背景:Triatomines(接吻虫)是锥虫的天然载体,它们是单细胞寄生原生动物,比如克氏锥虫,T.康诺希尼和T.兰格利。对科诺尔西尼和红景天在中国的传播周期的理解还不完全清楚。
方法:Tr的粪便和肠道内容物中的寄生虫。收集了红斑,和形态学指标在显微镜下测量以确定物种。从样本中提取DNA,和18SrRNA的片段,热休克蛋白70(HSP70)和糖体甘油醛-3-磷酸脱氢酶(gGAPDH)扩增并测序。然后使用BLAST搜索引擎识别获得的序列,接下来是几个系统发育分析。最后,进行实验室感染以测试是否Tr。rubrofasciata通过叮咬将寄生虫传播给大鼠(或小鼠)。此外,135Tr.从广西地区收集了rubrofasciata样本,并将其用于检测锥虫感染的患病率。
结果:锥虫。在Tr的粪便和肠道内容物中发现。rubrofasciata,收集在中国南方的广西地区,主要表现出典型的epimastigotes特征,比如原子核的存在,自由的鞭毛和动体。身体长度为6.3至33.9µm,鞭毛长度为8.7至29.8µm,细胞核指数为0.6,动体长度为-4.6。BLAST分析显示18SrRNA,锥虫的HSP70和gGAPDH序列。表现出与T.conorhini的最高相似度(99.7%,99.0%和99.0%,分别),并在靠近T.conorhini和T.vespertilionis的地方形成了一个支撑良好的进化枝,但与T.rangeli和T.cruzi不同。实验室实验表明,接种锥虫后,大鼠和小鼠均出现低寄生虫血症。和实验室喂养的Tr。喂食锥虫阳性的大鼠和小鼠后,rubrofasciata被感染。然而,受感染的Trrubrofasciata没有传播锥虫。给他们的后代。此外,我们的调查显示锥虫的患病率很高。Tr感染。rubrofasciata,在现场测试的标本中有多达36.3%被感染。
结论:我们的研究首次提供了来自Tr的T.conorhini的可靠记录。中国红斑的形态学和分子证据。这种中国T.conorhini不太可能通过Tr的经静脉曲张传播。rubrofasciata,但相反,寄生虫更有可能在Tr之间传播。rubrofasciata和小鼠(或大鼠)。然而,在Tr中,T.conorhini的患病率很高。来自我们收集地点的rubrofasciata和许多人类Tr病例。记录红斑咬伤。此外,这些T.conorhini菌株是否对人类有致病性尚未研究。
BACKGROUND: Triatomines (kissing bugs) are natural vectors of trypanosomes, which are single-celled parasitic protozoans, such as Trypanosoma cruzi, T. conorhini and T. rangeli. The understanding of the transmission cycle of T. conorhini and Triatoma rubrofasciata in
China is not fully known.
METHODS: The parasites in the faeces and intestinal contents of the Tr. rubrofasciata were collected, and morphology indices were measured under a microscope to determine the species. DNA was extracted from the samples, and fragments of 18S rRNA, heat shock protein 70 (HSP70) and glycosomal glyceraldehyde-3-phosphate dehydrogenase (gGAPDH) were amplified and sequenced. The obtained sequences were then identified using the BLAST search engine, followed by several phylogenetic analyses. Finally, laboratory infections were conducted to test whether Tr. rubrofasciata transmit the parasite to rats (or mice) through bites. Moreover, 135 Tr. rubrofasciata samples were collected from the Guangxi region and were used in assays to investigate the prevalence of trypanosome infection.
RESULTS: Trypanosoma sp. were found in the faeces and intestinal contents of Tr. rubrofasciata, which were collected in the Guangxi region of southern
China and mostly exhibited characteristics typical of epimastigotes, such as the presence of a nucleus, a free flagellum and a kinetoplast. The body length ranged from 6.3 to 33.9 µm, the flagellum length ranged from 8.7 to 29.8 µm, the nucleus index was 0.6 and the kinetoplast length was -4.6. BLAST analysis revealed that the 18S rRNA, HSP70 and gGAPDH sequences of Trypanosoma sp. exhibited the highest degree of similarity with those of T. conorhini (99.7%, 99.0% and 99.0%, respectively) and formed a well-supported clade close to T. conorhini and T. vespertilionis but were distinct from those of T. rangeli and T. cruzi. Laboratory experiments revealed that both rats and mice developed low parasitaemia after inoculation with Trypanosoma sp. and laboratory-fed Tr. rubrofasciata became infected after feeding on trypanosome-positive rats and mice. However, the infected Tr. rubrofasciata did not transmit Trypanosoma sp. to their offspring. Moreover, our investigation revealed a high prevalence of Trypanosoma sp. infection in Tr. rubrofasciata, with up to 36.3% of specimens tested in the field being infected.
CONCLUSIONS: Our study is the first to provide a solid record of T. conorhini from Tr. rubrofasciata in
China with morphological and molecular evidence. This Chinese T. conorhini is unlikely to have spread through transovarial transmission in Tr. rubrofasciata, but instead, it is more likely that the parasite is transmitted between Tr. rubrofasciata and mice (or rats). However, there was a high prevalence of T. conorhini in the Tr. rubrofasciata from our collection sites and numerous human cases of Tr. rubrofasciata bites were recorded. Moreover, whether these T. conorhini strains are pathogenic to humans has not been investigated.