Evaluation of cross-reactive cell-mediated immune responses among human, bovine and porcine adenoviruses

The absence of preexisting immunity against porcine adenovirus (Ad) serotype 3 (PAd3) and bovine Ad serotype 3 (BAd3) in humans makes them attractive alternatives to human Ad serotype 5 (HAd5) vectors. To determine whether there is significant cross-reactivity among HAd5, BAd3, and PAd3 at the level of cell-mediated immune responses, BALB/c mice were inoculated intraperitoneally with wild type (WT) or replication-defective (RD) HAd5, BAd3, or PAd3. Thirty-five days after the first inoculation, cross-reactive CD8+ cytotoxic T cells, as well as CD4+ Th1- and Th2-helper T cells, in the spleen were analyzed by ELISPOT, flow cytometry and cytotoxic T lymphocyte (CTL) assays. Virus neutralization assays were used to evaluate humoral cross-reactivity. CD8+ or CD4+ T cells primed with WT or RD HAd5, PAd3, or BAd3 demonstrated significant (P