Impacts Of Antiviral Therapy For Blocking Mother-to-child Transmission Of HBV On Postpartum Liver Function And Virus Quasispecies

BackgroundMother-to-child transmission(MTCT)is the main route for chronic hepatitis B virus(HBV)infection in China.High HBV DNA load in pregnant women is a risk factor for MTCT of HBV.A large number of clinical studies have shown that taking nucleos(t)ide analogues(NAs)during the second and third trimesters of pregnancy can further reduce MTCT of HBV in pregnant women with high HBV DNA load.Therefore,most domestic and foreign guidelines for prevention and control of hepatitis B recommend that pregnant women with a high HBV DNA load take NAs to reduce the risk of MTCT during second and third trimesters of pregnancy.Currently,there is still controversy about the optimal time of stopping antiviral therapy.In previous studies,antiviral therapy were mostly stopped 1-3 months after delivery and the results showed that antiviral drug withdrawal did not increase the risk of hepatitis flare.However,there were limited data on the safety of antiviral drugs withdrawal immediately after delivery.HBV exists in the host in a quasispecies form.The viral quasispecies not only affect the severity and prognosis of HBV-infected patients,but also are closely related to HBeAg immune clearance,the response to antiviral treatment and drug resistance.At present,studies on viral quasispecies in pregnant women with chronic HBV infection mainly focus on the role of the virus quasispecies in MTCT.There are few studies on the evolution of viral quasispecies and the risk of drug resistance during the short-course antiviral treatment in this patient population.A study reported that short-term lamivudine(LAM)treatment durnng pregnancy could raise the complexity of virus quasispecies in pregnant women with cheronic HBV infection and positively select resistance-associated variants(RAVs).However,the effects of short-course tenofovir disoproxil fumarate(TDF)and telbivudine(LdT)therapy durnng pregnancy on virus quasispecies heterogeneity,the evolution of quasispecies durnng treatment,and the potential risk of drug resistance remain unknown.The virus quasispecies heterogeneity is closely related to the host's immune response to HBV.At present,it is generally believed that the postpartum hepatitis flare occurred in pregnant women with chronic HBV infection is related to the irmmune clearance caused by rapid recovery of immune function after delivery.We hypothesized that HBV quasispecies heterogeneity may be associated with postpartum abnormal liver function.The next-generation sequencing technology is a new high throughput sequencing technology.It has high sensitivity and efficiency in detecting low abundance virus variants and quasispecies simulation.Objectives1.To explore the impact of cessation of antiviral drug at delivery on postpartum liver function in mother with chronic HBV infection who receive TDF or LdT therapy during pregnancy,and factors associated with postpartum liver function abnormality.2.To understand how the short-course TDF and LdT therapy for blocking MTCT of HBV during pregnancy affect the quasispecies heterogeneity of the HBV reverse transcriptase(RT)region and it's potential risk of drug resistance.3.To explore the correlation between the evolution of viral quasispecies in the HBV RT region during pregnancy and postpartum abnormal alanine aminotransferase(ALT).MethodsPart OneA retrospective cohort study was conducted at Nanfang Hospital and Guangzhou Eighth People's Hospital from June 2012 to June 2018.We enrolled chronic HBV inf-ection 412 pregnant women with HBV DNA>2>x106 xU/ml and ALT<2xULN.Clinical data including demographic information,NAs treatment information,HBV DNA loads during pregnancy and after delivery,as well as liver function were collected.According to the usage of antiviral drugs starting at baseline(28±4 weeks of gestation),these patients were divided into 3 groups,169 cases in TDF group,198 cases in LdT group,and 45 cases control group.Pregnant women in the TDF group and the LdT group received TDF and LdT once daily from 28±4 weeks of gestation until the time of delivery.1.The ALT levels and abnormal liver function(ALT?2XULN)rates after delivery were compared among the three groups.2.The outcomes of patients with postpartum abnormal liver function after delivery were described.3.A multivariate robust Poisson regression model was constructed to analyse the factors associated with postpartum abnormal liver function.Part TwoA prospective study was conducted at Nanfang Hospital,including 21 chronic HBV infection pregnant women who received antiviral treatment since the 28±4th week of gestation.The antiviral treatments was stopped at delivery.Blood samples for HBV DNA extraction were taken at the baseline,4 weeks of antiviral treatment,and 4-8 weeks after delivery.1.The NGS sequencing technique combined with bioinformatic methods was used to study the characteristics of quasispecies in the HBV RT region,and the dynamic changes of viral quasispecies heterogeneity during the treatment of and after the withdrawal of TDF and LdT were compared.2.The HBV RAVs durnng and after antiviral therapy were detected.3.To analyses the correlation between the evolution of viral quasispecies in the HBV RT region during pregnancy,and postpartum ALT abnormality(ALT>1 xULN).ResultsPart One1.Within 1 to 3 months after delivery,abnormal liver function was observed in 19.7%(81/412)patients.The rates of postpartum abnormal liver function in LdT group was significantly lower than that of control group(13.1%vs.37.8%,P<0.05).However,when the TDF group(22.5%)was compared with the LdT group and control group,no significant difference was noticed(all P>0.05).The postpartum ALT levels in the TDF group and LdT group were significantly lower than that of the control group(The medians and quartiles were 35(23-66)U/L,37(26-58)U/L and 62(31-110)U/L,respectively.The P values were 0.042 and 0.004,respectively),while no significant difference was found between these two medication groups(P=0.747)2.Most liver function abnormality is mild or moderate,vwhich usually could be relieved by antiviral treatment and/or liver-protective therapy,and some can resolve spontaneously.3.The higher the baseline ALT level was,the higher the risk of postpartum abnormal liver function would be(P=1.011,95%Cl:1.006?1.016,P<0.001).The risk of postpartum abnormal liver function was lower in patients treated with LdT during pregnancy than those without antiviral therapy(PR=0.353,95%Cl 0.188?0.663,P=0.001).Part Two1.During the treatment and after the withdrawal of antiviral drugs in pregnant women with chronic HBV infection who received short-term TDF and LdT treatment,no significant changes were noticed in the quasispecies complexity and diversity of HBV RT region.Whether the Sn value or the HD value,the main effect between the time points,the main effect between the two groups,and the interaction between the time points and the drugs did not reach statistical significance.(P>0.05).2.RAVs(Frequency?0.1%)could be detected in all patients in both the TDF group and LdT group.Apart from a patient in the TDF group who had a mutation frequency of 1.32%in A181T at 4 weeks postpartun(this value was 0.79%before treatment),all RAVs were detected at low frequency(<1.0%).3.The quasispecies complexity of HBV RT during pregnancy in the postpartum ALT abnormal group was significantly higher than that of the postpartum ALT normal group.Baseline quasispecies complexity(Sn)of HBV RT could predict the postpartum ALT abnormality,and the area under the ROC curve was 0.897(95%Cl,0.749?1.000,p=0.007).Conclusions1.For chronic HBV infection pregnant woman who received antiviral therapy with TDF or LdT during pregnancy,the cessation of antiviral drug at delivery does not increase the risk of postpartum abnormal liver function.The higher the baseline(28±4 week of gestation)ALT level was,the higher the risk of postpartum abnormal liver function would be.The risk of postpartum liver function abnormality was lower in patients treated with LdT during pregnancy than those without antiviral therapy.2.Short duration treatment of TDF and LdT for blocking MTCT of HBV during pregnancy had no significant effect on quasispecies heterogeneity in HBV RT region,with low potential risk of drug-resistant mutations.3.The baseline(28±4 week of gestation)HBV RT quasispecies complexity could predict the postpartum ALT abnormality in pregnant woman with chronic HBV infection.