| Dengue virus(DENV)is a significant pathogen transmitted by Aedes,which has caused severe damage to global and human health in recent years.Dengue fever(DF),as the general clinical symptom,usually occurred after DENV infection.However,dengue hemorrhagic fever(DHF)and dengue shock syndrome(DSS)will also occur in severe cases,which caused severe consequences for the health of cases.DENV can be divided into four serotypes,including DENV-1,DENV-2,DENV-3,and DENV-4,based on antigenicity differences.The serum type can be divided into different genotypes.Notably,all serotypes and genotypes of viruses will cause varying degrees of dengue symptoms once human infected.Due to the long borderline,the multiple entries and exit ports,the considerable cross-border passenger flow,and frequent cross-border population activities,Yunnan Province is prone to the epidemic risk of imported pathogens.The favorable ecological condition involving the dense forests,the numerous rivers,and the warm climate in the bordering regions of Yunnan Province provides an ideal place for the survival and reproduction of DENV’s vector,such as Aedes.A number of Southeast Asian countries bordering Yunnan are the main DF epidemic areas.The current difficulty of preventing DENV has been increased due to the uncontrollable range of activity in mosquitoes.Consequently,according to the problematic imported situation in the border ports of Yunnan Province,the monitoring and prevention of various diseases should be strengthened imperatively.Based on this background,molecular diagnostic method is used to study.In this study,280 antibody positive sera were collected during the DF outbreak in Jinghong city in 2019.The full-length amplification of DENV E gene and the phylogenetic analysis of the homology of gene sequences were carried out.The results showed that three types of DENV serotype 1,2 and3 were prevalent in Jinghong city in 2019,and DENV-1 was the dominant serotype.There are many genotypes of virus strains in each serotype.The MCC tree construction indicated that the imported source of DENV collected from the Jinghong City was influenced by strains from Southeast Asian countries and demonstrated as coevolution in 2019.The 193 sequences were obtained successfully after performing full-length amplification of the DENV E gene in 467 serum of DF patients in Ruili City from 2014 to 2020.The results showed DENV-1 in Ruili City maintained the epidemic state.However,the DENV-3 has progressively become the dominant serotype in Ruili City in recent years.The BEAST software was applied to analyze the origin and evolution of DENV strains in Ruili City,which found that the imported source and the evolution of DENV in Ruili were significantly influenced by the strains injected from Southeast Asian countries particularly from Myanmar.The current DENV strains in Ruili city had progressively developed towards the local evolution trend.The comparative analysis was conducted on the epidemiological characteristics of DENV between the DF epidemic regions in Yunnan Province and neighboring Laos and Myanmar.The results showed that Jinghong was vastly affected by Southeast Asian countries,and the imported source of the DENV strains was complex.The imported source of the DENV strains in Ruili city was mainly from Myanmar.In summary,This study clarified the epidemiological characteristics of various serotypes and genotypes during the 2019 Jinghong DF epidemic,and longitudinal analyzed the evolution of DENV in Ruili City from 2014 to 2020,as well as the relationship between the two regions and the neighboring countries in 2019.The results of this study will provide direct data support for the formulation of DF prevention and response strategies in Yunnan border areas. |
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