The molecular epidemiology of a local dengue fever outbreak in Shenzhen / 中华传染病杂志

ABSTRACT

Objective To determine the pathogen of a local dengue fever outbreak in Shenzhen city in 2010,and to analyze the molecular characteristics of the epidemic dengue virus strain as well as explore the possible origin.Methods The serum samples collected from the suspect dengue fever cases were detected for IgM, IgG by enzyme-linked immunosorbent assay ( ELISA ),immunochromatography and dengue virus nucleic acid by real-time polymerase chain reaction (PCR).Serum samples from patients with early stage dengue fever were used to isolate virus with C6/36 and BHK-21 cell lines.The type of isolated virus strain was determined by RT-semi-nested-PCR and realtime 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.Results IgM,IgG and RNA of type 1 dengue virus were detected in serum samples from dengue fever suspected patients.Type 1 dengue virus named DEV1-SZ1029 was successfully isolated from the serum sample.The homology of nucleotide sequence of E gene of SZ1029 strain with standard type 1 dengue virus HAWAII 45,Fj231/04,GD14/97 and GD05/99 were 94.8％,99.6％,97.7％ and 98.5 ％,respectively.The phylogenetic tree indicated that SZ1029 had the greatest similarity with the D1/Malaysia/36000/05 strain,SG(EHI)DED142808 strain and Fj231/04 strain and they lied in the same branch of the phylogenetic tree.The isolated dengue virus type 1 belonged to genetype Ⅰ with GZ/80,Taiwan87,All patients lived in a certain construction site in Shenzhen and had no recent travel history outside the area in one month before infection.Conclusions The virological,serological and molecular features all identify that the local dengue fever outbreak in Shenzhen in 2010 is caused by type 1 dengue virus and SZ1029 strain may be transferred from Southeast Asian region,and there may be a plague focus in Shenzhen.