Timing of post-vaccination tests in infants born to mothers with chronic hepatitis B virus infection

Immunoprophylaxis is routinely recommended for infants born to mothers with hepatitis B virus(HBV)infection within the first 12-24 hours.Detection of he-patitis B surface antibody(HBsAb)resulting from hepatitis B immunoglobulin administered at birth may be perceived as a real vaccine response.This makes it difficult to detect HBV infection.For this reason,it is recommended that infants born to hepatitis B surface antigen positive mothers and who received immunop-rophylaxis at birth should have HBsAb testing when they are 9-15 months old.

Hepatitis B virus infection and its treatment in Eastern Ethiopia

Hepatitis B virus(HBV)infection causes acute and chronic hepatitis,compensated and decompensated cirrhosis,and hepatocellular carcinoma worldwide.The actual status of HBV infection and its treatment in certain regions of Asian and African countries,including Ethiopia,has not been well-documented thus far.Antiviral therapy for HBV infection can prevent the progression of HBV-related liver diseases and decrease the HBV-related symptoms,such as abdominal symp-toms,fatigue,systemic symptoms and others.In Eastern Ethiopia,HBV-infected patients with cirrhosis were found to be positive for the HBV e antigen and to have a higher viral load than those without cirrhosis.Notably,54.4%of patients practiced khat chewing and 18.1%consumed excessive amounts of alcohol.Teno-fovir disoproxil fumarate effectively suppressed HBV DNA in those infected with HBV.It is important to elucidate the actual status of HBV infection in Eastern Ethiopia to eliminate HBV infection worldwide by 2030.HBV vaccination and the educational programs for Health Science students that provide practical strategies could help to reduce HBV infection in Eastern Ethiopia.

Rising incidence of acute hepatitis A among adults and clinical characteristics in a tertiary care center of Pakistan

BACKGROUND For decades,hepatitis A virus(HAV)has been a leading cause of acute hepatitis among children and was less prevalent among adults.However,recently a paradigm shift has been observed in the epidemiology of HAV,as evident by cases of acute hepatitis due to HAV among adults.AIM To estimate frequency of HAV in acute viral hepatitis and compare characteristics in HAV and hepatitis E virus(HEV)infection.METHODS This was a trend analysis conducted at Aga Khan University Hospital Karachi(Sindh,Pakistan)from February 2024 to May 2024.Individuals aged 18 years and older diagnosed with acute viral hepatitis attributed to hepatotropic viruses in 2024 were reviewed.To compare the trend patients admitted with acute hepatitis during 2019-2023 were also reviewed.Data regarding clinical and laboratory parameters were recorded.The yearly trend of acute hepatitis due to HAV and HEV was analyzed,and comparative analysis was done between HAV and HEV cases among adults.RESULTS A total of 396 patients were found to have acute hepatitis during our study duration.HAV was diagnosed in 234 patients(59%)while 157 patients(39.6%)were found to have acute HEV infection.Additionally,acute hepatitis B virus infection was identified in 3 patients(0.7%),whereas acute hepatitis C virus infection was found in 2(0.5%)cases of acute hepatitis.Yearly trends showed increasing occurrence of HAV infection among adults over last 5 years.The patients with acute HAV were younger than patients with HEV(28 years±8 years vs 30 years±8 years;P<0.01).Higher levels of total bilirubin were seen in HEV infection,while higher levels of alanine transaminase were seen in HAV infection.However,a higher proportion of acute liver failure(ALF),coagulopathy,and mortality were observed in HEV.CONCLUSION An increase in acute hepatitis A cases among adults shows less severity than hepatitis E,highlighting the need for better sanitation,hygiene,and adult hepatitis A vaccination programs.

Perception of Medical Students towards Hepatitis B Virus Infection and Hepatitis B Vaccination in a Private Tertiary Hospital in Jos North Local Government, Plateau State, Nigeria

Background: Prevention is one of the safe schemes against the high prevalence of viral Hepatitis. Negative perceptions or perceptions about the risks of hepatitis B among medical students and health care workers may influence the behavioral pattern and adoption of preventive measures against the virus and can affect the uptake of the Hepatitis B vaccine. This study assesses the perception of medical students towards Hepatitis B virus infection and Hepatitis B Vaccination in a Private Tertiary Hospital in Jos North Local Government, Plateau State, Nigeria. Methods: This was a descriptive cross-sectional study done in August 2021 among 236 clinical medical students using a multistage sampling technique. Data was collected using an interviewer-administered structured questionnaire and analysed using the IBM SPSS 28 (Statistical Package for the Social Sciences). Ethical approval was granted by Bingham University Teaching Hospital, Ethics Committee, Jos, Plateau State. Results: Two-thirds of respondents were of the opinion that they are at risk of contracting HBV. Half were of the opinion that the risk is very much while a third believed the risk is moderate. Among those who think they are not at risk of contracting HBV, the majority felt so because they are vaccinated while 10.3% believe that they are safe. 43.2% of respondents think that HBV Vaccine is very effective in preventing HBV infection while 39.8% think it is slightly effective, and 7.6% think it is not effective. Almost all respondents, 99.2% are of the opinion that HBV Vaccination is important for students while 0.8% think it is not important. The majority of the respondents at 95.8% were willing to be screened for HBV. The majority (85.6%) of respondents are willing to pay for HBV Vaccine as against 14.4% of respondents who are not willing to pay. Conclusion: Summarily, 21 (8.9%) of the students had a negative perception of Hepatitis B Vaccination, and 215 (91.1%) had a positive perception of Hepatitis B Vaccination. Perception-sustaining events like seminars, workshops, road shows, and campaigns should be organized among students and health workers.

Review of Albanian studies suggests the need for further efforts to counteract significant hepatitis B virus prevalence

BACKGROUND Hepatitis B virus(HBV)is categorized as one of the smallest enveloped DNA viruses and is the prototypical virus of the Hepatoviridae family.It is usually transmitted through body fluids such as blood,semen,and vaginal secretions.The majority(more than 95%)of immunocompetent adults infected with HBV spontaneously clear the infection.In the context of the high prevalence of HBV infection in Albania,the research gap is characterized by the lack of studies aimed at advancing the current understanding and improving the prevailing situation.The main objective of this study was to address the low rate of HBV diagnosis and the lack of a comprehensive national program to facilitate widespread diagnosis.AIM To analyze the prevalence of HBV infection in Albania and elucidate the persistently high prevalence despite efforts and measures implemented.METHODS Using a systematic literature review,we collected existing research on the epidemiology of HBV in Albania from PubMed,Cochrane Library,Google Scholar,and Albanian Medical Journals,focusing on studies published after the 1980s and conducted solely in the Albanian population.RESULTS The findings reveal a dynamic shift in HBV prevalence in Albania over several decades.Initially high,the prevalence gradually declined following the implementation of screening and vaccination programs.However,the prevalence rates have remained notably high,exceeding 8%in recent years.Contributing factors include vertical transmission,inadequate healthcare infrastructure,and challenges in screening and diagnosis.Studies among Albanian refugees in neighboring countries also reported high prevalence rates,emphasizing the need for transnational interventions.Despite advancements in screening,vaccination,and healthcare infrastructure,Albania continues to face a substantial burden of HBV infection.CONCLUSION The persistence of high prevalence underscores the complexity of the issue,requiring ongoing efforts to ensure a comprehensive understanding and effective mitigation.Addressing gaps in vaccination coverage,improving access to screening and diagnosis,and enhancing public awareness are crucial steps toward reducing HBV prevalence in Albania.

Immune response to hepatitis B virus vaccine in celiac subjects at diagnosis

AIM To evaluate hepatitis B virus(HBV) vaccine response and correlation with human leukocyte antigens(HLA) and/or gluten intake in celiac patients at diagnosis.METHODS Fifty-one patients affected by celiac disease, diagnosed at the Department of Pediatrics of the University of Catania(Italy), were recruited. All patients were tested at admission for immunization against HBV, according to findings from analysis of quantitative HBV surface antibody(anti-HBs). The anti-HBs titer was measured by enzyme-linked immunosorbent assay. Following the international standards, subjects with antibody titer < 10 IU/L were defined as non-responders. The prevalence of responders and non-responders among celiac subjects and the distribution of immunization for age were examined. In addition, the prevalence of responders and non-responders was assessed for correlation to HLA and clinical features at diagnosis of celiac disease.RESULTS The entire study population was divided into three groups according to age: 24 patients aged between 0to 5.5 years(48.9%, group A); 16 aged between 5.5 and 9.5 years(30.61%, group B); 9 aged between 9.5 and 17 years(18.75%, group C). Comparison of the percentage of responders and non-responders between the youngest and the oldest age group showed no significant difference between the two groups(P > 0.05). With regard to the HLA haplotype, comparison of the distribution of vaccination response showed no statistically significant difference between the different genotypes(homozygosity for the HLADQ2 haplotype compared with HLADQ2/DQ8 heterozygosity or other haplotypes; P > 0.05). Moreover, distribution of the responders according to clinical features of celiac disease showed no statistically significant differences(P > 0.05).CONCLUSION This prospective study confirmed the lower percentage of response to HBV vaccine in celiac subjects. However, the underlying mechanism remains unclear and further studies are needed.

Novel DNA vaccine based on hepatitis B virus core gene induces specific immune responses in Balb/c mice

AIM： To investigate the immunogenidty of a novel DNA vacoine, pSW3891/HBc, based on HBV core gene in Balb/c mice. METHODS： A novel DNA vaccine, pSW3891/HBc, encoding HBV core gene was constructed using a vector plasmid pSW3891. Balb/c mice were immunized with either pSW3891/HBc or empty vector DNA via gene gun. IgG anti-HBc responses in mouse sera were demonstrated by ELISA. Specific cytotoxicity of cytotoxic T lymphocytes （CTLs） of mice was quantitatively measured by lactate dehydrogenase release assay. RESULTS： HBcAg was expressed effectively in 293T cell line transiently transfected with pSW3891/HBc. Strong IgG anti-HBc responses were elicited in mice immunized with pSW3891/HBc. The end-point titers of anti-HBc reached the highest 1：97 200, 4 wk after the third immunization. The specific CTL killing with the highest specific lysis reached 73.25% at effector：target ratio of 20：1 in mice that received pSW3891/HBc DNA vaccine. CONCLUSION： pSW3891/HBc vaccination elicits specific anti-HBc response and induces HBc-specific CTL response in immunized Balb/c mice.

Targeting hepatitis B virus antigens to dendritic cells by heat shock protein to improve DNA vaccine potency

AIM： To investigate a novel DNA vaccination based upon expression of the HBV e antigen fused to a heat shock protein （HSP） as a strategy to enhance DNA vaccine potency.METHODS： A pCMV-HBeAg-HSP DNA vaccine and a control DNA vaccine were generated. Mice were immunized with these different construct. Immune responses were measured 2 wk after a second immunization by a T cell response assay, CTL cytotoxicity assay, and an antibody assay in C57BL/6 and BALB/c mice. CT26-HBeAg tumor cell challenge test in vivo was Performed in BALB/c mice to monitor anti-tumor immune responses.RESULTS： In the mice immunized with pCMV-HBe-HSP DNA, superior CTL activity to target HBV-positive target cells was observed in comparison with mice immunized with pCMV-HBeAg （44% ± 5% vs 30% ± 6% in E： T 〉 50：1, P 〈 0,05）, ELISPOT assays showed a stronger T-cell response from mice immunized with pCMV-HBe- HSP than that from pCMV-HBeAg immunized animals when stimulated either with MHC class I or class Ⅱ epitopes derived from HBeAg （74% ± 9% vs 31% ± 6%, P 〈 0.01）. ELISA assays revealed an enhanced HBeAg antibody response from mice immunized with pCMV- HBe-HSP than from those immunized with pCMV-HBeAg. The lowest tumor incidence and the slowest tumor growth were observed in mice immunized with pCMV- HBe-HSP when challenged with CT26-HBeAg.CONCLUSION： The results of this study demonstrate a broad enhancement of antigen-specific CD4^＋ helper,CD8^＋ cytotoxic T-cell, and B-cell responses by a novel DNA vaccination strategy. They also proved a stronger antigen-specific immune memory, which may be superior to currently described HBV DNA vaccination strategies for the treatment of chronic HBV infection.

Hepatitis E virus chimeric DNA vaccine elicits immunologic response in mice

AIM： To construct the plasmid pcHEV23 containing fragments of HEV ORF2 and ORF3 chimeric gene and to assess its ability to elicit specific immunologic response in mice. METHODS： The gene encoding the structural protein of HEV ORF2 fragment and full-length ORF3 was amplified by PCR. The PCR products were cloned into an eucaryotic expression plasmid pcDNA3. The resulting plasmid pcHEV23 was used as a DNA vaccine to inoculate BALB/c mice intramuscularly thrice at a dose of 100 or 200 ug. Mice injected with empty pcDNA3 DNA or saline served as control and then specific immune responses in the mice were detected. RESULTS： After 2-3 times of inoculation, all mice injected with pcHEV23 had anti-HEV IgG seroconversion and specific T lymphocyte proliferation. The lymphocyte stimulation index in the group immunized with pcHEV23 （3.1＋0.49） was higher than that in the control group （0.787±0.12, P〈0.01）. None in the control group had a detectable level of anti-HEV IgG. CONCLUSION： DNA vaccine containing HEV ORF2 and ORF3 chimeric gene can successfully induce specific humoral and cellular immune response in mice.

Interleukin-12 as a Genetic Adjuvant Enhances Hepatitis C Virus NS3 DNA Vaccine Immunogenicity

Hepatitis C virus (HCV) chronic infection is a worldwide health problem, and numerous efforts have been invested to develop novel vaccines. An efficient vaccine requires broad immune response induction against viral proteins. To achieve this goal, we constructed a DNA vaccine expressing nonstructural 3 (NS3) gene (pcDNA3.1-HCV-NS3) and assessed the immune response in C57BL/6 mice. In this study, the NS3 gene was amplified with a nested-reverse transcriptase-polymerase chain reaction (RT-PCR) method using sera of HCV-infected patients with genotype 1a. The resulting NS3 gene was subcloned into a pcDNA3.1 eukaryotic expression vector, and gene expression was detected by western blot. The resultant DNA vaccine was co-administered with interleukin-12 (IL-12) as an adjuvant to female C57BL/6 mice. After the final immunizations, lymphocyte proliferation, cytotoxicity, and cytokine levels were assessed to measure immune responses. Our data suggest that co-administration of HCV NS3 DNA vaccine with IL-12 induces production of significant levels of both IL-4 and interferon (IFN)-γ (p<0.05). Cytotoxicity and lymphocyte proliferation responses of vaccinated mice were significantly increased compared to control (p<0.05). Collectively, our results demonstrated that co-administration of HCV NS3 and IL-12 displayed strong immunogenicity in a murine model.

Hepatitis B virus subgenotype F3 reactivation with vaccine escape mutations:A case report and review of the literature

Hepatitis B represents a global health threat because its chronic course and sequelae contribute to a high morbidity and mortality. Hepatitis B virus(HBV) infection can be controlled by vaccines, antiviral treatment, and by interrupting transmission. Rare vaccine escape mutants are serious because they eliminate vaccine protection. Here, we present a 74-year-old vaccinated patient with HBV reactivation 11 years after kidney transplantation. The patient was HBV-positive but HBs Ag-negative prior to vaccination 6 years before transplantation. The reactivated virus was HBV genotype F3 with vaccine escape mutations G145 R, P120 Q, and Q129 P. The patient was successfully treated with entecavir. The epidemiological reasons for this subgenotype, which is extremely rare in Western Europe, were unclear. This case illustrates that second-generation vaccines are not always effective in a specific group of patients.

Development of hepatitis C virus vaccine using hepatitis B core antigen as immuno-carrier

AIM: To develop hepatitis C virus (HCV) vaccine using HBcAg as the immuno-carrier to express HCV T epitope and to investigate its immunogenicity in mice. METHODS: We constructed the plasmid pTrc-coreNheI using gene engineering technique, constructed the pcDNA3.1-coreNheI-GFP plasmid with GFP as the reporter gene, and transfected them into Hela cells. The expression of GFP was observed under confocal microscopy and the feasibility of using HBcAg as an immuno-carrier vaccine was studied. pTrc-core gene with a synthetic T epitope antigen gene of HCV (35-44aa) was fused and expressed in the plasmid pTrc- core-HCV (T). For the fusion of the HBcAg-T protein, sucrose, density gradient centrifugation was used, and its molecular weight and purity were analyzed by SDS- PAGE. Then balb/c mice were immunized by the plasmid with the HBcAg (expressed by pTrc-core) protein as control. The tumor regression potential was investigated in mice and evaluated at appropriate time. After three times of immunization, the peripheral blood and spleen of vaccinated mice were collected. HBcAb was detected by ELISA, and nonspecific T lymphocyte proliferation and response of splenocytes were respectively examined by MTT assay. T cell subset of blood and spleen were detected by FACS. RESULTS: GFP was successfully expressed. Tumor regression trial showed that no tumor formation was found in the group receiving immunization, while tumor xenograft progression was not changed in the control group. Strong nonspecific lymphocyte proliferation response was induced. FACS also showed that the ratio of CD8+ T cells in the experimental group was higher than the controls, but the serum HBcAb in experimental group was similar to the control. CONCLUSION: HBcAg can be used as an immuno-carrier of vaccine, the fusion of HBcAg-T protein could induce stronger cellular immune responses and it might be a candidate for therapeutic vaccines specific for HCV.

Is hemodialysis a reason for unresponsiveness to hepatitis B vaccine? Hepatitis B virus and dialysis therapy

Impaired renal function is associated with a high risk of chronicity of hepatitis B virus(HBV) infection.Patients on hemodialysis(HD) or peritoneal dialysis are at an increased risk of viral transmission due to frequent necessity of blood product transfer as well as use of contaminated dialysate or dialysis materials.Additionally,health professionals may cause viral spread via contaminated hands and carelessness against hygiene rules.The frequency of chronic HBV infection may be as high as 80% in patients on renal replacement therapies.This is because HBV vaccination is essential to eliminate chronic HBV infection.However,response rates of HD patients to HBV vaccination vary between 10%-50%.Dialysis adequacy and early vaccination before the onset of dialysis therapy seem to be major determinants of high seroconversion rates.Older age,male gender,duration of dialysis therapy and nutritional status are other well-known factors associated with seroconversion rate.There are controversial reports regarding the role of the presence of diabetes mellitus,HCV positivity,erythropoietin resistance,hyperparathyroidism,and vitamin D inadequacy.The role of genetic alteration in the functions or production of cytokines still needs to be elucidated.

Testing for hepatitis B virus alone does not increase vaccine coverage in non-immunized persons

AIM To determine whether hepatitis B virus(HBV)-testing could serve as a gateway to vaccinate non-immunized individuals in a low-prevalent country.METHODS Non-immunized subjects participating in a multi-center, HBV-testing campaign in Paris, France were identified and contacted via telephone 3-9 mo after testing in order to determine vaccination status. Vaccination coverage was evaluated in per-protocol(for all respondents) and intent-to-treat analysis(assuming all non-responders did not vaccinate).RESULTS In total, 1215/4924(24.7%) enrolled subjects with complete HBV serology were identified as nonimmunized and eligible for analysis. There were 99/902 successfully contacted subjects who had initiated HBV vaccination after screening: per-protocol, 11.0%(95%CI: 9.0-13.2); intent-to-treat, 8.2%(95%CI: 6.7-9.8). In multivariable analysis, vaccination was more likely to be initiated in individuals originating from moderate or high HBV-endemic countries(P < 0.001), patients with limited healthcare coverage(P = 0.01) and men who have sex with men(P = 0.02). When asked about the reasons for not initiating HBV vaccination, the most frequent response was "will be vaccinated later"(33.4%), followed by "did not want to vaccinate"(29.8%), and "vaccination was not proposed by the physician"(21.5%). Sub-group analysis indicated a stark contrast in vaccination coverage across centers, ranging from 0%-56%.CONCLUSION HBV-vaccination after HBV screening was very low in this study, which appeared largely attributed to physician-patient motivation towards vaccination. Increased vaccination coverage might be achieved by emphasizing its need at the organizational level.

Elicitation of strong immune responses by a DNA vaccine expressing a secreted form of hepatitis C virus envelope protein E2 in murine and porcine animal models

AIM： To characterize the immunogenicity of a hepatitis C virus （HCV） E2 DNA vaccine alone or with a protein vaccine boost in murine and porcine animal models. METHODS： A DNA vaccine expressing a secreted form of HCV E2 protein was constructed and used to vaccinate mice and piglets with or without boosting with a recombinant E2 protein vaccine formulated with CpG ODN and 10% Emulsigen. The immunogenicity of HCV E2 vaccines was analyzed by ELISA for antibody responses, MTT assay for lymphocyte proliferation, ELISPOT for the number of interferon-γ secreting cells, and cytotoxic T lymphocyte assays. RESULTS： Intradermal injection of E2 DNA vaccine induced strong Th1-1ike immune responses in mice. In piglets, E2 DNA vaccine elicited moderate and more balanced immune responses. A DNA vaccine prime and protein boost vaccination strategy induced significantly higher E2-specific antibody levels and shifted the immune response towards Th2-1ike ones in piglets. CONCLUSION： A DNA vaccine expressing a secreted form of HCV E2 protein elicited E2-specific immune responses in mice and piglets. Recombinant E2 protein vaccination following DNA immunization significantly increased the antibody response in piglets. These HCV E2 vaccines may represent promising hepatitis C vaccine candidates for further investigations.

Immune mechanisms of vaccine induced protection against chronic hepatitis C virus infection in chimpanzees

Hepatitis C virus(HCV) infection is characterized by a high propensity for development of life-long viral persistence. An estimated 170 million people suffer from chronic hepatitis caused by HCV. Currently,there is no approved prophylactic HCV vaccine available.With the near disappearance of the most relevant animal model for HCV,the chimpanzee,we review the progression that has been made regarding prophylactic vaccine development against HCV. We describe the results of the individual vaccine evaluation experiments in chimpanzees,in relation to what has been observed in humans. The results of the different studies indicate that partial protection against infection can be achieved,but a clear correlate of protection has thus far not yet been defined.

Construction of Three Nucleic Acid Vaccines of Swine Hepatitis E Virus ORF2 Ger\e Continuous Fragment

In order to develop swine hepatitis E （HE） genetically engineering vaccines, specific primers of genes LB1, LB2, LB3 of swine hepatitis E virus were designed and used for amplification, DNA amplieons generated by PCR assays were directly cloned into T-A plasmid and expressed using pEASY-M1 expression vector. Three recombinant eukaryotic expression plasmids of pEASY-LB1, pEASY-LB2 and pEASY-LB3 were constructed. The eukaryotic expression plasmids of pEASY-LB1, pEASY-LB2, and pEASY-LB3 were transfected into 293T cells, and three target genes were detected by real-time fluorescent quantitative RT-PCR. The results confirmed that three eukaryotic expression plasmids were transfected into 293Teells and target protein was expressed. Analysis by SDS-PAGE electrophoresis and Western-blot indicated that three target proteins were expressed in 293T cells transfected with eukaryotic expression plasmids of pEASY-LB1, pEASY-LB2 and pEASY-LB3. Antigenicity studies indicated good HEV responses. Therefore, three recombinant DNAs of HEV ORF2 nucleic acid vaccine candidates were ob- tained, which might lay the foundation for further studies in the future.

In the era of rapid mRNA-based vaccines:Why is there no effective hepatitis C virus vaccine yet?

Hepatitis C virus(HCV)is responsible for no less than 71 million people chronically infected and is one of the most frequent indications for liver transplanta-tion worldwide.Despite direct-acting antiviral therapies fuel optimism in controlling HCV infections,there are several obstacles regarding treatment accessibility and reinfection continues to remain a possibility.Indeed,the majority of new HCV infections in developed countries occur in people who inject drugs and are more plausible to get reinfected.To achieve global epidemic control of this virus the development of an effective prophylactic or therapeutic vaccine becomes a must.The coronavirus disease 19(COVID-19)pandemic led to auspicious vaccine development against severe acute respiratory syndrome coronavirus-2(SARSCoV-2)virus,which has renewed interest on fighting HCV epidemic with vaccination.The aim of this review is to highlight the current situation of HCV vaccine candidates designed to prevent and/or to reduce HCV infectious cases and their complications.We will emphasize on some of the crossroads encountered during vaccine development against this insidious virus,together with some key aspects of HCV immunology which have,so far,ham-pered the progress in this area.The main focus will be on nucleic acid-based as well as recombinant viral vector-based vaccine candidates as the most novel vaccine approaches,some of which have been recently and successfully employed for SARS-CoV-2 vaccines.Finally,some ideas will be presented on which methods to explore for the design of live-attenuated vaccines against HCV.

DNA-based vaccination induces humoral and cellular immune responses against hepatitis B virus surface antigen in mice without activation of Cmyc

AIM To develop a safe and effective DNAvaccine for inducing humoral and cellularimmunological responses against hepatitis Bvirus surface antigen(HBsAg).METHODS BALB/c mice were inoculated withNV-HB/s,a recombinant plasmid that had beeninserted S gene of hepatitis B virus genome andcould express HBsAg in eukaryotes.HBsAgexpression was measured by ABC immunohis-tochemical assay,generation of anti-HBs byELISA and cytotoxic T lymphocyte(CTL),byMTT method,existence of vaccine DNA bySouthern blot hybridization and activation ofoncogene C-myc by in situ hybridization,RESULTS With NV-HB/s vaccination byintramuscular injection,anti-HBs was initiallypositive 2 weeks after inoculation while all micetested were HBsAg positive in the muscles.Thetiters and seroconversion rate of anti-HBs weresteadily increasing as time went on and weredose-dependent.All the mice inoculated with100 μg NV-HB/s were anti-HBs positive onemonth after inoculation,the titer was 1:1024 ormore.The humoral immune response was similarinduced by either intramuscular or intradermalinjection.CTL activities were much stronger(45.26%)in NV-HB/s DNA immunized mice as compared with those(only 6%)in plasma-derived HBsAg vaccine immunized mice.Twomonths after inoculation,all muscle sampleswere positive by Southern-blot hybridization forNV.HB/s DNA detection,but decreased to 25%and all were undetectable by in situhybridization after 6 months.No oncogene C-myc activation was found in the muscle ofinoculation site.CONCLUSION NV-HB/s could generatehumoral and cellular immunological responsesagainst HBsAg that had been safely expressed insitu by NV-HB/s vaccination.

Long term efficacy of plasma derived hepatitis B vaccine among Chinese children: a 12 year follow up study

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