Figure 3 . HA-specific IgG1, IgG2a and Omicron BA.5 S-RBD-specific IgG1, IgG2a detection in immunized mouse sera. HA-specific IgG1(A) and IgG2a(C) endpoint titers on day 21 and day 35 in immunized mouse sera; Omicron BA.5 S-RBD-specific IgG1(B) and IgG2a(D) endpoint titers on day 21 and day 35 in immunized mouse sera. Statistical significance was determined by two-way ANOVA and is indicated as follows: * p< 0.05, ** p < 0.01, *** p < 0.001, **** p < 0.0001. Error bars represent SD.
3.3Influenza/SARS-CoV-2 Omicron Subunit Combined Vaccine Induced High Levels of H1N1 A/California/07/2009 Virus-specific Hemagglutination-inhibiting Antibodies in Mice
The H1N1 A/California/07/2009 virus-specific hemagglutination-inhibiting antibody titers in immunized mouse sera on day 21 and 35 were detected by HAI assay. As shown in Figure 4, a quite high level of H1N1 A/California/07/2009 virus-specific HAI titer was detected in mice immunized with HA with no significant difference between the HA and HA+SARS-CoV-2 Omicron BA.5 S immunized groups. HAI titer was significantly increased on day 35 in mice immunized with HA, again with no significant difference between the HA and HA+SARS-CoV-2 Omicron BA.5 S immunized groups.