Arteriviridae

Question 1

What is the only genus of the family Arterivirdae?

Answer 1

Arterivirus

Question 2

Where do arteriviruses have a tropism for?

Answer 2

Vascular endothelium

Question 3

T/F: Arteriviruses are not host restricted

Answer 3

FALSE

Highly host restricted

Question 4

Where in the body do arteriviruses replicate?

Answer 4

MACROPHAGES –> then move to vascular endothelium

Question 5

How do arteriviruses evade the immune system?

Answer 5

Inhibiting interferons (IFN)

Question 6

Where in the cell do arteriviruses replicate?

Answer 6

Cytoplasm

Question 7

Arteriviruses are _________ stranded, _______ sense RNA

Answer 7

Single stranded

positive sense

Question 8

What envelope proteins are receptor binding proteins for arterivirues?

Answer 8

GP2, GP3, GP4

Question 9

What is the function of GP5 (glycoprotein) in arteriviruses, why is that important?

Answer 9

GP5 induces neutralizing antibodies

**this is what you look for diagnostically

Question 10

What receptor does PRRSV bind to?

Answer 10

CD163

heparin sulfate and sialoadhesions

Question 11

What does Equine Arteritis virus cause?

Answer 11

Equine viral arteritis

Question 12

Who is the main culprit for spreading EAV? By which mode of transmission?

Answer 12

Non-symptomatic stallions - venereal

*also transmitted via aerosol

Question 13

What are the clinical signs of EAV

Answer 13

*many infections are asymptomatic

Fever at onset
Depression, excessive lacrimation and conjunctivitis, nasal discharge, *urticarial of the neck, edema of the eyes –> progressing back to chest, abdomen, and limbs

Question 14

Where do persistent EAV infections reside?

Answer 14

Reproductive system

**abortion in females (between 3-10 months gestation)

Question 15

T/F: EAV will affect the smooth muscle of arteries and the uterine wall - causing abortions.

Answer 15

TRUE

Question 16

What dx method(s) are used to dx EAV?

Answer 16

RT-PCR and ELISA

Question 17

T/F: There is no vaccine available for EAV

Answer 17

FLASE

There are attenuated and inactivated vax, although not many horses are vaccinated for EAV. **Mares should be vaccinated prior to pregnancy

Question 18

What is PRRSV?

Answer 18

Porcine reproductive and respiratory syndrome virus

Question 19

Where is this virus active?

Answer 19

Present worldwide in swine breeding countries

Question 20

How long do infected pigs shed PRRSV?

Answer 20

at least 60 days

Question 21

Who are the most susceptible to PRRSV?

Answer 21

Gilts - young sows

Question 22

What clinical signs are seen in gilts with PRRSV?

Answer 22

Anorexia, fever, lethargy, depression
**Respiratory distress **Cyanosis starting at the ears and working backwards along the body,
then repro issues: still births, mummification, abortions, if piglets are born they die within days

Question 23

What is the progression of PRRSV?

Answer 23

Primary infection begins in the upper respiratory system –> moves to lymphoid tissue –> crosses placenta and replicated within the umbilical cord

Question 24

What diagnostics are performed when you suspect PRRSV?

Answer 24

virus isolation
FAT - flurescent AB test
Immunohistochemistry
PCR
ELISA

Question 25

When and what samples should be collected for PRRSV testing?

Answer 25

Collect blood samples at peak viremia - when pigs are febrile.
Can also take samples at necropsy from adults and fetus (any tissue/organs that appear to be affected or abnormal)

Question 26

What are the four main methods to control PRRSV?

Answer 26

1. Vaccines - killed and live available (must be done before breeding)
2. Intentional whole herd infection - controversial/risky. Must use a LOW virulence strain of infection. Pigs that will be left with a good immunity to all strains of PRRSV
3. Aggressive acclimation of replacement breeding stock: quarantine (60-90d) all new animals and have multiple negative dx tests before introduction to the herd
4. Cut your losses and repopulate with a new healthy stock

Question 27

T/F: it is easier to control PRRSV in a small herd population

Answer 27

TRUE