mCuMVTT-RBM promotes IgA production and IgG responses are dominated with IgG2a subclass
Previous studies have shown that the different IgG subclasses play an essential role against viruses by complement fixation, enhancing opsonization and immune effector function (28). Accordingly, it is of interest to assess the IgG subclasses induced by the developed vaccine candidate. We have tested the vaccine for its ability to induce IgG1, IgG2a, IgG2b and IgG3. The results indicated that mCuMVTT-RBM induces the production of all four subclasses when binding is assessed on RBD protein as shown in Figure 3A and B. Analysis of OD50 showed a predominance of IgG2a and IgG1. These results were confirmed when assessing the binding to the spike protein (Fig 3C and D).
Next, we tested the ability of mCuMVTT-RBM to induce immunoglobulin class-switching to IgA using the two regimens D0/14 and D0/28. Following, D0/28 regimen induced higher RBD-specific IgA titers in comparison to D0/14 regimen (Fig. 3E). Measuring the OD50 of IgA titers in both regimens confirmed the difference in antibody titers (Fig. 3F).