Elledge and colleagues improved upon a well-established technique called phage display in which bacterial viruses, called bacteriophage, display DNA-encoded protein fragments on their surfaces. As Nicole Solimini, co-corresponding author on the paper, explained, the researchers "built a reproduction of all the proteins in the human body (collectively, the human proteome) by synthesizing the corresponding DNA fragments for expression on the surface of bacteriophage."
This new proteome library provides a physical link between the protein being studied and the gene that makes it, allowing researchers to look for and identify interactions between any human proteins, such as that between an autoantibody in a patient's blood and a self-protein that prompts an autoimmune response. In fact, this technology can be used to look for any type of interaction between human proteins, providing a powerful new tool to biomedical investigators in any discipline.
Applying their technology to autoimmune disease, the team developed a technique called phage immunoprecipitation sequencing ("PhIP-Seq"). Using cerebrospinal fluid from three patients suffering from an autoimmune disorder called paraneoplastic neurological disease, the researchers could identify known and previously unreported self-proteins targeted by patients' immune systemsthat is, interactions between an autoantibody in the cerebrospinal fluid and the self-protein that drives the autoimmune response.
According to Larman, "a small sample of blood from a diabetic patient, synovial fluid from an arthritic joint, or cerebrospinal fluid from a patient with multiple sclerosis would be mixed together with the proteomic library. The self-reactive antibodies in the patient's sample will seek out and then bind to the targeted proteins in our library. We can then separate out the antibody-bound protein fragments and determine their identity by high-throughput, next-g
|Contact: David Cameron|
Harvard Medical School