Booster Vaccination in Infancy Reduces the Incidence of Occult HBV Infection in Maternal HBsAg-positive Children

Background and Aims: Occult HBV infection (OBI) in chil-dren has proven to be associated with their immune re-sponse to hepatitis B vaccine (HepB). This study aimed to investigate the effect of a booster HepB on OBI, which is rarely investigated. Methods: This study enrolled 236 ma-ternal HBsAg-positive children who were followed up annu-ally until 8 years of age and were hepatitis B surface antigen (HBsAg) negative. Of those 100 received a booster HepB be-tween 1 and 3 years of age (booster group), and 136 were never boosted (non-booster group). Serial follow-up data of children and baseline data of their mothers were collected and between-group differences were analyzed. Results: The incidence of OBI varied dynamically during follow-up, with 37.14% (78/210), 19.09% (42/220), 20.85% (44/211), 31.61% (61/193), 8.65% (18/208) and 12.71% (30/236) at 7 months, 1, 2, 3, 4, and 8 years of age. At 8 years of age, the negative conversion rate of HBV DNA in the booster group was significantly higher than that in non-booster group [57.89% (11/19) vs. 30.51% (18/59), p=0.032]. For chil-dren without OBI at 7 months old, the incidence of OBI in booster group was significantly lower than that in non-boost-er group [25.64% (10/39) vs. 67.74% (63/93), p<0.001]. Conclusions: The incidence of OBI in maternal HBsAg-positive children was high, serum HBV DNA in children with OBI was intermittently positive at low levels, and a booster HepB in infancy reduced the incidence of OBI in children with HBsAg-positive mothers.

Elicitation of strong immune responses by a DNA vaccine expressing a secreted form of hepatitis C virus envelope protein E2 in murine and porcine animal models

AIM： To characterize the immunogenicity of a hepatitis C virus （HCV） E2 DNA vaccine alone or with a protein vaccine boost in murine and porcine animal models. METHODS： A DNA vaccine expressing a secreted form of HCV E2 protein was constructed and used to vaccinate mice and piglets with or without boosting with a recombinant E2 protein vaccine formulated with CpG ODN and 10% Emulsigen. The immunogenicity of HCV E2 vaccines was analyzed by ELISA for antibody responses, MTT assay for lymphocyte proliferation, ELISPOT for the number of interferon-γ secreting cells, and cytotoxic T lymphocyte assays. RESULTS： Intradermal injection of E2 DNA vaccine induced strong Th1-1ike immune responses in mice. In piglets, E2 DNA vaccine elicited moderate and more balanced immune responses. A DNA vaccine prime and protein boost vaccination strategy induced significantly higher E2-specific antibody levels and shifted the immune response towards Th2-1ike ones in piglets. CONCLUSION： A DNA vaccine expressing a secreted form of HCV E2 protein elicited E2-specific immune responses in mice and piglets. Recombinant E2 protein vaccination following DNA immunization significantly increased the antibody response in piglets. These HCV E2 vaccines may represent promising hepatitis C vaccine candidates for further investigations.