Dengue ; epidemiology ; Dengue Virus ; genetics ; isolation & purification ; Evolution, Molecular ; Genes, Viral ; Humans ; Viral Envelope Proteins ; genetics

Dengue virus infection has become a global threat affecting around 100 countries in the world. Currently, there is no licensed antiviral agent available against dengue. Thus, there is a strong need to develop therapeutic strategies that can tackle this life threatening disease. RNA interference is an important and effective gene silencing process which degrades targeted RNA by a sequence specific process. Several studies have been conducted during the last decade to evaluate the efficiency of siRNA in inhibiting dengue virus replication. This review summarizes siRNAs as a therapeutic approach against dengue virus serotypes and concludes that siRNAs against virus and host genes can be next generation treatment of dengue virus infection.
Animals ; Dengue ; therapy ; Dengue Virus ; genetics ; Humans ; RNA Interference ; RNA, Small Interfering ; genetics ; therapeutic use

To select the adaptive strain of Dengue-III virus D9964 strain (China strain) in KMB17 cells, elucidate the biological characteristics and proliferation kinetics of adapted strain,and to lay the foundation for the development dengue inactivated vaccine and attenuated live vaccine. Dengue-III virus D9964 strain was firstly identified by amplification of the type-specific gene segment of dengue virus by RT-PCR, and the titer was determined. The virus was then subcultured in KMB17 cells with 4.0 MOI till completely adaptive to multiply in cell S. After subculturing in KMB17 cells for 10 consecutive passages, the adapted strain was screened, and purified through plaque. Virus titer of each passage was measured by microtitrimetry, and the antigenicity was detected by IFA. The purified virus RNA extraction of 3-8 day cultured from KMB17 cells, was performed to detect the proliferation kinetics of adapted strain. The results showed that after continuous subculture, dengue-III virus D9964 (China) strain could stably proliferate in KMB17 cells, a highly puried virus adapted strain was obtained through plaque purification. Purified strain maintained the good antigenicity with a highest replicating activity during the 5th-6th day.
Cell Line ; Dengue ; virology ; Dengue Virus ; chemistry ; genetics ; growth & development ; physiology ; Humans ; Kinetics ; Virus Cultivation ; Virus Replication

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

Dengue virus (DENV) is a re-emerging disease transmitted by the Aedes mosquitoes and has become a major public health problem in southern China. Currently, no antiviral drug or effective vaccine exist to control this disease. The chimeric DENV structural protein vaccine cannot elicit balanced levels of protective immunity to each of the four viral serotypes; therefore, non-structural protein components may be required to construct an effective DENV vaccine. The Dengue virus non-structural 1 (DENV NS1) protein plays a critical role in viral pathogenesis and protective immunity. Therefore, immunity to Dengue 1-4 NS1 subtypes may be crucial for the prevention of severe disease. This review attempts to provide an overview about the structure and function of DENV NS1.
Animals ; Dengue ; immunology ; prevention & control ; virology ; Dengue Vaccines ; chemistry ; genetics ; immunology ; Dengue Virus ; chemistry ; genetics ; immunology ; Humans ; Viral Nonstructural Proteins ; chemistry ; genetics ; immunology

China ; epidemiology ; Dengue ; epidemiology ; virology ; Dengue Virus ; classification ; genetics ; Genome, Viral ; Open Reading Frames ; Phylogeny ; Viral Nonstructural Proteins ; genetics

OBJECTIVETo study the epidemiology and etiologic characteristics of a Dengue fever outbreak in Fuzhou from the beginning of September to the end of October in 2004 in order to understand the source of infection.

METHODSData on descriptive epidemiology was collected to study the characteristics and related factors to the epidemic. Dengue virus was isolated through the use of C6/36 cell line while viral serotypes were identified by indirect immunofluorecent assay with type-specific monoclonal antibody. The sources of infection were traced by nucleotide sequencing.

RESULTSDuring the epidemic, 93 cases occured consistently with the region entomoplily growth and decay. The viruses of 6 strains isolated from 10 patients' blood specimens were identified as dengue virus type 1. Phylogenetic evidence suggested that the viral isolate had high genetic relation with the isolates from Kampuchea (DENV-1/KHM/2001; GenBank Accession No. L0904278).

CONCLUSIONThe epidemic was caused by introduction of patients migrating into Fuzhou.

China ; epidemiology ; Dengue ; epidemiology ; Dengue Virus ; genetics ; isolation & purification ; Disease Outbreaks ; Emigration and Immigration ; Genetic Variation ; Humans ; Phylogeny

OBJECTIVETo achieve secretory and extracellular production of recombinant dengue virus serotypes I-IV envelope glycoprotein domain III (DENV-1-4 EDIII) in Pichia pastoris.

METHODSEDIII genes of DENVI-IV were amplified and cloned into vector pPIC9K, respectively. These recombinant plasmids were then linearized and transferred into Pichia pastoris strain GS115. Clones highly produced in 4.0 mg/ml G418 were amplified and induced by methanol to achieve the secreted recombinant proteins. Ni-NTA agarose beads were used for purification, while SDS-PAGE and Western blotting were used for identification.

RESULTSThe recombinant plasmids pPIC9K-DENV-1-4 EDIII were constructed and successfully transferred into Pichia pastoris strain GS115. The recombinant EDIII proteins were expressed in a secretory way with the molecular weight about 12 × 10(3) and specifically identified by anti-His monoclonal antibody and anti-DENVI-IV mice sera.

CONCLUSIONDENVI-IV EDIII proteins are successfully achieved from Pichia pastoris expression system and could be used for development of dengue vaccines, diagnostic reagents and study of biological function of the E protein.

Dengue Virus ; genetics ; Genetic Vectors ; Pichia ; metabolism ; Recombinant Proteins ; genetics ; Viral Envelope Proteins ; secretion

Codon ; Dengue Virus ; chemistry ; genetics ; Gene Expression ; Genes, Viral ; Hydrophobic and Hydrophilic Interactions ; Viral Structural Proteins ; genetics

To investigate the effects of DENV infection on the expression of Vascular endothelial growth factor (VEGF) in monocytes, and to explore which innate immune signaling pathway is responsible for VEGF induction. Real-time PCR was used to determine the expression levels of VEGF in DENV-infected THP-1. We found that different serotype viruses (DENV1, DENV2, DENV3) induced the VEGF expression. Moreover, VEGF expression was significantly increased in human primary monocytes infected with DENV 2. In addition, VEGF induction by DENV2 was significantly impaired by knockdown of TLR3 and interferon-beta promoter stimulator 1 (IPS-1), or by inhibition of ERK, JNK or NF-kappaB. These results demonstrated that DENV induced VEGF expression in monocytes, and the activation of TLR3, IPS-1 signal pathways were required for DENV2-triggered VEGF induction, suggesting that VEGF might be a promising therapeutic target for DHF.
Dengue ; genetics ; immunology ; virology ; Dengue Virus ; classification ; genetics ; physiology ; Humans ; MAP Kinase Signaling System ; Monocytes ; NF-kappa B ; genetics ; immunology ; Up-Regulation ; Vascular Endothelial Growth Factor A ; genetics ; immunology