PPD’s new molecular assays utilize reverse transcriptase, polymerase chain reaction (RT-PCR), a versatile analysis technique that can aid in the diagnosis of disease and give a measure of gene expression. These assays will detect SARS-CoV-2, the causative agent of COVID-19, and quantify the number of infectious particles to determine viral load. These assays target spike proteins that are specific to SARS-CoV-2 and nucleocapsid proteins that are more general to the coronavirus family. This assay uses MS2 bacteriophage as a monitor for ribonucleic acid (RNA) purification. The quantitative RT-PCR assay (RT-qPCR) solely targets nucleocapsid proteins and utilizes human ribonuclease P (RNase P) targets as a purification control.
Two enzyme-linked immunosorbent assays (ELISA) have been developed specifically for vaccine trials to detect immunoglobulin G to full-length recombinant protein, one for spike and the other for nucleocapsid. These assays can be used to include or exclude subjects from vaccine trials or to monitor antibody production after vaccination. They are supported by bioinformatics tools that analyze complex data sets from these high-throughput assays.
PPD Laboratories also has developed a plate-based functional assay to detect anti-spike antibodies in human serum that can prevent infection by disrupting the binding of angiotensin converting enzyme 2 (ACE2) to SARS-CoV-2 spike protein. The ACE2 binding inhibition assay can be used in COVID-19 therapy trials to detect antibodies that may be essential to neutralizing the virus and preventing infection.
PPD’s central lab also is validating molecular and serology in vitro diagnostic assays that are released for commercial use by regulatory agencies to support clinical trials.