Herpes

Question 1

When is severe herpes disease usually seen?

Answer 1

• Neonates/ Foetuses
• Immunocompromised individuals
• When virus enters a different host species

Question 2

What is the basic composition of a herpes virus?

Answer 2

• Double-Stranded DNA virus
• large linear genome
• circularises upon replication
• encodes many proteins

envoloped and unstable in the environment

Question 3

What are the 3 subtypes of BOHV-1?

Answer 3

• BoHV-1.1 (isolated from respiratory tract diseases & abortion).
• BoHV-1.2a (genital organs).
• BoHV-1.2b (genital organs).

Question 4

How is BOHV-1 transmissed

Answer 4

• Aerosols
• Direct contact

Question 5

What are the clinical signs of IBR?

Answer 5

• Coughing often first sign and heavy breathing.
• Conjunctivitis and mucopurulent ocular discharge.
• Fever for 7-10 days - milk yield drops.
• Discharge from nose (red nose) - serous then mucopurulent.
• Vesicles on the muzzle and in nares - pustules, may ulcerate.
• Abortion common (4-7 mo gestation).

Question 6

How is herpesvirus usually transmissed?

Answer 6

Via shedding of the virus in nasal, oral or genital secretions

Question 7

How do herpesvirus replicate (HSV-1) ?

Answer 7

• Glycoprotein attaches to the cell receptor
• Fusion of the viral and cell membranes
• Nucleocapsid enters the cytoplasm
• DNA/ protein complex enters the nucleus
• Protein synthesis
• Genome replication

Question 8

How does rolling circle genome replication work?

Answer 8

• Viral endonuclease creates a ‘nick’ in the origin of replication
• Assembly of replication machinery with DNA polymerase on the 3’ extremity
• DNA polymerase begins strand displacement synthesis creating a dsDNA fragment
• displaced strand is rejoined
• ss circularised DNA is used as a template to create dsDNA

Question 9

How is IBR mainly transmissed?

Answer 9

• Aerosols in short distance
• Direct contact

Question 10

How do IBR viruses replicate

Answer 10

• Mucous membranes of the URT
• Tonsils
• Conjunctiva

Question 11

What are the clinical signs of IBR disease?

Answer 11

• Coughing
• Conjunctivitis
• Fever for 7-10 days
• Discharge from nose
• Vesicles on the muzzle
• Abortion common (4-7 month gestation)
• Respiratory signs may last for several weeks

Question 12

How does equine rhinopneumonitis spread?

Answer 12

Aerolised virus- inhalation
* cell-associated viraemia
* most animals become infected before two years of age
* latency in the trigeminal ganglia and lymphoid tissue

Question 13

What are the clinical signs rhinopneumonitis?

Answer 13

• Fever
• Anorexia
• Sporadic cough
• Nasal exudate
• Conjunctivitis
• lymph node swelling

Question 14

What is catarrhal?

Answer 14

inflammation of mucous membrane in respiratory tract causes excessive secretions

Question 15

What is the peracute form of catarrhal fever?

Answer 15

• No clinical signs or depression
• Death can be rapid (1-2 days)

Question 16

What is the chronic form of malignant catarrhal fever?

Answer 16

• high fever
• bilateral corneal opacity
• profuse catrrhal discharge from the eyes

Question 17

what is malignant catarrhal fever pathology characterised by?

Answer 17

• lymphoid cell accumulation in non-lymphoid organs
• vascultitis and lymphocyte hyperplasia in lymphoid organs

Question 18

What does the herpesvirus exist as in the nucleus?

Answer 18

It exists as an episome

Question 19

What are the clinical signs of IBR disease?

Answer 19

• Coughing
• Conjunctivitis and fever
• Discharge
• Vesicles
• Abortion

Question 20

What are the control strategies for the virus in the UK?

Answer 20

• Detection and slaughter
• Vaccination and slaughter (DIVA vaccines are useful)
• Strict biosecurity measures
• Detection of antibody positive herds

Question 21

What is the aim of the BOHV-1 Vaccine?

Answer 21

Reduce the clinical impact
* Produce an attenuated live vaccine

Question 22

What are the two types of Equine rhinopneumonitis?

Answer 22

• EHV-1 associated with abortion
• EHV-4 associated with respiratory issues

Question 23

What are the two forms of malignant cattarhal fever?

Answer 23

• Wildebeeest-associated MCF
• Sheep-associated MCF

Problem only occurs when it enters cattle

Question 24

What is in the peracute form of MCF?

Answer 24

• no clinical signs, depression
• death can be rapid 1-2 days

Question 25

What is in the chronic form of MCF?

Answer 25

• High fever
• Bilateral Corneal Opacity
• Profuse Catarrhal discharge from the eye and nares

Question 26

What is the epidemiology of OvHV-2?

Answer 26

• Not present in lambs before two months of age
• Lambs between 6-9 months shed the virus more frequently and intensley
• Transmission from adult sheep is relatively low

Question 27

What are the 3 syndromes of Mareks disease in chickens?

Answer 27

• Lymphoproliferative syndrome
• Ocular lymphomatosis
• Cutaneous syndrome

Question 28

How do you get infected with Mareks disease?

Answer 28

• Subclinical infection
• Via inhalation of contaminated dust
• Infection is within lynphoid cells and macrophages
• Proliferation of CD4 + T cells
• Virus contains oncogenes (similiar to avian retroviruses)

Question 29

What are the clinical signs of Feline HerpesVirus during the incubation period (24-48 hours)

Answer 29

• Sudden bouts of sneezing and coughing
• dyspnea, anorexia, weight loss
• ulcers on the tongue
• keratitis associated with punctate corneal ulcers

Question 30

What are the clinical signs of EHV-1?

Answer 30

• Lethargy
• Anorexia
• Lameness