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Zhonghua Liu Xing Bing Xue Za Zhi ; 31(12): 1332-5, 2010 Dec.
Artigo em Chinês | MEDLINE | ID: mdl-21223658


OBJECTIVE: To evaluate the long-term immunogenicity and effectiveness of live attenuated hepatitis A (HA) vaccine (H2 strain) after one dose injection, through a 15 years' follow up observation. METHODS: A total of 220 children with negative anti-HAV antibody (aged 1-3 y) were involved and followed up in Jiaojiang district, Taizhou city, Zhejiang province. Indicators would include seroconversion and geometric mean titer (GMT) levels after inoculation the vaccine with single dose at 2 m, 12 m, 6 years, 10 years and 15 years. Epidemiological observation was carried out within the 15 years to evaluate the relationship between vaccine coverage, the incidence of HA and the overall effectiveness. In the studied population, serum was tested by ELISA (calibrated by WHO international reference) and ABBOTT Axsym HAVAB mEIA. RESULTS: Seroconversion rates were found to be 98.6% and 81.3% after 2 months and 15 years of inoculation and slowly decreased. GMT level was 128 mIU/ml after 15 years, significantly higher than the required protective level of 20 mIU/ml, recommended by WHO experts. Effectiveness through the 15-year follow up program showed a significant correlation between vaccine coverage and incidence of HA in 1-15 years aged group (Kendall-Rank test, τ =-0.931, P<0.01). There was no HA case seen among the observed accumulated 236 413 person-year vaccines, compared to 4 HA cases discovered in the 27 206 person-year of the non-vaccinees. The overall protective rate reached 100%. Through a mass vaccination program on children, the whole population established an immune-defence to enable the incidence of HA decreased by 96.7%. CONCLUSION: The long-term immunogenicity and effectiveness of live attenuated hepatitis A vaccine (H2 strain) after one dose injection could last as long as 15 years.

Vacinas contra Hepatite A , Hepatite A/imunologia , Hepatite A/prevenção & controle , Adolescente , Criança , Pré-Escolar , China/epidemiologia , Feminino , Hepatite A/epidemiologia , Vacinas contra Hepatite A/imunologia , Humanos , Incidência , Lactente , Masculino , Vacinação em Massa , Vacinas Atenuadas/imunologia
World J Gastroenterol ; 13(34): 4630-5, 2007 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-17729420


AIM: To investigate the hotspots, direction, and the time course of evolution of hepatitis A virus in the process of consecutive cell culture passage in human KMB17 diploid cells. METHODS: Wild type hepatitis A virus H2w was serially propagated in KMB17 cells until passage 30, and the full-length genomes of H2w and its six chosen progenies were determined by directly sequencing RT-PCR products amplified from viral genomic RNA. Alignment comparison of sequences from H2w with its six progenies and phylogenetic analysis of the whole VP1 region from H2w, progenies of H2w, and other cell culture adapted hepatitis A virus were then carried out to obtain data on the molecular evolution of hepatitis A virus in the process of consecutive passage in KMB17 cells. RESULTS: Most of the mutations occurred by passage 5 and several hotspots related to adaptation of the virus during cell growth were observed. After that stage, few additional mutations occurred through the remaining duration of passage in KMB17 cells except for mutation in the virulence determinants, which occurred in the vicinity of passage 15. The phylogenetic analysis of the whole VP1 region suggested that the progenies of H2w evolved closely to other cell culture adapted hepatitis A virus, i.e. MBB, L-A-1, other than its progenitor H2w. CONCLUSION: Hepatitis A virus served as a useful model for studying molecular evolution of viruses in a given environment. The information obtained in this study may provide assistance in cultivating the next generation of a seed virus for live hepatitis A vaccine production.

Proliferação de Células , Diploide , Evolução Molecular , Vírus da Hepatite A/genética , Pulmão/virologia , Mutação , RNA Viral , Vacinas contra Hepatite Viral/genética , Linhagem Celular , Análise Mutacional de DNA , Bases de Dados Genéticas , Vírus da Hepatite A/crescimento & desenvolvimento , Vírus da Hepatite A/imunologia , Vírus da Hepatite A/patogenicidade , Humanos , Pulmão/citologia , Pulmão/embriologia , Filogenia , Fatores de Tempo , Vacinas contra Hepatite Viral/biossíntese , Fatores de Virulência/genética , Replicação Viral
Chin Med J (Engl) ; 118(22): 1851-6, 2005 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-16313838


BACKGROUND: Live attenuated hepatitis A vaccine (H2 strain) is widely applied in prevention of hepatitis A epidemic in China and other countries now. It is essential to observe and confirm the vaccine immune efficacy, population antibody level and its persistent efficacy after mass immunization. METHODS: A total of 220 children with negative anti-HAV antibody (aged 1 - 3 years) were taken for follow-up assay to observe seroconversion and geometric mean titre (GMT) level 2 months, 12 months, 6 years, and 10 years after inoculation. Another survey sampled from subjects of different age groups (3, 6, 9, 15, 18, 25 and 35 years) to compare anti-HA antibody positive rate before and after inoculation performed 10 years previously. Epidemiological observations were taken for 10 years to evaluate the relationship between vaccine coverage and hepatitis A morbidity. Serum antibody to HAV was detected by enzyme linked immunoassay (ELISA, calibrated by WHO international reference) and ABBOTT Axsym HAVAB microparticle enzyme immunoassay. RESULTS: Seroconversion in follow-up assay 2 months and 10 years after inoculation was 98.6% and 80.2% respectively. For children, the vaccination anti-HA antibody positive rates were significantly different before and after 10 years, 7.69% cf 70.45% (aged 3 years) and 52.58% cf 71.78% (aged 18 years). When vaccine coverage rose from 57% to 74%, there were no any HA epidemics. When vaccine coverage reached 85%, there were no any HA cases. With vaccine coverage between 85% and 91%, there were no any HA cases in cohorts from the age of 1 year to 15 years during the 10 years. CONCLUSIONS: Live attenuated hepatitis A vaccine has an obvious long-term effectiveness in prevention and control of HA epidemics through mass vaccination.

Vacinas contra Hepatite A/imunologia , Hepatite A/prevenção & controle , Vacinação em Massa , Adolescente , Adulto , Criança , Pré-Escolar , Ensaio de Imunoadsorção Enzimática , Seguimentos , Anticorpos Anti-Hepatite/sangue , Humanos , Imunoglobulina G/sangue , Vacinas Atenuadas/imunologia
World J Gastroenterol ; 6(6): 829-832, 2000 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-11819704


AIM:To investigate the protective efficacy of H2 strain attenuated live hepatitis A vaccines (H2-strain vaccines) in hepatitis A (HA) outbreaks.METHODS:With the permission of their parents, 5551 pre-school and grade 1-3 primary school children were inoculated with 1 dose (10(6.5) TCID(50)) of H2 strain vaccines in a nonrandomized, controlled trial conducted in Fucheng County, Hebei Province in May 1997.Another 6485 children in the same grades and compatible in gender and age were enrolled as controls. Epidemiological and serological survey was conducted to evaluate the protective efficacy of the vaccines. ELISA was used to detect serum IgM anti-HAV.RESULTS:HA outbreak started in early May 1998, peaked in the middle of the same month, and lasted about 80 days. Overall 302 HA cases were found, 192(63.58%) were 5-9 years old. One vaccinee and 25 control cases were found to have hepatitis A, which account for 0.28% (1/356) and 5.92% (25/422) of all vaccinees and controls in the 14 villages, respectively. The protective efficacy of vaccines was 95.27% (95% CI: 85.83%-104.72%). In subjects tested for anti-HAV IgM from 13 villages, 1(0.40%) overt and 11(4.06%) asymptomatic HAV cases were found in 271 vaccinees but 21(6.69%) of overt and asymptomatic ones were found in 314 controls.CONCLUSION:H2 strain vaccines were excellent in preventing overt hepatitis A,but not so effective in preventing asymptomatic hepatitis A virus infection.A booster dose might be needed to get permanent reliable immunity.