Phage Display Tools for Automated Blood Typing

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DESCRIPTION (provided by applicant): Current technologies used in blood banking are extraordinarily labor intensive, prone to human error, and an order of magnitude more expensive per test that those in other clinical laboratories. Coupled with a growing shortage of skilled medical technologists, dwindling supplies of human plasma-derived phenotyping reagents, and an inherent difficulty in fully automating agglutination-based methodologies, the ability to perform rapid and accurate pre-transfusion testing in a cost-effective manner has become a significant challenge. PhenoTech's long-term objective is to use a set of novel molecular technologies to develop a new class of renewable, inexpensive, high-quality blood bank testing reagents that will function in a rapid, high- throughput, automatable assay system. At the core of the proposed technology are red blood cell antigen- specific monoclonal antibodies displayed on the surface of bacteriophage particles. Phase I studies proposed to exploit the naturally-occurring presence of unique DNA sequences within the particles to develop an assay system in which the phenotype of a cell is determined by assaying the genotype of the detecting reagent. Such a strategy would offer extraordinary sensitivity and specificity, would require minute amounts of testing materials and reagents, would be easily adapted to automation, and would be amenable to multiplexing strategies offering the possibility of simultaneous antigen profiling of a red cell sample in a single reaction vessel. This would make extended phenotyping and matching of blood beyond the traditional three-antigen A, B, and Rh(D) affordable and routine. Such a paradigm shift in the practice of transfusion medicine would then serve to reduce the incidence of red cell alloimmunization and occurrence of delayed hemolytic transfusion reactions, decrease the development of positive antibody screens and the costs in working them up, and improve the turn-around-time for the provision of immunologically-compatible blood. As reported in this Phase II proposal, PhenpTech was successful in demonstrating the feasibility of multiplexing red cell typing reactions using its novel reagent genotyping methodology. Reactions required less than 1/100,000 the number of RBCs of a conventional agglutination assay and used attogram equivalents of conventional antibody reagents. In addition, the ability to use phage particles which express anti-globulin-like molecules for performing indirect antiglobulin tests, the most labor-intensive and costly group of pre-transfusion tests, was also shown. Having demonstrated the feasibility of phage reagent genotyping methods, PhenoTech's Phase II program will now focus on the development of a suite of phage reagents to clinically important blood group antigens required for further development of its blood testing technologies. Combined with its concurrent development of a microfluidics-based "lab-on-a-chip" platform, PhenoTech will be able to provide the tools necessary to ensure the safe practice of transfusion medicine in the future by addressing the technical and fiscal limitations of conventional blood bank testing methods.