Fig. 4.

Titration of antibodies in mice immunized with RBDr produced in N. benthamiana. a Immunization schedule. From T0 to T42 we performed the administration of the recombinant antigen. The syringes (filled in red) throughout the entire period, show the time of the blood extraction of the inoculated animals. b Response in immunized mice in each trial period. The values represent the antibodies titters expressed as the base 10 logarithm. +RBDr: experimental group inoculated with the recombinant antigen produced in plants; –RBD: mice immunized with PBS; Graph show mean ± standard deviation (SD) for n = 9 mice/group. c Binding inhibition capacity of polyclonal antibodies RBDr to hACE2. +RBDr: sera of immunized mice with RBDr, C + sera of persons immunized with RBD produced in P. pastoris, that showed high percentages of inhibition and taken as the positive control; -RBD: mice immunized with PBS. For the evaluation, we chose all sera at time T57. We observed two sera with high inhibition capacity, similar to those used as the positive control. Data are mean ± SD. from n = 9 repetitions/groups. The different letters represent significant differences for P < 0.0001