Feline Herpes Virus

Feline Herpes Virus Background

​Feline herpesvirus type 1 (FHV-1; felid herpesvirus 1 (FeHV-1), family Herpesviridae, subfamily Alphaherpesvirinae, genus Varicellovirus) is an important pathogen that causes feline viral rhinotracheitis, a highly infectious upper respiratory tract infection of felids (Davison et al., 2009). There is only one serotype of FHV-1 and it is relatively homogenous genetically (Gaskell et al., 2007). FHV-1 causes half of all respiratory diseases in cats and is the most important of these diseases, being found worldwide. The other important cause of feline respiratory disease is feline calicivirus. Infection with FHV-1 is often fatal to kittens, but adult cats usually survive and exhibit lifelong latency (Povey, 1979; Maes et al., 1984). FHV-1 also causes ocular surface disease, dermatitis, and potentially intraocular disease in cats (Thomasy & Maggs, 2016).

Feline viral rhinotracheitis (FVR) is a typically acute, febrile, contagious disease of felids characterised by sneezing with ocular and nasal discharges. Clinical signs of FVR infection are characterized by lethargy, oculonasal discharge, severe rhinitis, and conjunctivitis (López & Martinson, 2017). The incubation period is 2-4 days, sometimes longer. Mortality is high in young or debilitated cats, but most recover in 7-10 days (Povey, 1979). The disease causes an impairment of pulmonary defense mechanisms predisposing cats to secondary bacterial pneumonia or to a coinfection with feline calicivirus. FeHV-1 targets both respiratory epithelial cells and pneumocytes and pneumonia is the consequence of continuous cell-to-cell viral spread from the upper airways via the trachea into the lungs. It is likely that FeHV-1-infected cells die primarily via apoptosis, following loss of cell-to-cell contact, rounding, and detachment (Monne Rodriguez et al., 2017). The virus can also remain latent in ganglia. The vast majority of cats that recover from FVR become carriers and shed FeHV-1, either spontaneously or following stress.

Antiviral drugs developed for the treatment of humans infected with herpesviruses have been used to treat cats infected with FHV-1, with varying degrees of success (Thomasy & Maggs, 2016). Vaccines that protect against feline viral rhinotracheitis and feline calicivirus are also available.

References

• Alfonso López, Shannon A. Martinson, Feline Viral Rhinotracheitis. In Pathologic Basis of Veterinary Disease (Sixth Edition), 2017.
• Davison et al. (2009). The order Herpesvirales. Arch. Virol. 154:171–177.
• Gaskell et al. (2007). Feline herpesvirus. Vet Res. 38(2):337–354.
• Maes et al. (1984). Immunogenic proteins of feline rhinotracheitis virus. J. Virol. 51:259–262.
• Monne Rodriguez et al. (2017). Feline Herpesvirus Pneumonia: Investigations Into the Pathogenesis. Vet Pathol. 54(6):922–932.
• Povey R.C. (1979). A review of feline viral rhinotracheitis (feline herpesvirus I infection) Comp. Immunol. Microbiol. Infect. Dis. 2:373–387.
• Thomasy SM, Maggs DJ. (2016). A review of antiviral drugs and other compounds with activity against feline herpesvirus type 1. Vet Ophthalmol. 19 Suppl 1(Suppl 1):119–130.