The prevalence of dengue infection poses a great public health concern among people living in tropical and subtropical countries like the Philippines. Just recently in 2019, the Philippines had a dengue virus (DENV) outbreak where nearly half of the mortalities were children between 5 and 9 years of age, and around 73% of confirmed DENV cases were under the age of 19. Children are disproportionately affected and are considered to be highly vulnerable to severe dengue infection compared to adults due to several factors. These include: immunological differences--poorly developed immune systems, making them more susceptible to the virus; smaller body sizes and weight means that they are more likely to experience severe symptoms; and their tendency to play outdoors, make them more exposed to mosquito bites. Hence, this article provides an overview of the current understanding for the vulnerability of children to severe dengue infection compared to adults
dengue virus ; dengue shock syndrome

Objective To perform quality control in live attenuated yellow fever vaccine(chicken embryo cell)virus seed bank at the genomic level using the new generation Illumina/Solexa sequencing platform.Methods The live attenuated yellow fever vaccine strain YF17D-204 was inoculated into primary chicken embryo cells,and the chicken embryo cell adapted strains of live attenuated yellow fever vaccine were screened to establish YFV17D-CEC tertiary virus seed bank. The genome RNA of virus seeds was extracted,and the RNA library was prepared. The new generation Illumina/Solexa sequencing platform was used for high-throughput RNA sequencing. The whole genome nucleic acid sequence of yellow fever virus was systematically analyzed by using biological softwares such as FastQC,Trimmomatic,SPAdes,GapFiller,PrInSeS-G,Prokka,RepeatMasker,CRT,NCBI Blast~+,KAAS,HMMER3,TMHMM,SignalP,LipoP,ProtCamp and MegAlign.Results The whole genome of YFV17D-CEC tertiary virus seed bank contained 10 862 nucleotides,including an open reading frame(ORF)from 119 to 10 354(10 236 bp),encoding 3 412 amino acids. Sequence alignment analysis showed that the sequence of YF17D-CEC tertiary virus seed bank was 100% identical with YFV17D RKI(JN628279.1),YF/Vaccine/USA/Sanofi-Pasteur-17D-204/UF795AA/YFVax(JX503529.1)and YFV17D-204(KF769015.1),and no mutation occurred in the whole genome of the tertiary virus seed bank. Comparison of the sequences of different live attenuated yellow fever vaccine strains showed that yellow fever virus had multiple polymorphic sites.Conclusion YFV17DCEC has good genetic stability in primary chicken embryo cells. High-throughput RNA sequencing technology can quickly detect the whole genome information of YF17D-CEC virus seed bank,and the sequence analysis data can be used in the gene level quality control of yellow fever vaccine virus seed banks.
High-throughput RNA sequencing ; Live attenuated yellow fever vaccine ; Gene expression ; Virus seed bank ; Quality control

Humans ; Animals ; Culicidae ; Flavivirus ; Cell Line ; Spiramycin

Flavivirus ; Humans ; Immunity ; Vaccines ; Zika Virus ; Zika Virus Infection/prevention & control*

In order to evaluate the immune effect of the genotype Ⅰ Japanese encephalitis virus prM-E DNA vaccine and the prM-EⅢ fusion protein subunit vaccine on mice using DNA prime-protein boost strategy, the prM-E gene was inserted into the pVAX1 eukaryotic expression vector. The recombinant expression vector prM-E-pVAX1 was constructed as a DNA vaccine for initial immunity, and the recombinant prM-EⅢ fusion protein was obtained using a prokaryotic expression system as a subunit vaccine for enhanced immunity. Thirty two female BALB/c mice aged 4-6 weeks were randomly divided into four groups, and a prM-E-pVAX1 DNA vaccine group, a DNA prime-protein boost immune group, a prM-EⅢ subunit vaccine group, and a pVAX1 vector control group were set up. The specific antibody level in serum was monitored by ELISA, the neutralizing antibody titer was detected by plaque reduction neutralization, and the cellular immune responses induced by different vaccine immune groups were analyzed by cytokine expression abundance and lymphocyte proliferation experiments. The results showed that the neutralizing antibody titers induced by mice immunized with the DNA prime-protein boost strategy were close to that of the group immunized with the single prM-EⅢ subunit vaccine, but significantly higher than that of the group immunized with the single prM-E-pVAX1 DNA vaccine. DNA prime-protein boost strategies induced effective Th1/Th2 immune responses in mouse models, in particular the Th1 cell-mediated immune responses. This study provides a new immune strategy that may facilitate the prevention of Japanese encephalitis.
Animals ; Antibodies, Neutralizing ; Antibodies, Viral ; DNA ; Disease Models, Animal ; Encephalitis Virus, Japanese/genetics* ; Female ; Mice ; Mice, Inbred BALB C ; Vaccines, DNA/genetics* ; Vaccines, Subunit

Japanese encephalitis (JE) virus is the leading cause of vaccine-preventable encephalitis in Asia and the Western Pacific, which mainly invades central nervous system. Vaccination is the most important strategy to prevent JE. Currently, both live attenuated Japanese encephalitis vaccines (JE-L) and inactivated vaccines (JE-I) are in use. Due to the supply of vaccines and the personal choice of recipients, there will be a demand for interchangeable immunization of these two vaccines. However, relevant research is limited. By reviewing domestic and foreign research evidence, this article summarizes the current situation of the interchangeable use of JE-L and JE-I, and makes recommendations when the interchangeable immunization is in urgent need, so as to provide reference for practical vaccination and policymaking in China.
Encephalitis Virus, Japanese ; Encephalitis, Japanese/prevention & control* ; Humans ; Immunization ; Japanese Encephalitis Vaccines ; Vaccination ; Vaccines, Inactivated

Objective: To assess the incidence of dengue fever and E gene evolution of dengue virus in Guangzhou in 2020 and understand the local epidemiological characteristics of dengue fever and spreading of dengue virus. Methods: The information of dengue fever cases in Guangzhou in 2020 was collected from Notifiable Infectious Disease System of Chinese Center for Disease Control and Prevention Information System. Serum samples from the cases were detected by real-time PCR. The E gene was sequenced and analyzed. Maximum likelihood phylogenetic trees were constructed using software MEGA 5.05. The statistical analysis was conducted using software SPSS 20.0. Results: A total of 33 dengue fever cases were reported in Guangzhou in 2020, including 31 (93.94%) imported cases and 2 (6.06%) local cases. Compared with the data during 2016 to 2019, the number of cases, overall incidence and local incidence all decreased with statistically significant differences (all P<0.05). The imported cases from Southeast Asia constituted 90.32% (28/31) of imported cases. The E gene sequences and the phylogenetic trees of imported and local cases demonstrated close relationship with the virus sequences from Southeast Asian, and they were less homologous with the sequences of dengue virus isolated in Guangzhou in previous years. Conclusions: The incidence of dengue in Guangzhou in 2020 was significantly affected by the imported cases, especially those from Southeast Asian countries. The study result demonstrated that dengue fever was not endemic in Guangzhou and it was caused by imported ones.
China/epidemiology* ; Dengue/epidemiology* ; Dengue Virus/genetics* ; Disease Outbreaks ; Evolution, Molecular ; Genotype ; Humans ; Phylogeny

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

Dengue virus (DENV) is the most widely transmitted arbovirus in the world. Due to the lack of diagnostic technology to quickly identify the virus serotypes in patients, severe dengue hemorrhagic fever cases caused by repeated infections remain high. To realize the rapid differential diagnosis of different serotypes of DENV infection by immunological methods, in this study, four DENV serotype NS1 proteins were expressed and purified in mammalian cells. Monoclonal antibodies (MAbs) against NS1 protein were obtained by hybridoma technology after immunizing BALB/c mice. Enzyme-linked immunosorbent assay, indirect immunofluorescence assay, dot blotting, and Western blotting were used to confirm the reactivity of MAbs to viral native NS1 and recombinant NS1 protein. These MAbs include not only the universal antibodies that recognize all DENV 1-4 serotype NS1, but also serotype-specific antibodies against DENV-1, DENV-2 and DENV-4. Double antibody sandwich ELISA was established based on these antibodies, which can be used to achieve rapid differential diagnosis of serotypes of DENV infection. Preparation of DENV serotype-specific MAbs and establishment of an ELISA technology for identifying DENV serotypes has laid the foundation for the rapid diagnosis of DENV clinical infection.
Animals ; Antibodies, Monoclonal ; Antibodies, Viral/metabolism* ; Dengue/diagnosis* ; Dengue Virus/immunology* ; Enzyme-Linked Immunosorbent Assay ; Humans ; Mice ; Mice, Inbred BALB C ; Sensitivity and Specificity ; Serogroup ; Viral Nonstructural Proteins/immunology*

OBJECTIVE: Tick-borne encephalitis virus (TBEV) is an emerging pathogen in Europe and North Asia that causes tick-borne encephalitis (TBE). A simple, rapid method for detecting TBEV RNA is needed to control this disease. METHODS: A reverse-transcription recombinase-aided amplification (RT-RAA) assay was developed. This assay can be completed in one closed tube at 39 °C within 30 minutes. The sensitivity and specificity of RT-RAA were validated using non-infectious synthetic RNA representing a fragment of the NS5 region of the wild-type (WT) TBEV genome and the Senzhang strain. Additionally, 10 batches of tick samples were used to evaluate the performance of the RT-RAA assay. RESULTS: The analytical limit of detection of the assay was 20 copies per reaction of the TBEV synthetic transcript and 3 plaque-forming units (pfu) per reaction of TBEV titers. With the specific assay, no signal due to other arboviruses was observed. Of the 10 batches of tick samples obtained from the Changbai Mountains of China, three were TBEV-positive, which was consistent with the results of the quantitative real-time PCR assay. CONCLUSION A rapid, highly sensitive, specific, and easy-to-use method was developed for the detection of the TBEV Far-Eastern subtype.
Encephalitis Viruses, Tick-Borne ; genetics ; isolation & purification ; Nucleic Acid Amplification Techniques ; RNA, Viral ; analysis