Herpesvirales Flashcards
Final production of infectious virions are released from the host cell by
Lysis
Characteristics of Equid Herpesvirus 3
Acute disease - mild
Does not cause systemic disease
Incidence of antibodies is 50% in sexually active horses
May be accompanied by respiratory disease in young horses
Infection of suid herpesvirus 1 during the first trimester results in
absorption of fetues and return to oestrrus
Categories of encoded genes of herpes viruses
Genes encoding proteins responsible for regulatory functions and virus replication (early genes)
Genes coding for structural proteins (late genes)
Optimal genes - not found in all herpes viruses and not essential for replication
Properties of herpes virions
Enveloped with core enclosed in capsid
Viral genome is simple linear dsDNA
Capsid surrounded by tegument covered by lipoprotein envelope
Suid Herpes Virus 1 disease may manifest as
Neurological, respiratory or reproductive failure
Clinical signs associated with equine herpesvirus 1 infection
Fever - 102-105
Decreased circulating WBCs
Mild serous or seromucous nasal discharge
Nasal mucosa bright red and congested with blood
Ocular discharge and conjunctivitis
Secondary hosts of Suid Herpesvirus 1
Cattle
Sheep
Dogs
Cats
Pathogenesis of Gallid Herpesvirus 2
Epithelial cells of respiratory tract infected productively
Viremia by macrophages leads to infection of lymphocytes
Proliferation of T cells transformed by the virus to produce lymphomas
Healthy chickens carry virus life long
Examples of diseases caused by Bovine Herpesvirus 1 (BHV 1)
Rhinotracheitis
Vulvovaginitis
Balanoposthitis
Conjunctivitis and Enteritis
Abortion
Ocular Lymphomatosis
Rare
Leads to graying of the iris of one or both eyes
Pupil irregular
Partial or total blindness
Mortality rare
Cutaneous Mareks Disease
Recognized after plucking the feathers
Round nodular lesions at feather follicles
Non feathered areas on legs are redded - Red leg syndrome
Transmission of Equid Herpesvirus 3
Direct genital contact
Nasogenital transmistion
Characteristics of Balanoposthitis in bulls
Similar clinical course as IPV
Lesions on penis and prepuce
Animal carries virus life long
Virus is latent in sciatic and trigeminal ganglia and sheds periodically
Characteristics of Gammaherpesvirinae
Narrow host range
Become latent in lymphocytes
Do not cause significant disease in natural host
Replication of herpes viruses
- Virion bind to cell PM, virion envelope fuses releasing capsid and tegument proteins into cytoplasm
- Capsid transported to nuclear pore, DNA released into nucleus
- Virion shut off protein (vhs) cause degradation of host mRNA
- VP16 localize in nucleus
- Viral DNA circularizes
- Viral DNA transcribed
- Alpha proteins transactivate Beta gene transcription
- Viral DNA synthesis stimulates Gamma gene expression
- Gamma proteins involved in assembling capsid in nucleus and modifying membranes for virion formation
- Viral DNA enclosed in capsid
- Capid buds through inner membrane to form enveloped virion
Etiology of malignant Catarrhal Fever (MCF)
Alcelaphine Herpesvirus
Ovine Herpesvirus 2
Processing of herpes virions occurs in the
Cytoplasm
Clinical signs of Infectious Bovine Rhinotrachitis
Fever
Depression
Inappetence
Profuse nasal discharge - serous to mucopurulent
Lesions in the nasal cavity
Smelly breath
Dyspnea
Bronchial cough
Conjunctivitis with profuse lacrimation
Gastroenteritis
Abortion
Synthesis of herpes viral DNA and capsid assembly occurs in the
Nucleus
Post mortem lesions of aborted fetuses infected with Equid herpesvirus 1
Advanced icterus
Excessive fluid in body cavities
Distention of lungs
Splenomegaly
Numerous pale necrotic foci on surface of liver and lung
Diagnosis of malignant catarrhal fever (MCF)
History
Clinical signs
Virus isolation from peripheral blood leukocytes
PCR
Malignant Catarrhal Fever (MCF)
Generalized lymphoproliferative disease of cattle and some wild ruminants
Often fatal
Virus infects lyphoid tissue and cells of the mucosal lining of the respiratory and GI tract
Acute infection bovine rhinotrachitits occurs how long after infection
5-10 days
Countries that claim to be free of Bovine Herpes Virus 1
Finland
Sweden
Denmark
Switzerland
Austria
Clinical features of malignant catarrhal fever (MCF)
Fever, depression, profuse nasal, ocular discharge and salivation
Bilateral corneal opacity often leading to blindness
Extensive nasal and GI mucosal erosion
Latent infections are common in herpes infections, reactivation can be due to
Stress
4 genera of Alphaherpesvirinae
Simplexvirus
Varicellovirus
Mardivirus
Iltovirus
Variations of Gallid Herpesvirus 2
Acute Mareks Disease
Ocular Lymphomatosis
Cutaneous Mareks Disease
Acute Mareks Disease
Young Chicken
Depression followed by ataxia
Paralysis
Mortality may occur without neurological signs
Nerve lesions found on post mortem
Transmission of Suid Herpesvirus 1
Pigs recovering from infection - excrete virus in saliva and nasal secretions, urine and feces
Diagnosis of equine herpes virus 1
Clinical presentation of abortion
Gross histiological lesions on aborted fetuses
Intranuclear inclusion bodies in tissues
Immunohistochemistry
PCR
Virus isolation
Samples for testing
Clinical signs of Gallid Herpesvirus 2
Lymphoproliferative syndrome
Lymphomas
Symmetric or asymmetric paralysis of wings or legs
Incoordination
Wing drooping
Twisted neck
T/F- Vaccination against Bovine Herpes Virus 1 prevents infection
False
____________________
Reduces incidence and severity of disease
Equid Herpesvirus 3 is analogous to
Human Genital Herpes caused by HSV 1 or 2
4 genera of Gammaherpesvirinae
Lymphocryptovirus
Macavirus
Rercavirus
Rhadinovirus
Infectious pustular vulvaginitis may result from
Coitus or artificial insemination with infected semen
Diagnosis of bovine herpes virus 1
Clinical presentation
PCR
Immunoflorescence
Virus isolation
ELISA
Histopathology
Pulmotest BHV1
_____________________
Many infections may be subclinical
Encephalomyelitis caused by equine herpesvirus 1 is caused by
Destruction of endothelial cells of arterioles of the brain and spinal cord
_______________________
NOT due to virus infection
Diagnosis of Gallid Herpesvirus 2
History, age, clinical signs and gross necropsy of large number of birds
Histopathology
Detection of viral antigens by immunofluorescence
Virus neutralization
PCR
Characteristics of respiratory disease caused by equine herpesvirus 1
Affects young horses
Virus replicates in upper respiratory tract epithelium and local lymph nodes
Mild illness
Transmission of herpes viruses
Mucosal contact
Droplet infection
Transplacental
Diagnosis of Equid Herpesvirus 3
Paired serology
Isolation of EHV 3 from active lesions
PCR
Biological properties of herpesviruses
Nucleic acid metabolism
DNA synthesis
Protein processing
Synthesis of viral DNA and capsid assembly in nucleus
Processing of virions in cytoplasm
Infectious virions cause lysis of host cell
Induce latency
Main method of control for Gallid Herpesvirus 2
Vaccination
Clinical signs of Suid Herpes Virus 1 in primary host
Young animal may die without symptoms
High fever, depression, anorexia, tremors, dog sitting position, vomiting, foaming from mouth, paddling, convulsions
Lesions from infectious pustular vulvaginitis disappear within how long
10-14 days
Common name for diseases caused by Suid Herpes Virus 1
Pseudorabies (PRV)
Aujeszky’s Disease Virus
Microscopic lesions characterisitc of Equid Herpes Virus infection
Bronchiolitis and intestinal pneumonitis
Severe necrosis of splenic white pulp
Focal necrossi of liver and adrenal glands
Presence of intranuclear inclusion bodies in many cells
Encephalomyelitis
Infection of suid herpesvirus 1 close to term may result in
Infected piglets that die within a few days
Clinical signs of Infectious pustular vulvaginitis (IPV)
Fever
Anorexia
Tail head away from vulva area
Frequent and painful micturtion
Vulva labia swollen
Light vulva discharge
Small pustules that form ulceration
Clinical features of Equid Herpesvirus 1
Infection through the respiratory tract
Virema and systemic disease manifestation
Abortion may occur with no premonitory signs
Systemic disease can occur in foals
Mild ataxia, urinary inconsistence, hind limb paralysis and death
Pathogenesis of Suid Herpesvirus 1
Virus replicates in tonsil epithelium
Short period of viremia
Spreads to CNS and becomes latent
4 genera of Betaherpesvirus
Cytomegalovirus
Muromegalovirus
Proboscivirus
Roseolovirus
Most important viral cause of abortion in horses world wide
Equid Herpesvirus 1
3 subfamilies of Herpesviridae family
Alphaherpesvirinae
Betaherpesvirinae
Gammaherpesvirinae
Transmission of Gallid Herpesvirus 2
Inhalation of dander
Diagnosis of Suid Herpesvirus 1
History
Signs
Gross and Macroscopic Leisons
Serologic testing
SN
Immunofluorescence
Alloherpesviridae Family
Includes herpesviruses of fish and frogs
Infection of suid herpesvirus 1 in the second or third trimester results in
Bortion or mummified, stillborn or weak piglets
Characteristics of Gallid Herpesvirus 2 (Mareks Disease)
Alphaherpesvirus
Important disease of chickens
Lymphoproliferative disease
Virus identification of equine herpesvirus 1 is important becasue
Equid herpesvirus 4 can also cause abortions, but is more sporadic
Clinical signs of suid herpesvirus 1 in secondary host
Intense pruritis
Psudorabies - paralysis of jaws and pharynx, drooling
Frenzied animals due to intense pruritis
Clinical signs of Equid Herpesvirus 3
Formation of pustular ulceration on vaginal and vestibular mucosae
Pustules develop on penis and prepuce
Malacoherpesviridae family
Includes herpesviruses of oysters
