The ultimate goal of T cell-based vaccination strategies is the induction of long-term immunological protection via effector memory T cells1. Adenovirus (Ad) vector-based vaccines using the backbone of human Ads have been shown in clinical studies
to be highly immunogenic with induction of specific antibody and/or T cell responses to viral or cancer antigens. However, pre-existing anti-Ad antibodies in vaccinated individuals reduces immunogenicity and efficacy of vaccines based on human Ads, which led to the development of non-human vectors based on chimpanzee viruses. Chimeric Ad vectors have been shown to induce long-lived T cell responses against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and to generate polyfunctional central and effector memory T cells against hepatitis C
Targeting of human fibroblasts by Ad vectors. Human Ads were first described as cytopathogenic agents isolated from human adenoid tonsils28. Here, we used sliced tissue cultures from human
palatine tonsils to assess the cellular tropism of green fluorescent protein (GFP)-expressing Ad vectors (Extended Data Fig. 1a). Both HuAd5-GFP and chimpanzee (Ch)AdOx1-GFP vectors readily transduced cells in the tissue slides, with PDPN+CD45− cells most
frequently expressing the GFP transgene (Fig. 1a,b). Next, we compared side-by-side the susceptibility to infection with recombinant Ad vectors of short-term cultured tonsillar stromal cells (TSCs) and peripheral blood mononuclear cells (PBMCs). Both ChAdOx1-GFP (Fig. 1c,d) and HuAd5-GFP (Fig. 1e,f ) efficiently transduced TSCs following an incubation of 3 h, while the transduction rate of PBMCs remained low. Even at the high multiplicity of infection (MOI) of 1,000 particles per cells, less than 2% of the hematopoietic cells were GFP-positive.