Transfer of Anti-Rotavirus Antibodies during Pregnancy and in Milk Following Maternal Vaccination with a Herpes Simplex Virus Type-1 Amplicon Vector

Meier, Anita F.; Suter, Mark; Schraner, Elisabeth M.; Humbel, Bruno M.; Tobler, Kurt; Ackermann, Mathias; Laimbacher, Andrea S.

In a next experiment dams were immunized in a prime-boost regimen with either sWa[VP2/6/7] amplicon or as control GFP amplicon or Hanks' balanced salt solution (HBSS) ( Figure 3A ; Tables A6 and A7 for milk and serum rIgG levels of dams used for this experiment), but pups were swapped after birth as shown in Figure 3E . A similar RV specific IgG titer was found in terminal sera of pups from sWa[VP2/6/7] immunized dams as in sera from pups nursed from HBSS control injected dams ( Figure 3E , group A, B). The RV specific IgG of the sWa[VP2/6/7] immunized dams was thus passed to their offspring or the nursed control pups by the lactogenic route. We also exchanged the offspring from sWa[VP2/6/7] immunized dams with the offspring of HBSS injected control dams immediately after birth. Because of the terminal exsanguination, only the remaining maternal antibody titer of the pups after six days following the transfer to the control dam could be analyzed ( Figure 3E , group "C"). This antibody titer was still elevated compared to the controls ( Figure 3E , group "D"). All data to generate the plot in Figure 3E and the number of included animals for this experiment are shown in Table A8 in the Appendix A. Table A9 in the Appendix A shows p-values between all groups in Figure 3E . Before the immunization of female BALB/c mice a blood sample was collected from each animal. Five days after intra muscular (i.m.) injection of the prime dose, a male was added for mating. Before booster immunization, blood samples were taken. For the first set of experiments, mice received a booster immunization at 19 days after prime dose injection, and, for the second set of experiments, at 20 days after prime dose injection. Blood and milk samples were taken on a regular basis starting on the day of parturition. (B-D) Rotavirus specific immunoglobulin G (IgG) serum (B,D) or milk (C) levels of immunized mouse dams determined by enzyme-linked immunosorbent assay (ELISA). Rotavirus-specific IgG in sera (1:5000 dilution) or milk (1:500 dilution) of either sWa[VP2/6/7] or GFP amplicon vector immunized animals was measured and plotted relative to the positive control applied on each ELISA plate that was taken as 100%. As positive control always the same sera of a RV hyperimmunized mouse from a previous study [17] (E) Rotavirus-specific IgG levels in pup sera determined by ELISA. Rotavirus-specific IgG in terminal sera from the offspring of either sWa[VP2/6/7] or GFP amplicon vector immunized dams or Hanks' balanced salt solution (HBSS) injected control dams was plotted in relation to the positive control (set as 100%). In group A, offspring was born and raised by sWa[VP2/6/7] immunized dams. In group B, offspring was born from HBSS injected dams but raised by sWa[VP2/6/7] immunized dams. Group C includes offspring born from sWa[VP2/6/7] immunized dams and raised by HBSS injected control dams. Group D includes offspring born and raised by HBSS-injected control animals. Group E includes offspring born and raised by GFP vector immunized dams. Here, dams obtained the booster dose 20 days after prime immunization. The standard deviation of each group is indicated. p-values of A versus C, D or E or B versus C, D or E are indicated: ***, p < 0.001.