Objective:To conduct whole-genome sequencing of two serum samples from imported dengue fever (DF) cases in Gansu province in 2023, analyze the molecular biological characteristics of the dengue virus (DENV) strains, accumulate baseline data for DF research in Gansu province, and provide a scientific basis for the prevention and control of imported epidemics.Methods:Two serum samples that tested positive for DENV nucleic acid were sequenced for their entire genome using a third-generation sequencing platform. The obtained sequences were subjected to phylogenetic analysis, sequence homology analysis, amino acid sequence similarity analysis, and analysis of differences in mutation sites.Results:Two complete DENV genomes were obtained through third-generation sequencing, with sequence lengths of 10 715 bp and 10 714 bp respectively. The nucleotide similarity between them was 99.11%, and the amino acid similarity was 99.59%. Homology and phylogenetic analyses indicated that both sequences belonged to DENV type 1 genotype Ⅲ and were highly homologous to isolates from Singapore, India, Nepal, and the Guangzhou city of China. The nucleotide similarity is greater than 96.91%, and the amino acid similarity is greater than 98.70%. Analysis of amino acid site differences showed that DENV-2023-GS001 and DENV-2023-GS002 had 10 and 14 mutation sites in the E protein, respectively, but the main sites related to virulence remained unchanged.Conclusions:In 2023, two cases of imported DF in Gansu province were identified as genotype Ⅲ of DENV type 1. In terms of genetic evolutionary relationships, these viruses are most closely related to those from countries such as Singapore, India, and Nepal. This indicates that there remains a risk of DENV importation and transmission in Gansu province.

Objective:To investigate the species and distribution of mosquito-borne arboviruses in the southeastern part of Gansu province.Methods:In 2023, mosquitoes were collected using ultraviolet lights in Longnan and Tianshui regions of Gansu province. After classification by morphology, about 50 are only 1 batch. RT-qPCR was used to detect the RNA of Japanese encephalitis virus (JEV), Banna virus (BAV), Getah virus (GETV), Culex flavivirus (CxFV) and Tahyna virus (TAHV). The genomes of the positive samples were sequenced and the genetic evolution of the virus genomes were analyzed by bioinformatics software.Results:In total, there were 8 176 mosquitoes from 4 genera and 9 species collected from Longnan and Tianshui from June to August 2023. Culex tritaeniorhynchus was the most common species with 55.80% (4 562/8 176) of the total mosquitoes collected, followed by 16.43% (1 343/8 176) of Culex pipiens pallens. A total of 263 batches of samples were obtained, and the nucleic acid test showed that 1 batch was positive for JEV, 2 batches were positive for BAV, 3 batches were positive for GETV and 25 batches were positive for CxFV. Conclusions:Culex tritaeniorhynchus was the dominant mosquito species in the southeastern part of Gansu province, and local mosquitoes carried a variety of arboviruses.

Objective:To investigate the species and distribution of mosquito-borne arboviruses in the southeastern part of Gansu province.Methods:In 2023, mosquitoes were collected using ultraviolet lights in Longnan and Tianshui regions of Gansu province. After classification by morphology, about 50 are only 1 batch. RT-qPCR was used to detect the RNA of Japanese encephalitis virus (JEV), Banna virus (BAV), Getah virus (GETV), Culex flavivirus (CxFV) and Tahyna virus (TAHV). The genomes of the positive samples were sequenced and the genetic evolution of the virus genomes were analyzed by bioinformatics software.Results:In total, there were 8 176 mosquitoes from 4 genera and 9 species collected from Longnan and Tianshui from June to August 2023. Culex tritaeniorhynchus was the most common species with 55.80% (4 562/8 176) of the total mosquitoes collected, followed by 16.43% (1 343/8 176) of Culex pipiens pallens. A total of 263 batches of samples were obtained, and the nucleic acid test showed that 1 batch was positive for JEV, 2 batches were positive for BAV, 3 batches were positive for GETV and 25 batches were positive for CxFV. Conclusions:Culex tritaeniorhynchus was the dominant mosquito species in the southeastern part of Gansu province, and local mosquitoes carried a variety of arboviruses.

Objective:To conduct whole-genome sequencing of two serum samples from imported dengue fever (DF) cases in Gansu province in 2023, analyze the molecular biological characteristics of the dengue virus (DENV) strains, accumulate baseline data for DF research in Gansu province, and provide a scientific basis for the prevention and control of imported epidemics.Methods:Two serum samples that tested positive for DENV nucleic acid were sequenced for their entire genome using a third-generation sequencing platform. The obtained sequences were subjected to phylogenetic analysis, sequence homology analysis, amino acid sequence similarity analysis, and analysis of differences in mutation sites.Results:Two complete DENV genomes were obtained through third-generation sequencing, with sequence lengths of 10 715 bp and 10 714 bp respectively. The nucleotide similarity between them was 99.11%, and the amino acid similarity was 99.59%. Homology and phylogenetic analyses indicated that both sequences belonged to DENV type 1 genotype Ⅲ and were highly homologous to isolates from Singapore, India, Nepal, and the Guangzhou city of China. The nucleotide similarity is greater than 96.91%, and the amino acid similarity is greater than 98.70%. Analysis of amino acid site differences showed that DENV-2023-GS001 and DENV-2023-GS002 had 10 and 14 mutation sites in the E protein, respectively, but the main sites related to virulence remained unchanged.Conclusions:In 2023, two cases of imported DF in Gansu province were identified as genotype Ⅲ of DENV type 1. In terms of genetic evolutionary relationships, these viruses are most closely related to those from countries such as Singapore, India, and Nepal. This indicates that there remains a risk of DENV importation and transmission in Gansu province.

Objective:To determine neutralizing antibodies against Japanese encephalitis virus (JEV) among healthy people of Southeast Gansu province, and to evaluate immunologic barrier, and provide the data for Japanese encephalitis (JE) control.Methods:Healthy people were divided into the following 3 groups: less than 14 years, 15-39 years, and above 40 years in 2018 in four cities (Pingliang city, Qingyang city, Longnan city, Tianshui city) of Southeast Gansu province. Serum samples of the participants were obtained, and JEV antibody was detected by plaque reduction neutralization assays. The JEV neutralizing antibody positive rates among different groups were compared by chi square test.Results:A total of 1 590 people were investigated. The total positive rate of JEV neutralizing antibody was 28.81%, and the geometric mean titer (GMT) of JEV neutralizing antibody was 1∶27.09. The antibody positive rates of 0-14, 15-39 and ≥ 40 years groups were 32.96%, 20.32%, 30.63%, the difference of antibody positive rates among different age groups was statistically significant ( χ2=22.29, P<0.001). The antibody positive rates in Pingliang city, Qingyang city, Longnan city, Tianshui city were 29.62%, 22.22%, 33.00%, 30.30%, the difference of antibody positive rates among cities was statistically significant( χ2=12.39, P=0.006). Conclusions:The positive rates of neutralizing antibodies against JEV was low among healthy people in Southeast Gansu province, and there is an epidemic risk of JE.