Family: Herpeviridae, Subfamily: Gammaherpesvirus

Question 1

Gammaherpesvirus properties

Answer 1

Lymphotropic - replicate in B or T lymphocytes

Question 2

2 important Malignant Catarrhal Fever (MCF)

Answer 2

1. Wildebeest-associated MCF = Alcephaline Herpesvirus 1

2. Sheep-associated MCF = Ovine Herpesvirus 2

Question 3

Transmission of Wildebeest-associated MCF

Answer 3

Between wildebeest - horizontal and intrauterine, inapparent infection; does not cause disease in principal host
From wildebeest to cattle - in nasal and ocular secretion of wildebeest in a cell-free state; ingestion of contaminated pasture

Virus in cell-associated form in adult wildebeest, so rarely transmitted from adults

Question 4

Transmission of Sheep-associated MCF

Answer 4

Between sheep - respiratory (aerosol), contact with nasal secretions
From sheep to cattle - not known; presumably inhalation or ingestion

Question 5

Transmission of MCF viruses in primary hosts vs. secondary hosts

Answer 5

Wildebeest and Sheep - inapparent infection

Cattle - dead-end hosts, no transmission of virus from cattle to cattle; they have cell-associated virus (not cell free)

Question 6

Pathogenesis of MCF

Answer 6

Infection followed by cell-associated viremia
Lymphoid proliferation and infiltration
Necrotizing vasculitis

Question 7

4 forms of clinical signs of MCF infection

Answer 7

1. Peracute
2. Head and eye
3. Alimentary/Intestinal
4. Mild

Question 8

Peracute form of MCF infection

Answer 8

Sudden (death)

High fever, acute gastroenteritis

Question 9

Head and eye form of MCF infection

Answer 9

Early stages - reddened yeelids, bilateral corneal opacity, crusty muzzle/nares, nasal discharge
Later stages - erosions on tongue, ard palate, buccal papillae; joints and lymph nodes swell; horn and hoof coverings slough

Question 10

Alimentary/intestinal form of MCF infection

Answer 10

Initially like head and eye form bu death occurs from severe diarrhea
Diarrhea is rare in wildebeest-associated MCF, but common in sheep-associated MCF

Question 11

Necropsy findings of MCF infection

Answer 11

Zebra Striping - severe, longitudinal linear congestion of the mucosa (colon)

Question 12

Control of MCF

Answer 12

Separation of cattle form wildebeest and sheep

Incidence is too low to justify development of a vaccine