Analysis of 16S rRNA and 51-kilodalton antigen gene and transmission in mice of Ehrlichia risticii in virgulate trematodes from Elimia livescens snails in Ohio
Analysis of 16S rRNA and 51-kilodalton antigen gene and transmission in mice of Ehrlichia risticii in virgulate trematodes from Elimia livescens snails in Ohio
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DOI：
10.1128/jcm.38.9.3349-3358.2000
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发表时间：
2000-09-01
影响因子：
9.4
通讯作者：
Rikihisa, Y
中科院分区：
文献类型：
--
作者：
Kanter, M;Mott, J;Rikihisa, Y
1998年6月至10月期间，从俄亥俄州中部一条多次发生波托马克马热（PHF）的河流中采集了有盖螺（侧角螺科：光亮埃利米螺）。在采集的螺中，始终有50% - 80%携带复殖吸虫的尾蚴和胞蚴组合。从每只螺获取的吸虫汇集在一起，使用针对16S rRNA基因的特异性引物通过巢式聚合酶链反应（PCR）检测波托马克马热病原体——立氏埃立克体。在总共209个吸虫汇集样本中，通过PCR检测发现50个样本呈阳性。在一个吸虫汇集样本中鉴定出的16S rRNA基因的DNA序列与立氏埃立克体的模式菌株相同，另一个样本中鉴定出的该基因序列与模式菌株有1个核苷酸的差异。对来自不同来源的部分51 - kDa抗原基因推导的氨基酸序列进行比较，结果显示马里兰州、俄亥俄州（除俄亥俄081外）和肯塔基州的菌株形成一个簇，与从加利福尼亚州和俄勒冈州来源获得的序列不同。先前通过抗原成分分析表明俄亥俄081与其他组不同。然而，所检测的所有序列并没有根据其来源（马血或受感染的吸虫）进行分离。通过PCR分析确定，立氏埃立克体可从吸虫传播给小鼠，并随后从受感染的小鼠传播给其他小鼠。我们的研究结果表明立氏埃立克体在不同地理区域的自然宿主中进化，并且在夏季和初秋吸虫种群持续感染立氏埃立克体。该研究还表明小鼠可用于从受感染的吸虫中分离立氏埃立克体。
Operculate snails (the family Pleuroceridae: Elimia livescens) were collected between June and October 1998 from a river in central Ohio where repeated cases of Potomac horse fever (PHF) have occurred. Of collected snails, consistently 50 to 80% carried a combination of cercariae and sporocysts of digenetic virgulate trematodes. The trematodes obtained from each snail were pooled and tested for Ehrlichia risticii, the agent of PHF, by nested PCR using primers specific to the 16S rRNA gene. Out of a total of 209 trematode pools, 50 pools were found to be positive by PCR. The DNA sequence of the 16S rRNA gene identified in one trematode pool was identical to that of the type strain of E. risticii, and the sequence of the gene identified in another pool differed from that of the type strain by 1 nucleotide. Comparison of the deduced amino acid sequence of the partial 51-kDa antigen gene from various sources revealed that Maryland, Ohio (except Ohio 081), and Kentucky strains are in a cluster distinct from the sequences obtained from sources in California and Oregon. Ohio 081 was shown previously by antigenic composition analysis to be distinct from other groups. However, all sequences examined were not segregated according to their sources: horse blood or infected trematodes. E. risticii was found to be transmittable from trematodes to mice and was subsequently passaged from infected mice to additional mice, as determined by PCR analysis. Our findings suggest the evolution off. risticii in the natural reservoir in separate geographic regions and persistent infection of trematode populations with E. risticii during summer and early fall. The study also suggests that the mouse can be used to isolate E. risticii from the infected trematode.