从中国龙游县一例严重发热伴血小板减少综合征的临床病例中了解大别病毒的遗传学

摘要(中文译文)

对浙江省龙游县2025年4月报告的一起严重发热伴血小板减少综合征（SFTS）病例进行流行病学调查，并对患者血清样本中的大别病毒（DBV）进行核酸检测和遗传特征分析，旨在为当地预防和控制SFTS提供科学依据和技术支持。对该病例进行了流行病学调查。收集了确诊病例和密切接触者的血清样本，以及相关的载体宿主样本。使用实时荧光定量PCR检测DBV特异性核酸。通过RT-PCR扩增病毒基因组并进行全基因组测序。使用专业计算机软件（SeqMan Ultra 17.2、Clustal X 2.1、BioEdit V7.2.6.1和MEGA V7.0.26等）进行核苷酸和氨基酸序列比对、系统发育树构建以及遗传距离和同源性百分比计算。该病例有蜱虫叮咬史，没有在该地区以外的旅行史。荧光定量PCR检测显示，只有该病例的血清样本对DBV核酸呈阳性，而密切接触者和相关载体宿主样本的血清样本均对DBV核苷酸呈阴性。经过扩增和测序，成功获得了L、M和S三个片段。遗传进化分析表明，它们分别属于L（C）、M（C）和S（A）基因型。与系统发育树中最接近的参考菌株HZ2023-16相比，L、M、NS和NP基因的核苷酸同源性分别为99.74%、99.53%、99.66%和99.19%，氨基酸同源性分别是100%、99.72%、99.66%、99.59%。与C型参考菌株AHL/China/2011（L（C）/M（C）/S（D））相比，L、M、NS和NP基因的核苷酸同源性分别为96.87%、96%、93.76%和95.66%，氨基酸同源性分别是99.42%、98.51%、98.29%和99.18%。与A型参考菌株JX23XSH（L（A）/M（A）/S（A））相比，L、M、NS和NP基因的核苷酸同源性分别为96.24%、95.97%、95.35%和97.02%，氨基酸同源性分别是99.52%、98.14%、99.32%和99.18%。与HZ2023-16参考菌株相比，L、M和S基因的平均遗传距离分别为0.003、0.005和0.005；与C型参考菌株AHL/China/2011（L（C）/M（C）/S（D））相比，它们分别为0.031、0.04和0.053；与A型参考菌株JX23XSH（L（A）/M（A）/S（A））相比，它们分别为0.038、0.04和0.038。氨基酸变异分析表明，与参考菌株相比，该菌株在L蛋白（如V68I、A140V）中有0-12个氨基酸替换，在M蛋白（如D151E、G863S）中有3-20个替换，在NS蛋白中有1-5个替换，而在NP蛋白中则有1-2个替换。结合病例的临床表现、流行病学史和实验室检测结果，本次疫情可确定为局部严重发热伴血小板减少综合征病例。该菌株在遗传上与人类来源的参考菌株密切相关，并具有特定的基因组特征。

Abstract

To conduct an epidemiological investigation on a case of severe fever with thrombocytopenia syndrome (SFTS) reported in Longyou County, Zhejiang Province in April 2025, and to perform nucleic acid detection and genetic characterization of Dabie bandavirus (DBV) in the patient's serum sample, aiming to provide scientific evidence and technical support for local SFTS prevention and control. An epidemiological investigation was conducted on the case. Serum samples from the confirmed case and close contacts, as well as related vector host specimens, were collected. DBV-specific nucleic acid was detected using real-time fluorescent quantitative PCR. The viral genome was amplified by RT-PCR and subjected to whole-genome sequencing. Professional computer software (SeqMan Ultra 17.2, Clustal X 2.1, BioEdit V7.2.6.1, and MEGA V7.0.26, etc.) was used for nucleotide and amino acid sequence alignment, phylogenetic tree construction, and calculation of genetic distances and homology percentages. The case had a history of tick bite and no history of travel outside the area. Fluorescence quantitative PCR detection showed that only the case's serum sample was positive for DBV nucleic acid, while serum samples from close contacts and related vector host specimens were all negative for DBV nucleic acid. After amplification and sequencing, the three fragments L, M, and S were successfully obtained. Genetic evolution analysis showed that they belonged to genotypes L (C), M (C), and S (A), respectively. Compared with the closest reference strain HZ2023-16 in the phylogenetic tree, the nucleotide homologies of the L, M, NS, and NP genes were 99.74%, 99.53%, 99.66%, and 99.19%, respectively, and the amino acid homologies were 100%, 99.72%, 99.66%, and 99.59%, respectively. Compared with the type C reference strain AHL/China/2011 (L(C)/M(C)/S(D)), the nucleotide homologies of the L, M, NS, and NP genes were 96.87%, 96%, 93.76%, and 95.66%, respectively, and the amino acid homologies were 99.42%, 98.51%, 98.29%, and 99.18%, respectively. Compared with the type A reference strain JX23XSH (L(A)/M(A)/S(A)), the nucleotide homologies of the L, M, NS, and NP genes were 96.24%, 95.97%, 95.35%, and 97.02%, respectively, and the amino acid homologies were 99.52%, 98.14%, 99.32%, and 99.18%, respectively. The average genetic distances of the L, M, and S genes compared with the HZ2023-16 reference strain were 0.003, 0.005, and 0.005, respectively; compared with the type C reference strain AHL/China/2011 (L(C)/M(C)/S(D)), they were 0.031, 0.04, and 0.053, respectively; compared with the type A reference strain JX23XSH (L(A)/M(A)/S(A)), they were 0.038, 0.04, and 0.038, respectively. Amino acid variation analysis showed that compared with the reference strains, this strain had 0-12 amino acid substitutions in the L protein (e.g., V68I, A140V), 3-20 substitutions in the M protein (e.g., D151E, G863S), 1-5 substitutions in the NS protein, and 1-2 substitutions in the NP protein. Combining the clinical manifestations, epidemiological history, and laboratory test results of the case, this outbreak can be determined as a local case of severe fever with thrombocytopenia syndrome. The strain is genetically closely related to human-derived reference strains and possesses specific genomic characteristics.

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