Development of surrogate SARS-Cov-2 virus neutralization test method using plant-produced recombinant proteins

Abstract

Detecting immunity against SARS-CoV-2 is vital for evaluating vaccine response and natural infection, but a conventional virus neutralization test (cVNT) requires BSL3 and live viruses, and a pseudo-virus neutralization test (pVNT) needs specialized equipment and trained professionals in BSL2. The surrogate virus neutralization test (sVNT) was developed to overcome these limitations. This study explored the use of angiotensin converting enzyme (ACE2) produced from Nicotiana benthamiana for the development of an affordable neutralizing antibodies detection assay. The results showed that the plant-produced ACE2-His can bind to the receptor binding domain (RBD) of the SARS-CoV-2, and was used to develop sVNT with plant-produced RBD protein. The sVNT developed using plant-produced proteins showed high sensitivity and specificity when validated with a group of 30 RBD-Fc vaccinated mice sera and the results were correlated with cVNT titer. This preliminary finding suggests that the plants could offer a cost-effective platform for establishing antibody detection assays.