Child ; China ; epidemiology ; Encephalitis Virus, Japanese ; Encephalitis, Viral ; epidemiology ; prevention & control ; Female ; Humans ; Japanese Encephalitis Vaccines ; immunology ; Male ; Vaccination

OBJECTIVETo explore on the immunity of live attenuated Japanese Encephalitis (JE) vaccine (SA14-14-2) to different wild JE virus (JEV) strains.

METHODSThe neutralizing effect of the vaccine against different wild JE virus strains was detected by plaque reduction neutralization test (PRNT), and the immunogenicity was studied on mice by vaccination -challenge protection test. In the PRNT, pooled sera from vaccinated human were tested against 10 strains of JEV, one isolated in Taiwan and 9 from other Asian countries. In the vaccination challenge test, mice received one dose of the live vaccine subcutaneously and were challenged intraperitoneally 14 days later against 22 JEV virus strains, 11 were isolated in China and the other 11 from Tailand, Vietnahailam, Indonesia, India, Philippines and Japan.

RESULTSThe protection rates to all the 22 challenge virus were 90% - 100% when 340 PFU/0.1 ml vaccinate virus was administered. The neutralizing effect showed that all the JEV isolates many have neutralized by the sera.

CONCLUSIONSA14-14-2 live attenuated prepared with strain SA14-14-2 is broadly immunogenic and may have effective protection against in Asian JE affected countries.

Adolescent ; Animals ; Child ; Encephalitis, Japanese ; prevention & control ; Humans ; Japanese Encephalitis Vaccines ; immunology ; Mice ; Neutralization Tests ; Vaccination ; Vaccines, Attenuated

Japanese encephalitis virus(JEV)is one of the leading cause of viral encephalitis in Asia. The phenotypic and genotypic characteristics of isolated virus strains are reviewed in this paper. Studies on the biological characteristics of the isolates showed that different isolates existed apparent differences in virus plaque morphology, neuroinvasive pathogenicity in mice, protective antigenicity and hemagglutination property. In China, only genotype III JEV strains were isolated before 1977. But since 1977, both genotype I and I JEV strains were isolated and the genotype I virus, which was isolated from mosquitoes mostly, has become the dominant strain. Study on the genomic sequence indicated that there was only a few amino acid difference (< or = 43%) between the two genotype isolates. Comparison between both genotype isolates and widely used live vaccine strain SA14-14-2 revealed that there were only < or = 3% amino acid differences, most of which were the SA14-14-2 unique attenuating sites. These results indicate that the SA14-14-2 live vaccine is able to protect people against infection of the both genotype I and Ill JEV strains.
Animals ; China ; Culicidae ; virology ; Encephalitis Virus, Japanese ; classification ; genetics ; immunology ; isolation & purification ; Encephalitis, Japanese ; immunology ; prevention & control ; virology ; Genome, Viral ; genetics ; Genotype ; Humans ; Japanese Encephalitis Vaccines ; immunology ; Mice ; Phenotype ; Species Specificity ; Vaccines, Attenuated ; immunology

To screen the best genotypeⅠJapanese encephalitis virus subunit vaccine candidate antigens, the prMEIII gene, the polytope gene and the prMEIII-polytope fusion gene of the GenotypeⅠJapanese encephalitis virus GS strain were cloned into prokaryotic expression vector pET-30a. The recombinant proteins were obtained after the induction and purification. The prepared recombinant proteins were immunized to mice, and the immunogenicity of the subunit vaccine candidate antigens was evaluated through monitoring the humoral immune response by ELISA, detecting the neutralizing antibody titer by plaque reduction neutralization test, and testing the cell-mediated immune response by lymphocyte proliferation assay and cytokine profiling. The recombinant proteins with the molecular weights of 35 (prMEIII), 28 (polytope antigen) and 57 kDa (prMEIII-polytope) induced strong humoral and cellular immune responses in mice. Compared with prMEIII-polytope and polytope proteins, the prMEIII protein induced a significant expression of IL-2 and IFN-γ (P<0.05) and the significant lymphoproliferation of splenocytes (P<0.05). The neutralizing antibody titer induced by the prMEIII protein was close to that induced by the commercial attenuated vaccine SA14-14-2 (P>0.05). The study suggests that the prMEIII protein can be used for the development of the Japanese encephalitis virus subunit vaccine.
Animals ; Antibodies, Viral ; blood ; Antigens, Viral ; immunology ; Encephalitis Virus, Japanese ; immunology ; Encephalitis, Japanese ; immunology ; prevention & control ; Immunogenicity, Vaccine ; Mice ; Mice, Inbred BALB C ; Vaccines, Subunit ; immunology ; Viral Vaccines ; immunology

Effective and tolerable vaccination is an essential strategy to prevent Japanese encephalitis (JE) in endemic areas. Although the live attenuated SA 14-14-2 JE vaccine (LAJEV) has been widely used since its introduction, the systemic data of LAJEV was very rarely available in Korea. We conducted the open-label, prospective cohort study to assess the immunogenicity and safety of this vaccine. Ninety subjects were enrolled, and LAJEV in a 2-dose primary series was given with a 12-month interval. Neutralizing antibody titers were measured before and after each vaccination, and active monitoring for adverse events was performed. After the first dose, 91.1% of subjects had seroprotection with a geometric mean titer (GMT) of 40.9. Seroprotection rate after the second dose was 97%, and GMT showed an increase of 6.5-fold. Most adverse events following immunization were self-limited, and no serious adverse events were reported until 42 days after each dose. The 2-dose administration of LAJEV in the primary immunization schedule appeared to be highly immunogenic and safe.
Antibodies, Neutralizing/analysis/immunology ; Antibodies, Viral/analysis/immunology ; Antibody Formation ; Child, Preschool ; Cohort Studies ; Encephalitis, Japanese/*prevention & control ; Female ; Humans ; Infant ; Japanese Encephalitis Vaccines/*immunology ; Male ; Prospective Studies ; Vaccination ; Vaccines, Attenuated/*immunology

Genes encoding for the premembrane and envelope (prME), envelope (E) and nonstructural protein (NS1) of Japanese encephalitis virus (JEV) were cloned. Each protein was expressed in baculovirus expression system. Of the three proteins expressed in baculovirus system, only prME had hemagglutination activity. The prME (72 and 54 kDa), E (54 kDa) and NS1 (46 kDa) proteins could be detected by Western blotting in the recombinant virus infected cells. Immunogenicity of the recombinant proteins obtained from infected Spodoptera frugiperda (Sf-9) cells was examined in mice. The 3 week-old ICR mice immunized intraperitoneally with three recombinant proteins three times were challenged with a lethal JEV. A survival rate was increased from about 7.7% in unimmunized mice to 92.3% in E + prME and only E groups. The complete protection was shown in prME and live vaccine inoculated groups, respectively. We also measured neutralizing antibody and three immunoglobulin subtypes of IgG1, IgG2a and IgG2b in the sera of mice before and after challenge. Titers of IgG1 antibodies were approximately two to three times higher than that of IgG2b antibodies in all the immunized groups as compared to the control group. However, IgG2a antibody level somewhat increased after challenge, indicating T-helper type 1 (Th1) cell response. The results of this study can provide useful information for developing efficacious subunit vaccine against JEV.
Animals ; Antibodies, Viral/blood ; Baculoviridae/genetics ; Blotting, Western ; Cloning, Molecular ; Encephalitis Virus, Japanese/genetics/*immunology ; Encephalitis, Japanese/*immunology/prevention&control ; Female ; Immunization ; Immunoglobulin Isotypes/blood ; Japanese Encephalitis Vaccines/*immunology/standards ; Mice ; Mice, Inbred ICR ; Microscopy, Fluorescence ; Plasmids ; Recombinant Proteins/genetics/immunology ; Viral Envelope Proteins/genetics/*immunology ; Viral Matrix Proteins/genetics/*immunology ; Viral Nonstructural Proteins/genetics/*immunology

The cDNA fragment of JEV prME gene was cloned into the baculovirus shuttle vector (bacmid) to construct a recombinant baculovirus vector, defined as AcBac-prME. Then the recombinant baculovirus Ac-prME was obtained by transfecting Sf9 cells with AcBac-prME. Western blot analysis and immunofluorescence results indicated that both prM and E proteins were efficiently expressed in Sf9 cells. Electron microscopy suggested that prME was assembled into JEV-VLPs. To further evaluate the potential of JEV-VLPs as vaccine, the mice were immunized with JEV-VLPs and then challenged with lethal JEV. The results of mice survival and pathological changes demonstrated that the JEV-VLPs performed complete protection against JEV-P3 strain and relieved pathological changes in the mice brain significant. This study suggest that JEV-VLPs would be a potential vaccine for Japanese encephalitis virus.
Animals ; Antibodies, Viral ; immunology ; Encephalitis Virus, Japanese ; genetics ; immunology ; Encephalitis, Japanese ; immunology ; prevention & control ; virology ; Humans ; Japanese Encephalitis Vaccines ; administration & dosage ; genetics ; immunology ; Mice ; Mice, Inbred BALB C ; Sf9 Cells ; Vaccination ; Vaccines, Virus-Like Particle ; administration & dosage ; genetics ; immunology ; Viral Envelope Proteins ; administration & dosage ; genetics ; immunology

This study aimed to investigate the immune adjuvant effect and mechanism induced by chitosan nanoparticles carrying pJME/GM-CSF. In this study, plasmid DNA (pJME/GM-CSF) was encapsulated in chitosan to prepare chitosan-pJME/GM-CSF nanoparticles using a complex coacervation process. Immunohistochemistry was used to detect the type of infiltrating cells at the site of intramuscular injection. The phenotype and functional changes of splenic DCs were measured by flow cytometry after different immunogens were injected intramuscularly. The killing activity of CTLs was assessed using the lactate dehydrogenase (LDH) release assay. The preparation of chitosan-pJME/GM-CSF nanoparticles matched the expected theoretical results. Our results also found that, after pJME/GM-CSF injection, the incoming cells were a mixture of macrophages, neutrophils, and immature DCs. Meanwhile, pJME/GM-CSF increased the expression of MHC class II molecules on splenic DCs, and enhanced their Ag capture and presentation functions. Cell-mediated immunity was induced by the vaccine. Furthermore, chitosan-pJME/GM-CSF nanoparticles outperformed the administration of standard pJME/GM-CSF in terms of DC recruitment, antigen processing and presentation, and vaccine enhancement. These findings reveal that chitosan could be used as delivery vector for DNA vaccine intramuscular immunizations, and enhance pJME/GM-CSF-induced cellular immune responses.
Adjuvants, Immunologic ; administration & dosage ; Animals ; Chitosan ; administration & dosage ; immunology ; Dendritic Cells ; immunology ; virology ; Encephalitis Virus, Japanese ; genetics ; immunology ; Encephalitis, Japanese ; immunology ; prevention & control ; virology ; Female ; Granulocyte-Macrophage Colony-Stimulating Factor ; administration & dosage ; genetics ; immunology ; Humans ; Immunity, Cellular ; Japanese Encephalitis Vaccines ; administration & dosage ; genetics ; immunology ; Mice ; Mice, Inbred BALB C ; Nanoparticles ; administration & dosage ; Spleen ; immunology ; T-Lymphocytes, Cytotoxic ; immunology ; virology ; Vaccines, DNA ; administration & dosage ; genetics ; immunology

OBJECTIVEThe aim of the study was to establish the contemporary epidemiological characteristics of Japanese encephalitis (JE) in Guizhou Province.

METHODSA retrospective study of National Notifiable Disease Reporting System (NNDRS) data from 1971 through 2009, was conducted to ascertain the geographical, seasonal, and age distributions of JE incidence in Guizhou Province, China.

RESULTSA total of 68 425 JE cases were reported in Guizhou from 1971-2009. The JE cases occurred sporadically in all 9 prefectures of Guizhou, mostly among residents of rural areas. Seasonal distribution of JE remained consistent over the period from 1971-2009 with the main transmission season starting from June to September and peaking in August. JE occurred mainly in children under the age of 15 years with peak incidence in the 0-6-year age group. Pearson's correlation analysis showed that JE vaccine distribution had a negative correlation with JE incidence rates during 1971-2009 (coefficient of correlation=-0.475, P<0.01).

CONCLUSIONOver the period of 1971-2009, the JE incidence rate had declined dramatically in terms of geographical and age distributions due to JE vaccination to children at risk.

Adolescent ; Age Distribution ; Child ; Child, Preschool ; China ; epidemiology ; Encephalitis, Japanese ; epidemiology ; mortality ; prevention & control ; Humans ; Incidence ; Infant ; Infant, Newborn ; Seasons ; Time Factors ; Viral Vaccines ; immunology