FIV establishes a latent infection in feline peripheral blood CD4+ T lymphocytes in vivo during the asymptomatic phase of infection.
BACKGROUND
Feline immunodeficiency virus (FIV) is a lentivirus of cats that establishes a lifelong persistent infection with immunologic impairment.


RESULTS
In an approximately 2 year-long experimental infection study, cats infected with a biological isolate of FIV clade C demonstrated undetectable plasma viral loads from 10 months post-infection onward. Viral DNA was detected in CD4+CD25+ and CD4+CD25- T cells isolated from infected cats whereas viral RNA was not detected at multiple time points during the early chronic phase of infection. Viral transcription could be reactivated in latently infected CD4+ T cells ex vivo as demonstrated by detectable FIV gag RNA and 2-long terminal repeat (LTR) circle junctions. Viral LTR and gag sequences amplified from peripheral blood mononuclear cells during early and chronic stages of infection demonstrated minimal to no viral sequence variation.


CONCLUSIONS
Collectively, these findings are consistent with FIV latency in peripheral blood CD4+ T cells isolated from chronically infected cats. The ability to isolate latently FIV-infected CD4+ T lymphocytes from FIV-infected cats provides a platform for the study of in vivo mechanisms of lentiviral latency.
Department of Pathology, Microbiology & Immunology, School of Veterinary Medicine, University of California, Davis, 4206 Vet Med 3A, Davis, CA 95616, USA. bmurphy@ucdavis.edu
Brian
B
Murphy
Natasha
N
Vapniarsky
Chad
C
Hillman
Diego
D
Castillo
Samantha
S
McDonnel
Peter
P
Moore
Paul A
PA
Luciw
Ellen E
EE
Sparger
D000818:Animals; D058345:Asymptomatic Infections; D015496:CD4-Positive T-Lymphocytes / Q000821:virology*; D002415:Cats; D004279:DNA, Viral / Q000032:analysis; D016089:Immunodeficiency Virus, Feline / Q000302:isolation & purification / Q000472:pathogenicity*; D053645:Interleukin-2 Receptor alpha Subunit / Q000032:analysis; D016180:Lentivirus Infections / Q000821:virology*; D008297:Male; D010949:Plasma / Q000821:virology; D012367:RNA, Viral / Q000032:analysis; D016176:T-Lymphocyte Subsets / Q000737:chemistry / Q000821:virology; D019562:Viral Load; D014775:Virus Activation; D017735:Virus Latency
D004279:DNA, Viral; D053645:Interleukin-2 Receptor alpha Subunit; D012367:RNA, Viral