[A seroepidemiologic analysis of hepatitis B in Sichuan province].

OBJECTIVE: To understand the changes of hepatitis B infection rates, before and after the hepatitis B vaccine was included into EPI, and to evaluate the effect of immunization which would lead to the development of a more appropriate hepatitis B control strategy. METHODS: Seroepidemiologic method, with multi-section random sampling method were chosen. 14 sites from 8 counties were involved. 2-4 ml of the vein blood was drawn from all the individuals engaged in the study including 3806 samples. HBsAg, anti-HBs, anti-HBc of the samples were tested with ELISA. RESULTS: Standardized positive rates of HBsAg and HBsAb were found as 7.05% and 29.77% respectively with the overall infection rate of HBV as 40.30%. The hepatitis B vaccine coverage of the children under 15 years was 70.73% and the positive rates for both HBsAg and anti-HBs were 2.62% and 56.68%, respectively. The coverage of hepatitis B vaccine among children under 3 years was 83.44% and the positive rates of both HBsAg and anti-HBs were 1.47% and 67.69% respectively, hepatitis B vaccine coverage of children under 3 years was 85.77%, with positive rates of HBsAg and anti-HBs as 1.78% and 75.44% respectively. CONCLUSION: Results from our study revealed that since the introduction of hepatitis B vaccination, the prevalence rates of HBsAg and HBV infection had an obvious decline, especially in children aged under 15 years of old, suggesting that some changes had occurred in the epidemic characteristics of hepatitis B in Sichuan.

[Analysis on mutation of S gene and P gene of hepatitis B virus in two counties of Sichuan Province].

OBJECTIVE: To analyze HBV S gene/P gene mutation in 2 counties (districts) of Sichuan province. METHODS: HBV DNA were extracted from sera positive both for HBsAg and HBeAg. After PCR and nucleotide sequencing, nucleotide/amino acid mutation in S and P gene were compared and analyzed. RESULTS: Of 47 serum samples from patients with chronic HBV infection, amino acid mutation in 'a' determinant occurred in 12 samples (25.53%,12/47), correlating with T126A, I126T/S, P127T, T131N, M133L, M133T and T140I; high proportion of mutation clustered in first loop of 'a' determinant (92.86%,13/14), rtV207I mutation in C domain of reverse transcription occured in one sample. CONCLUSION: Naturally occurring mutation in 'a' determinant clustered predominantly in the first loop and usually associated with altered antigenicity, posing a potential threat to successfully vaccinated individuals; Lamivudine-resistant mutant might occur in patient even without nucleotide analogue treatment.

[D9 measles virus was first isolated from an imported measles case in Sichuan Province of China].

OBJECTIVE: To isolate and identify the genotype and molecular characteristic of an imported D9 measles virus. METHOD: To isolate the virus with Vero/SLAM cell line. And RT-PCR (reverse transcription-polymerase chain reaction) were performed to amplify the 450 nucleotide acids of carboxyl terminal of N (nucleoprotein, N) protein. The phylogenetic tree was constructed and the homology similarity was analyzed. RESULTS: Sichuan isolate MVi/Sichuan.CHN/07.09/1 was clustered within the same genotype group with WHO D9 genotype reference strain, the homology of nucleotide acid between Sichuan isolate and WHO D9 genotype reference strain was 96.9%. The homology of nucleotide acid and amino acid between Sichuan isolate and 2008 D9 genotype representative strain were 99.8%-100% and 99.3%-100% respectively. Compared with the Chinese measles vaccine strain, the homology of nucleotide acid and amino acid of Shanghai-191 were 92.3% and 90.7% respectively. Compared with the endemic H1 genotype representative measles strain, the homology of nucleotide acid and amino acid were 90.8% and 92.1% respectively. CONCLUSION: The imported virus was D9 genotype measles virus.

[Genetic characterization of Chinese rubella virus isolates from 2003 to 2007].

57 rubella virus strains were isolated using Vero cell line or Vero/SLAM cell line from patients' throat swabs during rubella outbreaks and sporadics in 10 provinces of China from 2003 to 2007. Fragments of 1107 nucleotides of E1 genes of the isolates were amplified by RT-PCR, the PCR products were directly sequenced and analyzed. The phylogenetic analysis based on 739 nucleotides showed that out of 57 Chinese rubella virus strains, 55 belong to a distinguish branch of 1E genotype when comparing with 1E genotype rubella strains from other countries, and the other 2 Chinese rubella virus strains belong to 2B genotype. Most of the nucleotide mutations of 57 rubella viruses were silent mutations, and the amino acid sequences were highly conserved. Except one amino acid change (Thr212 --> Ser212) in two rubella viruses at the hemagglutination inhibition and neutralization epitopes, there had no change found at the important antigenic epitope sites of the other rubella viruses. 1E genotype rubella viruses isolated from 10 provinces of China from 2003 to 2007, and two imported 2B genotype rubella viruses from Vietnam suggested that 1E genotype was the predominant genotype in this period of time. The rubella virus genotypes circulated during 2003 to 2007 were different from that circulating during 1979 to 1984 and 1999 to 2002, the rubella prevailed in recent years was mainly caused by 1E genotype rubella viruses with multi-transmission routes.