Abstract

To interrogate the role of specific immune cells in infection, cancer and autoimmunity, immunologists commonly use monoclonal depletion antibodies (depletion-mAbs) or genetically engineered mouse models (GEMMs). To generate a tool that combines specific advantages and avoids select drawbacks of the two methods we engineer adeno-associated viral vectors expressing depletion-mAbs (depletion-AAVs). Single-dose depletion-AAV administration permanently eliminates lymphocyte subsets in mice while avoiding accessory deficiencies of GEMMs such as marginal zone defects in B cell-deficient animals. Depletion-AAVs can be used irrespective of the animals genetic background, and multiple depletion-AAVs can readily be combined. Exploiting depletion-AAV technology, we show that B cells are required for unimpaired CD4 and CD8 T cell responses to chronic viral infection. Importantly, CD8 T cells fail to suppress viremia when B cells are depleted, and they only help resolving chronic infection if antibodies suppress viral loads. Our study positions depletion-AAVs as a versatile tool for immunological research.