Trend of hepatitis B virus infection in freshmen classes at two high schools in Hualien,Taiwan from 1991 to 1999

Taiwan is an endemic area of hepatitis B virus (HBV) infection. A nationwide mass vaccination program to prevent HBV infection was started in 1985. Perinatal and horizontal transmission of HBV decreased substantially after the launching of this program. However, the influence of this program on children born before 1985 has not been studied. From 1991 to 1999, annual surveys of hepatitis B virus surface antigen (HBsAg) and antibody (anti-HBs) were carried out in freshmen at two high schools in Hualien, Taiwan. The average age was 16 years old. Although these students were born 2-10 years after the start of the national HBV vaccination program, there is a significant trend of decreasing HBsAg carrier rate (from 21.0% to 10.5% in males and 14.3% to 4.7% in females) and increasing anti-HBs rate (from 56.6% to 67.8% in males and 70.3% to 75.9% in females) over the 9 years. With yearly comparison, the carrier rate of HBsAg started to show significant decrease since 1994, while the anti-HBs began to rise significantly after 1996, especially in male students. The HBsAg carrier rate in male students was significantly higher, while the anti-HBs rate was significantly lower, than that in female students in most of the years. It is concluded that the effect of HBV vaccination also reduced horizontal transmission of HBV to children born up to 7 years before the start of the program.     

Decline of hepatitis B carrier rate in vaccinated and unvaccinated subjects: sixteen years after newborn vaccination program in Taiwan

Taiwan was an endemic area for hepatitis B virus (HBV) infection, and related liver diseases cause a significant drain of public resources. To control the endemic, a nation-wide newborn vaccination program was started in 1985. We reviewed the results of the annual survey for HBV surface antigen (HBsAg) performed in freshmen class of two high schools in Hualien, eastern Taiwan, from 1991 to 2001. A total of 10,194 students, most of them 15 years old, were tested for serum HBsAg using enzyme immunoassays. There is a significant trend (P < 0.0001) of decreasing HBsAg carrier rate from 20.3 to 4.4% in males and 14.3% to 2.4% in females, respectively, over 11 years. The HBsAg carrier rate was 16.0-20.3% in students surveyed during 1991-1993 (born more than 6 years before the start of the national vaccination program), which decreased to 7.7-11.9% during 1994-1999 (born 1-6 years before the program). It further declined to 4.7% and 3.4% in 2000 and 2001 (born after the start of the program). The HBsAg carrier rate in male students was significantly higher than that in female students in most of the years. The HBV newborn vaccination program not only successfully prevented most of the perinatal transmission of HBV but also reduced horizontal transmission of HBV to children born up to 6 years before the start of the program. Also, the protection persisted for at least 15 years.     

Significance of isolated anti-HBc seropositivity by ELISA: implications and the role of radioimmunoassay.

Hepatitis B virus (HBV) surface antigen (HBsAg) and antibody to HBsAg (anti-HBs) are excellent markers for HBV infection and its immunity. The significance of isolated antibody to HBV core antigen (anti-HBc) seropositivity is not certain. To elucidate this, sera from 638 Chinese adult subjects, aged 18-52 years, seronegative for both HBsAg and anti-HBs, were tested for anti-HBc. Fifty-one (8%) were found to have an isolated anti-HBc seropositivity by ELISA, and all were negative for IgM-anti-HBc. The anti-HBc persisted in all subjects who attended follow-up for hepatitis B vaccination (n = 48) for a period of 8 months. These 48 subjects received 3 doses of hepatitis B vaccine (HB-VAX, 10 micrograms or 20 micrograms) at 0, 1, and 6 months: 72.9% developed a primary anti-HBs response (suggestive of a false-positive anti-HBc seropositivity), 4.2% developed an anamnestic or secondary anti-HBs response, and 22.9% did not develop an anti-HBs response. Increasing the cutoff point of the ELISA or reconfirmation with radioimmunoassay (RIA) reduced only a minor half of the false positives. This low specificity of anti-HBc ELISA/RIA, together with the high rate of anti-HBs response to hepatitis B vaccine, indicates that subjects with isolated anti-HBc seropositivity should be included in vaccination programs.     

Distribution of anti-HBs levels in Korean adults

Exact titration of anti-HBs with mIU/mL unit is necessary in evaluating the success of HBV vaccination or in making a decision to increase the dose of HBV vaccination. Data of distribution of anti-HBs titers can contribute to cutting of public health costs by reducing unnecessary HBV booster doses. Moreover, anti-HBc is also an important marker for differentiation of vaccination-induced anti-HBs from infection-acquired anti-HBs. However, not much study about these subjects has been done in Korea. So we evaluated anti-HBs associated with anti-HBc and vaccination history. HBsAg and anti-HBs tests were done in 1,465 cases. The positive rates of HBsAg and anti-HBs were 4.5% and 74.6%, respectively. Anti-HBs positive rate was higher in the vaccinated group than that in the non-vaccinated group. The rates of anti-HBs positive cases with lower titers (10-< 100 mIU/mL) were 31.9%, while cases with higher titers (> or = 100 mIU/mL) were 68.1%. This suggested about 70% of anti-HBs-positive Korean adults (about 53% of the general adult population) have long-lasting immunity against HBV infection and may not require booster doses of HBV vaccination for a long time. Anti-HBs titers in the vaccine-induced anti-HBs group were higher than those in the infection-acquired anti-HBs group. No statistical differences were noted between male and female or among age groups. 25.7% of the HBsAg (-)/anti-HBs (-) group showed anti-HBc positive and HBV-DNA was detected in 11.1% among HBsAg (-)/anti-HBs (-)/anti-HBcAb (+) cases. Further study about post vaccination anti-HBs titer decay in Korean should be performed to help cut vaccination costs.     

Hepatitis B virus DNA in sera of virus carriers positive exclusively for antibodies to the hepatitis B core antigen

The prevalence of serum HBV DNA in individuals positive for anti-HBc alone was determined by the polymerase chain reaction in two groups with endemic HBV infection from Canton (group A) and Hainan (group B), provinces of China. Twenty-one out of 294 individuals in group A (7.2%) and 193 out of 1995 in group B (9.7%) were positive for anti-HBc but negative for other markers of ongoing or past HBV infection (HBsAg and anti-HBs). HBV DNA was detected in 6/21 sera in group A (28.6%) and 68/193 in group B (35.2%) in their initial serum specimen. One of the six HBV-DNA-positive individuals in group A became negative after 6 months and four of the 58 positive in group B became negative at 4 years of follow-up. All of the individuals remained positive for anti-HBc and negative for anti-HBs, but one of them became positive for HBsAg on follow-up. None of the anti-HBc- and HBV-DNA-positive subjects had symptoms of liver diseases. They were, therefore, defined as chronic asymptomatic HBV carriers with undetectable HBsAg. This type of carrier should be added to the typical HBsAg-positive carrier, who constitutes about 10-15% of the general Chinese population, to give a more complete estimate of asymptomatic HBV carriers in China.     

Seroepidemiological studies on hepatitis B and D viruses infection among five ethnic groups in southern Taiwan

In order to compare the prevalence of hepatitis B virus (HBV) and hepatitis D virus (HDV) infection among five ethnic groups in Pingtung County of southern Taiwan, a total of 240 serum samples were collected from September to October, 1985, from the following five ethnic groups: Taiwanese, Hakka, Mainland Chinese, aboriginal Paiwanese, and aboriginal Rukaiese. Ages of subjects ranged from 5 to 69 years. All sera were tested for hepatitis B surface antigen (HBsAg), surface antibody (anti-HBs), and core antibody (anti-HBc) by radioimmunoassay (RIA). Hepatitis B e antigen (HBeAg) and antibody to hepatitis D antigen (anti-HDV) were also tested for those with HBsAg-positive sera. Results showed that 44.1% of all sera examined were negative for HBsAG but positive for both anti-HBs and anti-HBc; additionally, 24.6% were negative for both HBsAg and anti-HBs but positive for anti-HBc. Only 134 serum samples showed negative results for HBV markers, indicating an HBV infection rate of 88.8%. The anti-HDV positive rate was estimated to be 2.7% among HBsAg-positive subjects. The HBsAg-positive rates among Rukaiese, Paiwanese, Hakka, Taiwanese, and Mainland Chinese were 25.8, 22.5, 16.7, 12.9, and 10.0%, respectively; while the prevalence rates of HBV infection among the above five groups were 94.2, 94.6, 85.4, 87.5, and 82.5%, respectively. Differences in the HBsAg-positive rate and HBV infection rate among these ethnic groups were statistically significant. We conclude that people living in Pingtung County are more frequently infected with HBV when compared with inhabitants in northern Taiwan.     

Seroprevalence of Hepatitis-B infection amongst Taiwanese university students 18 years following the commencement of a national Hepatitis-B vaccination program

In Taiwan, the nation-wide Hepatitis-B virus (HB) vaccination program was first launched in July 1984 and was directed to those infants born to hepatitis B surface antigen (HBsAg) carrier mothers in Taiwan. From July 1986 onwards, all infants born in Taiwan were immunized against HB. This study examined the HB-infection status amongst students at a Taiwanese university 18 years subsequent to the implementation of universal HB vaccination. A total of 1,969 new university entrants in 2005 were grouped into 1 of 3 distinct birth cohorts according to their HB-vaccination schedule (cohort-1 students born prior to July 1, 1984; cohort-3 students born subsequent to June 30, 1986) and were examined for their serum HBsAg, antibody to hepatitis B surface antigen (anti-HBs), and antibody to hepatitis B core antigen (anti-HBc) status. Immunity arising from vaccination was defined as an anti-HBs level 10 mIU/ml. We observed a trend toward a decreasing anti-HBc-positive rate and a decreasing HBsAg carrier rate from, respectively, 26.5 and 8.7% for cohort-1 to 4.7 and 1.7% for cohort-3 students. The prevalence of students featuring seronegativity for all three HB markers increased from 12.3% for cohort-1 to 48.8% for cohort-3 individuals. Amongst the 1,695 subjects revealing seronegativity for HBsAg and anti-HBc, their anti-HBs level was analyzed according to their birth year. The prevalence of students featuring a non-protective anti-HBs level increased from 11.9% for birth-year 1984 individuals to 48.2% for birth-year 1987 students. The introduction of HB vaccine has effectively reduced the transmission of HBV infection in Taiwan, 18 years subsequent to the commencement of the universal HB-vaccination program. A "waning-off" effect of anti-HBs seropositivity acquired from the HB vaccination program has also been observed.     

Hepatitis B virus transmission pattern and vaccination efficiency in Uzbekistan

A national program of universal vaccination for the prevention of chronic hepatitis B virus (HBV) infection was launched in Uzbekistan since 1998. To evaluate the 6 years' outcome of the program, 567 children were enrolled in the study. Among those enrolled, 333 had immunized with adw2 type based Engerix-B (Glaxo Smith Kline Beechem, Rixensart, Belgium) and 48 with adr type based Hepavax-Gene (Green Cross Vaccine Corporation, Korea). A cohort of 186 children born before the immunization program, was also included in the study. When 45 vaccinated children were compared to age/sex-matched 45 unvaccinated children, the sero-prevalence of HBsAg was 0 versus 11% (P = 0.56), and of anti-HBc was 0% versus 44% (P < 0.0001), respectively. Loss of anti-HBs was observed in 18.4% after 5 years. Among 13 HBsAg carriers found in this study, genotype HBV/D was found in 69%, HBV/A in 23% (all in unvaccinated group) and HBV/C in 8% (in vaccinated group). No significant differences were observed in this study between groups which received different vaccine formulation. Phylogenetic analysis of the HBV isolates obtained from family members of the HBsAg-positive children, revealed evidence suggesting that transmission in the vaccinated group was exclusively perinatal, whereas in the unvaccinated group horizontal transmission pattern predominated. In conclusion, HBV universal vaccination is efficient in Uzbekistan irrespective of the vaccine formulation used, because the horizontal transmission pattern predominates currently in this endemic region.     

奉贤地区HBsAg阴性的HBV自然感染母亲对新生儿影响的研究

目的　为揭示HBsAg阴性的乙型肝炎病毒 (HBV)自然感染孕妇的宫内感染及其危险因素。方法　采用多聚酶链反应 (PCR)技术结合酶联免疫吸附法 (ELISA) ,对奉贤地区 131例HBsAg阴性的HBV自然感染孕妇外周血 ,及其分娩后的脐带血进行HBV血清学标志物 (HBVM)和HBVDNA检测。结果　HBsAg阴性的HBV自然感染孕妇宫内的感染率 (除外单一抗 -HBs阳性 )为 5 2 6 7% ;脐血中不同HBVM组合的HBVDNA检出率依次为 :抗 -HBe( )、抗 -HBc( ) >抗 -HBs( )、抗 -HBe( )、抗 -HBc( ) >抗 -HBs( )、抗 -HBe( ) >抗 -HBs( )、抗 -HBc( ) >抗 -HBs( ) ;脐血HBVDNA总检出率为 16 79%。结论　HBsAg阴性的HBV自然感染孕妇也可能发生宫内感染。提议HBsAg阴性的HBV自然感染孕妇和新生儿有进行自动和被动免疫接种的必要性     

Prevalence of HBsAg carriers in native and immigrant pregnant female populations in Israel and passive/active vaccination against HBV of newborns at risk.

Israel has no official prevention policy at present against perinatal and horizontal transmission of hepatitis B virus (HBV) infection in newborns and children at risk. The present study was designed to assess the prevalence of HBV carrier state in a population of 11,123 pregnant women at term. Among this population (mean age 29.7 +/- 5.9), 98 women (0.88%) were found to be asymptomatic HBsAg+ carriers, and 97% of these carriers were anti-HBe+. Evidence for HBV replication, as determined by serum HBV-DNA, was established in 6.6% of the HBsAg+/anti-HBe+ population. The HBsAg carrier rate was strongly influenced by religion, continent, and country of birth of the carrier mothers. The highest relative carrier rate was found among women of Moslem origin (4.3%), as compared to Jewish women (0.67%). Most carrier women were born in Israel (56.1%) to mothers who had emigrated from regions with intermediate or high endemicity of HBV, such as North Africa or the Middle East. In these groups, the HBsAg carrier rate ranged between 1.2 and 3.0%. Ninety-three percent of newborns receiving passive/active vaccination against HBV developed protective levels of anti-HBs. Finally, evidence for horizontal transmission of HBV was found in 19.3% of 83 non-vaccinated children in families of HBsAg carriers. The present study therefore establishes HBsAg prevalence rates in specific risk groups of women at term and confirms the need for an official policy on immunization against HBV in Israel. Since over 50% of women at term belong to the defined risk groups, universal active vaccination of the entire newborn population each year is suggested as the most rational and needed policy in Israel.     

Isolated core antibody hepatitis B in sub-Saharan African immigrants

Chronic hepatitis B virus (HBV) infection is a major health problem in sub-Saharan Africa, where prevalence is > or =8%, and is increasingly seen in African immigrants to developed countries. A retrospective audit of the medical records of 383 immigrants from sub-Saharan Africa attending the infectious diseases clinics at the Royal Melbourne Hospital was performed from 2003 to 2006. The HBV, human immunodeficiency virus (HIV) and hepatitis C virus (HCV) serological results are reported, with a focus on the isolated core antibody HBV pattern (detection of anti-HBc without detection of HBsAg or anti-HBs). Two-thirds (118/174, 68%) of those tested had evidence of HBV infection with detectable anti-HBc. Chronic HBV infection (serum HBsAg detected) was identified in 38/174 (22%) and resolved HBV infection (both serum anti-HBs and anti-HBc detected) in 45/174 (26%). The isolated core antibody pattern was identified in 35/174 (20%), of whom only 1/35 (3%) had detectable serum HBV DNA on PCR testing, indicating occult chronic HBV (OCHB). Only 8/56 (14%) patients with negative anti-HBc had serological evidence of vaccination (serum anti-HBs detected). HIV infection was detected in 26/223 (12%). HCV antibodies were detected in 10/241 (4%), of whom 8 (80%) had detectable HCV RNA. Viral co-infection was detected in only 2/131 (1.5%) patients tested for all three viruses. The isolated core antibody HBV pattern was common among sub-Saharan African patients in our study. These patients require assessment for OCHB infection and monitoring for complications of HBV.     

Baseline seroepidemiology of hepatitis B virus infection in children in Taipei, 1984: a study just before mass hepatitis B vaccination program in Taiwan

Hepatitis B virus (HBV) markers were studied by radioimmunoassays in serum samples of 1,200 (647 male, 553 female) apparently healthy children under 15 years of age in Taipei between June and October 1984. The prevalence rate of hepatitis B surface antigen (HBsAg) was 5.1% in infancy, increased to 10.7% between 1 and 2 years of age, and then remained constant at about 10% thereafter. The prevalence rate of surface antibody (anti-HBs), core antibody (anti-HBc), and seropositivity (at least one marker of hepatitis B detectable) were 39.0, 30.5, and 52.5%, respectively, in infancy, then decreased to 10.7, 14.3, and 17.9%, respectively, between 1 and 2 years of age. Thereafter, the antibody prevalence increased in parallel with age. By the age of 13-14 years, nearly half of the children were infected by HBV. The results suggested that in our children, most HBsAg carriers resulted from infections before 3 years of age, and HBV infections after 3 years of age infrequently resulted in a carrier state. One hundred (83.3%) of the 120 HBsAg-positive children had hepatitis B e antigen (HBeAg), indicating high prevalence in young asymptomatic HBsAg carriers. The prevalence rate of HBeAg tended to decrease with age and a reversed trend was observed with anti-HBe. Our study, just before our government extends mass hepatitis B vaccination program from newborns to children, provides background seroepidemiologic data of HBV infections in the healthy children in Taiwan.     

Seroprevalence and risk factors for hepatitis B infection in an adult population in Northeast China

Background and aim: The prevalence of the hepatitis B virus (HBV) is higher in adults than in children. We determined the seroepidemiology of HBV infection in an adult population in JiLin, China, to guide effective preventive measures.Methods: A cross-sectional serosurvey was conducted throughout JiLin, China. A total of 3833 people was selected and demographic and behavioral information gathered. Serum samples were tested for HBV markers and liver enzymes.Results: The prevalence of the hepatitis B surface antigen (HBsAg), the antibody to the hepatitis B surface antigen (anti-HBs), the hepatitis B e antigen (HBeAg), the antibody to HBeAg (anti-HBe), and the antibody to the hepatitis B core antigen (anti-HBc) were 4.38%, 35.66%, 1.38%, 6.65%, and 40.88%, respectively. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were significantly higher among HBsAg (+) than HBsAg (-) subjects. By multivariate logistic regression analysis, independent predictors for chronic HBV infection were smoking, poor sleep quality; occupation as private small-businessmen, laborers, or peasants; male gender; family history of HBV; personal history of vaccination; and older age. Independent predictors for exposure to HBV were large family size, occupation as a private small-businessman, male gender, family history of HBV, personal history of vaccination, and older age. Independent predictors for immunity by vaccination were occupation as a private small-businessman, high income, personal history of vaccination, and young age. Independent predictors for immunity by exposure were drinking, male gender, personal history of vaccination, and older age.Conclusions: The prevalence rate of HBV infection (4.38%) was lower than the previous rate of general HBV vaccination. However, 44.59% of the population remained susceptible to HBV. The prevalence of HBV infection was high in young adults, private small-businessmen, peasants, those with a family history of HBV, and males. Therefore, immunization of the non-immune population is reasonable to reduce hepatitis B transmission between adults.     

Occult hepatitis B virus infection in the setting of hepatitis C virus (HCV) and human immunodeficiency virus (HIV) co‐infection: Clinically relevant or a diagnostic problem?

The clinical relevance of occult hepatitis B virus (HBV) infection, defined as detectable HBV DNA serum/liver, in the absence of hepatitis B surface antigen (HBsAg), is unclear. We determined the prevalence of serum occult HBV infection in HIV/HCV co-infected patients enrolled in APRICOT, a randomized multinational trial that investigated the efficacy and safety of peginterferon alfa-2a (40 kDa) plus ribavirin for treatment of HCV. We also examined the effect of prior HBV exposure to liver histology at baseline. Only HBsAg-negative patients were eligible. At screening, serum HBV DNA was assessed by commercial assay (detection limit = 200 copies/mL). Patients were divided into four serological groups: anti-HBs+/anti-HBc+; anti-HBs-/anti-HBc+; anti-HBs+/ anti-HBc-; anti-HBs-/anti-HBc-. Baseline liver biopsy grade and stage were compared among groups. Serum HBV DNA was undetectable in all patients, (n = 866). Results of anti-HBs and anti-HBc was available for 176 patients: 60 (34.1%) anti-HBs+/anti-HBc+; 60 (34.1%) anti-HBs-/anti-HBc+; 11 (6.3%) anti-HBs+/anti-HBc-; 45 (25.6%) anti-HBs-/anti-HBc-. There were no differences among the groups in the histological grade or stage at baseline liver biopsies. Occult HBV infection in serum was not detected in this large immunocompetent cohort. Moreover, prior exposure to HBV did not appear to have any affect on baseline liver histology.     

Hepatitis A and hepatitis B virus infection in children and adolescents in north-east Italy

The sera of 722 children and adolescents without overt liver disease were tested for hepatitis B surface antigen (HBsAg), antiHBs and anti-hepatitis B core anti-HBc; 658 of the sera were also tested for anti-hepatitis A virus anti-HAV. Except for the "passive" antibody peak observed in babies, the anti-HAV age-specific prevalence was negligible until the age of 3; it then increased, reaching 35% by the age of 15. Serological evidence of HBV was present in 16% of the subjects: this prevalence was almost constant at all ages. The HBsAg carrier rate was highest in children under 5 years of age (7.6%) and decreased with age. However, only one HBsAg carrier was under 1 year of age. Anti-HBs age-specific prevalence increased progressively from 2.7% to 11.4%. Anti-HBc alone was present in 4.1% of the subjects. No significant sex differences were found in the prevalence of HBV serum markers or in the HBsAg carrier rate. Neither HAV nor HBV infection was significantly influenced by place of residence or socioeconomic status. It is concluded that in this area both HAV and HBV are endemic, but while HAV is mainly acquired at school, most of the HBV infections occur within the household. The results suggest that not only perinatal transmission, but also intrafamilial horizontal infection, plays a role in HBV spread among infants.     

Hepatitis B and D virus infection among drug abusers in Taiwan

Approximately 15 to 20% of the general population in Taiwan are chronic hepatitis B surface antigen (HBsAg) carriers. However, the incidence of hepatitis D virus (HDV) infection is low (5-8%) in patients with HBsAg-positive chronic liver diseases in this area. To evaluate the prevalence of hepatitis B virus (HBV) and HDV infection among drug abusers in Taiwan, serum samples were collected from 152 drug abusers at the Taipei Municipal Anti-Narcotic Institute and test for HBV and HDV markers. Of these, 24 (15.8%) were HBsAg positive, and only 15 (9.9%) were seronegative for all HBV markers. Of the 115 intravenous drug abusers, serum antibody to hepatitis D antigen (anti-HD) was positive in 78.9% of 19 persons who were HBsAg positive, and in 7.5% of 80 persons who were positive for antibody to HBsAg (anti-HBs). Anti-HD was not detected in the sera from all 37 nonintravenous drug abusers regardless of the status of their HBV markers. Also, none of 63 asymptomatic HBsAg carrier pregnant women or 23 patients with acute type B viral hepatitis had measurable anti-HD in their sera. Thus, the high frequency of HDV detected among Chinese HBsAg carrier intravenous drug abusers in Taiwan is similar to that reported in Western countries.     

Evaluation of Immune Response to Hepatitis B Vaccine in Healthcare Workers at a Tertiary Care Hospital

Purpose: Healthcare workers (HCWs) are at high risk of acquiring hepatitis B virus (HBV) infection through occupational exposure which is preventable through hepatitis B vaccination. In the current study, the response to HBV surface antigen (HBsAg) vaccine was assessed in a selected group of HCWs by testing for antibodies against HBsAg (anti-HBs). Methods: Blood samples were collected in all HCWs, who have received the complete schedule of hepatitis B vaccination and anti-HBs levels, were assessed quantitatively in sera using ELISA. Results: The age range of the study participants was 20–55 years. The mean months after the last dose of vaccination were 60.36. Among the 85 participants, 96.5% (n = 82) have protective immunity to hepatitis B. The anti-Hbs response was similar in both male and female (P > 0.05). There was a decline in immune response as the age was increasing (P < 0.05). The results of the study found a significant decline in the immune response with time (P < 0.05). The anti-Hbs response was declined with smoking habit (P < 0.05) and with increasing body mass index (P < 0.05). Conclusion: Post-HBsAg vaccination immunity to hepatitis B was 96.5% in HCW and was similar to that of global rates. Increasing age, time period, smoking habit, and overweight were associated with decreased immunity. Many studies are needed in developing newer HBV vaccines with very high immunogenicity. Giving highly immunogenic vaccine to HCWs will ensure safety at work by reducing nosocomial transmission which is very much desired in a resource-limited country.     

Age- and sex-related study of hepatitis B virus chronic carrier state in infants from an endemic area (Senegal)

This report concerns hepatitis B virus (HBV) infections observed in 155 infants from Senegal, studied with a view to determining the factors involved in development of the chronic carrier state. A chronic carrier state was observed in 50.3% of the infants. This study confirms that the risk of chronic carriage is linked to age. This risk declines very rapidly with age, falling from 82% in infants under 6 months old, to 15% in children between the ages of 2 and 3 years. Spontaneous elimination of hepatitis B surface antigen (HBsAg) is uncommon in HBsAg carriers during childhood. The difference observed in chronic carriage between males and females is due to a difference in susceptibility of the two sexes to the development of the chronic carrier state: HBV infections (before 2 years of age) lead to a chronic carriage in 77% of males as against 50% of females. These conclusions are important in view of the immunisation programs being carried out against hepatitis B virus in endemic areas. For a maximum efficacy, vaccination must be carried out at birth, or shortly afterwards.     

Vaccination with a fusion DNA vaccine encoding hepatitis B surface antigen fused to the extracellular domain of CTLA4 enhances HBV-specific immune responses in mice: Implication of its potential use as a therapeutic vaccine

Fusion of specific antigens to extracellular domain of cytotoxic-T-lymphocyte-associated antigen 4 (CTLA4) represents a promising approach to increase the immunogenicity of DNA vaccines. We evaluated this interesting approach for its enhancement on HBV-specific immune responses and its antiviral effects in HBV transgenic mice. A fusion plasmid encoding the extracellular domain of CTLA4 linked with HBsAg was constructed. Mice were immunized by this fusion plasmid. Vaccination with the CTLA4-fused DNA not only induced much higher level of anti-HBs antibody, but also increased HBsAg-specific CD8+ response as well as CTL response in BALB/c mice. Furthermore, both Th1 and Th2 responses were augmented. In HBV transgenic mice, the levels of circulating HBsAg and HBV DNA replication were down-regulated by induction of higher anti-HBs antibody and HBsAg-specific CD8+ response after vaccination with the fusion plasmid. Thus, the CTLA4-fused DNA vaccine led to breakdown of immune tolerance to viral infection in HBV transgenic mice, which might be used as a therapeutic vaccine in HBV infection.