Priming of immune responses to hepatitis B surface antigen in young mice immunized in the presence of maternally derived antibodies

Early vaccination is necessary to protect infants from various infectious d iseases. However. this is often unsuccessful largely due to the immaturity of the neonatal immune system. Furthermore, maternally derived antibodies c an interfere with active immunization. We have previously shown in young mi ce that immune responses against several different antigens can be improved by the addition of oligodeoxynucleotides containing immunostimulatory CpG motifs (CpG ODN). In this study we have evaluated immunization of neu born (1-7-day-old) BALB/c mice against hepatitis B surface antigen (HBsAg), with alum and/or CpG ODN, in the presence of high levels of maternal antibody a gainst HBsAg (anti-HBs). Seroconversion rates and anti-HBs titers were comp ared to those induced by a HBsAg-expressing plasmid, since other studies ha d suggested DNA vaccines to be superior to protein vaccines in young mice w ith maternal antibody. HBsAg/alum/CpG ODN was superior to DNA vaccine in in ducing HBsAg-specific CTL responses in young mice in the presence of matern ally transferred anti-HBs antibodies. However, B cell responses to both HBs Ag/alum/CpG ODN and DNA vaccines remained weak in the presence of maternall y transferred anti-HBs antibodies. (C) 2001 Federation of European Microbio logical Societies. Published by Elsevier Science B.V. All rights reserved.