2.3 Neutralizing antibody assays
Serum samples from participants were initially 10-fold diluted and subsequently 3-fold serially diluted. The diluted serum samples were then combined with an equal volume of GX_P2V (100 TCID50, GenBank accession number MW532698) incubated at 37℃ in a 5% CO2 incubator for 2 hours. Following incubation, 100 µL of the virus-serum mixture was transferred into 96-well plates and combined with an equal volume of BGM cells (3×104 cells/well). The inoculated plates were incubated continuously at 37℃ in a 5% CO2 incubator for an additional 5 days, after which the cytopathic effect (CPE) of the virus were observed using a light microscope. GX_P2V neutralization titers were calculated using the Reed-Muench equation and expressed as the sample dilution at which a 50% neutralization titer (NT50) was achieved.