Relationship of hepatitis B virus infection of placental barrier and hepatitis B virus intra-uterine transmission mechanism

Hepatitis B vaccination with or without hepatitis B immunoglobulin at birth to babies born of HBsAg-positive mothers prevents overt HBV transmission but may not prevent occult HBV infection in babies: a randomized controlled trial

Vertical transmission of Hepatitis B virus HBV can result in a state of chronic HBV infection and its complications. HBV vaccination with or without hepatitis B immunoglobulin (HBIG) prevents transmission of overt infection to the babies. However, whether it also prevents occult HBV infection in babies is not known. Consecutive pregnant women of any gestation found to be HBsAg positive were followed till delivery, and their babies were included in the study. Immediately after delivery, babies were randomized to receive either HBIG or placebo in addition to recombinant HBV vaccine (at 0, 6, 10 and 14 weeks). The primary end-point of the study, assessed at 18 weeks of age, was remaining free of any HBV infection (either overt or occult) plus the development of adequate immune response to vaccine. The babies were further followed up for a median of 2 years of age to determine their eventual outcome. Risk factors for HBV transmission and for poor immune response in babies were studied. Of the 283 eligible babies, 259 were included in the trial and randomized to receive either HBIG (n=128) or placebo (n=131) in addition to recombinant HBV vaccine. Of the 222 of 259 (86%) babies who completed 18 weeks of follow-up, only 62/222 (28%) reached primary end-point. Of the remaining, 6/222 (3%) developed overt HBV infection, 142/222 (64%) developed occult HBV infection, and 12/222 (5%) had no HBV infection but had poor immune response. All 6 overt infections occurred in the placebo group (P=0.030), while occult HBV infections were more common in the HBIG group (76/106 [72%] vs. 66/116 [57%]; P=0.025). This may be due to the immune pressure of HBIG. There was no significant difference between the two groups in frequency of babies developing poor immune response or those achieving primary end-point. The final outcome of these babies at 24 months of age was as follows: overt HBV infection 4%, occult HBV infection 42%, no HBV infection but poor immune response 8% and no HBV infection with good immune response 28%. Women who were anti-HBe positive were a low-risk group, and their babies were most likely to remain free of HBV infection (occult or overt) and had good immune response to the vaccine. Maternal HBeAg-positive status and negativity for anti-HBe predicted not only overt but also any infection (both overt and occult) in babies. In addition, high maternal HBV DNA and treatment with vaccine alone were significant factors for overt HBV infection in babies. The current practice of administration of vaccine with HBIG at birth to babies born of HBsAg-positive mothers is not effective in preventing occult HBV infection in babies, which may be up to 40%. Because the most important risk factors for mother-to-baby transmission of HBV infection are the replicative status and high HBV DNA level in mothers; it will be worthwhile investigating the role of antivirals and HBIG administration during pregnancy to prevent mother-to-child transmission of HBV infection.

Risk factors of HBV intrauterine transmission among HBsAg-positive pregnant women

Little is known about the risk factors associated with hepatitis B virus (HBV) intrauterine transmission among HBsAg-positive mothers. We conducted a study in Taiyuan, China, including 1133 HBsAg-positive mothers and their babies. A total of 101 neonates had HBsAg and/or HBV DNA positive with an intrauterine transmission rate of 8.9%. Maternal menstrual irregularity (OR = 4.95, 95% CI: 1.71, 14.33) and severe nausea during the first trimester (OR = 1.86, 95% CI: 1.11, 3.09) were associated with an increased risk of intrauterine transmission, while caesarean delivery (OR = 0.32, 95% CI: 0.20, 0.51) was associated with a decreased risk after adjusting for potential confounders. Maternal HBeAg positive was a strong independent predictor for intrauterine transmission (OR = 2.56, 95% CI: 1.54, 4.27). A positive association between maternal HBV DNA levels and intrauterine transmission was suggested. Maternal HBIG administration during pregnancy, family history of HBV infection and premature rupture of membranes was not associated with the risk of intrauterine transmission. The study confirmed that maternal HBeAg positive was a risk factor and caesarean delivery was a protective factor for intrauterine transmission. The new findings associated with menstrual irregularity and severe nausea during the first trimester warrant further investigation.

Role of maternal viremia and placental infection in hepatitis B virus intrauterine transmission

The mechanism of intrauterine hepatitis B virus infection has not been established. In this study, venous blood, cord blood, and placental tissues from 171 chronic hepatitis B virus infected pregnant women were tested for hepatitis B surface antigen, hepatitis B core antigen, and hepatitis B virus DNA. We found that residence, mode of delivery, age, and number of gestational weeks of pregnant women were not correlated with intrauterine hepatitis B virus infection, while neonates of mothers who were hepatitis B s antigen positive and hepatitis B e antigen positive (P < 0.01) or who had high hepatitis B virus DNA levels (≥10(6) copies/ml) were more likely to get an intrauterine infection (P < 0.01). The hepatitis B virus infection rate in placental cell layers gradiently decreased from the mother's side to the fetus's side of the placenta, but the odds ratio value of correlation between placental hepatitis B virus infection and intrauterine infection gradiently increased. The way of intrauterine hepatitis B virus infection may be through a layer-layer transmission pathway, although the possibility of placental leakage cannot be excluded.

Towards complete eradication of hepatitis B infection from perinatal transmission: review of the mechanisms of in utero infection and the use of antiviral treatment during pregnancy

Hepatitis B infection remains the most common form of chronic hepatitis. Mother to child transmission occurs despite immunoprophylaxis with vaccination and immunoglobulin. In utero infection is suggested to account for most of the cases with immunoprophylaxis failure. Infants who suffer from hepatitis B infection at birth have a higher risk of becoming chronic carriers and may develop liver cirrhosis or hepatocellular carcinoma in the future. Infected germ cells, transplacental infection, invasive prenatal diagnostic tests and various perinatal factors are possible factors leading to in utero infection and subsequent immunoprophylaxis failure. Hepatitis B e antigen positive status and high viral load increase the risk of immunoprophylaxis failure. Recent evidence shows promising results regarding the use of antiviral treatment in late gestation to suppress viral load, so as to decrease the risk of vertical transmission. This review discusses the possible mechanisms of in utero infection and the use of antiviral treatment during pregnancy.

Optimal management of HBV infection during pregnancy

Chronic hepatitis B virus (HBV) infection in pregnancy presents a unique and important challenge. Over 50% of chronic HBV carriers in endemic areas acquire infection vertically from their mothers. More importantly, over 90% of perinatally acquired infections progress to chronic HBV infection. Thus, management of chronic HBV during pregnancy and strategies to prevent mother-to-child transmission is an important step in eradicating or reducing the global burden of chronic hepatitis B. In addition, chronic HBV infection in pregnancy presents a unique clinical challenge because of the complex relationship between the physiological changes of pregnancy and the pathophysiological response to HBV. This review will present the current knowledge and a practical approach to management of HBV in pregnancy.

Correlation between vertical transmission of hepatitis B virus and the expression of HBsAg in ovarian follicles and placenta

Background

The aim of this study was to investigate the correlation between the expression of hepatitis B surface antigen (HBsAg) in human ovary and placenta and the vertical transmission of hepatitis B virus (HBV).

Methodology/Principal Fidnings

Ovarian and placental tissue specimens of pregnant women infected with HBV were collected during cesarean section and immunostained for HBsAg. The sera of the corresponding newborns were tested for HBV markers and HBV DNA. HBsAg was detected in 15 out of 33 (45%) placental tissues and was further detected in capillary endothelial cells in 4 specimens (26%), of which 3 (75%) corresponding infants were infected with HBV in utero. Out of the 33 ovarian tissues, 7 (21%) were positive for HBsAg, of which 2 (28%) showed HBsAg in ovarian follicles and the 2 corresponding infants (100%) had intrauterine HBV infection.

Conclusions/Significance

HBsAg expression in cells of the ovarian follicle or placental capillary endothelium signal a higher risk for intrauterine HBV infection.

HBV perinatal transmission

Hepatitis B is a serious public health problem all around the world. It is a blood-borne and sexually transmitted DNA virus in adults, but mother to child transmission of hepatitis B virus also occurs in infants born to hepatitis B surface antigen positive mothers.

Evaluation of liver enzymes in asymptomatic chronic hepatitis B virus infected pregnant women

BACKGROUND

The major risk factor for perinatal transmission of hepatitis B virus (HBV) infection and/or immunoprophylaxis failure is the level of maternal HBV-DNA. The aim of this study was to evaluate commonly used laboratory parameters in HBeAg-negative chronic HBV-infected pregnant women and to correlate the findings with the presence or absence of viremia.

METHODS

166 consecutive chronic HBV-infected pregnant women were hematologically, serologically and virologically evaluated between the 28th and 32nd week of gestation. 101 women were finally evaluated (66 HBV-DNA positive and 35 HBV-DNA negative). Twenty-one women exhibited HBV-DNA levels above 2000 IU/mL.

RESULTS

Viremic women exhibit significantly higher ALT (25.43 IU/L vs. 15.50 IU/L, P=0.016) and GGT (17.47 IU/L vs. 10.22 IU/L, P=0.001) values as well as significantly lower white blood cell (10527 vs. 13793, P=0.008) and neutrophil count (7776 vs. 11088, P=0.001), compared to non-viremic women. The optimal cut-off points discriminating those women with a high probability to have detectable serum HBV-DNA were 7 IU/L for GGT (sensitivity = 81.6%, specificity = 69.6%, area under the ROC curve (AUC) = 75.3%) and 12 IU/L for ALT (sensitivity = 74.1%, specificity = 56.2%, AUC = 65.4%). The positive predictive value of detectable HBV-DNA in women with both serum parameters above the new limits proposed was 88.8% whereas the negative predictive value was 75%.

CONCLUSION

Presence of HBV-DNA in maternal blood during the third trimester of pregnancy is significantly associated with maternal serum GGT levels. Women with GGT above 7 IU/L and ALT above 12 IU/L have a higher probability of HBV-DNA presence in maternal blood.

HIV-1 Nef breaches placental barrier in rat model

The vertical transmission of HIV-1 from the mother to fetus is known, but the molecular mechanism regulating this transmission is not fully characterized. The fetus is highly protected by the placenta, which does not permit microbial pathogens to cross the placental barrier. In the present study, a rat model was established to observe the effect of HIV-1 protein Nef on placental barrier. Evans blue dye was used to assay permeability of placental barrier and fourteen day pregnant Sprague Dawley rats were injected intravenously with 2% Evans blue dye along with various concentrations of recombinant Nef. After an hour, animals were sacrificed and dye migration was observed through the assimilation of peripheral blood into fetus. Interestingly, traces of recombinant Nef protein were detected in the embryo as well as amniotic fluid and amniotic membrane along with placenta and uterus. Our study indicates that recombinant HIV-1-Nef protein breaches the placental barrier and allows the migration of Evans blue dye to the growing fetus. Further the concentration of Nef protein in blood is directly proportional to the intensity of dye migration and to the amount of Nef protein detected in uterus, placenta, amniotic membrane, amniotic fluid and embryo. Based on this study, it can be concluded that the HIV-1 Nef protein has a direct effect on breaching of the placental barrier in the model we have established in this study. Our observations will be helpful to understand the molecular mechanisms related to this breach of placental barrier by Nef in humans and may be helpful to identify specific Nef inhibitors.

Chronic hepatitis B virus infection and pregnancy

Planning of pregnancy and management of chronic hepatitis B virus during pregnancy includes recognition of maternal virological status, assessment of liver disease severity and minimization of risk for mother to infant transmission of infection. Decisions regarding the use of antivirals during pregnancy need to be individualized. Monitoring for infection and immunization in newborns is also important. For mothers on antiviral therapy, breastfeeding is not recommended.

Hepatitis B in pregnancy

Chronic hepatitis B virus (HBV) infection affects about 350 million individuals worldwide. Management of HBV infection in pregnancy is difficult because of several peculiar and somewhat controversial aspects. The aim of the present review is to provide a tool that may help physicians to correctly manage HBV infection in pregnancy. This review focuses on (1) the effect of pregnancy on HBV infection and of HBV infection on pregnancy; (2) the potential viral transmission from mother to newborn despite at-birth prophylaxis with immunoglobulin and vaccine; (3) possible prevention of mother-to-child transmission through antiviral drugs, the type of antiviral drug to use considering their efficacy and potential teratogenic effect, and the timing of their administration and discontinuation; and (4) the evidence for the use of elective caesarean section vs vaginal delivery and the possibility of breastfeeding.

Hepatitis B virus infection and pregnancy: a practical approach

Hepatitis B virus (HBV) infection is a global problem and the world has 350 million carriers of chronic hepatitis B. Over 50 % of these have acquired their infection vertically from their mothers (mother-to-child transmission [MTCT]). Majority (>90 %) of vertically-acquired infection results into chronic infection, due to induction of an immune-tolerant state. Hence, management of chronic HBV during pregnancy and strategies to prevent MTCT would go a long way in global control of HBV infection and the morbidity and mortality associated with it. However, chronic HBV infection in pregnancy presents a unique challenge, because of existence of a complex relationship between the physiological changes of pregnancy and the pathophysiological response of body to HBV. This relationship may lead to a varied presentation of the patient to the doctor depending on the period of her pregnancy and stage of her liver disease. Each of these modes of presentation raises issues that need to be addressed for successful maternal and fetal outcome, including prevention of MTCT of HBV. This review will try to give a practical approach in addressing these issues.

Virologic factors associated with failure to passive-active immunoprophylaxis in infants born to HBsAg-positive mothers

In infants born to hepatitis B surface antigen (HBsAg)-positive mothers, failure after passive-active immunization still occurs. The role of maternal hepatitis B DNA level and other risk factors in this setting remains unclear. This study retrospectively evaluated virologic and other risk factors associated with immunoprophylaxis failure in infants born to HBsAg-positive mothers. Between January 2007 and March 2010, we reviewed the clinical and virologic tests in 869 mother-infant pairs. All infants received the identical passive-active immunization schedule after birth. The failure infants (HBsAg positive at 7-12 months of age) were compared to infants who were HBsAg negative when tested during this time period. Among 869 infants, 27 (3.1%) infants were immunoprophylaxis failures and the other 842 (96.9%) infants remained HBsAg negative. When mothers' pre-delivery HBV DNA levels were stratified to <6, 6-6.99, 7-7.99 and ≥ 8 log(10) copies/mL, the corresponding rates of immunoprophylaxis failure were 0%, 3.2% (3/95), 6.7% (19/282) and 7.6% (5/66), respectively (P < 0.001 for the trend). All failure infants were born to hepatitis B e antigen (HBeAg)-positive mothers. Multivariate logistic regression analysis identified maternal HBV DNA levels [odds ratio (OR) = 1.88, 95% confidence interval (CI): 1.07-3.30] and detectable HBV DNA in the cord blood (OR = 39.67, 95% CI: 14.22-110.64) as independent risk factors for immunoprophylaxis failure. All failure infants were born to HBeAg-positive mothers with HBV DNA levels ≥ 6 log(10) copies/mL. The presence of HBV DNA in cord blood predicted failure to passive-active immunization.

A meta-analysis of lamivudine for interruption of mother-to-child transmission of hepatitis B virus

AIM: To determine the therapeutic effect of lamivudine in late pregnancy for the interruption of mother-to-child transmission (MTCT) of hepatitis B virus (HBV).

METHODS: Studies were identified by searching available databases up to January 2011. Inclusive criteria were HBV-carrier mothers who had been involved in randomized controlled clinical trials (RCTs) with lamivudine treatment in late pregnancy, and newborns or infants whose serum hepatitis B surface antigen (HBsAg), hepatitis B e antigen (HBeAg) or HBV DNA had been documented. The relative risks (RRs) for interruption of MTCT as indicated by HBsAg, HBV DNA or HBeAg of newborns or infants were calculated with 95% confidence interval (CI) to estimate the efficacy of lamivudine treatment.

RESULTS: Fifteen RCTs including 1693 HBV-carrier mothers were included in this meta-analysis. The overall RR was 0.43 (95% CI, 0.25-0.76; 8 RCTs; P_{heterogeneity} = 0.04) and 0.33 (95% CI, 0.23-0.47; 6 RCTs; P_{heterogeneity} = 0.93) indicated by newborn HBsAg or HBV DNA. The RR was 0.33 (95% CI, 0.21-0.50; 6 RCTs; P_{heterogeneity} = 0.46) and 0.32 (95% CI, 0.20-0.50; 4 RCTs; P_{heterogeneity} = 0.33) indicated by serum HBsAg or HBV DNA of infants 6-12 mo after birth. The RR (lamivudine vs hepatitis B immunoglobulin) was 0.27 (95% CI, 0.16-0.46; 5 RCTs; P_{heterogeneity} = 0.94) and 0.24 (95% CI, 0.07-0.79; 3 RCTs; P_{heterogeneity} = 0.60) indicated by newborn HBsAg or HBV DNA, respectively. In the mothers with viral load < 10⁶ copies/mL after lamivudine treatment, the efficacy (RR, 95% CI) was 0.33, 0.21-0.53 (5 RCTs; P_{heterogeneity} = 0.82) for the interruption of MTCT, however, this value was not significant if maternal viral load was > 10⁶ copies/mL after lamivudine treatment (P = 0.45, 2 RCTs), as indicated by newborn serum HBsAg. The RR (lamivudine initiated from 28 wk of gestation vs control) was 0.34 (95% CI, 0.22-0.52; 7 RCTs; P_{heterogeneity} = 0.92) and 0.33 (95% CI, 0.22-0.50; 5 RCTs; P_{heterogeneity} = 0.86) indicated by newborn HBsAg or HBV DNA. The incidence of adverse effects of lamivudine was not higher in the mothers than in controls (P = 0.97). Only one study reported side effects of lamivudine in newborns.

CONCLUSION: Lamivudine treatment in HBV carrier-mothers from 28 wk of gestation may interrupt MTCT of HBV efficiently. Lamivudine is safe and more efficient than hepatitis B immunoglobulin in interrupting MTCT. HBV MTCT might be interrupted efficiently if maternal viral load is reduced to < 10⁶ copies/mL by lamivudine treatment.

Hepatitis B Virus Infection during Pregnancy: Transmission and Prevention

Hepatitis B virus (HBV) infection is a global public health problem. In endemic areas, HBV infection occurs mainly during infancy and early childhood, with mother to child transmission (MTCT) accounting for approximately half of the transmission routes of chronic HBV infections. Prevention of MTCT is an essential step in reducing the global burden of chronic HBV. Natal transmission accounts for most of MTCT, and providing immunoprophylaxis to newborns is an excellent way to block natal transmission. Prenatal transmission is responsible for the minority of MTCT not preventable by immunoprophylaxis. Because of the correlation between prenatal transmission and the level of maternal viremia, some authors find it sound to offer lamivudine in women who have a high viral load (more than 8 to 9 log 10 copies/mL). In addition to considerations regarding the transmission of HBV to the child, the combination of HBV infection and pregnancy raises several unique management issues. Chronic HBV infection during pregnancy is usually mild but may flare after delivery or with discontinuing therapy. Management of chronic HBV infection in pregnancy is mostly supportive with antiviral medications indicated in a small subset of HBV infected women with rapidly progressive chronic liver disease.

Hepatitis B in pregnancy: challenges and treatment

Hepatitis B virus (HBV) during pregnancy presents unique management challenges. Varying aspects of care must be considered, including the effects of HBV on maternal and fetal health, effects of pregnancy on the course of HBV infection, treatment of HBV during and after pregnancy, and prevention of perinatal infection. Antiretroviral therapy has not been associated with increased risk of birth defects or toxicity, but despite studies designed to elucidate the drug efficacy and safety in affected individuals and the developing fetus, recommendations are inconclusive. Clinicians and patients must make individualized decisions after carefully evaluating the risks and benefits summarized in this article.

Importance of maternal and cord blood viremia in pregnant women with chronic hepatitis B virus infection

BACKGROUND/AIM

The spontaneous preterm birth (SPB) rates in a group of HBeAg-negative chronic HBV infected pregnant women without several known risk factors for preterm delivery as well as the mother to infant HBV transmission rates was evaluated. Moreover the role of maternal data during perinatal period as well as the role of HBsAg and/or HBV-DNA presence in cord blood in respect to preterm labour and vertical transmission of the infection was examined.

METHODS

138 consecutive chronic HBV infected pregnant women were haematologically, serologically and virologically evaluated during the perinatal period. 102 women were finally evaluated and fifteen of them (14.7%) exhibited SPB. Overall, 44 infants who had completed the proposed vaccination schedule were evaluated at month 12 of their life.

RESULTS

A significant association between SPB and HBV-DNA presence in cord blood was observed (p=0.007). HBV-DNA positivity in cord blood was significantly associated with maternal HBV-DNA levels (p=0.002). The relative risk of HBV-DNA presence in cord blood was 6.43 times higher among women with serum HBV-DNA ≥ 10.000 copies/ml and lymphocyte count<1500 compared to those with all the other combinations of both parameters (p=0.001). All infants evaluated at month 12 were HBsAg-negative and exhibited undetectable HBV-DNA levels.

CONCLUSION

The presence of HBV-DNA in cord blood is significantly associated with SPB in chronic HBV infected pregnant women. Maternal or cord blood viremia does not pose an additional risk factor for vertical transmission of HBV infection, in passive-active immunoprotected infants from HBeAg-negative chronic HBV infected mothers.

In vitro study on hepatitis B virus infecting human choriocarcinoma JEG3 cells and its mechanism

AIM

To build a hepatitis B virus (HBV)-infected human trophoblast cell model in vitro and determine the mechanism of intrauterine HBV infection.

METHODS

Serum from hepatitis B-infected patients containing HBV DNA >10(9) was drawn, subsequently inoculated into human trophoblast cells in vitro (JEG3) and passage-cultured. The supernatants and intracellular HBV viral load of inoculated cells were tested by real-time PCR, and HBV DNA was determined by Southern blot.

RESULTS

From inoculation of the 1st passage JEG3 cells, the supernatant viral load of the 1st passage was seen increasing over time, which peaked at 120 h, whereas the HBV viral load was seen decreasing gradually in subsequent passages, and tested negative after the 6th passage. In addition, infected cells of HBV DNA were tested by Southern blot, and showed continual expression in the subsequent cell passages 1-5 while passage 6 was negative. HBsAg was tested as positive from different passages 1-5, and its concentration was also seen decreasing with each subsequent passage cultured until the 6th passage when it tested negative.

CONCLUSION

HBV could infect human trophoblast cells (JEG3) in vitro, and it showed continual expression in subsequent cell passages 1-5.

Viral infection of the placenta leads to fetal inflammation and sensitization to bacterial products predisposing to preterm labor

Pandemics pose a more significant threat to pregnant women than to the nonpregnant population and may have a detrimental effect on the well being of the fetus. We have developed an animal model to evaluate the consequences of a viral infection characterized by lack of fetal transmission. The experiments described in this work show that viral infection of the placenta can elicit a fetal inflammatory response that, in turn, can cause organ damage and potentially downstream developmental deficiencies. Furthermore, we demonstrate that viral infection of the placenta may sensitize the pregnant mother to bacterial products and promote preterm labor. It is critical to take into consideration the fact that during pregnancy it is not only the maternal immune system responding, but also the fetal/placental unit. Our results further support the immunological role of the placenta and the fetus affecting the global response of the mother to microbial infections. This is relevant for making decisions associated with treatment and prevention during pandemics.

Cellular immunity in children with successful immunoprophylactic treatment for mother-to-child transmission of hepatitis B virus

BACKGROUND

The administration of hepatitis B immunoglobulin followed by hepatitis B vaccine can result in a protective efficacy of almost 90% in mother-to-child transmission of hepatitis B virus (HBV). However, little is known about immunity against HBV infection in children after immunoprophylactic treatment. We tried to assess the association between T-cell responses and viremia in children after successful prophylactic treatment.

METHODS

Thirteen children and their 8 HBV carrier mothers (8 families), who were positive for human leukocyte antigen (HLA)-A24, were enrolled in this study. All of the 13 children received immunoprophylactic treatment and became negative for hepatitis B surface antigen (HBsAg) after birth. HBV-specific cytotoxic T lymphocyte (CTL) responses were evaluated using IFNgamma - enzyme-linked immunosorbent spot (ELISPOT) and major histocompatibility complex class I peptide pentamer assays. Serum HBV DNA was measured by real-time PCR.

RESULTS

Significant HBV-specific T-cell responses were detected in 2 (15%) of the 13 children by ELISPOT. However, the frequency of HLA-A24-HBV-specific CTLs was very low in both HBV carrier mothers and children using pentamers. Of the 13 children, 4 (31%) were positive for serum HBV DNA. However, the levels of serum HBV DNA were 100 copies/ml or less. One of the 2 children in whom significant HBV-specific CTL responses were detectable was positive for serum HBV DNA.

CONCLUSIONS

HBV core and polymerase-specific T-cell responses were detected and a low-dose viremia was observed in children after successful immunoprophylaxis treatment. Although the presence of viremia was not related to HBV-specific T-cell responses, CTLs might play a role in the control of HBV infection in children born to HBsAg-positive mothers after immunoprophylactic treatment.

HEPATITIS B AND PREGNANCY, THE SCIENTIFIC BASIS FOR PERINATAL PREVENTION

Hepatitis B and its complications are one of the major global health problems. Around 2 billion individuals are infected by hepatitis B virus (HBV) worldwide, more than 350 million are chronically infected, and approximately 15 to 40 percents of them will develop serious complications such as liver cirrhosis, hepatic failure, or hepatocellular carcinoma (HCC). The worldwide prevalence of chronic HBV infection ranges from 0.1 to 20 percent and varies widely in different geographic areas. According to the prevalence rate, WHO has classified countries into 3 levels: high areas (>8%) such as Africa, Asia, Western Pacific and Middle East; intermediate areas (2–8%) such as South America and Eastern Europe, and low areas (<2%) such as Western Europe, North America, and Australia.

Pregnancy and chronic hepatitis B virus infection

The combination of chronic hepatitis B virus (HBV) infection and pregnancy presents unique management questions. Aspects of care that need to be considered include effects of hepatitis B on pregnancy, effects of pregnancy itself on the course of hepatitis B infection, treatment of hepatitis B during pregnancy and prevention of mother-to-infant transmission. Chronic HBV infection is usually mild in pregnant women, but may flare shortly after delivery. Effect of HBV infection on pregnancy outcomes are generally favorable, but may depend on severity of liver disease. Mother-to-infant transmission can be minimized by current immunoprophylaxis strategies, however, high levels of viremia in mothers may be a factor in the small but reproducible failure rate of current immunoprophylaxis strategies. Use of antivirals during pregnancy needs to be individualized. Careful planning and management of pregnancy must be done among patients with chronic HBV infection.

Hepatitis B and pregnancy: an underestimated issue

Hepatitis B infection during pregnancy presents a unique set of management issues. Aspects of care that must be considered include maternal and fetal effects of hepatitis B, effects of pregnancy itself on the course of hepatitis B infection and its complications, treatment of hepatitis B during pregnancy and prevention of perinatal infection. There are insufficient studies to date regarding these concerns; most are from the Far East, and many have important limitations, but some have yielded valuable data. Pregnant women with acute hepatitis B virus (HBV) infection typically have a course not very different from that in the general adult population, but the risk of transmission of HBV to neonates increases the later in gestation the acute infection occurs. Chronic HBV infection is usually mild in pregnant women, but may flare shortly after delivery. The risk of perinatal transmission is highest in women with high levels of viraemia; this may be a factor in the small but reproducible failure rate of current immunoprophylaxis strategies. Obstetrical policies must be assessed with respect to detection of maternal infection and liver disease, as well as with respect to perinatal transmission risk. In addition to the usual issues of drug efficacy and safety in the affected individuals, effects on the developing fetus must be considered. This paper reviews the current experience in each of these areas, and highlights the need for further investigation into this critical but often underestimated topic.