Duffy Negative Antigen Is No Longer a Barrier to Plasmodium vivax - Molecular Evidences from the African West Coast (Angola and Equatorial Guinea)
Duffy Negative Antigen Is No Longer a Barrier to Plasmodium vivax - Molecular Evidences from the African West Coast (Angola and Equatorial Guinea)
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DOI：
10.1371/journal.pntd.0001192
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发表时间：
2011-06-01
影响因子：
3.8
通讯作者：
Arez, Ana Paula
中科院分区：
文献类型：
--
作者：
Mendes, Cristina;Dias, Fernanda;Arez, Ana Paula
背景：间日疟原虫在西非和中非的流行率较低，因为达菲阴性人群的流行率较高。然而，在达菲阳性人群高发的地区也有达菲阴性个体感染间日疟原虫的报道，这些人可能是能够侵入达菲阴性红细胞的间日疟原虫毒株的来源。我们在两个西非国家调查了间日疟原虫的存在，使用了在两项正在进行的研究中收集的血液样本和蚊子。方法/结果：在安哥拉和赤道几内亚的7个村庄共采集了995人的血液样本，在赤道几内亚采集了820只按蚊。通过巢式PCR扩增小亚基rRNA基因实现疟原虫种类鉴定；间日疟原虫通过csp基因分析进一步鉴定。人间日疟原虫阳性分离株经DARC基因分析为Duffy血型。15名达菲阴性个体感染了两种不同的间日疟原虫（VK210和VK247），其中8人来自赤道几内亚（97人中的8人），7人来自安哥拉（898人中的7人）。结论：在本研究中，我们证明间日疟原虫感染在人类和蚊子中都存在，这意味着正在发生主动传播。鉴于蚊子感染的高流行率，我们可以推测这种在肝脏形成催眠虫的物种可能无法通过外周血样本分析检测到。此外，这是安哥拉和赤道几内亚首次报告达菲阴性个体感染两种不同的间日疟原虫毒株（VK247和经典毒株）。这一发现强化了这种寄生虫能够使用Duffy以外的受体侵入红细胞的观点，这可能对间日疟原虫的电流分布有巨大的影响。
Background: Plasmodium vivax shows a small prevalence in West and Central Africa due to the high prevalence of Duffy negative people. However, Duffy negative individuals infected with P. vivax have been reported in areas of high prevalence of Duffy positive people who may serve as supply of P. vivax strains able to invade Duffy negative erythrocytes. We investigated the presence of P. vivax in two West African countries, using blood samples and mosquitoes collected during two on-going studies.Methodology/Findings: Blood samples from a total of 995 individuals were collected in seven villages in Angola and Equatorial Guinea, and 820 Anopheles mosquitoes were collected in Equatorial Guinea. Identification of the Plasmodium species was achieved by nested PCR amplification of the small-subunit rRNA genes; P. vivax was further characterized by csp gene analysis. Positive P. vivax-human isolates were genotyped for the Duffy blood group through the analysis of the DARC gene. Fifteen Duffy-negative individuals, 8 from Equatorial Guinea (out of 97) and 7 from Angola (out of 898), were infected with two different strains of P. vivax (VK210 and VK247).Conclusions: In this study we demonstrated that P. vivax infections were found both in humans and mosquitoes, which means that active transmission is occurring. Given the high prevalence of infection in mosquitoes, we may speculate that this hypnozoite-forming species at liver may not be detected by the peripheral blood samples analysis. Also, this is the first report of Duffy negative individuals infected with two different strains of P. vivax (VK247 and classic strains) in Angola and Equatorial Guinea. This finding reinforces the idea that this parasite is able to use receptors other than Duffy to invade erythrocytes, which may have an enormous impact in P. vivax current distribution.