Developing a lateral flow immunoassay for monitoring anti-SARS-CoV-2 antibodies in plasma

COVID-19 is caused by the highly contagious severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pathogen, a novel β-coronavirus. When first detected in 2019, there were limited diagnostic tests and treatment options, making disease management challenging. By mid-2021, serological assays were being developed to detect antibodies against SARS-CoV-2, which are typically linked to present or past infection. Conventional assays such as enzyme-linked immunosorbent assays (ELISAs), neutralising antibody assays, and chemiluminescent immunoassays (CLIAs) were primarily being used for disease tracking, but these can be expensive, time-consuming, and labour-intensive. Alternatively, lateral flow immunoassays (LFIAs) are adaptable, rapid, and require minimal sample preparation or lab equipment. Therefore, this project aimed to develop an adaptable gold nanoparticle-based barcode-style LFIA to rapidly and affordably screen plasma for anti-SARS-CoV-2 antibodies to distinguish between antibody levels in different individuals. Various gold nanoparticle sizes, conjugation strategies, and membranes were explored to obtain the most optimal LFIA configuration. This proof-of-concept design was tested using pre- and post-COVID-19 plasma samples obtained from the Australian Red Cross Lifeblood. Ultimately, this LFIA technology may be adapted in the future to conduct large scale screen of other pathogens, potentially advance emerging technology in multiplexed LFIA design or measure varying concentrations of different analytes.