Antibody Responses Specific to Hepatitis B Virus Vaccine in Children Exposed InUtero to Antiretroviral Therapy

The use of antiretroviral (ARV) has been one of the most effective means of preventing vertical transmission of the human immunodeficiency virus (HIV) to exposed children born of HIV infected mothers. Nevertheless, responses to childhood vaccination against Hepatitis B virus (HBV) infections remain suboptimal in HIV exposed uninfected children irrespective of maternal ARV prophylaxis. In a cross-sectional study we have assessed the impact of in-utero exposure to ARV on paediatric HBV vaccination. Anti-HBV surface antigen specific antibodies (anti-HBs abs) were measured in plasma specimens from 44 healthy children unexposed to both HIV and ARV (HU), 25 HIV-exposed uninfected children naïve to intrauterine exposure to ARV (HEU.AR - ), 29 ARV and HIV-exposed uninfected children during pregnancy (HEU.ARV +), 50 children vertically infected with HIV but naïve to intrauterine exposure to ARV (HEI.ARV - ) and 22 children vertically infected with HIV with in utero exposure to ARV (HEI.ARV +). The protective seroconversion rate after childhood HBV vaccination (anti-HBs ≥10 mUI/ml) among HEU.ARV + children (58%) was significantly lower relative to both HEU.ARVc - (100%, P=0.0010) and the healthy unexposed children (92 %, P=0.0069). Similarly, HEI.ARV + children also had significantly lower anti-HBs IgM antibody responses when compared to both HU (p=0.0003) and HEI.ARV - (0.0001) children respectively. Thus in-utero exposure to ARV probably contributes in reducing HBV vaccine antibody response rate in both HIV exposed uninfected and vertically infected children after childhood vaccination. Nevertheless, the overall impact of ARV was to improve anti-HBs IgG responses in HIV infected children suggesting a possible role in immune reconstitution leading to improved IgG antibody responses.