Felis catus gammaherpesvirus 1; a widely endemic potential pathogen of domestic cats

• A newly discovered herpesvirus of domestic cats, FcaGHV1, is widely endemic.
• Retroviral infections or poor health status are risk factors for FcaGHV1 infection.
• FcaGHV1 may impact feline health worldwide.
• FcaGHV1 loads are high in feline immunodeficiency virus-infection.
• A model for pathogenesis of human gammaherpesviruses is suggested.

Felis catus gammaherpesvirus 1 (FcaGHV1), recently discovered in the USA, was detected in domestic cats in Australia (11.4%, 95% confidence interval 5.9–19.1, n=110) and Singapore (9.6%, 95% confidence interval 5.9–14.6, n=176) using qPCR. FcaGHV1 qPCR positive cats were 2.8 times more likely to be sick than healthy. Risk factors for FcaGHV1 detection included being male, increasing age and coinfection with pathogenic retroviruses, feline immunodeficiency virus (FIV) or feline leukaemia virus. FcaGHV1 DNA was detected in multiple tissues from infected cats with consistently high virus loads in the small intestine. FcaGHV1 viral load was significantly higher in FIV-infected cats compared with matched controls, mimicking increased Epstein–Barr virus loads in human immunodeficiency virus-infected humans. FcaGHV1 is endemic in distant geographic regions and is associated with being sick and with coinfections. Horizontal transmission of FcaGHV1 is supported, with biting being a plausible route. A pathogenic role for FcaGHV1 in domestic cats is supported.