Fig 1.
Progression of absolute CD4+ T cell counts in peripheral blood of FIV-infected and uninfected cats over 290 weeks post-inoculation.
Systematic monitoring of the absolute CD4+ T cell counts in the peripheral blood of FIV-infected cats (dashed red lines) demonstrated a progressive decline below that of the two FIV-uninfected cats (gray lines), with the exception of cat 187 (bold red line, FIV-infected LTNP cat) who maintained an absolute CD4 T cell count indistinguishable from FIV-uninfected cats. The black arrow denotes the time of PLN removal.
Fig 2.
Percentages of CD4+ T cells and CD21+ leukocyte cell populations in the blood and PLNs of FIV-infected progressor and uninfected cats.
Bars represent the mean, and the range by error bars.
Table 1.
Detection of cell-associated FIV proviral DNA and viral RNA (gag) in temporally paired unfractionated blood-derived PBMCs and PLN-derived leukocytes.
Proviral DNA was detected in unfractionated blood-derived PBMCs and PLN-derived leukocytes from all FIV-infected cats by real-time PCR. Viral RNA (FIV gag) was only detected in PLN-derived unfractionated leukocytes and was not detected (N.D.) in blood-derived leukocytes by real-time RT-PCR. Data are derived from triplicate real-time PCR reactions performed with cellular DNA or cDNA (FIV gag RNA).
Fig 3.
Proviral DNA load in CD4+ T cells and CD21+ leukocytes cells derived from the blood and PLN of each FIV-infected cat.
The mean proviral load of blood and PLN-derived CD4+ T cells from LTNP cat 187 are less than those of progressor cats 165, 184 and 186.
Fig 4.
Viral gag RNA quantification in blood and PLN-derived CD4+ and CD21+ leukocyte subsets.
Viral RNA was detected in PLN-derived CD4+ T cells and CD21+ cells of all FIV-infected progressor cats, while it was not detected in all of the blood-derived cells with the exception of cat 184 who had detectable vRNA in peripheral CD4+ T cells. In the non-progressor cat (187) vRNA was only detected in PLN-derived CD4+ T cells (red box).
Fig 5.
Detection FIV Gag protein by Western Blot.
The p24 FIV Gag protein was detected in the positive control (in vitro FIV-infected MCH 5–4 cells, lane 2) and in PLN-derived leukocytes of all FIV-infected cats (lanes 9–12), but was not detected in blood-derived leukocytes (14–17). Protein size 24 KD. Lanes: (1) ladder, (2) in vitro FIV infected MCH 5–4 cells, (3) cat 184 PBMC 28 weeks post-FIV infection, (4) media alone, (5) FIV uninfected MCH 5–4 cells, (6) cat 185 FIV-uninfected PLN leukocytes, (7) cat 185 FIV-uninfected PBMCs, (8) ladder, (9–12) cats 165, 184, 186, 187 FIV-infected PLN leukocytes, (13) media alone, (14–17) cats 165, 184, 186, 187 FIV-infected PBMC leukocytes.
Fig 6.
Immunohistochemistry of the PLNs for FIV antigens.
Positive immunoreactivity was present in the PLNs of all FIV-infected cats. (a) Germinal center of FIV-infected cat 184 displayed at 200x using polyclonal serum from infected cat 165 (18 weeks post FIV-infection) demonstrating multiple cytoplasmic positive leukocytes within the B-cell zone. High magnification (inset at 960x magnification) demonstrates cytoplasmic immunopositivity of germinal center leukocytes. Scale bar = 50μm (b) Germinal center of FIV-uninfected control cat (185) PLN did not demonstrate immunopositivity for FIV antigens (scale bar = 50μm, inset at 960x magnification).
Fig 7.
Histology and immunohistochemistry of representative FIV-infected and uninfected cats.
PLNs from FIV-infected cats (a) were larger and demonstrated marked follicular hyperplasia with paracortical atrophy relative to uninfected cats (b) (Hematoxylin and eosin stains). Immunohistochemistry for CD79 demonstrated well-developed B cell germinal centers with prominent mantle zones in FIV-infected cats (c) relative to uninfected cats (d). Immunohistochemistry for CD3 demonstrated a decreased density of T cells in the paracortical zone of FIV-infected cats (e) relative to uninfected cat (f). FIV-infected cats (j) had a greater number of CD3 positive T cells in cortical B cell follicles (60x magnification) relative to uninfected cats (j) (100x magnification). There were greater numbers of proliferating Ki-67 positive cells in the paracortical T cell zones of FIV-infected cats (k) relative to uninfected cats (l) (400x magnification).