| Objective: to investigate the epidemiological characteristics of dengue fever(DF)from 2011 to 2019 in Hebei province and to explore the interactions and molecular mechanism of dengue virus type ?(DENV-1)and autophagy and to provide the gist of prevention and control of dengue fever and vaccine development.Methods:1.Descriptive epidemiological methods were used to analyze the information of dengue cases in Hebei province from 2011 to 2019 from the perspectives of time,region,population(gender,age,occupation).2.Serum samples were collected and Ig M and Ig G antibodies and NS1 antigen of dengue virus were detected by colloidal gold method.Vero E6 cells were used to isolate and culture dengue virus from the patient's early serum,and the typing was identified by Real time-PCR.The whole gene fragment of the virus was amplified and sequenced,and the sequence was compared with the sequences isolated from China and abroad,also compared with reference strains in the international epidemic area,and the phylogenetic tree was constructed.3.DENV-1 induced autophagy level of Vero E6 cells were detected by Western blot and Real time PCR,and the uninfected group was used as the control group.4.After promoting or inhibiting the autophagy level of cells with chemical reagents that regulated autophagy,the replication level of DENV-1 was detected,and the control group was only infected without chemical treatment.Results:1.A total of 108 cases of DF were reported in Hebei province from 2011 to 2019,all of which were imported cases.The main source of input was from the southeast Asia,and the main country was Cambodia.From 2011 to 2019,the number of DF cases fluctuated and increased,with the most cases reported in 2019,54(50%).DF cases were reported throughout the year,with high incidence from April to December,accounting for 93.52% of all cases.Baoding city,Shijiazhuang city,Tangshan city,Qinhuangdao city were more,76 cases,accounting for 70.37%.Baoding and Shijiazhuang reported the most cases,accounting for 50.93%.The gender distribution was more male than female,with 92 cases of male and 16 cases of female,and the ratio of male to female was 5.75:1.The age distribution was mainly 20-49 years old,with 91 cases(84.26%).In the occupational distribution,farmers were the majority(45 cases,41.67%).2.Colloidal gold method test results showed that the patients with DF suspected dengue virus Ig M and Ig G antibody in serum and NS1 antigen were all positive.The virus isolated from the patient's early serum was identified as DENV-1,genomic molecular evolution analysis reveals the isolated virus strain was most similar with the strain in southeast Asia and the nucleotide sequence similarity was more than 99%.3.After infected cells,LC3 ?/LC3 ?ratio in 3 d was significantly higher than control group(t = 64.54,P < 0.0001)LC3 ?/?-actin ratio at all time points were higher than the control group(0 d,t = 30.51,P < 0.0001;1d,t=26.07,P < 0.0001;3d,t=16.80,P < 0.0001;5d,t=3.18,P < 0.05).4.After treatment with autophagy promoter,the intracellular DENV-1 replication level was significantly higher than that of the control group.After treatment with autophagy inhibitors,the intracellular DENV-1 replication level was significantly lower than that of the control group(F=23.25,P < 0.0001).Conclusions:1.The reported cases of DF in Hebei province from 2011 to 2019 were imported cases,and 2019 was a year with high incidence of DF.Baoding and Shijiazhuang were the key prevention and control areas of DF,and young and middle-aged male farmers from southeast Asian countries,especially Cambodia,were the key control people.2.Vero E6 cells were able to successfully isolate DENV.3.DF continues to spread in the southeast Asia and surveillance of imported cases should be strengthened.3.DENV-1 infection of Vero E6 cells can induce and promote autophagy.4.Promoting autophagy was conducive to the replication of DENV-1,while inhibiting the replication of DENV-1 is reduced;DENV-1 replication may utilize the entire process of autophagy. |
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