B cells engineered to express pathogen-specific antibodies protect against infection

Abstract

Effective vaccines inducing lifelong protection against many important infections such as respiratory syncytial virus (RSV), HIV, influenza virus, and Epstein-Barr virus (EBV) are not yet available despite decades of research. As an alternative to a protective vaccine, we developed a genetic engineering strategy in which CRISPR-Cas9 was used to replace endogenously encoded antibodies with antibodies targeting RSV, HIV, influenza virus, or EBV in primary human B cells. The engineered antibodies were expressed efficiently in primary B cells under the control of endogenous regulatory elements, which maintained normal antibody expression and secretion. Using engineered mouse B cells, we demonstrated that a single transfer of B cells engineered to express an antibody against RSV resulted in potent and durable protection against RSV infection in RAG1-deficient mice. This approach offers the opportunity to achieve sterilizing immunity against pathogens for which traditional vaccination has failed to induce or maintain protective antibody responses.

Vaccine Elicitation of HIV Broadly Neutralizing Antibodies from Engineered B cells

“…The gene sequences of HIV bnAbs and other desirable antibodies can however be engineered into the genomes of ex vivo activated primary B cells, such that they are expressed as functional B cell antigen receptors (BCRs) using endogenous heavy chain (HC) constant genes 3–5 . As such, engineered BCRs can undergo class switching for eventual secretion as protective antibodies from plasma cells.…”

“…As such, engineered BCRs can undergo class switching for eventual secretion as protective antibodies from plasma cells. B cells engineered in this way have been shown to confer protective levels of pathogen-specific antibody in vivo for several weeks following adoptive transfer into immunocompromised hosts 5 , or for several days following transfer into immunocompetent hosts 4,5 .…”

“…However, their elicitation is made difficult by low frequencies of appropriate precursor B cell receptors and the complex maturation pathways required to generate bnAbs from these precursors 2 . Antibody genes can be engineered into B cells for expression as both a functional receptor on cell surfaces and as secreted antibody 3–5 . Here, we show that HIV bnAb-engineered primary mouse B cells can be adoptively transferred and vaccinated in immunocompetent wild-type animals resulting in the expansion of durable bnAb memory and long-lived plasma cells.…”

De novo protein design enables precise induction of functional antibodies in vivo

“…The ability to selectively boost subdominant nAbs targeting defined, broadly protective epitopes that are surrounded by strain-specific epitopes could overcome long-standing challenges in vaccine development, given that crossneutralizing antibodies can persist for years once elicited (39). A tantalizing future application for epitope-focused immunogens could marry this technology with engineered components of the immune system, which could be used to stimulate antibody production of adoptively transferred, engineered B-cells that express monoclonal therapeutic antibodies in vivo (40).…”

“…Four sequences were experimentally tested (S0_1. [37][38][39][40]. The best variant according to binding, S0_1.39, bound with 5 nM affinity to antibody D25, and, importantly, also gained binding to the 5C4 antibody (KD = 5 nM).…”