关键词: 登革热, 输入性, 登革热1型, 登革热4型, 基因亚型, E基因, 分子溯源

Abstract:

Objective To confirm the laboratory diagnosis of dengue fever and trace the molecular origin of the pathogen in Zhejiang province, China, 2013. Methods The serum samples from the dengue fever patients were used to detect the dengue IgM antibodies and viral nucleic acids, and to isolate the virus. The envelope (E) gene of the isolated strains was amplified by RT-PCR. The amplicons were sequenced and subjected to homologous and phylogenetic analyses. Results All 18 dengue fever patients had been to endemic areas of dengue fever overseas. Fifteen (83.3%) out of 18 serum samples from the patients were positive for anti-dengue IgM, and 8 (44.4%) were positive for dengue viral nuclei acids. Six strains of Dengue virus type 1 (DV-1) and 1 strain of DV-4 were isolated. The nucleotide sequence homology of the E gene and the amino acid sequence homology were 90.9%-99.7% and 96.8%-100%, respectively, among the 6 DV-1 strains, and 91.4%-98.5% and 96.6%-99.0%, respectively, between the 6 DV-1 strains and the DV-1 stains isolated in 2004 in Zhejiang province. The phylogenetic analysis of E gene showed that the gene subtypes of DV-1 strains were genotypeⅠ (GⅠ), GⅣ and GⅤ, and the subtype of DV-4 strain was GⅠ. All the 7 strains of dengue virus isolated in 2013 had a far phylogenetic relationship with the strains isolated from 2004 to 2009 in Zhejiang province. Conclusion All the dengue fever cases in Zhejiang province in 2013 are imported from countries including Philippines, Angola, Sri Lanka, and Brazil. The DV-1 strains are derived from the subtypes in Asia, South Pacific and America/Africa. The DV-4 strain is derived from the subtype in Southeast Asia, and it is the first detection in Zhejiang province.

Key words: Dengue fever, Imported case, Dengue virus type 1, Dengue virus type 4, Gene subtype, Envelope gene, Molecular tracing