Involvement of cytolytic and non-cytolytic T cells in the control of feline immunodeficiency virus infection.
The appearance of non-cytolytic T cells that suppressed feline immunodeficiency virus (FIV) replication in vitro, and FIV-specific cytotoxic T cell (CTL) responses was compared in a group of seven, specific pathogen free (SPF) domestic cats following primary infection with the Glasgow(8) isolate of FIV (FIV(GL-8)). FIV proviral burdens were quantified in the blood and lymphoid tissues by real-time PCR. Non-cytolytic T cell suppression of FIV replication was measured by co-cultivating lymphoblasts prepared from the cats at different time-points during infection with FIV-infected MYA-1 cells in vitro. Non-cytolytic suppressor activity was detected as early as 1 week after infection, and was evident in all the lymphoid tissues examined. Further, this activity was present in subpopulations of T cells in the blood with normal (CD8(hi)) or reduced (CD8(lo)) expression of the CD8 molecule, and temporal modulations in non-cytolytic suppressor activity were unrelated to the circulating CD8(+) T cell numbers. Virus-specific CTL responses, measured by (51)Cr release assays, were not detected until 4 weeks after infection, with the emergence of FIV-specific effector CTLs in the blood. Throughout infection the response was predominantly directed towards FIV Gag-expressing target cells, and by 47 weeks after infection CTL responses had become localised in the lymph nodes and spleen. The results suggest that both non-cytolytic T cell suppression of FIV replication and FIV-specific CTL responses are important cellular immune mechanisms in the control of FIV replication in infected asymptomatic cats.
Flynn
J Norman
JN
Department of Veterinary Pathology, Retrovirus Research Laboratory, University of Glasgow, Bearsden Road, Bearsden, Glasgow G61 1QH, UK. n.flynn@vet.gla.ac.uk
Dunham
Stephen
S
Mueller
Alex
A
Cannon
Celia
C
Jarrett
Oswald
O
D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D002371:Cat Diseases / Q000097:blood / Q000276:immunology* / Q000821:virology; D002415:Cats; D004279:DNA, Viral / Q000737:chemistry / Q000302:isolation & purification; D005434:Flow Cytometry / Q000662:veterinary; D016089:Immunodeficiency Virus, Feline / Q000235:genetics / Q000254:growth & development / Q000276:immunology*; D016180:Lentivirus Infections / Q000097:blood / Q000276:immunology / Q000662:veterinary* / Q000821:virology; D008137:Longitudinal Studies; D016133:Polymerase Chain Reaction / Q000662:veterinary; D013047:Specific Pathogen-Free Organisms; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D019562:Viral Load / Q000662:veterinary
D004279:DNA, Viral