Involvement of cytolytic and non-cytolytic T cells in the control of feline immunodeficiency virus infection
2002
Flynn, J.N. | Dunham, S. | Mueller, A. | Cannon, C. | Jarrett, O.
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 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 (15)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.
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