Neutralization of B.1.617.2 variant through antibodies elicited by ChAdOx1-S, BBIBP-CorV, and Gam-COVID-Vac in an Argentinean cohort

Abstract

Serum samples from HCW were tested for their neutralization ability against SARS-CoV-2 live Wild Type B.1 (GISAID, accession number ID: EPI_ISL_499083) and SARS-CoV-2 B.1.617.2 variant (GISAID Accession ID: EPI_ISL_6032417) and by the plaque-reduction neutralization test (PRNT), as previously described2. Briefly, the virus neutralization test was performed with Vero Cl76 cells (ATCC CRL-1587) that were seeded in 24-well plates 48 h before infection. Plasma samples were heat-inactivated by incubation at 56°C for 20 minutes and centrifuged at 10,000 rpm 30 minutes before use. Treated samples were two-fold diluted and then an equal volume of virus stock containing 100 plaque forming units (PFU) was added to each corresponding well until reaching final dilutions ranging from 1/10 to 1/640. Sample dilutions-virus were incubated at 37°C for 60 min in a 5% CO2 incubator and then added to each well of the cell culture plate. After incubation for 1 hour at 37°C in a 5% CO2 incubator, cells were incubated with 0.5% agarose with DMEM supplemented with 2% FBS for 4 days at 37°C in a 5% CO2 incubator.