Department of Tropical Medicine and Inha Research Institute for Medical Science, Inha University School of Medicine, Incheon, Republic of Korea.
Department of Parasitology and Tropical Medicine, and Institute of Health Sciences, Gyeongsang National University College of Medicine, Jinju, 52727, Republic of Korea.
Malar J. 2020 Feb 4;19(1):60. doi: 10.1186/s12936-020-3134-y.
Plasmodium lactate dehydrogenase (pLDH) is a major target in diagnosing the erythrocytic stage of malaria parasites because it is highly expressed during blood-stage parasites and is distinguished from human LDH. Rapid diagnostic tests (RDTs) for malaria use pLDH as a target antigen; however, genetic variations in pLDH within the natural population threaten the efficacy of pLDH-based RDTs.
Genetic polymorphisms of Plasmodium vivax LDH (PvLDH) and Plasmodium falciparum LDH (PfLDH) in Myanmar isolates were analysed by nucleotide sequencing analysis. Genetic polymorphisms and the natural selection of PvLDH and PfLDH were analysed using DNASTAR, MEGA6, and DnaSP ver. 5.10.00 programs. The genetic diversity and natural selection of global PvLDH and PfLDH were also analysed. The haplotype network of global PvLDH and PfLDH was constructed using NETWORK ver. 5.0.0.3. Three-dimensional structures of PvLDH and PfLDH were built with YASARA Structure ver. 18.4.24 and the impact of mutations on structural change and stability was evaluated with SDM ver. 2, CUPSAT and MAESTROweb.
Forty-nine PvLDH and 52 PfLDH sequences were obtained from Myanmar P. vivax and P. falciparum isolates. Non-synonymous nucleotide substitutions resulting in amino acid changes were identified in both Myanmar PvLDH and PfLDH. Amino acid changes were also identified in the global PvLDH and PfLDH populations, but they did not produce structural alterations in either protein. Low genetic diversity was observed in global PvLDH and PfLDH, which may be maintained by a strong purifying selection.
This study extends knowledge for genetic diversity and natural selection of global PvLDH and PfLDH. Although amino acid changes were observed in global PvLDH and PfLDH, they did not alter the conformational structures of the proteins. These suggest that PvLDH and PfLDH are genetically well-conserved in global populations, which indicates that they are suitable antigens for diagnostic purpose and attractive targets for drug development.
疟原乳酸脱氢酶（pLDH）是诊断疟原虫红细胞期的主要靶标，因为它在血期寄生虫中高度表达，并且与人类 LDH 区分开来。疟疾快速诊断测试（RDT）将 pLDH 用作靶抗原；然而，自然人群中 pLDH 的遗传变异威胁到基于 pLDH 的 RDT 的功效。
通过核苷酸测序分析分析了缅甸分离株中间日疟原虫乳酸脱氢酶（PvLDH）和恶性疟原虫乳酸脱氢酶（PfLDH）的遗传多态性。使用 DNASTAR、MEGA6 和 DnaSP ver.5.10.00 程序分析 PvLDH 和 PfLDH 的遗传多态性和自然选择。还分析了全球 PvLDH 和 PfLDH 的遗传多样性和自然选择。使用 NETWORK ver.5.0.0.3 构建了全球 PvLDH 和 PfLDH 的单倍型网络。使用 YASARA Structure ver.18.4.24 构建了 PvLDH 和 PfLDH 的三维结构，并使用 SDM ver.2、CUPSAT 和 MAESTROweb 评估突变对结构变化和稳定性的影响。
从缅甸间日疟原虫和恶性疟原虫分离株中获得了 49 个 PvLDH 和 52 个 PfLDH 序列。在缅甸 PvLDH 和 PfLDH 中均发现了导致氨基酸变化的非同义核苷酸取代。在全球 PvLDH 和 PfLDH 人群中也发现了氨基酸变化，但它们没有导致两种蛋白质的结构改变。全球 PvLDH 和 PfLDH 的遗传多样性较低，这可能是由于强烈的纯化选择所致。
本研究扩展了全球 PvLDH 和 PfLDH 的遗传多样性和自然选择知识。尽管在全球 PvLDH 和 PfLDH 中观察到氨基酸变化，但它们并没有改变蛋白质的构象结构。这表明 PvLDH 和 PfLDH 在全球人群中遗传上得到了很好的保护，这表明它们是适合诊断目的的抗原，也是药物开发的有吸引力的靶标。
