Diseases Caused by Arteriviruses Flashcards
What is the order of arteriviruses?
Nidovarales
What are the characteristics of genome organisation?
- Single stranded RNA, positive sense, nested set of subgenomic mRNA
- Monocistronic mRNA produces multiple proteins through ribosmal frame s
What is the meaning of Monocistronic?
the Mrna only has one cistron within the transcriptional unit
What is the structure of the virion?
Single nucleocapsid protein- 6 different enveloped proteins
What cellular receptors are found on arteriviruses?
- Heparin-Like receptors
- CD163 and sialoadhesins
What types of cell would an arterivirus target?
- Macrophages, Monocytes, dendritic cells and lymphocytes
What effect may an arterivirus have on the infected cells?
Necrosis or apoptosis directly
* Supression of type I AFN’S by DC and macrophages
What is the arterivirus replication cycle?
- 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
What are the three bases of arterivirus pathogenesis?
- Dysregulation of cytokine production via macrophages
- Immuno-suppression
- Persistent infection
What is Equine Viral Arteritis?
an economically important, contagious, viral disease
of equids caused by equine arterivirus
How many recognised serotypes of EAV are there?
Only one recognised serotype
What is the incubation period of EAV?
Between 2 days and 2 weeks
What are the three clinical symptoms seen in horses with EAV?
- Death- in old/ immunocompromised animals
- Abortion rate of between 10% and 60%
- influenza-like symptoms in adult horses (fever, runny nose)
What are the four main ways EAV can be transmitted?
- Horizontal
- Venereal
- Vertical
- Mechanical
How may EAV cause edema?
- 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
How may EAV cause pyrexia?
- infects monocytes/ macrophages
- release of pro-inflammatory cytokines
- dysfunction of the vascular endothelium
How could you manage the venereal transmission of EAV?
- Separate pregnant mares from other horses
- Isolate new arrivals
- Breed carrier stallions only to well-vaccinated
or seropositive mares
What is the specific treatment for carrier stallions with EAV?
no specific treatment, the only option is surgical castration
What are the two distinct genotypes of PRRS virus?
- European- 1
- American- 2
What are the three subtypes of PRRS virus?
- Attenuated strains
- Immunosupressive (type I)
- Inflammatory
What are the clinical symptoms of PRRS in young animals?
- Dyspnoea/ nasal exudate
- slow growth
- reddening of the skin
What are the clinical signs of PRRS in pregnant sows?
- Dyspnoea
- Lethargy
- Loss of appetite
- Abortion, stillborn, mummified foetus
