Going Solo: Engineering Single-Chain Antibody Immunity to Explore Evolutionary Constraints

of Molecular Biology, and the University of Cambridge—and developed with major industry partners including AstraZeneca, Illumina, Alloy Therapeutics, and other industry partners, alongside the Babraham Research Campus and its network of bioscience companies.

Starting January 2027, a 4-year Research Studentship will be available leading to a University of Cambridge PhD degree in the laboratory of Dr Dinis Calado.

Project Details

In most vertebrates, antibodies are composed of paired heavy (VH) and light (VL) chains, whose variable regions combine to form the antigen-binding site. This structural architecture enables combinatorial diversity, high-affinity antigen binding, and robust immune protection. Camelids and cartilaginous fish have independently evolved a radically simplified alternative: heavy-chain only antibodies (VHH), and light-chain only antibodies (VNAR), respectively, which function with a single antigen-binding domain. These single-domain antibodies are smaller, more stable, and can access hidden or concave epitopes that conventional antibodies cannot. Their growing utility in research and therapeutics has driven widespread interest, but their feasibility as a complete immune solution in mammals remains untested.

In collaboration with Alloy Therapeutics, a leader in transgenic mouse platforms for antibody discovery, this PhD project will engineer and characterise a novel class of transgenic mice that express only single-chain antibodies. Alloy Therapeutics has generated advanced mouse strains designed to support the development of single-domain antibody repertoires (VHH- or VNAR-like) without compromising B cell development. These platforms offer a unique opportunity to experimentally investigate how the immune system adapts to the absence of heavy or light chains and to explore whether such a simplified architecture can support functional immunity in mammals.

The central hypothesis is that a single-chain antibody repertoire is sufficient for immune protection but may alter key checkpoints of B cell development, central tolerance, affinity maturation, and effector cell differentiation. To pursue this investigation, the student will work in the Calado Laboratory at the Babraham Institute, leveraging their expertise in B cell biology, and utilise Alloy Therapeutics’ innovative transgenic mouse models specifically engineered to generate single-chain antibodies for in vivo functional studies. The student will assess:

• B cell development and selection in the bone marrow and periphery in the absence of heavy or light chain recombination.
• Tolerance mechanisms and the potential emergence of autoreactive clones due to reduced structural constraints on antigen binding.
• Humoral responses following immunisation or infection, including class-switch recombination, germinal centre formation, affinity maturation, and plasma/memory B cell differentiation.
• Protective efficacy and antibody repertoire features using bulk and single-cell sequencing, flow cytometry, and antigen-specific B cell tracking.

The project provides a unique opportunity to explore the evolutionary trade-offs and immunological consequences of simplified antibody formats. It will clarify whether conventional VH-VL pairing is essential for protective immunity or whether single-domain architectures can be successfully integrated into mammalian immune systems. The outcomes will directly inform next-generation therapeutic antibody discovery and the design of synthetic immune systems for biotechnology and medicine.

The student will be co-supervised through a close academic–industry partnership and gain cutting-edge training in molecular immunology, B cell biology, in vivo modelling, single-cell techniques, and translational antibody engineering, with placement and direct collaboration with Alloy Therapeutics’ discovery teams.

Keywords: Single-domain antibodies, B cell development, immune tolerance, antibody engineering, synthetic immunology.