Plasmodium falciparum glutamate dehydrogenase is genetically conserved across eight malaria endemic states of India: Exploring new avenues of malaria elimination

Analysis of diagnostic biomarkers for malaria: Prospects on rapid diagnostic test (RDT) development

Accurate malaria diagnosis remains a formidable challenge in remote regions of malaria-endemic areas globally. Existing diagnostic methods predominantly rely on microscopy and rapid diagnostic tests (RDTs). While RDTs offer advantages such as rapid results and reduced dependence on highly skilled technicians compared to microscopy, persistent challenges emphasize the critical need to identify novel diagnostic biomarkers to further enhance RDT based malaria diagnosis. This comprehensive review presents a range of promising diagnostic targets. These targets could be useful in developing more robust, accurate, and effective diagnostic tools. Such tools are crucial for the detection of the Plasmodium falciparum (P.falcipaum) malaria parasite. The potential biomarkers discussed here significantly address the challenges posed by HRP2 gene deletion in P.falciparum. Researchers, RDT manufacturers, industrial and other stakeholders involved in malaria diagnosis can harness the crucial information described in this article, to drive the development of advanced RDTs as viable alternatives. By diversifying the available tools for diagnosis, we can attempt to enhance our ability to knock out malaria effectively and contribute to better health outcomes for people residing in malaria-endemic regions. This review serves as a valuable resource for advancing research and development in the field of malaria diagnostics, ultimately aiding to the global fight against this devastating ancient disease.

A novel peptide pair-based rapid fluorescent diagnostic system for malaria Plasmodium falciparum detection

Advanced diagnostic materials, such as aptamers, are required due to the scarcity of efficient diagnostic antibodies and the low sensitivity of rapid diagnostic kits at detecting the malaria parasite, Plasmodium falciparum.

METHODS

Two peptides M2.9 [(KPTAEQTESPELQSAPEN) and M2.17 (KILFNVYSPLGCTCECWV)] were designed using simple epitope prediction tools and modified against the merozoite surface antigen 2 of P. falciparum (Pf.MSP2) by 3-dimensional modeling based on binding affinity. Based on five prediction tools for hydropathy, M2.17 was selected as an appropriate capture peptide. A peptide-based fluorescence-linked immunosorbent assay (FLISA) and a peptide pair-based fluorescent immunochromatographic test strip (FICT) were developed to detect P. falciparum 3D7 (drug-sensitive) and P. falciparum K1 (multi drugs-resistant) strains.

RESULTS

Bioinformatic analysis of two peptides demonstrated the potential binding affinity with the merozoite surface protein 2 of P. falciparum (Pf.MSP2) with a positive hydropathy value. The limit of detection (LOD) of FLISA was 10 parasites/μL and of a peptide pair-linked rapid FICT system was 5 and 200 parasites/μL for P. falciparum 3D7 and K1, respectively. Compared to commercial rapid detection systems (RDTs), a peptide pair-linked FICT system exhibited a 20-fold greater efficiency in detecting P. falciparum 3D7 and specifically discriminated another protozoan spp.

CONCLUSION

A peptide pair-linked rapid diagnostic strip could be an alternative to conventional RDTs for monitoring wild-type and drug-resistant malaria parasites.

Microfluidic device: A versatile biosensor platform to multiplex aptamer-based detection of malaria biomarkers

Plasmodium falciparum malaria remains a dominant infectious disease that affects Africa than the rest of the world, considering its associated cases and death rates. It's a febrile illness that produces several reliable biomarkers, for example, P. falciparum lactate dehydrogenase (PfLDH), P. falciparum Plasmodium glutamate dehydrogenase (PfGDH), and P. falciparum histidine-rich proteins (HRP-II) in blood circulatory system that can easily be employed as targets in rapid diagnostic tests (RDTs). In recent times, several DNA aptamers have been developed via SELEX technology to detect some specific malaria biomarkers (PfLDH, PvLDH, HRP-II, PfGDH) in a biosensor mode with good binding affinity properties to overcome the trend of cross-reactivity, limited sensitivity and stability problems that have been observed with immunodiagnostics. In this review, we summarized existing diagnostic methods and relevant biomarkers to suggest promising approaches to develop sensitive and species-specific multiplexed diagnostic devices enabling effective detection of malaria in complex biological matrices and surveillance in the endemic region.

Improving synthesis and binding affinities of nucleic acid aptamers and their therapeutics and diagnostic applications

Nucleic acid aptamers have captivated the attention of analytical and medicinal scientists globally due to their several advantages as recognition molecules over conventional antibodies because of their small size, simple and inexpensive synthesis, broad target range, and high stability in varied environmental conditions. These recognition molecules can be chemically modified to make them resistant to nuclease action in blood serum, reduce rapid renel clearance, improve the target affinity and selectivity, and make them amenable to chemically conjugate with a support system that facilitates their selective applications. This review focuses on the development of efficient aptamer candidates and their application in clinical diagnosis and therapeutic applications. Significant advances have been made in aptamer-based diagnosis of infectious and non-infectious diseases. Collaterally, the progress made in therapeutic applications of aptamers is encouraging, as evident from their use in diagnosing cancer, neurodegenerative diseases, microbial infection, and in imaging. This review also updates the progress on clinical trials of many aptamer-based products of commercial interests. The key development and critical issues on the subject have been summarized in the concluding remarks.

Cloning, Expression, Purification, and Characterization of Lactate Dehydrogenase from Plasmodium knowlesi: A Zoonotic Malaria Parasite

Plasmodium knowlesi is the only Plasmodium that causes zoonotic disease among the Plasmodium that cause infection in humans. It is fatal due to its short asexual growth cycle within 24 h. Lactate dehydrogenase (LDH), an enzyme that catalyzes the final step of glycolysis, is a biomarker for diagnosing infection by Plasmodium spp. parasite. Therefore, this study aimed to efficiently produce the soluble form of P. knowlesi LDH (PkLDH) using a bacterial expression system for studying malaria caused by P. knowlesi. Recombinant pET-21a(+)-PkLDH plasmid was constructed by inserting the PkLDH gene into a pET-21a(+) expression vector. Subsequently, the recombinant plasmid was inserted into the protein-expressing Escherichia coli Rosetta(DE3) strain, and the optimal conditions for overexpression of the PkLDH protein were established using this strain. We obtained a yield of 52.0 mg/L PkLDH from the Rosetta(DE3) strain and confirmed an activity of 483.9 U/mg through experiments. This methodology for high-efficiency PkLDH production can be utilized for the development of diagnostic methods and drug candidates for distinguishing malaria caused by P. knowlesi.

Innovations in Plasmodium spp. diagnosis on diverse detection platforms

In 2019, 229 million cases of malaria were recorded worldwide. For epidemiologic surveillance and proper treatment of persons infected with Plasmodium spp., rapid detection of infections by Plasmodium spp. is critical. Thus, Plasmodium spp. diagnosis is one of the indispensable measures for malaria control. Although microscopy is the gold standard for diagnosis, it has restrictions related mainly to the lack of qualified human resources, which is a problem in many regions. Thus, this review presents major innovations in diagnostic methods as alternatives to or complementary to microscopy. Detection platforms in lateral flow systems, electrochemical immunosensors, molecular biology and, more recently, those integrated with smartphones, are highlighted, among others. The advanced improvement of these tests aims to provide techniques that are sensitive and specific, but also quick, easy to handle and free from the laboratory environment. In this way, the tracking of malaria cases can become increasingly effective and contribute to controlling the disease.

Malaria Elimination in India: Bridging the Gap Between Control and Elimination

India observed a significant reduction in malaria cases in the previous year, reaffirming our trust and efficiency of the existing tools to achieve malaria elimination. On 25 April, 2019, countries around the world marked World Malaria Day under the theme “Zero malaria starts with me”. This provides an opportunity to rejoice the success and re-evaluate ongoing challenges in the fight against this preventable and treatable parasitic disease. We highlight the potential gaps in the malaria elimination program, and underscore potential solutions and strategies to implement, improve and intensify the success of the national goal of malaria elimination by 2030.

Glutamate dehydrogenase: a novel candidate to diagnose Plasmodium falciparum through rapid diagnostic test in blood specimen from fever patients

In recent years, Plasmodium falciparum histidine-rich protein 2 gene deletion has been reported in India. Such isolates are prone to selective transmission and thus form a challenge to case management. As most of the rapid malaria diagnostic tests are based on the detection of HRP2 protein in the blood, we attempted to use Glutamate Dehydrogenase (GDH) as a biomarker for the diagnosis of P. falciparum. Recombinant PfGDH was successfully cloned, expressed and purified using the Ni-NTA approach. Polyclonal antibodies were raised against full-length rPfGDH and its peptides. Antibodies for rPfGDH showed a strong immune response against the recombinant protein. However, antibody showed no affinity towards the peptides, which suggests they failed as antigen. Antibodies for rPfGDH significantly detected the GDH in human blood specimens. This is the first report where P. falciparum GDH was detected in malaria cases from various parts of India. The raised polyclonal antibodies had shown an affinity for PfGDH in quantitative ELISA and are capable to be exploited for RDTs. This research needs further statistical validation on a large number and different sample types from candidates infected with P. falciparum and other species.

Recent Advances in the Development of Biosensors for Malaria Diagnosis

The impact of malaria on global health has continually prompted the need to develop more effective diagnostic strategies that could overcome deficiencies in accurate and early detection. In this review, we examine the various biosensor-based methods for malaria diagnostic biomarkers, namely; Plasmodium falciparum histidine-rich protein 2 (PfHRP-2), parasite lactate dehydrogenase (pLDH), aldolase, glutamate dehydrogenase (GDH), and the biocrystal hemozoin. The models that demonstrate a potential for field application have been discussed, looking at the fabrication and analytical performance characteristics, including (but not exclusively limited to): response time, sensitivity, detection limit, linear range, and storage stability, which are first summarized in a tabular form and then described in detail. The conclusion summarizes the state-of-the-art technologies applied in the field, the current challenges and the emerging prospects for malaria biosensors.

Diagnosis of Malaria Parasites Plasmodium spp. in Endemic Areas: Current Strategies for an Ancient Disease

Fast and effective detection of the causative agent of malaria in humans, protozoan Plasmodium parasites, is of crucial importance for increasing the effectiveness of treatment and to control a devastating disease that affects millions of people living in endemic areas. The microscopic examination of Giemsa-stained blood films still remains the gold-standard in Plasmodium detection today. However, there is a high demand for alternative diagnostic methods that are simple, fast, highly sensitive, ideally do not rely on blood-drawing and can potentially be conducted by the patients themselves. Here, the history of Plasmodium detection is discussed, and advantages and disadvantages of diagnostic methods that are currently being applied are assessed.