In-Vivo Engineered B Cells Retain Memory and Secrete High Titers of Anti-HIV Antibodies in Mice

As a potential single-shot HIV therapy, transplanted engineered B cells allow robust secretion of broadly neutralizing antibodies (bNAbs). However, ex vivo engineering of autologous B cells is expensive and requires specialized facilities, while allogeneic B cell therapy necessitates MHC compatibility. Here, we develop in vivo B cell engineering, by injecting two adeno associated viral vectors, one coding for saCas9 and another coding for a bNAb. Following immunizations, we demonstrate memory retention and bNAb secretion at neutralizing titers. We observed minimal CRISPR/Cas9 off-target cleavage, using unbiased CHANGE-Seq analysis, while on-target cleavage at undesired tissues is reduced by expressing saCas9 from a B cell specific promoter. In vivo B cell engineering is thus a safe, potent and scalable method for expressing desired antibodies against HIV and beyond. One sentence summary B cells can be engineered in vivo to robustly secrete anti-HIV bNAbs in a safe, durable and scalable manner. ### Competing Interest Statement A.D.N., M.H.-F., I.D., and A.B. are listed as inventors on patent applications covering B cell engineering. S.Q.T. is a co-inventor on patents covering the CHANGE-seq method. S.Q.T. is a member of the scientific advisory boards of Kromatid, Inc. and Twelve Bio.