Influenza/SARS-CoV-2 Omicron Subunit Combined Vaccine Induced High Levels of IgG1 and IgG2a Antibodies in Mice
Endpoint titers of HA or SARS-CoV-2 Omicron BA.5 S-RBD-specific IgG1 and IgG2a in immunized mouse sera on day 21 and 35 were also detected by ELISA. As shown in Figure 3A, a quite high level of HA-specific IgG1 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 IgG1 was significantly increased on day 35 in mice immunized with HA and HA+SARS-CoV-2 Omicron BA.5 S, respectively. As shown in Figure 3B, a high level of SARS-CoV-2 Omicron BA.5 S-RBD-specific IgG1 was observed in mice immunized with SARS-CoV-2 Omicron BA.5 S. The level of IgG1 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, HA or SARS-CoV-2 Omicron BA.5 S-RBD-specific IgG2ain immunized mouse sera on day 21 was detected. Moreover, the level of IgG2a was significantly increased on day 35 in mice immunized with HA and SARS-CoV-2 Omicron BA.5 S, respectively. Importantly, the influenza/SARS-CoV-2 Omicron subunit combined vaccine induced balanced Th1/Th2 cellular immune response in BALB/c mice.