Figure 1. Schematic presentation of parvoviruses effects on the immune system (IS). The direct effects were observed upon in vitro infection of human total peripheral blood mononuclear cells (PBMCs) and PBMC subpopulations or in vivo treatment of tumors in rodent models. Indirect effects were observed in co-culture systems upon viro- or combined chemovirotherapy of tumor cell lines in vitro. Antigen-presenting cells (APCs) and natural killer (NK) cells were activated directly upon oncolysis of tumor cells, while CTL killing was stimulated by dendritic cells (DCs) conditioned with tumor H-1PV oncolysates.