Herpesviridae - Betaherpesvirinae

Question 1

Describe the general characteristics of the subfamily Betaherpesvirinae.

Answer 1

-slow rep virus
-chronic inf & continuous viral excretion
-inf cells are enlarged (cytomegaly)
-maintained in latent form in:
>secretory glands (salivary glands)
>lymphoreticular cells (Macs & lymphocytes)

Question 2

Describe inclusion body rhinitis & pathogenesis.

Answer 2

1. Etiology: porcine herpes virus 2 ‘porcine cytomegalovirus’ (PCMV)
2. Host: pigs & severe dz in piglets
3. Transmission:
   -inhalation (primarily)
   -transplacental

Question 3

Describe the clinical signs of inclusion body rhinitis.

Answer 3

-suckling pigs <3wk old
-mucopurulent rhinitis
-inf neonatal piglets are weak, anemic, stunted + edema around throat & tarsal joints
-fetal mummification, still birth, neonatal death & failure of piglets to thrive in inf of naive preg sows
-subclinical dz in older animals

Question 4

Describe the general characteristics of subfamily Gammaherpesvirinae.

Answer 4

-lymphotrophic (rep in B or T lymphocyte)
-slowly cytopathic for epi & fibroblastic cells = cause death w/o virion prod
-shed cont from epi surface
-latency in lymphoid tissue
-some cause lymphoid tumors

Question 5

Describe malignant catarrhal fever (MCF).

Answer 5

‘Bovine Malignant Catarrhal, Malignant Head Catarrhal’
1. Host: fatal dz of cattle & wild ruminants
2. Etiology: 10 MCF viruses -> 2 most imp …
A) alcelaphine herpesvirus 1 (AHV1)
-‘wildebeest-associated MCF’
B) ovine herpesvirus 2 (OvHV2)
-‘sheep associated MCF’
*in Africa MCF is predom found where cattle in contact w blue/black wildebeest VS outside of Africa its cattle in contact w sheep & other sus species

Question 6

Describe alcelaphine herpesvirus 1 (AHV1).

Answer 6

-FROM wildebeest TO cattle
-African countries where cattle come into contact w inf normal wildebeest
-doesn’t cause dz in wildebeest
-Epizootic & seasonal (during wildebeest calving season)

Question 7

Describe alcelaphine herpesvirus 1 (AHV1) transmission.

Answer 7

1. Between wildebeest
   -horizontal
   -intrauterine
   -inapparent inf
2. Wildebeest to cattle
   A) AHV1 in nasal & ocular secretion of young wildebeest in cell free state
   B) ingestion of pasture contaminated w nasal or ocular secretion from young wildebeest
   C) direct or close contact, inhalation of aerosol w young wildebeest
   D) direct or close contact w wildebeest during calving (virus in cell free state in young)
   E) virus in cell associated form in adult wildebeest (rarely transmitted from adults)

Question 8

Describe the ovine herpes virus (OcHV2).

Answer 8

-worldwide
-FROM sheep TO cattle
-goats can act as source of inf to cattle
-year round in cattle, inc in lambing season
-sporadic, occasional outbreaks

Question 9

Describe the ovine herpes virus (OcHV2) transmission.

Answer 9

1. Between sheep
   -respiratory (aerosol)
   -transplacental (rare)
   -contact w nasal secretion
2. Sheep to cattle
   -not known
   -inhalation or ingestion ?

Question 10

Describe the transmission of MCF viruses (AHV1 & OvHV2).

Answer 10

1. Wildebeest & sheep
   -inapparent inf in wildebeest & sheep
   -virus transmitted from wildebeest to wildebeest & sheep to sheep
2. Cattle
   -dead end host (no cattle to cattle)
   -cell associated virus but not cell free virus in secretions
   -explains the non contagious MCF when contact w MCF affected cattle

Question 11

Describe the MCF pathogenesis, clinical signs, and control.

Answer 11

1. Pathogenesis
   -necrotizing vasculitis
   -vascular lesion -> gross lesion like epi erosions & keratoconjunctivitis
2. CS
   -peracute = sudden death
   -head & eye = majority of cattle cases
   -alimentary/intestinal = initially like head & eye form but death occurs from severe diarrhea
   >diarrhea rarely seen in wildebeest MCF but is more common in sheep MCF
   -mild form = inoculated animals -> recovery expected
   -zebra striping = in bovine colon - severe longitudinal linear congestion of mucosa
3. Control
   -sep cattle from wildebeest & sheep
   -incidence too low to justify development of a vaccine