Dengue ; epidemiology ; Dengue Virus ; genetics ; isolation & purification ; Evolution, Molecular ; Genes, Viral ; Humans ; Viral Envelope 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 analyse the genetic relationship of local strains of dengue type 1 viruses isolated in different years and regions from Guangdong Province, and to explore the genetic links with strains of adjacent countries by comparing with the sequences of relevant strains in Genbank.

METHODSThe viral RNAs were extracted and used for one-step reverse transcriptase polymerase chain reaction (RT-PCR) to amplify the partial nucleotide fragments in E/NS1 gene junction which were then cloned into the plasmid pBluescript II SK for sequencing, the results were analysed by DNASTAR software.

RESULTSThe phylogenetic tree of the sequenced 14 strains of dengue type 1 viruses branches into two genotypic groups. The nucleotide sequences showed a maximal homologies of 99.2% with Indonesia strains, 100% with Philippines strains and 98.8% with Thailand strains.

CONCLUSIONSThe dengue type 1 viruses of Guangdong Province are closely related to the Philippines, Indonesia and Thailand strains, which may indicate the possibility of importation from those countries.

Base Sequence ; China ; Dengue Virus ; classification ; genetics ; isolation & purification ; Genes, Viral ; genetics ; Sequence Analysis, DNA ; Sequence Homology, Nucleic Acid

OBJECTIVETo determine a dengue fever outbreak in Yiwu city, Zhejiang Province in 2009 and to trace the origin of the pathogen.

METHODSThe dengue virus IgM, IgG antibodies and viral nucleic acid were detected and virus was isolated using 40 serum samples from the suspected patients. The viral RNA of the isolated virus strains was extracted and the E gene was amplified by RT-PCR. The amplicons were sequenced and the phylogenetic and homological analyses were also constructed.

RESULTSAmong 40 serum samples from dengue fever suspected patients, 17 were positive from for dengue IgM (42.5%); 4 were IgG positive (10.0%); 34 samples were dengue virus RNA positive (85.0%), 28 dengue virus type 3 (D3) strains were isolated (70.0%). The complete coding region of envelope genes (E) from 13 D3 strains was all 1479 nt without any insertion or deletion, which encoded with 493 amino acids (aa). E gene from the 13 D3 strains from Zhejiang in 2009 (D3/ZJ/2009) was 100.0% identical. The strain from Saudi Arabia shared the highest similarity with the D3 strain, 99.3% and 100.0% of their E genes and deduced amino acids were identical, respectively, whereas they were 93.4% and 97.4% between D3/ZJ/2009 strain and its prototype strain (D3/H87/1956), and 93.6% and 97.4% between D3/ZJ/2009 and a D3 strain isolated in Guangxi Province in 1980. The phylogenetic tree of E genes also indicated that D3/ZJ/2009 had maximum similarity with the D3/Saudi Arabia/2004. They all belonged to the D3/GIII branch, which was originated from Indian Subcontinent.

CONCLUSIONThe outbreak of dengue fever in Zhejiang in 2009 was caused by type 3 dengue virus III genotype. The virus was most likely originated from Saudi Arabia.

Adolescent ; Adult ; Aged, 80 and over ; China ; epidemiology ; Dengue ; epidemiology ; virology ; Dengue Virus ; classification ; genetics ; isolation & purification ; Disease Outbreaks ; Female ; Humans ; Male ; Middle Aged

OBJECTIVETo isolate and identify the pathogen of Dengue fever from Shenzhen city in 2005 - 2006, and to analyze the molecular characteristics of the isolated Dengue virus strain as well as to explore its possible origin.

METHODSIgM and IgG of serum samples taken from 60 suspected Dengue fever patients were detected by ELISA and immunochromatography, and 9 specimens were positive. Nine samples from patients with early stage Dengue fever were used to isolate virus with C6/36 cell line and the positive cell cultures were identified by MGB fluorescent PCR. The type of isolated virus strain was determined by RT-semi-nested-PCR and fluorescent PCR. E gene of isolated virus strain was amplified by RT-PCR and sequenced. Homology and phylogenetic tree of E gene of Shenzhen Dengue virus with the strains isolated from other areas were constructed.

RESULTSOf nine antibody-positive serum samples, one strain of Dengue virus was successfully isolated. The isolated virus strain was confirmed as Dengue virus type 2 and designated as DEN2-SZ0521. The homology of nucleotide sequence and the deduced amino acid sequence of E gene of SZ0521 with standard type 2 Dengue virus NGC strain was 94.2% and 98.2%, but the homology with standard Dengue virus 1, 3, 4 in the same fragment were 59.1%, 57.2%, 58.5% and 68.1%, 66.7%, 63.2%, respectively. The phylogenetic tree indicated that SZ0521 had the greatest similarity with the Malay0412a/Tw strain and they lied in the same branch of the phylogenetic tree. The corresponding homology of nucleotide sequence and amino acid sequence was 99.8% and 100%, respectively. The isolated Dengue virus type 2 belonged to genotype IV with Indonesia-76, Somalia-84 and Sri Lanka-90.

CONCLUSIONDengue virus was isolated from Shenzhen for the first time, and it was classified as type 2. It was confirmed that the type 2 Dengue virus may come from the epidemic area in Malaysia.

Aedes ; virology ; Animals ; China ; Dengue ; virology ; Dengue Virus ; classification ; genetics ; isolation & purification ; Genes, Viral ; Humans ; Phylogeny ; Sequence Analysis, Protein ; Sequence Analysis, RNA

OBJECTIVETo construct the cDNA subclones spanning the entire genome of dengue 2 virus NGC strain for further construction of full-length infectious viral cDNA clone.

METHODSTwo pairs of primers were designed according to the restriction endonuclease sites in the viral genome of dengue 2 virus NGC strain. After viral RNA extraction from the brain of infected new-born mice, two parts of full-length viral cDNA were amplified by long RT-PCR and cloned into the vector pCR-XL-TOPO. The partial sequence of the recombinant plasmid was determined.

RESULTS AND CONCLUSIONSequence analysis and digestion with restriction enzymes demonstrated that the two cDNA subclones were specific for dengue 2 virus NGC strain, suggesting the successful construction of the two cDNA subclones of dengue 2 virus NGC strain.

Animals ; Animals, Newborn ; Brain ; virology ; Cloning, Molecular ; DNA, Complementary ; biosynthesis ; genetics ; DNA, Viral ; biosynthesis ; genetics ; Dengue ; virology ; Dengue Virus ; classification ; genetics ; isolation & purification ; Genome, Viral ; Mice ; RNA, Viral ; genetics ; isolation & purification ; Recombination, Genetic ; Reverse Transcriptase Polymerase Chain Reaction

OBJECTIVETo express the domain III of DENV II envelop protein in Escherichia coli, obtain the purified recombinant protein and identify its immunoreactivity.

METHODSSuckling mice were inoculated with live DENV II in the brain. The total RNA was extracted from the brain of the infected mice, and the envelope protein DNA fragment was amplified by RT-PCR and ligated into pMD 18-T to construct pMD 18-T-DV2-E. The domain III DNA fragment of the envelope protein was amplified by PCR with pMD 18-T-DV2-E as the template and cloned into pET-32a(+) to construct the expression plasmid pET-32a(+)-DV2-E-DIII. The recombinant plasmid was transformed into E.coli BL21(DE3) and induced by IPTG, and the expressed products were analyzed by SDS-PAGE and Western blotting.

RESULTSAfter RT-PCR amplification, a specific DNA fragment of about 1.5 kb was obtained and ligated into pMD 18-T to construct pMD 18-T-DV2-E. With pMD 18-T-DV2-E as the template, the domain III DNA fragment about 320 bp in length was amplified and the expression plasmid pET-32a(+)-DV2-E-DIII was successfully constructed. After induction with IPTG, a specific soluble protein with a relative molecular mass of 29000 was obtained and the expression product accounted for 52.50 percent; of the total protein of the cell lysate. Western blotting demonstrated reactivity of the recombinant protein with His-Tag McAb and DENV (Type I-IV) McAb.

CONCLUSIONThe recombinant plasmid can be highly expressed in E.coli BL21(DE3) in a soluble form and the recombinant protein can react with DENV (Type I-IV) McAb.

Animals ; Dengue Virus ; genetics ; isolation & purification ; Escherichia coli ; metabolism ; Genetic Vectors ; Mice ; Mice, Inbred Strains ; Plasmids ; Protein Interaction Domains and Motifs ; Viral Envelope Proteins ; genetics ; isolation & purification

OBJECTIVETo identify the virus isolated from Jiangmen, Guangdong province and to discuss the possible origin.

METHODSUsing characteristics of indirect fluorescent antibody tests (IFA), reverse transcription-polymerase chain reaction (RT-PCR), mouse neurovirulence and cell culture to identify the isolated virus. According to the nature of dengue virus type 2 NGC strain, two pairs of primers were designed. The structural protein gene of isolated dengue virus type 2 strain was then amplified by RT-PCR, cloned into pMD18-T vector and sequenced.

RESULTSTwenty-two of 37 serum samples showed a positive reaction to dengue antibody IgG, and 36 of 37 with IgM with the highest antibody titer 1:640. Ten samples were resulted in a cytopathy on C6/36 cells and showed a neurovirulence in suckling mice when inoculated intracerebrally. The structural gene of new isolate GD19/2001 containing 2 325 nucleotides which encoded 774 amino acids. Data on nucleotide homology were 98%, 96%, 94%, 94%, 92%, 92%, 92% and 91% compared with TSV01, GD06/93, NGC and 44, ThNH81/93, 04 and GD08/98, and S1 respectively.

CONCLUSIONThe isolated virus from Jiangmen, Guangdong province belonged to dengue virus type 2, which might come from Australia.

Animals ; Antibodies, Viral ; blood ; China ; epidemiology ; DNA, Viral ; genetics ; Dengue ; epidemiology ; virology ; Dengue Virus ; genetics ; immunology ; isolation & purification ; Fluorescent Antibody Technique ; Humans ; Polymerase Chain Reaction ; RNA, Viral ; genetics ; Sequence Analysis, DNA

From 2013 to 2015, the National Institute of Health, Pakistan, received 1,270 blood samples of suspected dengue cases reported from inpatient and outpatient departments of various hospitals in Khyber Pakhtunkhwa (KPK) province. In this study, we determined the circulating dengue virus (DENV) serotypes using real-time reverse transcriptase (RT)-PCR to understand the serotype-based epidemiology of DENV. All four serotypes (DENV-1 [6%], DENV-2 [33%], DENV-3 [47%], and DENV-4 [0.1%]) were found circulating during the study period. Our findings suggest the need for an active surveillance system coupled with the laboratory diagnosis, especially in the chronic endemic areas of the country. Public awareness programs are needed for effective control and prevention of outbreaks in the future.
Adolescent ; Adult ; Dengue/diagnosis/*epidemiology/virology ; Dengue Virus/genetics/*isolation & purification ; Disease Outbreaks ; Female ; Humans ; Male ; Middle Aged ; Pakistan/epidemiology ; RNA, Viral/genetics/metabolism ; Real-Time Polymerase Chain Reaction ; Serogroup ; Young Adult

OBJECTIVETo analyze the clinical and epidemiological characteristics of Dengue fever (DF) during the Dengue-1 epidemic in Guangzhou.

METHODSClinical and epidemiological data of 1032 patients with DF from May 2002 to November 2003 were retrospectively analyzed. Dengue virus were isolated by cell culture and typed by reverse transcriptase polymerase chain reaction (RT-PCR).

RESULTSAge of the patients ranged from 55 days to 91 years old (average 34.7 +/- 13.2 years) with sex ratio 1.03:1. Incubation period ranged from 2 to 12 days with mean periods of 5.3 +/- 2.4 days. Most (45.0%) cases appeared in September and the epidemic last from July to November. Dengue outbreak had involved 675 cases in 26 common places. The common manifestations were seen as fever (100%), headache (90.9%), myalgia (68.4%), bone soreness (48.8%), fatigue (79.3%), skin rash (60.1%), positive tourniquet test (45.3%), leukopenia (63.3%) and thrombocytopenia (60.8%), respectively. Dengue virus was isolated from serum of 19 out of 54 patients' and identified as Dengue virus type 1. DNA sequence analyzes on rates of nucleotide homology were 97%, 97% and 98% compared with those of Dengue virus type 1 strain of DF outbreak in Cambodia, in 1997 and 1999 in China.

CONCLUSIONThe epidemic of DF in Guangzhou in 2002/2003 was caused by Dengue virus type-1 with most patients showing classic type of the disease. Date suggested that change can happen from non-endemic to hypoendemic regions in Guangdong province.

Adolescent ; Adult ; Aged ; Aged, 80 and over ; Base Sequence ; Child ; Child, Preschool ; China ; epidemiology ; Dengue ; epidemiology ; Dengue Virus ; classification ; genetics ; isolation & purification ; Female ; Humans ; Incidence ; Infant ; Male ; Middle Aged ; Molecular Sequence Data