Presentation of SIVgag to monkey T cells using dendritic cells transfectedwith a recombinant adenovirus

To pursue the capacity of monkey dendritic cells (DC) to be modified by ade noviral vectors and present the encoded antigens, we generated DC from bloo d monocytes and infected them with recombinant adenoviruses encoding GFP re porter and SIVgag or nef genes. Recombinant, E1 - and E3-deleted, adenoviru ses could transfect immature DC to >90% efficiency. When differentiated in the presence of a maturation stimulus, the infected cells were identical to control uninfected DC in surface markers and potent stimulatory activity f or the mixed leukocyte reaction. Recombinant adeno-SIVgag was comparable to vaccinia-gag in stimulating IFN-gamma -secreting CD8(+) T cells from PBMC of macaques vaccinated with SIVmax239 Delta nef and challenged with pathoge nic SIV or chimeric SIV/HIV. Small numbers of adeno-SIVgag-infected DC were sufficient to trigger specific ELISPOT responses by CD8(+) T cells from th ese animals. Some CD4(+) IFN-gamma -secreting cells were also found in the three of eight vaccinated animals with the highest CD8(+) responses. T cell s from control animals did not respond to DC transfected with adeno-gag. Th erefore recombinant adenoviruses efficiently transfect monkey DC in a nonpe rturbing fashion, and these DC efficiently present antigens to SIVgag immun e CD8(+) T cells. These findings will allow autologous DC, expressing SIV g enes with high efficiency, to be tested in vivo to achieve strong specific T cell immunity.