Comparison of IL-10 levels in leaves agroinfiltrated with the different targeting constructs. N. tabacum cv. Petit Havana SR1 leaves were vacuum-infiltrated with A. tumefaciens carrying the different plant expression constructs. For each construct, three to four leaves from different wild-type plants were infiltrated; they were incubated on wet filter paper for 3 d, with a 16-h photoperiod at ~20°C. Quantification of IL-10 accumulation levels in the leaf extracts was performed by sandwich ELISA. The gray and solid bars represent the data for the viral and murine IL-10, respectively; the localizations reported on the x axis refer to the constructs described in Figure 1. Values are the means ± SD of three independent experiments.