(P-TS-33) Developing Rapid Tests to Screen Blood Donations for Therapeutic Potential

During the COVID-19 pandemic, convalescent plasma (CP), containing SARS-CoV-2 antibodies, was one of the only available treatments for severely affected patients. CP donations were classified as being suitable for direct therapeutic transfusion or for hyperimmune production based on the antibody titre provided from additional testing conducted at accredited laboratories.
Despite CP becoming increasingly redundant, developing a rapid point-of-care test that is scalable and cost-effective to categorise CP donations is of value for rapid response in preparation for any future infectious diseases.
COVID-19 rapid antigen tests developed for the general community only provided a binary viral infection result and were not aimed towards classifying antibody levels following infection.
In this study, we aim to develop a proof-of-concept semi-quantitative gold nanoparticle based lateral flow assay (LFA) to screen for antibodies to SARS-CoV-2 to enable CP donation classification according to the therapeutic levels of antibodies.

Study

Design/Methods: The LFA was designed as described in Figure A. The sample is added to the sample pad and flows to the conjugate pad where it interacts with gold nanoparticles coated with SARS-CoV-2 Spike proteins to form a sample/gold nanoparticle complex. The complex then flows to the reaction membrane and binds to antibodies coated on the test lines, the accumulation of bound gold nanoparticles on the lines provides a readout based on the amount of antibody present in the sample. Assay specificity and sensitivity were tested using CP samples with known classifications based on Vero E6 cell microneutralization assay screening. COVID-19 negative samples from prior to SARS-CoV-2 detection in Australia were also tested.

Results/Findings: Samples from a cohort of 340 CP donor samples with antibody levels varying in titre levels from < 40 (low), 41-79 (medium) and >80 (high) were collected to enable testing.  Negative samples from 100 donors prior to detection of SARS-CoV-2 were also collected. Preliminary results indicate 1 donor sample from each titre range have been trialled with concordant results to the initial Vero E6 assay.

Conclusions: The development of rapid tests with the ability to screen blood donations for therapeutic potential should be explored to enable the preparation for the any future infectious disease that may impact the community and require therapeutic products from blood donors.