Topic 33: Nidovirales – (Coronaviridae, Arteriviridae)

Question 1

33. Nidovirales – (Coronaviridae, Arteriviridae)

CORONAVIRIDAE (Corona – solar crown)

Answer 1

• Genus
• Alphacorona-,
• Betacorona-,
• Gammacorona-,
• Toro-virus
• Morphology: +ssRNA genome – especially long Enveloped
• Resistance: Good (despite enveloped) – pH resistance 3-9
• Biological properties (Unique expression of genetic material – common for whole order)
• Baltimore IV – subgenomic mRNA synthesis
• Host specific CPE – cell rounding, but not characteristic
• HA – hemaggluttinating activity – in some cases
• Antigenic property: Good antigens but immune response can increases aspects of disease, Cross reactions w/i Genera – depends on serogroup – IF, ELISA
• Diagnosis: Difficult to isolate and shows no CPE, so IF investigation also needed
  Clinical signs: IF, IEM
  Indirect – ELISA, IF (cross reactions)

Question 2

33. Nidovirales – (Coronaviridae, Arteriviridae)
    CORONAVIRIDAE (Corona – solar crown)
    - Alphacorona-,

Answer 2

• Porcine transmissible gastroenteritis virus (TGE) – esp. piglets
• Porcine epidemic diarrhea virus (ED)
• Feline infectious peritonitis virus (FIP)
  2 forms – Wet and dry
• Canine coronavirus
• Human coronavirus

Question 3

33. Nidovirales – (Coronaviridae, Arteriviridae)
    CORONAVIRIDAE (Corona – solar crown)
    -Betacorona-,

Answer 3

• Bovine coronavirus “winter dysentery”
• Porcine hemagluttinating encephalomyelitis virus (HEV)
• Severe acute respiratory syndrome – SARS
• Human pneumonia – destroys type II cells of lung

Question 4

33. Nidovirales – (Coronaviridae, Arteriviridae)
    CORONAVIRIDAE (Corona – solar crown)
    -Gammacorona-,

Answer 4

Avian infectious bronchitis – (IB)
Chickens
– can damage oviduct also
- egg production hindered

Question 5

33. Nidovirales – (Coronaviridae, Arteriviridae)
    CORONAVIRIDAE (Corona – solar crown)
    Toro-virus

Answer 5

• Berne virus – Foal gastroenteritis

* Breda virus- Calf gastroenteritis

Question 6

33. Nidovirales – (Coronaviridae, Arteriviridae)

ARTERIVIRDAE

Answer 6

Arteriviridae –

• Genus – Arterivirus
• Morphology: + ssRNA genome, Enveloped
• Weak resistance
• Biological properties
  – Baltimore IV -
• Use sub-genomic mRNA
• No typical CPE
• Transmission – sexual or aerogenus
• Antigenic properties – Good antigens No cross reactions

*Diagnosis - Clinical signs			Difficult to isolate
Histopathology, 
IF, 
RT-PCR	
Indirect – ELISA

Question 7

33. Nidovirales – (Coronaviridae, Arteriviridae)
    ARTERIVIRDAE
    Genus – Arterivirus

Answer 7

• Equine arteritis virus – (EAV)
• Affects capillaries of small arteries => abortion, respiratory symptoms
• Stallions can become persistently infected - Virus shed via semen
• Porcine respiratory & reproductive syndrome (PRRS)
• Early abortion, infertility
• Respiratory systems – cyanosis – (Blue ear)