Arteriviridae Flashcards
Describe the virions and genome of family Arteriviridae
Enveloped, spherical
Linear, positive-sense, single stranded RNA
*Genomic RNA is infectious
T or F: Family Arteriviridae frequently establishes persistent infections
True!
Where does Arteriviridae replication take place?
Cytoplasm!
Virions are formed by budding into ER (enveloped, duh)
Released via exocytosis
To which genus does equine viral arteritis belong?
Genus arterivirus
One serotype only!
Where can equine viral arteritis be found?
Most countries in equines
How is equine viral arteritis transmitted?
Spread by carrier stalion (reservoir) Lateral spread (masturbation, fomites, personnel) or venereal transmission (natural breeding, artificial breeding) or horizontal (aerosol/respiratory***, fomites, personnel)
If transplacental transmission of EAV to the fetus occurs in late gestation, what may result?
A foal with congenitally acquired EAV infection
What are the primary sites of virus replication of EVA?
Macrophages and endothelial cells
Damage to blood vessels/endothelium leads to generalized edema and hemorrhages
What are secondary sites of replication that can cause problems?
Kidney/seminiferous tubules: temporary infertility in stallions
Placenta: infect fetus and cause fetal death by severe necrotizing myometritis and placental detachment
What are clinical signs of EVA in adult horses?
Most asymptomatic
Fever, depression, anorexia, limb edema (hind limbs), preputial edema
Urticaria
What are clinical signs of EVA in neonatal foals?
Severe interstitial pneumonia and/or enteritis
T or F: mares can abort pregnancy if a natural outbreak of EAV occurs?
True..
What is stallion ‘subfertility?’
Not due to the direct effect of the virus but due to intratesticular temperature increase and extensive scrotal edema
What signs would you see at necropsy that would help you diagnose this condition?
Edema, congestion and hemorrhages of subcutaneous tissues, visceral organs, lymph nodes
Is there a vaccine available? How is it best used?
Yes, colts vaccination can be done at 6-8 mos of age, non-carrier stallions should be vaccinated annually! At least 4 weeks before breeding season
Carriers should only be bred to vaccinated females
What is another name for porcine reproductive and respiratory syndrome (PRRS)?
Swine mystery disease (SMD) or Blue Ear Disease
How is PRRS transmitted?
Aerosols, direct contact, infected semen, transplacental
Infected piglets can be born viremic and transmit virus for 112 days after infection!!
Where is the primary site of replication for PRRS?
Macrophages in lungs and lymphoid tissues!
What are the characteristic lesions of acute PRRS infection?
Lymph node enlargement and interstitial pneumonia
What are the two phases of PRRS?
Reproductive failure and post weaning respiratory diseases
Describe the reproductive failure phase:
Late term abortions, still births, mummified fetuses, premature farrowing, birth of weak piglets
Umbilical cord lesions primarily
Describe the post weaning respiratory disease phase:
Severe respiratory distress, characteristic thumping respiratory pattern, severe necrotizing interstitial pneumonia
Labored breathing, fever, loss of appetite, red discoloration of body and BLUE EARS!
What is the most common diagnostic method for PRRS?
ELISA to measure IgG antibodies to PRRS virus
How is PRRS controlled?
Live-attenuated and inactivated vaccines are commercially available
Control of this virus by exclusion because virus spreads between herds by movement of infected swine/semen
