Objective: To understand the situation and genotype distribution of spotted fever group rickettsia (SFGR) in the border area of Tumen River Basin in free ticks in Yanbian Korean Autonomous Prefecture (Yanbian Prefecture), Jilin Province. Methods: From April to September, 2017, ticks were collected using flagging method from Hunchun, Tumen, Helong and Longjing cities in the Tumen River basin of Yanbian Prefecture. Outer membrane protein A (ompA) was detected by Polymerase Chain Reaction (PCR), then, the species were identified by gene sequencing and analyzed systematically. The positive rate of pools and MIR(minimum infection rate per 100 ticks,MIR) of SFGR were calculated, and the difference of positive rate of pools among ticks with different characteristics was compared by Chi-square test. Results: A total of 3 079 ticks were collected and divided into 536 pools. The positive rate of pools of SFGR nucleic acid was 39.7% (213 pools). The MIR of SFGR was 6.9%.The positive rate of pools of SFGR in Dermacentor silvarum, Haemaphysalis concinna, Haemaphysalis japonica, Haemaphysalis longicornis and Ixodes persulcatus were 80.4% (41/51), 14.0% (25/179), 20.2% (18/89), 78.9% (101/128) and 25.9% (21/81), and the difference was statistically significant (P<0.001). There was statistical difference in the positive rate of pools of SFGR in developmental stages of ticks (P<0.001); the positive rate of pools of female adults, male adults, nymph and larvae were 36.4% (95/261), 34.2% (67/196), 56.3% (40/71) and 7/8, and the MIR was 7.9%, 7.7%, 4.9% and 3.5%. The five genotype was detected which was Candidatus Rickettsia longicornii, Rickettsia raoultii, Rickettsia heilongjiangensis, Candidatus Rickettsia tarasevichiae,Rickettsia monacensis and have 98%-100% homology with known gene sequences. Candidatus Rickettsia longicornii, Rickettsia raoultii, Rickettsia heilongjiangensis and Candidatus Rickettsia tarasevichiae showed close evolutionary relationship with known specie (have 98%-100% homology with known gene sequences); Rickettsia monacensis showed Far from evolutionary relationship with known species (have 98% homology with known gene sequences). Conclusion: SFGR infection of ticks is common in the border areas of the Tumen River Basin. There was high diversity in SFGR species and tick species in the areas surveyed.
目的： 了解吉林省延边朝鲜族自治州（延边州）图们江流域边境地区游离蜱携带斑点热群立克次体（SFGR）情况及基因型分布。 方法： 2017年4—9月，在延边州图们江流域边境地区的珲春、图们、和龙、龙井市用布旗法采集游离蜱进行分类鉴定；采用PCR方法检测蜱体内SFGR ompA基因，通过基因测序鉴定其种类，并进行系统进化分析。计算采用SFGR的组阳性率和最低感染率（MIR），比较不同特征蜱虫间组阳性率的差异。 结果： 本研究共采集蜱虫3 079只，共分成536个组，SFGR核酸组阳性率为39.7%（213组），MIR为6.9%。森林革蜱、嗜群血蜱、日本血蜱、长角血蜱、全沟硬蜱SFGR核酸组阳性率分别为80.4%（41/51）、14.0%（25/179）、20.2%（18/89）、78.9%（101/128）和25.9%（21/81）（P<0.001）；MIR分别为19.4%、3.0%、3.4%、10.8%和5.9%。雌性成虫、雄性成虫、若虫和幼虫SFGR核酸组阳性率分别为36.4%（95/261）、34.2%（67/196）、56.3%（40/71）和7/8（P<0.001）；而MIR分别为7.9%、7.7%、4.9%和3.5%。共鉴定5种SFGR基因型，分别为立克次体Candidatus Rickettsia longicornii、拉欧蒂立克次体、黑龙江立克次体、新塔拉塞维奇立克次体和立克次体Rickettsia monacensi，其同源性均达到了98%~100%。Candidatus Rickettsia longicornii、拉欧蒂立克次体、黑龙江立克次体、新塔拉塞维奇立克次体与已知种进化关系较近；Rickettsia monacensis进化关系较远。 结论： 图们江流域边境地区蜱类SFGR感染普遍，存在常见蜱种感染SFGR基因型多样性和携带SFGR蜱虫种类多样性。.
Keywords: Polymerase chain reaction; Rickettsia infections; Sequence analysis; Spotted fever group rickettsia; Ticks.