An “immune barrier” is formed in the placenta by hepatitis B immunoglobulin to protect the fetus from hepatitis B virus infection from the mother

Abstract

The effect of hepatitis B immunoglobulin (HBIG) on hepatitis B virus (HBV) DNA load and its protective mechanism are not well understood. Twenty-eight hepatitis B surface antigen (HBsAg)–positive pregnant women and their newborns were assigned to an experimental (n = 12) or control group (n = 16) according to whether they received HBIG during pregnancy. HBV DNA load and markers titer of the mothers and newborns were tested. These markers and HBV DNA load in mothers of the experimental group did not fluctuate significantly and were comparable to the control. In the experimental group, there was a positive correlation between mothers and their newborns with regard to hepatitis B surface antibody titer. Immunohistochemical staining of placenta sections showed that HBsAg-positive areas mainly included trophoblastic cells and villous mesenchymal cells without HBIG colocalization, whereas HBIG-positive areas principally included villous capillary endothelial cells and villous mesenchymal cells. Additionally, compared with the control group, the positive rate and mean density of HBIG in the experimental group were remarkably higher. HBIG deposition was seen in Hofbauer cells. Thus, rather than influencing virus replication, HBIG forms an immune barrier between the mother and fetus to prevent HBV transmission.

Placental Immune Responses to Viruses: Molecular and Histo-Pathologic Perspectives

“…Reported histopathologic changes that occur following HBV infection of the placenta include stromal fibrosis, syncytial knotting, fibrinoid deposition, fibrinoid necrosis, villous capillary congestion and proliferation [ 81 ]. Xu et al studied a cohort of 101 full-term placentas from HBsAg-positive pregnant women and reported HBV infection rates decreased in cell layers from the maternal side to the fetal surface.…”

Hepatitis B and Pregnancy: Virologic and Immunologic Characteristics

“…HBV MTCT can occur prenatal or intrauterine, natal or at the time of birth, and postnatal or postpartum (Fig. ) . Most HBV infections occur perinatally (at birth or soon after) in unvaccinated infants, but reports suggest that approximately 3% to 8% of infections may occur through the intrauterine route .…”

Benefits and Risks of Antiviral Treatment during Pregnancy in Patients with Chronic Hepatitis B

“…In addition to serial vaccination of HBV, administration of HBIG is critical for preventing MTCT. The immune barrier formed by HBIG provides protection against MTCT of HBV with safety and efficacy [ 29 ]. In a RCT of HBeAg-positive mothers in Hong Kong, the rates of MTCT of HBV without vaccination, with only vaccination, and with vaccination + HBIG administration were 73.2%, 21.0%, and 6.8%, respectively [ 30 ].…”