blood vessels and selected epithelia
• there are alterations in the vascular permeability
• this causes edema

Question 16

How may EAV cause pyrexia?

Answer 16

• infects monocytes/ macrophages
• release of pro-inflammatory cytokines
• dysfunction of the vascular endothelium

Question 17

How could you manage the venereal transmission of EAV?

Answer 17

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

Question 18

What is the specific treatment for carrier stallions with EAV?

Answer 18

no specific treatment, the only option is surgical castration

Question 19

What are the two distinct genotypes of PRRS virus?

Answer 19

• European- 1
• American- 2

Question 20

What are the three subtypes of PRRS virus?

Answer 20

• Attenuated strains
• Immunosupressive (type I)
• Inflammatory

Question 21

What are the clinical symptoms of PRRS in young animals?

Answer 21

• Dyspnoea/ nasal exudate
• slow growth
• reddening of the skin

Question 22

What are the clinical signs of PRRS in pregnant sows?

Answer 22

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