3. Results
3.1 Influenza/SARS-CoV-2 Omicron Subunit Combined
Vaccine Induced High Levels of IgG Antibody Titers
BALB/c mice were intramuscularly immunized with PBS, HA, SARS-CoV-2
Omicron BA.5 S or HA+SARS-CoV-2 Omicron BA.5 S adjuvanted with MF59,
respectively, three times at two-week intervals. Serum samples were
collected one week after each immunization for HA or SARS-CoV-2 Omicron
BA.5 S-RBD-specific IgG
detection. Based on mouse sera
collected on day 21, one week after the first boost immunization, as
shown in Figure 2A, a high level of HA-specific IgG was observed in mice
immunized with HA with no significant difference between the HA and
HA+SARS-CoV-2 Omicron BA.5 S immunized groups. The level of IgG was
significantly increased on day 35, one week after the second boost
immunization, in mice immunized with HA and HA+SARS-CoV-2 Omicron BA.5
S, respectively. Similarly, based on mouse sera collected on day 21, as
shown in Figure 2B, a high level of SARS-CoV-2 Omicron BA.5
S-RBD-specific IgG was observed in mice immunized with SARS-CoV-2
Omicron BA.5 S with no significant difference between the SARS-CoV-2
Omicron BA.5 S and HA+SARS-CoV-2 Omicron BA.5 S immunized groups. The
level of IgG was significantly increased on day 35 in mice immunized
with SARS-CoV-2 Omicron BA.5 S and HA+SARS-CoV-2 Omicron BA.5 S,
respectively. As shown in Figure 2C and 2D, mouse sera collected on day
35 showed good binding ability with coated HA and Omicron S-RBD
proteins.