Potential use of polyclonal antibodies as a therapeutic intervention for SARS-CoV-2

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of the 2019 coronavirus disease pandemic (COVID-19). The virus primarily effects the respiratory system and has caused unprecedented impact on the world?s population, with over 243 million cases and more than 5 million covid-related deaths. Vaccines and therapeutics are an essential countermeasure in response to this pandemic, protecting individuals from serious respiratory complications and death. Currently, there is growing vaccine and therapeutic inequity, with developing nations having limited manufacturing and cold-chain necessary. In this study, we investigate the production of SARS-CoV-2 neutralising polyclonal antibodies (pAbs) from immunised sheep and alpaca. A candidate vaccine regime was developed from a trimeric spike (S) protein and Freunds adjuvant, shown to produce high titres of anti-S antibodies in sheep and alpaca capable of neutralising VIC31 and B.1.167.2 SARS-CoV-2 variants. Further modification of the polyclonal serum involved isolation of IgG antibodies by purification and creating F(ab?)2 fragments by endopeptidase enzyme pepsin. Resulting antibody samples were found to sufficiently neutralise both SARS-CoV-2 variants. The results from this study support further investigations into a potential cost-effective therapeutic, which may offer increased support to developing nations at risk of COVID-19.