2.2 Proteins, Reagents, Cell Lines and Viruses
HA, Omicron BA.5 S, and Omicron BA.5 S-RBD
proteins were purchased from
SinoBiological. MF59 adjuvant was prepared according to our previously
published paper.18 Horseradish Peroxidase
(HRP)-labeled goat anti-mouse IgG and 3,3’,5,5’-Tetramethylbenzidine
(TMB) were purchased from Beyotime (Shanghai, China). HRP-labeled goat
anti-mouse IgG1 and IgG2a were purchased
from Abcam (Shanghai, China). VeroE6-TMPRSS2 cells were purchased from
the American Type Culture Collection (ATCC). Dulbecco’s Modified Eagle’s
Medium (DMEM) was purchased from Meilun (Dalian, China). Fetal bovine
serum (FBS) was purchased from Gibco (New York, USA). Experiments
involving the SARS-CoV-2 Omicron BA.5.2 strain and H1N1
A/California/07/2009 strain were conducted by following the approved
standard operating procedures of the biosafety level 3 facility at the
University of Hong Kong.