FIGURE 4.

Induction of specific IgG antibodies by different vaccine preparation in mice groups. Immunisations were carried out two times during 2 weeks with 100 μL intramuscular injection of different vaccine preparations according to Table 1. A PBS solution containing three or 5 μg of purified inactivated viruses as antigens, administered alone or in combination with alum. The control groups received alum or PBS. Anti‐whole virus particle IgG, Anti‐spike glycoprotein (S) IgG and Anti‐receptor binding domain (RBD) IgG antibody titres in different dilutions of serum were assayed by ELISA at 2, 4 and 5 weeks post‐immunisation. Data are mean ± SD. The levels of statistical significance for differences between test groups were determined using two‐way ANOVA followed by Tukey’s post hoc test. a: Statistical significance (P < 0.0001) in comparison with groups that received 3 or 5 μg antigen alone and b: Statistical significance (P < 0.0001) between groups that received 3 μg antigens + alum and groups immunised with 5 μg antigens + alum