Abstract: Objective To investigate the prevalence of Bartonella infection and gene polymorphisms of Bartonella in small mammals in Maixiu National Forest Park in the Qinghai-Tibet Plateau, China, and to provide a scientific basis for the control and prevention of local natural focal diseases. Methods The night trapping method was used to capture small mammals, whose liver and spleen tissues were collected and cultured for Bartonella isolation. The suspected positive colonies were confirmed using PCR amplification and sequencing of the citrate synthase (gltA) gene. BLAST and MEGA 7.0 softwares were used to perform the nucleotide sequence homology comparison and phylogenetic analysis, and DnaSP 5.10 software was used to analyze the genetic diversity. Results A total of 21 rodents were captured, including 10 Cricetulus longicaudatus rodents, 6 Apodemus speciosus rodents, 4 Mus musculus rodents, and 1 Microtus oeconomus rodent. In addition, one small mammal of Soricidea, which belonged to Insectivora, was also captured. Except M. oeconomus, Bartonella was detected in all the other four species of small mammals, with an overall positive rate of 59.09% (13/22). Specifically, nine cases showed positive results in both the liver and spleen tissues, one showed positive results in the liver tissue alone, and three showed positive results in the spleen tissue alone. There was no statistical difference in the positive rate between liver and spleen tissues (45.45% vs 54.55%, P=0.625). The phylogenetic analysis showed that the isolated Bartonella species were as follows: Bartonella grahamii (10 strains), B. taylorii (1 strain), B. khabarovsk (1 strain), and B. japonica (1 strain), among which B. grahamii was the dominant prevalent species with potential pathogenicity. In addition, the traceability analysis showed that the B. grahamii isolates from C. longicaudatus and M. musculus belonged to the same cluster as those from A. speciosus in Japan, and the B. grahamii isolates from A. speciosus belonged to the same cluster as those from Ochotona curzoniae in this area. The genetic diversity analysis showed that the nucleotide sequences in B. grahamii were quite different between various rodent species. There were 8 polymorphic loci in the 10 sequences, resulting in 3 haplotypes. The haplotype diversity (Hd) was 0.622±0.138; the average number of nucleotide differences (k) was 3.200, and the nucleotide diversity (π) was 0.010. The fragment diversity was highest between 152 bp and 251 bp. Conclusion The small mammals in Maixiu National Forest Park have a high infection rate with Bartonella, and B. grahamii is the dominant species, which has genetic diversity and may cause human infection and diseases.

Key words: Bartonella, Small mammal, Genetic characteristics, Maixiu National Forest Park

摘要： 目的 了解青藏高原麦秀国家森林公园小型哺乳动物巴尔通体感染状况和基因多态性，为当地自然疫源性疾病防控提供科学依据。方法 采用夹夜法捕获小型哺乳动物，采集肝脏和脾脏组织进行巴尔通体培养分离，对可疑菌落进行枸橼酸合酶（gltA）基因PCR扩增并测序，利用BLAST和MEGA 7.0软件进行核苷酸序列同源性比较和遗传进化分析，DnaSP 5.10软件进行遗传多样性分析。结果 共捕获啮齿动物21只，其中长尾仓鼠10只，大林姬鼠6只，小家鼠4只，根田鼠1只，另捕获1只食虫目鼩鼱科动物，除根田鼠外，其余4种小型动物均检出巴尔通体，总阳性率为59.09%（13/22）。肝、脾组织双阳性9份，肝脏组织单阳性1份，脾脏组织单阳性3份，肝、脾组织培养阳性率差异无统计学意义（45.45% vs 54.55%，P=0.625）。遗传进化分析显示，分离出的巴尔通体分别为格拉汉姆巴尔通体（Bartonella grahamii，10株）、泰勒巴尔通体（B. taylorii，1株）、哈巴罗夫斯克巴尔通体（B. khabarovsk，1株）和日本巴尔通体（B. japonica，1株）。其中格拉汉姆巴尔通体是具有潜在致病性的优势流行株，溯源分析显示长尾仓鼠和小家鼠分离株与日本大林姬鼠分离株聚为一簇，而大林姬鼠分离株与当地高原鼠兔分离株聚为一簇。遗传多样性分析发现不同鼠种所携带的格拉汉姆巴尔通体核苷酸序列存在较大差别，10条序列中存在8个多态位点，产生3种单倍型，单倍型多样度为0.622±0.138，平均核苷酸差异数为3.200，核苷酸多样度为0.010，其中在152～251 bp间的片段多样度最高。结论 麦秀国家森林公园小型哺乳动物巴尔通体感染率较高，格拉汉姆巴尔通体为优势流行株，且具有遗传多样性，存在人类感染致病风险。

关键词: 巴尔通体, 小型哺乳动物, 遗传特征, 麦秀国家森林公园