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52 HIV+ve Lymphocytes Infected in Vitro with Recombinant Fowlpox Virus (rFPV) Vaccines Stimulate Autologous HIV-Specific Cytotoxic T Cells (CTLs)
E. Benson*1, M. Bharadwaj2, J. Clarkson3, C. Webber1, and S. Adams1
1Westmead Hosp., NSW, Australia; 2Queensland Inst. of Med. Res., QLD, Australia; and 3Westmead Childrens’ Hosp., NSW, Australia
Background: We studied 2 rFPV vaccines, FPV.gag.pol. and FPV.gag.pol.IFN, encoding the HIV proteins gag and pol, ( human interferon-gamma. Human cells infected with these rFPVs express the encoded cytokine and/or gag antigen, however only those infected with FPV.gag.pol are recognised as targets by autologous CTLs. This study determined whether HIV-positive lymphocytes infected in vitro with these rFPVs can stimulate anti-HIV activity in autologous CTLs.
Methods: PBMCs from HIV-positive (CD4 > 400 cells/muL) or HIV-negative volunteers were divided into 3 equal portions, and one-fifth of each portion was infected with 1 of the rFPVs or with wild-type FPV. These infected “stimulator cells” were then recombined with the uninfected cells from that portion, and rhIL-7 was added at 330 U/ml. After 7 days, HIV-specific CTL activity in the stimulated cells was determined in a CTL assay by measuring their lysis of autologous rVaccinia-infected targets expressing HIV gag, pol, or env, or a non-HIV protein, lac. The degree of HIV-specific lysis was determined by subtracting the percentage lysis values against lac targets from percentage lysis values against HIV targets.
Results: In HIV+ve subjects both rFPVs induced higher anti-HIV CTL responses to gag targets (23(44% lysis) and pol targets (10(63% lysis) than did the control FPV (3(5% vs. gag; 3(10% vs. pol). In HIV-negative subjects HIV-specific lysis of gag and pol targets after rFPV stimulation was no higher than 10% above control. There were no consistent differences in the pattern or degree of CTL activity induced by the 2 rFPVs. rFPV-stimulated CTL activity was specific for the encoded HIV gag and pol antigens, but not for other HIV antigens.
Conclusions: Both rFPVs stimulate specific, anti-HIV CTLs from HIV-positive individuals. Interferon-gamma expression by FPV.gag.pol.IFN-infected cells did not influence the level of stimulation.
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