Snails of the genus Biomphalaria are intermediate hosts of Schistosoma mansoni, the causative agent of the human intestinal schistosomiasis. Two Biomphalaria species (Biomphalaria pfeifferi and Biomphalaria camerunensis) are involved in the transmission in Cameroon, where the disease is present nationwide. However, difficulty in the identification of both vectors impedes proper assessment of the epidemiological burden caused by each species. To overcome this issue, we designed a PCR-based molecular diagnostic tool to improve the identification of these species. We analyzed the internal transcribed spacer 2 (ITS2) region of Biomphalaria ribosomal DNA (rDNA) using polymerase chain reaction amplification (PCR) and restriction fragment length polymorphism (RFLP). The amplification of the ITS2 region of Biomphalaria snails resulted in a 490 bp fragment and produced two profiles for each species after digestion with the restriction enzyme Hpa II. The profile 1 (Bc-HpaII-1: 212-bp and 139-bp bands) for B. camerunensis, was common in all the sampling points; the profile 2 (Bc-HpaII-2: 212-bp and 189-bp bands), was only observed in the Lake Monoun Njindoun sampling site. Biomphalaria pfeifferi profile 1 (Bpf-HpaII-1: 211-bp and 128-bp bands) was common in most of B. pfeifferi sampling points; the profile 2 (Bpf-HpaII-2: 289-bp and 128-bp bands) was only observed in Mokolo (Far North Cameroon).The second restriction enzyme TaqαI, revealed three band profiles, Bc-TaqαI-1 (243-bp, 136-bp and 118-bp bands) and Bc-TaqαI-2 (244-bp, 136-bp and 99-bp) for B. camerunensis and Bpf-TaqαI-1 (242-bp, 135-bp and 107-bp bands) for B. pfeifferi. Sequencing analysis revealed the occurrence of six haplotypes for B. camerunensis and three haplotypes for B. pfeifferi. The level of gene flow was low and the Biomphalaria populations were not in demographic expansion according to neutrality tests (Tajima’s D and Fu’s Fs). The PCR-RFLP technique revealed genetic diversity in Biomphalaria snails, and the combination with the morphological method could improve the identification of B. pfeifferi and B. camerunensis in Cameroon. This could help focus on the infection to evaluate the transmission risk with respect of the different species and to develop efficient and cost-effective control measures.

中文翻译：

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的两个中间蜗牛主机的基于PCR的分子鉴定曼氏血吸虫在喀麦隆

Biomphalaria蜗牛是曼氏血吸虫的中间宿主，曼氏血吸虫是人类肠道血吸虫病的病原体。喀麦隆有两种Biomphalaria种类（Biomphalaria pfeifferi和Biomphalaria camerunensis）参与了该疾病的传播。但是，两种载体的识别困难，阻碍了对每种物种造成的流行病学负担的正确评估。为了克服这个问题，我们设计了一种基于PCR的分子诊断工具来改善对这些物种的识别。我们使用聚合酶链反应扩增（PCR）和限制性片段长度多态性（RFLP）分析了Biomphalaria核糖体DNA（rDNA）的内部转录间隔区2（ITS2）区域。用限制酶Hpa II消化后，Biomphalaria蜗牛的ITS2区的扩增产生了一个490 bp的片段，并为每个物种产生了两个图谱。在所有采样点，卡梅伦布鲁氏菌的图谱1（Bc-HpaII-1：212 bp和139 bp谱带）是相同的；图2（Bc-HpaII-2：212 bp和189 bp的带）仅在莫农湖Njindoun采样点观察到。大部分Bfei pfeifferi采样点都存在Biomphalaria pfeifferi配置文件1（Bpf-HpaII-1：211 bp和128 bp的带）。仅在Mokolo（远北喀麦隆）中观察到2型（Bpf-HpaII-2：289bp和128bp带）。第二个限制性酶TaqαI揭示了三个条带，Bc-TaqαI-1（243bp）。 ，B.-camrunensis和Bpf-TaqαI-1（242-bp，136-bp和118-bp）和Bc-TaqαI-2（244-bp，136-bp和99-bp），135 bp和107 bp条带）。测序分析显示，卡梅隆布鲁姆氏菌有六种单倍型，而费非氏芽孢杆菌则有三种单倍型。根据中性测试（Tajima's D和Fu's Fs），基因流水平较低，Biomphalaria种群没有人口膨胀。PCR-RFLP技术揭示了蜗牛的遗传多样性，并与形态学方法相结合可以提高喀麦隆的B. pfeifferi和B. camerunensis的鉴定。这可能有助于集中精力进行感染，以评估不同物种的传播风险，并制定有效和具有成本效益的控制措施。根据中性测试（Tajima's D和Fu's Fs），基因流水平较低，Biomphalaria种群没有人口膨胀。PCR-RFLP技术揭示了蜗牛的遗传多样性，并与形态学方法相结合可以提高喀麦隆的B. pfeifferi和B. camerunensis的鉴定。这可能有助于集中精力进行感染，以评估有关不同物种的传播风险，并制定有效和具有成本效益的控制措施。根据中性测试（Tajima's D和Fu's Fs），基因流水平较低，Biomphalaria种群没有人口膨胀。PCR-RFLP技术揭示了蜗牛的遗传多样性，并与形态学方法相结合可以提高喀麦隆的B. pfeifferi和B. camerunensis的鉴定。这可能有助于集中精力进行感染，以评估不同物种的传播风险，并制定有效和具有成本效益的控制措施。喀麦隆的camerunensis。这可能有助于集中精力进行感染，以评估不同物种的传播风险，并制定有效和具有成本效益的控制措施。喀麦隆的camerunensis。这可能有助于集中精力进行感染，以评估不同物种的传播风险，并制定有效和具有成本效益的控制措施。