Herpesviridae

VIRUSES

Introduction

• Equine herpes virus 1 and 4 in rhinitis, see respiratory infections
• Canine herpes virus 1 in respiratory disease

• In skin infections
  • Bovine herpes virus 1, 2 4
  • Equine herpes virus 3
  • Feline herpes virus 1

Feline herpesvirus -1

• Feline viral rhinotracheitis in rhinitis, see respiratory infections
  • One of the causes of Feline viral rhinotracheitis
    • Viruses and bacteria are involved in the complex. The most frequent aetiologic agent is FHV-1, and less frequently feline calicivirus and/or Chlamydophia psittaci (NB: previously called Chlamydia psittaci var felis)
    • All three agents infect URT respiratory epithelium, although FHV-1 has the highest affinity for this epithelium
    • Feline calicivirus more frequently infects the oral mucosa -> ulcerative stomatitis
    • C.psittaci more frequently infects the conjunctival epithelium -> chronic conjunctivitis
    • Infection of the respiratory epithelium by FHV-1 results in a typical neutrophilic rhinitis with intraepitheial intranuclear eosinophilic inclusion bodies, with expected clinical signs
    • Resolution of clinical signs usually occurs by 7-14 days.
    • FHV-1 remains latent in the trigeminal ganglion, and can reactivate at times of stress. Can infect the cornea -> ulcerative keratitis.
    • Occasional mortality in kitten or immunocompromised animals usually associated with secondary bacterial infection.

Bovine herpesvirus -1

• Bovine herpesvirus - 1 (Infectious bovine rhinotracheitis virus) contributes to undifferentiated neonatal calf diarrhoea, a mixed viral enteritis in calves; and rhinitis
• Causes Infectious bovine rhinotracheitis (IBR)
• Highly infectious URT disease of cattle
• High morbidity, low mortality
• Aerosol transmission - requires close contact between animals
• BHV-1 infects the respiratory mucosal epithelial cells (intranuclear inclusion eosinophilic inclusion bodies)from nasal mucosa down to bronchioles
  • leading to neutrophilic inflammation of varying severity.... serous -> catarrhal -> purulent nasal discharge, sneezing, coughing.
  • with secondary bacterial infection (eg: Pasturella spp., Mycoplasma spp., Fusobacterium necrophorum) can lead to fibrinous to necrotizing inflammation; mucosal sloughing, ulceration... pyrexia, dyspnoea ... inhalation pneumonia... death.
• Clinical signs include coughing, discharge, lacrimation, and increased respiratory rate.
• Clinical disease most severe in young calves - can develop mucosal ulcerative lesions in the oesophagus and forestomachs and viraemia with multiorgan infection.
• Cause of abortion >5 months of gestation

• Also causes infectious vulvovaginitis/balanoposthitis and meningoencephalitis
• May contribute to Enzootic pneumonia of calves

Inclusion body rhinitis (porcine cytomegalovirus)

• in rhinitis and sometimes in atrophic rhinitis progressing to pneumonia, see Inclusion body rhinitis

• Cytomegaloviruses
  • Porcine cytomegalovirus
    • Causes Inclusion body rhinitis
      • Disease of suckling piglets 1-5 wks of age
      • Clinical signs: those associated with acute/subacute rhinitis (ie: serous nasal discharge, progressing to catarrhal or purulent discharge with time and secondary bacterial infections; sneezing; pyrexia)
      • Morbitity high, mortality low
      • Histology: large basophilic intranuclear inclusion bodies in the nasal and sinus respiratory epithelium with lymphocytic infiltration of the mucosa.
      • Can develop viraemic stage, with inclusions in other organs eg: renal tubular epithelium. Piglets can die during this phase.

Gammaherpesviridae

Alcephaline-1 Virus