title: Contrasting clinical outcomes in two cohorts of cats naturally infected with feline immunodeficiency virus (FIV).
abstract: Despite over 25 years of feline immunodeficiency virus (FIV) research, relatively little is known about the longitudinal course of FIV infection following natural infection. In contrast to published reports of experimental infections using lethal strains of the virus, clinical signs of naturally acquired FIV infection can be mild or inapparent, rather than life-threatening. In this prospective, longitudinal controlled study, based in Chicago, IL (n=17) and Memphis, TN (n=27), we investigated two cohorts of privately owned, naturally infected cats kept under different housing conditions. Cats in the Chicago cohort (Group 1) were kept in households of ≤2 cats, while the Memphis cohort (Group 2) comprised part of a large multi-cat household of over 60 cats kept indoors only, with unrestricted access to one another. The majority of cats from Group 1 did not display clinical signs consistent with immunodeficiency during the 22-month observation period. In contrast, the outcome of infection in Group 2 was dramatically different; 17/27 (63%) of cats lost a median of 51.3% of their bodyweight (P<0.0005) and died during the study period, with lymphoma being the most common cause of mortality. Although the decrease in CD4+ T cell count between enrolment and terminal disease was significant (P=0.0017), the CD4:CD8 ratio at the time of enrolment did not reliably distinguish FIV-positive cats classified as 'healthy' and 'not healthy' at either cohort. FIV load at enrolment was significantly lower in Group 1 than in Group 2 (P<0.0001), but there were no significant differences at enrolment between healthy and not healthy cats at either group. In conclusion, the results of this study suggest that management and housing conditions impact on disease progression and survival times of FIV-positive cats.
authors.affiliation: MRC Centre for Virus Research, University of Glasgow, Glasgow, UK; Small Animal Hospital, University of Glasgow, Glasgow, UK. Electronic address: pawel.beczkowski@glasgow.ac.uk.
authors.forename: Paweł M
authors.initials: PM
authors.lastname: Bęczkowski
authors.affiliation: Department of Veterinary Clinical Sciences, Purdue University, West Lafayette, IN 47907, USA.
authors.forename: Annette
authors.initials: A
authors.lastname: Litster
authors.affiliation: Indiana Animal Disease Diagnostic Laboratory and Department of Comparative Pathobiology, Purdue University, West Lafayette, IN 47907, USA.
authors.forename: Tsang Long
authors.initials: TL
authors.lastname: Lin
authors.affiliation: School of Veterinary Medicine, University of Glasgow, Glasgow, UK.
authors.forename: Dominic J
authors.initials: DJ
authors.lastname: Mellor
authors.affiliation: MRC Centre for Virus Research, University of Glasgow, Glasgow, UK.
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Willett
authors.affiliation: MRC Centre for Virus Research, University of Glasgow, Glasgow, UK.
authors.forename: Margaret J
authors.initials: MJ
authors.lastname: Hosie
mesh_terms: D000818:Animals; D016516:CD4-CD8 Ratio; D015496:CD4-Positive T-Lymphocytes; D002371:Cat Diseases / Q000821:virology*; D002415:Cats; D015331:Cohort Studies; D018450:Disease Progression; D016181:Feline Acquired Immunodeficiency Syndrome / Q000821:virology*; D005260:Female; D016089:Immunodeficiency Virus, Feline / Q000235:genetics / Q000502:physiology*; D008297:Male; D010802:Phylogeny; D011446:Prospective Studies; D014764:Viral Proteins / Q000235:genetics
chemical_list: D014764:Viral Proteins
keywords: CD4:CD8; Clinical outcome; FIV; FIV load; Lymphoma; Natural infection