LEC 11 - Herpesvirus I Flashcards
What genomic viruses are herpes viruses?
DNA
What is the general structure of the herpes virus?
Enveloped
How does the herpes virus attach to the host cell?
Glycoprotein
What happens one the herpes virus is attached to the host cell?
Viral envelope fuses with plasma membrane
Nucleocapisid enters cytoplasm
Transported to nucleus
How is the herpes virus released?
budding from nuclear membrane
Accumulate in vacuoles
Released by cytolysis
What is seen upon histological exams when herpesvirus is present?
Rapid cyopathic effect
– and –
Nuclear inclusion bodies
What is the transcription method of herpesvirus?
Mucosal surface contact
– or –
Droplet transmission
Fomites
How is the herpes virus present in the body?
Establishes permanent latency
Maintained as episome
What is occurring during latency of the herpes virus?
Few genes expressed
Infection truly hidden
What causes reactivation of the herpes virus?
Stress -
Transport
Crowding
Boarding
Weather
How can you get false positives in herpes testing?
Use of rapid nucleic acid tests (PCR)
Latency + High sensitivity leads to false positives
What does BHV-1 cause?
Rhinotracheitits
Infectious pustular vulvovaginitis
Conjunctivitis
Abortion
Enteritis
What can BHV-1 lead to in feedlots?
Complicated secondary infections - Bovine respiratory disease
= Shipping fever
What are the clinical signs of BHV-1?
High temperature
Coughing
Eye/nasal discharge
Weight loss
Abortion
What are the risk factors for a BHV-1 outbreak?
Large herds/high density
Presence of dairy cattle
Input of new stock
Visitors
When can BHV-1 be most problemative?
Naive herds
What are the preventative mechanisms for BHV-1?
Keep herds closed + Vaccination
Live attenuated + Inactivated vaccines avalible
what is the problem with attenuated vaccines for BHV-1?
Potentially abortigenic + pose risk to unvaccinated animals
What are the pros and cons of attenuated BHV-1 vaccines?
Work fast
Useful for controlling outbreaks
Allow latency establishment + potential furture virus reactivation
What are the pros and cons of inactivated BHV-1 vaccines?
OK for pregnant animals
Do not create immunosuppression
Reduce latency shedding of virus
What does OHV-2 cause?
Malignant catarrhal fever in cattle or bison
What is the source of OHV-2?
Recently lambed sheep or goats
What symptoms ares seen with malignant catarrhal fever?
High fever
Depression
nasal/ocular discharges
extensive ulcerations in oral cavity
Corneal opacity
What does EHV-1,4 cause?
Acute febrile respiratory disease
Rhinopharyngitis
Tracheobronchitis
Which EHV is most common with annual outbreaks in foals?
EHV-4
What is important to note about EHV-1?
Neuropathic
Increasing in virulence + prevalence
= Emerging infection
What specific diseases processes do EHV-1 cause?
Abortion in horses
Respiratory disease
Encephalomyelitis
What does EHV-1 do in the blood stream?
Produce viremia
Focus on vascular endothelium of nasal mucosa + lungs + CNS
Neuropathogenic strinas produce much high viremic loads (less gross pathology)
What are the risk factors for an EHV-1 infection?
Age
Stabled vs pastured
High traffic of animals + humans
Frequant transport
Season
What seasons are EHV-1 infections most common?
Late Autumn - Winter - Spring
What is done to control the spread of EHV-1?
Cease transport
Seperate/Quarantine diseased stock
Sanitary precautions for handlers
Regular serial vaccinatiosn
How long should a horse be quarantined for EHV-1?
21 to 28 days
Where do EHV-4 infections target?
Respiratory epithelium
Associated with lymph nodes
What is the most common disease process caused by EHV-4?
Foals infected early
Acute respiratory disease (over 2 months old)
Why do foals tend to become infected with EHV-4 after 2 months of age?
Passive immunity from mare declines
What is the therapy for EHV-4?
Rest
Nursing care + anti-pyretics
Valacyclovir
What does gallid herpesvirus 1 cause in chickens/
Infectious laryngotracheitis
At what age do chickens tend to get infectious laryngotracheitis?
4 to 18 months of age
What are the common symptoms of infectious laryngotracheitis?
Coughing
Sneezing
Nasal/Ocular discharge
What do you see in chickens with infectious laryngotracheitis?
Pump handle respiration
(neck raised + head extened during inspiration)
How does a flock of chickens acquire GHV-1?
Introduced by carrier birds
How is GHV-1 spread?
Aerosol transmission
Fomite transmission
How is GHV-1 diagnosed?
PCR
Detection of virus antigens in tissues/smears
Why must caution be used when using the GHV-1 vaccines?
Attenuated vaccines stop disease but not that caused by virulent strains
Latency established - infection from carrier animals is possible
What does GHV-2 cause?
Marek’s disease
What are the forms of Marek’s disease?
Neural
Visceral
Ocular
What does GHV-2 target?
Proliferation of T cells - causes several different syndromes
What occurs in the neural form of Marek’s disease?
Tumors in the nerves + brain
= Asymmetric weakness/paralysis of wings + legs
What occurs in the visceral form of marek’s disease?
Tumors of internal organs
(Liver + Spleen + Gonads + Feather follicles + Heart + Kidney)
What is death normally caused by with Marek’s disease?
Dehydration
– or –
Starvation
What can Marek’s disease lead to?
Progressive lymphoproliferative disease
Lymphoma with early pahse incoordination sign + wing dropping of head/neck
What is seen in acute disease with Marek’s?
Explosive outbreaks of ataxia + paralysis in young
Significant mortality
What is skin leucosis caused by GHV-2?
Cutaneous diease signs where non-feathered areas become reddened with nodular lesions at feather follicles
What does GHV-2 do to the eyes?
Ocular lymphomatosis
Transformed lymphocytes migrate to eye - produce graying with irregular eccentric pupil + blindness
How long can the Marek’s virus remain stable outside the body?
Weeks
When are chickens most susceptible to Marek’s disease?
Early in life
What is seen on necropsy that suggests Marek’s disease?
Unilateral enlargement of peripheral nerve trunks
How is Marek’s disease controlled?
Vaccination
What is the GHV-2 vaccine made out of?
Weak Marek’s virus strain + turkey herpes virus
Cell-associated vaccine preps to vaccinate chicks with maternal antibodies
When are vaccinates done for GHV-2?
in ovo
What does the vaccinations for GHV-2 do in reagards to disease control?
Does not prevent infection
Makes the clinical disease less
