Adenoviridae

Question 1

Describe the morphology, genome & replication, and general characteristics of Adenoviridae.

Answer 1

1. Morphology
   -non enveloped
   -hexagonal
   -12 vertex penton capsomers each w fiber protrude from surface of capsid
2. Genome & replication
   -intranuclear inclusion body w lg # of virions in para-crystalline arrays
3. General characteristics
   -agglutinate RBC
   >hemagglutination when tips of penton fibers bind to surface receptor on RBC
   -some oncogenic in lab animals
   -stable in environment but inactivated by disinf
   -narrow host range

Question 2

Describe the pathogenesis of Adenoviruses.

Answer 2

-cause acute respiratory or gastroenteritis dz (most subclinical but vary in severity)
-immunosuppresion
-long period of latency
>virus persist in lymphoid & other tissues like tonsil, adenoids, peyer patch
>reactivated in immunocompromised
>highly pathogenic in immunodeficienct
-oncogenesis
>under special conditions

Question 3

Describe infectious canine hepatitis.

Answer 3

‘ICH, Rubarths Disease’
1. Etiology
-canine adenovirus 1 (CAV1)
2. Transmission
-acute inf: CAV1 in all secretion & excretion
>after, virus shed in urine for 6-9mo
3. Route
-oronasal
>contact w:
A) secretions/excretion of inf dog
B) contam fomites
C) ectoparasites harbor CAV1

Question 4

Describe the sites of virus replication of ICH.

Answer 4

Mac, kupffer cells, hepatocytes, vascular endothelium of diff organs (incl CNS), parenchymal cells of organs & tissues
LIVER, KIDNEYS, SPLEEN, LUNGS = main target organs

Question 5

Describe hepatitis pathogenesis of ICH in dogs.

Answer 5

1. At time of inf dogs have Ab titer of >500 & show little clinical evidence of dz
2. Acute case = sufficient Ab response by day 7 post inf (>500 Ab response by day 7 PI) clear virus from blood & liver & restrict hepatic damage
3. Persistent low Ab titer (<4) -> widespread centrilobular to panlobular hepatic necrosis
4. Partial immunity (Ab titer >16 but <500) -> chronic active hepatitis & hepatic fibrosis

Question 6

Describe other pathogenesis of ICH in dogs.

Answer 6

1. Chronic case = cirrhosis in liver or kidney
2. Acute inf = kidney glomerulonephritis
3. Immune complex reaction after recovery from acute or subclinical dz = chronic kidney lesions (chronic glomerulonephritis)
4. Ocular lesions (corneal edema) ‘blue eye’
   -occur in 20% natural inf
   -less than 1% dogs after S/C MLV-CAV1 vacc
   -dogs during recovery, or chronic cases

Question 7

Describe how corneal edema develops in ICH.

Answer 7

CAV1 Ab prod inc & form viral Ab immune complex -> complement activation (neutrophil chemotaxis) -> damage to corneal endothelium -> disrupt intact corneal endothelium & allows aqueous to enter cornea -> accumulate edematous fluid in corneal stroma = corneal edema

Question 8

Describe the complications from ICH.

Answer 8

1. DIC from:
   -damage to endothelium
   -inability of dz liver to remove activated clotting factors
2. Bacterial pyelonephritis from renal damage

Question 9

Describe the clinical signs of ICH.

Answer 9

-freq in dogs <1yr
-concurrent parvoviral or distemper inf worsens prognosis
-unvaccinated dogs of all age sus
-most inf asymp
-signs from fever to death

Question 10

Describe ICH peracute VS acute cases.

Answer 10

1. Peracute
   -severely inf dogs moribund & die in few hrs after CS
2. Acute
   -CS in dogs that survive acute viremic phase
   -fever >104 (40c), depression, anorexia
   -vomiting
   -ab pain, tenderness, hepatomegaly
   -hyperemia or petechiae hemorrhage of oral mucosa
   -pale MM, jaundice
   -enlarged tonsil, swollen LN
   -SQ edema of head, neck, trunk
   -CNS involvement unusual & result of vascular injury
   -icterus uncommon in early acute phase
   -corneal edema & anterior uveitis when clinical recovery begins ‘blue eye’

Question 11

Describe the diagnosis of ICH.

Answer 11

1. CS
2. Necropsy & histopath
   -paint brush hemorrhage on gastric serosa, LN, thymus, pancreas, SQ tissue
   -centrilobular necrosis in liver, w neutrophilic & monocytic infiltration, & hepatocellular intranuclear inclusions
   -grayish white foci in kidney cortex of recovered dogs or dogs w chronic dz
3. Biochem & hematology
   -leukopenia persist thruout febrile period
   -inc ALT & AST due to hepatic injury
   -proteinuria
   -prolonged prothrombin time, thrombocytopenia
4. Virus isolation: urine, blood, tissue homogenates

Question 12

Describe the treatment & immunity of ICH.

Answer 12

1. Treatment
   -symptomatic & supportive
   -limit secondary bacterial invasion, support fluid balance, & control hemorrhage
2. Immunity
   -recovered immune to systemic form of dz
   -maternal Ab interfere w active immunization until puppies are 9-12weeks
   -attenuated CAV1 live vacc = make transient unilateral or bi lateral opacities of cornea
   >cause mild subclinical interstitial nephritis & shed in urine
   -CAV2 attenuated live virus strain = cross protection against CAV1, CAV2
   >little tendency to make corneal opacities or uveitis & virus not shed in urine preferred

Question 13

Describe canine infectious tracheobronchitis.

Answer 13

‘ITB, Kennel Cough’
self limiting URT dz of dogs
1. Etiology
-multiple
-CAV2, bordetella bronchiseptica
2. Transmission
-contagious (aerosol droplets)
-stress, unfavorable conditions inc severity of dz
3. Treatment
-antitussives + bronchodilators
4. Immunity
-MLV vacc against distemper, parainfluenza, CAV2 (provides protection against CAV1)

Question 14

Describe complicated VS uncomplicated ITB.

Answer 14

1. Complicated
   -severe pneumonia or bronchopneumonia
   -life threatening
2. Uncomplicated
   -paroxysms of harsh, dry cough, etching, gagging
   -coughing = high pitched honking sound
   -rhinitis, serous nasal discharge, conjunctivitis

Question 15

Describe equine adenovirus general characteristics & clinical signs.

Answer 15

GC:
-EAV1 & EAV2
-asympt or mild upper or lower respiratory tract dz
-EAV1 = severe respiratory dz in SCID foals
-maternal Ab wanes = foals sus to adenovirus inf
>inf progressive & foals die within 3mo of age
CS:
-severe bronchiolitis & pneumonia + respiratory distress