DB Warnell School of Forestry and Natural Resources, The University of Georgia, Athens, GA 30602, USA.
Ecohealth. 2009 Jun;6(2):219-28. doi: 10.1007/s10393-009-0250-0. Epub 2009 Nov 12.
During a recent study of red-backed salamanders (Plethodon cinereus), we discovered an intraerythrocytic organism typified by violet-staining, intracellular inclusions, consistent with descriptions of Cytamoeba or Aegyptianella (bacteria). Here we characterize its taxonomic status using molecular techniques and ask basic questions about its nature. Blood smears from 102 salamanders were examined from Pennsylvania, New York, and Virginia to determine prevalence, and whole blood from several infected animals was tested using a PCR which targets the 16S rRNA gene of bacteria. Phylogenetic analysis of partial 16S rRNA gene sequence (1201 bp) indicated this organism was in the order Rickettsiales and is likely a member of the family Anaplasmatacea. The organism differed from currently described taxa and was clearly differentiated from Aegyptianella pullorum of birds and "Candidatus Hemobacterium ranarum" (formally A. ranarum) of frogs. Of all salamanders, 17 (16.7%) were infected and these were significantly larger (snout-vent length) and had higher body condition scores than uninfected ones, and males were more likely to be infected than females. Erythrocytes affected by the pathogen were 5% larger than unaffected ones, but otherwise similar in morphology. Infected animals tended to have a greater number of circulating white blood cells, based on estimates from smears, indicating a nonspecific response to the pathogen by the innate immune system. Given its phylogenetic position, this pathogen is likely transmitted by an arthropod vector, and the male-biased prevalence strongly implicates trombiculid mites, which also live in leaf litter and affect male salamanders more so than females.
在最近对红背蝾螈（Plethodon cinereus）的研究中，我们发现了一种红细胞内的生物体，其特征为紫罗兰染色的、细胞内的内含物，与 Cytamoeba 或 Aegyptianella（细菌）的描述一致。在这里，我们使用分子技术来描述其分类地位，并提出有关其性质的基本问题。我们检查了来自宾夕法尼亚州、纽约州和弗吉尼亚州的 102 只蝾螈的血液涂片，以确定其患病率，并用针对细菌 16S rRNA 基因的 PCR 测试了来自几个感染动物的全血。部分 16S rRNA 基因序列（1201bp）的系统发育分析表明，该生物体在立克次体目中，可能是 Anaplasmataceae 科的一员。该生物体与目前描述的分类群不同，与鸟类的 Aegyptianella pullorum 和青蛙的“Candidatus Hemobacterium ranarum”（以前称为 A. ranarum）明显不同。在所有的蝾螈中，有 17 只（16.7%）被感染，这些蝾螈的体型明显更大（吻肛长），身体状况评分更高，且雄性感染的可能性大于雌性。受病原体影响的红细胞比未受影响的红细胞大 5%，但在形态上相似。根据涂片的估计，受感染的动物的循环白细胞数量往往更多，这表明先天免疫系统对病原体产生了非特异性反应。鉴于其系统发育位置，这种病原体可能通过节肢动物媒介传播，而雄性偏向性的患病率强烈暗示了恙螨，它们也生活在落叶层中，对雄性蝾螈的影响大于对雌性蝾螈的影响。
