We may come closer to developing vaccines that confer instant immunity in a not-too-distant future if the promise from a recent study holds up. The study, reported in PNAS, describes a strategy that combines the biology-based induction of reactive antibodies with ligand design and assembly to create programmable vaccines that can confer instant immunity.

Current vaccines can take several days to weeks to induce immunity and frequently, the immunity developed declines as age progresses. Directing immunity against a self-antigen, such as in cancer, also presents a major challenge in vaccinology because it involves breaking of immunological tolerance. To address these issues, Popkov et al., from The Scripps Research Institute, describe a chemistry-driven approach to vaccination that bestows instant immunity against self- or nonself- antigens.

The central idea described by the authors is the following—reactive chemicals, when used as immunogens, induce the immune system to produce covalent antibodies that can recognize and react with these antigens. The immune system is now primed to mount a response against a specific pathogen or self-antigen as directed by an adapter ligand. To demonstrate, Popkov et al. used murine models of melanoma and colon cancer. They immunized mice with a diketone hapten containing antigen, and show induction of covalent antibodies (of IgG, IgM and IgA isotypes) after injection of two antigen-boosting doses. Once the polyclonal covalent antibody response was elicited, they administered RGD-diketone adapter ligands that reacted with the antibodies via the diketone group and targeted them to tumor cells expressing integrins at the cell surface. At 30 days post-tumor induction, they observed upto a 90% reduction in tumor volume—a drastic decrease in tumor growth.

Previous work from the same group has shown that covalent monoclonal antibodies have therapeutic effects in animal models of several diseases. Clinical trials are also currently exploring the efficacy of such chemically programmed monoclonal antibodies in treatment of human diseases including cancer. In the present study, the authors have taken the idea of chemically programmed antibodies a step further, and demonstrated that it could be a promising vaccination strategy as well. The approach should be better than using monoclonal therapy, because the induction of different antibody subtypes allows a range of effector functions and valencies to become available to the immune system. From a public health point of view, they point out that if the universal covalent approach is widely adopted, it would be possible to instantly immunize populations using stockpiled ligands in response to a biological threat or pandemic. Now, wouldnt that be fantastic?