[Long-term immunogenicity and effectiveness of live attenuated hepatitis A vaccine (H2-strain)-a study on the result of 15 years' follow up].

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.

Molecular evolution of hepatitis A virus in a human diploid cell line.

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.

Persistent efficacy of live attenuated hepatitis A vaccine (H2-strain) after a mass vaccination program.

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.