Nema Shrikant, Kumari Monika, Verma Kanika, Krishna Sri, Ali Nazia A, Verma Anil Kumar, Das Aparup, Anvikar Anup R, Udhayakumar Venkatachalam, Bharti Praveen Kumar
Molecular Epidemiology department, ICMR-National Institute of Malaria Research, Sector 8, Dwarka, 110077 New Delhi, India.
Division of Vector Borne Diseases, ICMR-National Institute of Research in Tribal Health, Jabalpur, 482003 Madhya Pradesh, India.
Trans R Soc Trop Med Hyg. 2025 Jul 1;119(7):741-747. doi: 10.1093/trstmh/traf029.
Rapid diagnostic tests (RDTs) are vital for malaria diagnosis, especially in resource-limited areas. RDTs targeting histidine-rich protein 2 (PfHRP2) and its structural homologue PfHRP3 are commonly used for detecting Plasmodium falciparum. However, genetic deletions in these proteins can affect test accuracy. This study aims to examine the gene deletions and sequence variation in the Pfhrp2 and Pfhrp3 genes in P. falciparum isolates from Chhattisgarh, India, and assess their correlation with RDT reactivity.
A total of 264 microscopically confirmed P. falciparumpositive samples from Chhattisgarh were analyzed for deletions in the Pfhrp2 and Pfhrp3 genes. Nucleotide sequences were obtained for the Pfhrp2 (n=101) and Pfhrp3 (n=95) genes. The sequence data were analyzed for repeat motifs and correlated with the RDT performance, especially at low parasite densities.
The deletion rates for Pfhrp2 and Pfhrp3 were found to be 3.8% and 14%, respectively. The Pfhrp2 gene exhibited 15 distinct repeat motifs, while the Pfhrp3 gene showed 10 repeat motifs. No significant correlation was observed between variations in repeat types 2 and 7 of Pfhrp2 and the commercial RDT performance, particularly at low parasite densities.
The results indicate that the deletion rates and sequence diversity of Pfhrp2 and Pfhrp3 in Chhattisgarh are below the WHO threshold of 5% for a policy change regarding Pfhrp2 gene deletion. Sequence diversity does not appear to compromise the performance of current PfHRP2-based RDTs. However, a larger-scale study encompassing other endemic regions of India is recommended for a more comprehensive understanding of the impact on RDT efficacy over time.
快速诊断检测（RDTs）对于疟疾诊断至关重要，尤其是在资源有限的地区。针对富含组氨酸蛋白2（PfHRP2）及其结构同源物PfHRP3的RDTs常用于检测恶性疟原虫。然而，这些蛋白质中的基因缺失会影响检测准确性。本研究旨在检测印度恰蒂斯加尔邦恶性疟原虫分离株中Pfhrp2和Pfhrp3基因的缺失及序列变异，并评估它们与RDT反应性的相关性。
对来自恰蒂斯加尔邦的264份经显微镜确诊的恶性疟原虫阳性样本进行Pfhrp2和Pfhrp3基因缺失分析。获得了Pfhrp2（n = 101）和Pfhrp3（n = 95）基因的核苷酸序列。对序列数据进行重复基序分析，并与RDT性能相关联，特别是在低寄生虫密度情况下。
发现Pfhrp2和Pfhrp3的缺失率分别为3.8%和14%。Pfhrp2基因表现出15种不同的重复基序，而Pfhrp3基因表现出10种重复基序。未观察到Pfhrp2的重复类型2和7的变异与商业RDT性能之间存在显著相关性，特别是在低寄生虫密度时。
结果表明，恰蒂斯加尔邦Pfhrp2和Pfhrp3的缺失率和序列多样性低于世界卫生组织关于Pfhrp2基因缺失政策变化的5%阈值。序列多样性似乎并未影响当前基于PfHRP2的RDTs的性能。然而，建议开展一项涵盖印度其他流行地区的更大规模研究，以更全面地了解随着时间推移对RDT效力的影响。
