Molecular Epidemiological Study On Blocking Mother-to-Child Transmission Of Hepatitis B Virus

Objective:To observe the immunoprophylactic effect of interrupting Mother-to-Child-Transmission(MTCT)of HBV in areas where have implemented the Cooperation Project of Hepatitis B Vaccine Safe Injection of Global Alliance for Vaccines and Immunization;Analyze the Characteristics of HBV serology and gene sequence,and try to find the risk factors associated with immunoprophylactic failure.Methods:During 2013 to 2015,HBsAg positive mothers,as well as their newborns were recruited to the study in Jilin,Henan,Gansu and Sichuan Province.Acording to the '0-1-6' month planned process,comprehensive Immunization program with Hepatitis B vaccine(HepB)and Hepatitis B immune globulin(HBIG)was carried out to all children.Blood collection from mother-child pairs was conducted when the course was complete.Detect the serological makers of mother-child pairs,as well as the HBV DNA load of mothers,and analyze the virologic factors associated with children's immunoprophylactic failure.Amplify and sequence the HBV and analyze the genotype,serotype and gene mutations.Finally,make statistical analysis to the data above.Part 1:Results:Totally,960 mother-child pairs were recruited,including 960 HBsAg positive mothers and their 969 children.1.The serological markers of mothers Group A:Mothers with ' HBsAg(+),Anti-HBc(+)' accounted for 13.85%(133/960);Group B:Mothers with 'HBsAgc(+),HBeAg(+),Anti-HBc(+)'accounted for 27.60%(265/960);Group C:Mothers with 'HBsAg(+),Anti-HBe(+),Anti-HBc(+)' accounted for 58.54%(562/960).Provincial serological profiles were not different in statistics(P>0.05).2.The HBV DNA load of mothers Mothers of Group B had the highest HBV DNA load(imedian:1.17×107 IU/ml):and Mothers of Group A(median:1.55×102 IU/ml);Mothers of Group C had the lowest load(median:9.30×101IU/ml).There was no difference between Group A and C.3.The serological markers of childrenThe positive rate of Children's HBsAg,Anti-HBs,Anti-HBc,HBeAg and Anti-HBe were 4.02%(39/969),91.64%(888/969),13.73%(133/969),2.37%(23/969)and 1.96%(19/969),respectively.4.The correlation between mother's HBeAg and children's HBV infectionThe positive rate of HBsAg in Children delivered by HBeAg positive mothers was 9.67%,while it was 1.86%in the negative group(?2=30.6717,P<0.0001;RR=5.654,95%CI:2.860?11.179);The positive rate of HBeAg in Children delivered by HBeAg positive mothers was 7.43%,while it was 0.43%in the negative group(?3=41.1663,P<0.0001;RR=18.661,95%CI:5.498-63.341).5.The correlation between mother's HBV DNA load and children's HBV infection The positive rate of HBsAg in Children delivered by mothers with HBV DNA load higher than 106IU/ml was 9.05%,while it was 2.34%in children delivered by mothers with HBV DNA load lower than 106IU/ml(?2=21.2329,P<0.0001;RR=4.152,95%CI:2.166-7.958).The positive rate of HBeAg in Children of mothers with HBV DNA load higher than 106IU/ml was 6.17%,while it was 1.10%in children of mothers with HBV DNA load lower than 106IU/ml(?2=20.2032,P<0.0001;RR=5.905,95%CI:2.472?14.107)?6.The immunoprophylactic effect of children(1)The immune response to HepBThe unresponsiveness(the Anti-HBs titer<10mIU/ml)rate was 8.36%;the low response(the Anti-HBs titer:10?100mIU/ml)rate was 18.89%;and the normal response(the Anti-HBs titer ? 100mIU/ml)rate was 72.26%.(2)The immunoprophylactic success in childrenTotally,881 children had the Anti-HBs higher than 1 OmIU/ml,and with negative HBsAg.Then the immunoprophylactic success rate was 90.92%(881/969).(3)The immunoprophylactic failure in childrenThe immunoprophylactic failure rate of children was 5.26%(51/969).And the HBeAg positive children accounted for 45.10%(23/51).The immunoprophylactic failure rate of children delivered by HBeAg positive mothers was 10.04%,while it was 3.43%in the negative group(?2=17.0208,P<0.0001;RR=3.143,95%CI:1.779?5.553).The immunoprophylactic failure rate of children delivered by mothers with HBV DNA load higher than 106IU/ml was 9.47%,while it was 3.86%in children delivered by mothers with HBV DNA load lower than 106IU/Ml(?2=11.4845,P=0.0007;RR=2.606,95%CI:1.471?4.618).Summary:In studied areas,the proportion of HBeAg seroconversion in chronically HBV infected pregnant women was lower than other domestic areas.The positive HBeAg predicts higher HBV DNA load and HBV replicates highly in the body.The immunoprophylactic failure rate of children in studied areas was low.The positive HBeAg and the HBV DNA load higher than 106IU/ml in mothers were risk factors for children's immunoprophylactic failure,which indicated the research direction of reducing mother's HBV DNA load to promote the mmunoprophylactic effect.The children had good immune response effect to current HepB.The positive rate of Children's HBeAg was relative high,which predict the immune tolerance.Part 2:Results:1.The comparison of the whole HBV sequences in mother-child pair The evolution distance of all the fourteen pairs were between 0.000?0.009.Mothers had the same genotype and serotype with their children,including 10 pairs of genotype C,3 pairs of genotype B,and one pair of C/D recombinant type;10 pairs of serotype adr,3 pairs of serotype adw,and one pair of serotype ayw.The gene mutations between mother and child in the same pair were not completely same.Amino acid mutations of S3N,V14A,T123A,S174N in the S gene region,BCP A1762T/G1764A,G1896A and deletion mutation(nt2068-2298)in the C gene region did not transmit to children;But amino acid mutations of G44E,P46T,S53L,S61L,168T,L1101,T113S,F134Y,A159G,V168A,V194A,N207 and I218L in the S gene region.S87G in the C gene region transmitted to the children.New mutations occurred in the process of MTCT,G7R,G10R and Q129H,for example.2.The HBV genotype and serotype in chronically HBV infected mothers Genotype:The dominant genotype in Jilin and Henan Province was C,with 84.48%and 92.13%.Genotype C(58.14%)and D(32.56%)were dominant in Gansu Province.And genotype B(62.75%)and C(33.33%)were dominant in Sichuan Province.Serotype:The dominant serotype in Jilin and Henan Province was adr;and it was adr and ayw in Gansu,adw and adr in Sichuan.Genotypes correlated with serotypes:genotype B was primarily composed of serotype adw(96.36%),genotype C was primarily composed of serotype adR(98.05%),and genotype D was composed of serotype ayw(P<0.0001).3.The amino acid mutations in the S gene region and a determinant The amino acid mutation rate of the S gene was 62.00%(173/279),and the most active sites were V/T47A/E/K/L/P,F134Y/L,N207S/T and so on.The mutation rate of a determinant was 15.77%(44/279),and the most active sites were F134Y/L,I/T126S/A and so on.Compared to genotype B and C,genotype D had the highest mutation rate in the S gene region(100%)and a determinant(93.75%)(P<0.05).4.The correlation between genotype,amino acid mutation and immunoprophylactic failure5.There were no statistical differences of genotype composition,amino acid mutation rate between immunoprophylactic failure group and success group(P>0.05).Summary:The evolution distance based on the whole HBV genome between mother and child was very near,with the same genotype and serotype.But the gene mutations were not completely same between mother and child.There were geographic distributions both in genotype and serotype:In studied mothers,C and adr were the dominant type in Jilin and Henan Province,B and adw were the dominant types in Sichuan Province,and genotype C,D and serotype ayw,adr were prevailed in Gansu.The genotypes with communication superiority were not found.The current HepB seems had the equal immunoprophylactic effect for the three genotypes.The S gene region was mutable.The frequency of amino acid mutations associated with immune escape in the a determinant was low both in the success and failure group.The a determinant mutation could not account for the immunoprophylactic failure for all the children.Conclusion:Acording to the '0-1-6' month planned process,the comprehensive Immunization program with Hepatitis B vaccine(HepB)and Hepatitis B immune globulin(HBIG)carried out to all children born to HBsAg positive mothers,achieved good effect in Chinese areas covered by the GAVI Program:the immunoprophylactic success rate up to 90%,failure rate about 5%and the unresponsiveness rate about 8%.The positive HBeAg and the HBV DNA load higher than 106IU/ml in mothers were risk factors for children's immunoprophylactic failure,which indicated the research direction of reducing mother's HBV DNA load to promote the mmunoprophylactic effect.There were geographic distributions both in genotype and serotype:In studied mothers,C and adr were the dominant type in Jilin and Henan Province,B and adw were the dominant types in Sichuan Province,and genotype C,D and serotype ayw,adr were prevailed in Gansu.The genotypes with communication superiority were not found.The current HepB seems had the equal immunoprophylactic effect for the three genotypes.The evolution distance based on the whole HBV genome between mother and child was very near,with the same genotype and serotype.But the gene mutations were not completely same between mother and child.The frequency of amino acid mutations associated with immune escape in the a determinant was low both in the success and failure group,which could not account for the immunoprophylactic failure for all the children.