[Long-term efficacy of infant hepatitis B immunization program].

OBJECTIVE: To evaluate the long-term efficacy of infant hepatitis B (HB) immunization program on preventing hepatitis B virus (HBV) infection, and to assess its impact on the incidence of HB in children. METHODS: Since 1986, the universal HB vaccination for newborn babies with standard, pediatric dose had been launched without serologic prescreening of pregnant women for HBsAg, in a high endemic county of Long-An. A hepatitis surveillance system was set up to evaluate the possible impact on the incidence of hepatitis B. To serologically evaluate the effectiveness of the program, a stratified random sampling of 1000 children in 1987 birth cohorts, who received plasma-derived HB vaccine, was recruited for long-term follow up at the age of 1 to 13 years. A cross-sectional seroepidemiological survey was conducted in the county in 1985, before the program, and in 2001, for 1551 children born in 1996-2000 who were administered yeast recombinant HB vaccine. RESULTS: During the 1 to 13 years after the program, the rates of HBsAg-positive were 0.7% to 2.9% with an average of 1.7% and the protective rates were 83.5% to 96.6%. HBV infection rates were 1.1% tp 5.1% with an average of 2.4% and the protective rates were 93.5% to 98.4%. For the population aged 1 to 4 years who were immunized with recombinant HB vaccine, HBsAg positive rates were 1.8% to 2.4% with an average of 2.0% and the protective rates were 78.4 to 85.2%. 14 years after the program, the cumulative incidence of acute hepatitis B in the children aged 1 to 14 years fell to 1.5 cases per 100,000 children, down 91.8% as compared with that in 1985 to 1987. However, the cumulative incidence of 14.4 cases per 100,000 population in unvaccinated children was not significantly different from that in the history controls. Acute hepatitis B children had not been reported, showing that the vaccination program was 100% protective in children. CONCLUSION: The universal infant HB vaccination program in a hyperendemic area has proved to be effective in controlling HBV infection and decreasing the incidence of acute hepatitis B in children. Booster dose is unnecessary in 13 years after the immunization. The protective efficacy of yeast recombinant HB vaccine is similar to that of plasma-derived HB vaccine.

Enhancement effect of ultrasound-induced microbubble cavitation on branched polyethylenimine-mediated VEGF(165) transfection with varied N/P ratio.

One isoform of the vascular endothelial growth factor, VEGF(165), has been reported to be a dominant mediator and regulator of angiogenic process, which plays an important role in treating cardiovascular diseases and chronically ischemic wounds. Branched polyethylenimine (bPEI) has been widely used as a non-viral delivery vector for gene therapy. Although bPEI-mediated DNA transfection efficiency can be raised by increasing the PEI nitrogen:DNA phosphate (N/P) ratio, cytotoxicity increases as well. In this study, the enhancement effect of microbubble inertial cavitation (IC) on bPEI-mediated VEGF(165) transfection was investigated, in an effort to optimize transfection efficiency using low N/P ratios. HEK 293T cells, mixed with bPEI:VEGF(165) complexes, were exposed to 1-MHz ultrasound pulses. The results show that: (1) IC activity induced by microbubble destruction can be quantified as an IC "dose" (ICD) and will increase with increasing acoustic driving pressure; (2) larger sonoporation pores can be generated by increasing ICD; (3) the transfection efficiency can be enhanced by increasing ICD until reaching a saturation level; and (4) microbubble IC activity has less cytotoxicity than bPEI, although a combinatorial effect of microbubble IC activity and bPEI could be observed on cell viability. The results suggest that, with appropriate ultrasound parameters, it is possible to optimize bPEI-mediated VEGF transfection efficiency using relatively low N/P ratios by employing ultrasound-induced microbubble inertial cavitation.

[Efficacy of recombinant hepatitis B vaccine and low-dose hepatitis B immune globulin in preventing mother-infant transmission of hepatitis B virus infection].

OBJECTIVE: To determine the efficacy of recombinant hepatitis B (rHB) vaccine and low-dose hepatitis B immune globulin (HBIG) in the prevention of mother-infant transmission of hepatitis B virus (HBV) infection. METHODS: rHB vaccine was administered to two groups of healthy neonates born to mothers with both hepatitis B surface antigen and e antigen positive in Guangxi, Hunan and Hebei province. Two hundred eighty-nine subjects were included in active immunization group, receiving triple doses of rHB vaccine given i.m. at 0, 1 and 6 month intervals; while 186 subjects receiving 50 IU HBIG at birth with triple doses of rHB vaccine in the low-dose HBIG group. RESULTS: Efficacy of active immunization alone was 87.8% (95% CI: 83.6 - 91.9). Efficacy of rHB vaccine and HBIG was 91.2% (95% CI: 86.7 - 95.6). No significant differences in efficacy by type of rHB vaccine (P = 0.707 2), immunoprophylaxis programs (P = 0.295 5) and regions of living (P = 0.998 7) were noticed. Seroprotection rates (anti-HBs >or= 10 mIU/ml) were detected in 91.1% and 93.5% in rHB vaccine alone recipients and rHB vaccine plus HBIG recipients, with geometric mean titer (GMT) of 153 mIU/ml and 164 mIU/ml at 1 year of age, respectively. Anti-rHBs decreased significantly with years after vaccination (chi(2) = 60.47, P = 0.000 1). Seroprotection rates of anti-rHBs antibodies decreased to 65.0% and 66.6% at 4 years of age in rHB vaccine alone recipients and rHB vaccine plus HBIG recipients, with GMT of 55 mIU/ml and 56 mIU/ml, respectively. CONCLUSION: These results suggested that the effectiveness of rHB vaccine plus low-dose HBIG was much better than only active plasma-derived vaccine; however, methods used for anti-rHBs assay need to be evaluated and verified.

A 12-year cohort study on the efficacy of plasma-derived hepatitis B vaccine in rural newborns.

AIM:To understand the anti HBs persistence and the long-term preventive efficacy in rural newborns after vaccination with plasma-derived hepatitis B vaccine.METHODS:In the time of expanded program on immunization (EPI), the newborns were vaccinated with 10&mgr;gcenter dot3 doses of hepatitis B vaccine and 762 newborns who were HBsAg negative after primary immunization were selected for cohort observation from 1986 to 1998. Their serum samples were detected qualitatively and quantitatively for hepatitis B infecting markers, including HBsAg, anti-HBs and anti-HBc by SPRIA Kits. The annual HBsAg positive conversion rate was counted by life-table method.RESULTS:(1)The anti-HBs positive rate was 94.44% for the babies born to HBsAg negative mothers and 84.21% for those born to HBsAg positive mothers in the 1st year after immunization, and dropped to 51.31% and 52.50% in the 12th year respectively.GMT value was dropped from 31.62 to 3.13 and 23.99 to 3.65 in the 2nd to the 12th year respectively. There was a marked drop in GMT at the 3rd to the 5th year, and in anti HBs positive rate at the 9th to the 10th year. (2) In the period of 12 years observation, the person-year HBsAg positive conversion rates were 0.12% (5/4150.0) in newborns born to HBsAg negative mothers and 0.20% (1/508.0) in those born to HBsAg positive mothers, and none of the HBsAg positive converted children became HBsAg chronic carriers. Compared with the baseline before immunization, the protective rates were 97.19% and 95.32% respectively.CONCLUSION:The protective efficacy of plasma-derived hepatitis B vaccine persisted at least 12 years, and a booster dose seems not necessary within at least 12 years after the primary three-doses immunization to newborns born to HBsAg negative mothers.