Prevention Of HBV Transmission In Uterus With Hepatitis B Immunoglobulin

Background : There were not agreement on prevention of HBV transmission in uterus with hepatitis B immunoglobulin(HBIG)before delivery. Its mechanism and influence on HBV gene mutation is unknown. Therefore the efficacy and the mechanism of different dose HBIG on prevention of HBV intrauterine infection and the relationship of HBIG injection before delivery and HBV gene mutation were investigated.Subjects and methods: asymptomatic HBsAg carrier mother and their newborninfants1. In the efficacy and mechanism trial, eighty-one HBsAg carrier pregnant women were divided into HBIG A group, HBIG B group and control group. Each subject in the HBIG A group received 200 IU or 400IU(for HBsAg and HBeAg double positive carrier) intramuscularly at 3,2, 1month before delivery. Each subject in the HBIG B group received 200 IU intramuscularly at 3, 2, lmonth before delivery. The subjects in the control group did not receive any treatment. Maternal blood samples were taken before HBIG injection and at delivery. Neonatal blood samples of all newborn infants after birth were taken before immunoprophylaxis. Blood specimens were tested for HBsAg and anti-HBs by enzyme immunoassay (EIA) and for HBVDNA by fluorescence quantitative polymerase chain reaction (FQ-PCR).2. In the viral gene mutation research, HBVDNA were extracted from 52 serum of the newborn infants of HBV infected in uterus and their mothers , and then amplification and direct sequencing of S gene region.Results:1. The rate of HBV intrauterine infection in the HBIG group(14.5%) was lower than that in the control group (35.7%) ( X~2=4.896, p=0.027).2. The rate of HBV intrauterine infection of newborns from HBsAg and HBeAg double positive carrier mother in the HBIG A group (37. 5%) were lower than control group (100%) (X~2=7.273, p=0.007), while the rate was no different in the HBIG B group (71.5%) and the control group (X~2=2.637, p=0.104).3. Maternal HBsAg titers and HBVDNA levels were no different among three groups before HBIG injection. Maternal HBsAg titers and HBVDNA levels of the HBIG A group were lower than those of the HBIG B group and the control group at delivery.4. Among the 26 neonatal serum samples in the HBIG A group , 10(38%) were positive for anti-HBs, while in the HBIG B group and in the control group, no neonatal serum samples was positive.5. There was no significant difference of nucleotide and amino acid changes in the S gene between the HBIG group and the control group.6. The majority HBV strains of newborn (17/18) were identical to their mother's dominant strains, including 4 mutation HBV strains. A mutation HBV strain of one mother failed to infect her infant.Conclusion:1. HBV infection in the uterus may be interrupted by injected HBIG intramuscularly before delivery. More efficacy would be found using vary HBIG dose according to different HBV viremia and must be once more again injection just before one week delivery.2. Anti-HBs transported to the fetus via the placenta and protecting the fetus from HBV infection may be the important mechanism of HBIG prevention, while reduction of maternal HBV viremia may not be the major mechanism .3. Asymptomatic HBsAg carrier mother received injections of HBIG before delivery should not influence HBV gene mutation.4. HBV intrauterine transmission may be with or without gene mutation . Gene mutation of HBV is not the main factor in intrauterine transmission of HBV.