Genetic structure of Plasmodium falciparum field isolates in eastern and north-eastern India
Genetic structure of Plasmodium falciparum field isolates in eastern and north-eastern India
复制标题
DOI：
10.1186/1475-2875-6-60
复制
发表时间：
2007-05-21
期刊：
影响因子：
3
通讯作者：
Dash, Aditya P.
中科院分区：
文献类型：
--
作者：
Joshi, Hema;Valecha, Neena;Dash, Aditya P.
背景：分子技术促进了对疟原虫物种遗传多样性的研究，特别是直接从患者身上收集的现场分离株。 msp-1和msp-2是高度多态性标记，并且在msp-1基因的块2和msp-2基因的中央重复结构域(块3)中报道了大的等位基因多态性。核苷酸序列和重复序列数量（长度变异）不同的家族被用于基因分型目的。由于关于印度恶性疟原虫种群中存在的遗传多样性的报告有限，本报告评估了印度东部和东北部地区恶性疟原虫现场分离株的遗传多样性程度。 方法：一项研究旨在使用等位基因特异性巢式 PCR 测定和序列分析来评估印度现场分离株中 msp-1 和 msp-2 的多样性。从阿萨姆邦、西孟加拉邦和奥里萨邦三个州的五个地点收集了现场分离株。结果：研究地点的恶性疟原虫分离株在长度和序列基序方面高度多样化，所有报告的 msp-1 和 msp-2 等位基因家族普遍存在。相同等位基因组成的普遍性以及等位基因的高水平序列同一性表明不同状态的恶性疟原虫种群之间存在大量基因流动。在疟疾高发地区卡尔比安隆（阿萨姆邦）和桑德加尔（奥里萨邦）的分离株中观察到多克隆分离株的比例相对较高，感染复数（MOI）也较高。在所有五个位点中，观察到 msp-1 的 R033 家族是单态的，等位基因大小为 150/160 bp。观察到的印度分离株与其他地区的数据有 80 - 90% 的序列同一性，表明印度恶性疟原虫群体是不同菌株的混合物。结论：本研究表明，印度东部和东北部地区的现场分离株在 msp-1（第 2 区）和 msp-2（中央重复区，第 3 区）方面具有高度多样性。正如预期的那样，印度分离株呈现出更接近东南亚、巴布亚新几内亚和拉丁美洲国家的多样性图景，与疟疾高流行至全流行的非洲地区相比，这些地区的疟疾流行程度为低流行至中流行。
Background: Molecular techniques have facilitated the studies on genetic diversity of Plasmodium species particularly from field isolates collected directly from patients. The msp-1 and msp-2 are highly polymorphic markers and the large allelic polymorphism has been reported in the block 2 of the msp-1 gene and the central repetitive domain (block3) of the msp-2 gene. Families differing in nucleotide sequences and in number of repetitive sequences ( length variation) were used for genotyping purposes. As limited reports are available on the genetic diversity existing among Plasmodium falciparum population of India, this report evaluates the extent of genetic diversity in the field isolates of P. falciparum in eastern and north-eastern regions of India.Methods: A study was designed to assess the diversity of msp-1 and msp-2 among the field isolates from India using allele specific nested PCR assays and sequence analysis. Field isolates were collected from five sites distributed in three states namely, Assam, West Bengal and Orissa.Results: P. falciparum isolates of the study sites are highly diverse in respect of length as well as sequence motifs with prevalence of all the reported allelic families of msp-1 and msp-2. Prevalence of identical allelic composition as well as high level of sequence identity of alleles suggest a considerable amount of gene flow between the P. falciparum populations of different states. A comparatively higher proportion of multiclonal isolates as well as multiplicity of infection (MOI) was observed among isolates of highly malarious districts Karbi Anglong ( Assam) and Sundergarh ( Orissa). In all the five sites, R033 family of msp-1 was observed to be monomorphic with an allele size of 150/160 bp. The observed 80 - 90% sequence identity of Indian isolates with data of other regions suggests that Indian P. falciparum population is a mixture of different strains.Conclusion: The present study shows that the field isolates of eastern and north-eastern regions of India are highly diverse in respect of msp-1 ( block 2) and msp-2 ( central repeat region, block 3). As expected Indian isolates present a picture of diversity closer to southeast Asia, Papua New Guinea and Latin American countries, regions with low to meso-endemicity of malaria in comparison to African regions of hyper- to holo-endemicity.