Quantifying primaquine effectiveness and improving adherence: a round table discussion of the APMEN Vivax Working Group

The goal to eliminate malaria from the Asia-Pacific by 2030 will require the safe and widespread delivery of effective radical cure of malaria. In October 2017, the Asia Pacific Malaria Elimination Network Vivax Working Group met to discuss the impediments to primaquine (PQ) radical cure, how these can be overcome and the methodological difficulties in assessing clinical effectiveness of radical cure. The salient discussions of this meeting which involved 110 representatives from 18 partner countries and 21 institutional partner organizations are reported. Context specific strategies to improve adherence are needed to increase understanding and awareness of PQ within affected communities; these must include education and health promotion programs. Lessons learned from other disease programs highlight that a package of approaches has the greatest potential to change patient and prescriber habits, however optimizing the components of this approach and quantifying their effectiveness is challenging. In a trial setting, the reactivity of participants results in patients altering their behaviour and creates inherent bias. Although bias can be reduced by integrating data collection into the routine health care and surveillance systems, this comes at a cost of decreasing the detection of clinical outcomes. Measuring adherence and the factors that relate to it, also requires an in-depth understanding of the context and the underlying sociocultural logic that supports it. Reaching the elimination goal will require innovative approaches to improve radical cure for vivax malaria, as well as the methods to evaluate its effectiveness.

Spatio-temporal distribution of PfMDR1 polymorphism among uncomplicated Plasmodium falciparum malaria cases along international border of north east India

PfMDR1 single nucleotide polymorphisms (SNP) are good correlate markers for antimalarial drug resistance worldwide. Present study is a comprehensive view of screening of PfMDR1 polymorphism to antimalarials practiced with geography and time. Study sites Mizoram, Tripura, Meghalaya chosen are at multivariate drug pressure due to cross border migration and transmission. Mizoram is gateway to south east Asia through Myanmar whereas Tripura, Meghalaya share porous border with Bangladesh. Baseline finger pricked blood stained filter paper for confirmed uncomplicated Plasmodium falciparum infected patients (year 2015) were obtained from National Institute of Malaria Research, New Delhi, India. PfMDR1 polymorphism for codon N86Y, Y184F, D1246Y was determined by PCR-RFLP, further confirmed by sequencing. There observed marked predominance of Plasmodium isolates with PfMDR1 wild type alleles for all codons under study i.e. 86, 184, 1246. Spatially, Plasmodium isolates from Mizoram were most diverse with co-existence of PfMDR1 genotype with NYD, YYD, NFD haplotypes, followed by Tripura. Isolates from Meghalaya were of all NYD haplotype. Reports, referring to screening of PfMDR1 SNPs to CQ/SP/AS-SP across India, were archived. Temporal study show distinct rise in proportion of PfMDR1 wild type N86 allele since introduction of Artemether-Lumefantrine as first line antimalarial. Hence spatio-temporal screening of Plasmodium population with PfMDR1 single nucleotide polymorphism accounts for its association with antimalarial susceptibility and validate PfMDR1 SNPs as antimalarial drug resistant marker.

Establishment and application of a novel isothermal amplification assay for rapid detection of chloroquine resistance (K76T) in Plasmodium falciparum

Chloroquine (CQ) resistance in Plasmodium falciparum is determined by the mutations in the chloroquine resistance transporter (Pfcrt) gene. The point mutation at codon 76 (K76T), which has been observed in more than 91% of P. falciparum isolates in India, is the major determinant of CQ resistance. To overcome the limitations and challenges of traditional methods, in this investigation we developed an easy to use loop mediated isothermal amplification (LAMP) protocol for rapid detection of the K76T mutation associated with CQ resistance in P. falciparum with naked eye visualization. In- house designed primers were synthesized and optimized to specifically distinguish the CQ resistant mutants of P. falciparum. The LAMP reaction was optimal at 61 °C for 60 min and calcein dye was added prior to amplification to enable visual detection. We demonstrate the detection limit of <2 ng/μl respectively, supporting the high sensitivity of this calcein based LAMP method. To the best of our knowledge this is the first report on the establishment of an easy, reliable and cost effective LAMP assay for rapid and specific detection of highly CQ resistance in P. falciparum malaria.

Engineering Nucleotide Specificity of Succinyl-CoA Synthetase in Blastocystis: The Emerging Role of Gatekeeper Residues

Charged, solvent-exposed residues at the entrance to the substrate binding site (gatekeeper residues) produce electrostatic dipole interactions with approaching substrates, and control their access by a novel mechanism called “electrostatic gatekeeper effect”. This proof-of-concept study demonstrates that the nucleotide specificity can be engineered by altering the electrostatic properties of the gatekeeper residues outside the binding site. Using Blastocystis succinyl-CoA synthetase (SCS, EC 6.2.1.5), we demonstrated that the gatekeeper mutant (ED) resulted in ATP-specific SCS to show high GTP specificity. Moreover, nucleotide binding site mutant (LF) had no effect on GTP specificity and remained ATP-specific. However, via combination of the gatekeeper mutant with the nucleotide binding site mutant (ED+LF), a complete reversal of nucleotide specificity was obtained with GTP, but no detectable activity was obtained with ATP. This striking result of the combined mutant (ED+LF) was due to two changes; negatively charged gatekeeper residues (ED) favored GTP access, and nucleotide binding site residues (LF) altered ATP binding, which was consistent with the hypothesis of the “electrostatic gatekeeper effect”. These results were further supported by molecular modeling and simulation studies. Hence, it is imperative to extend the strategy of the gatekeeper effect in a different range of crucial enzymes (synthetases, kinases, and transferases) to engineer substrate specificity for various industrial applications and substrate-based drug design.

In vitro sensitivity pattern of chloroquine and artemisinin in Plasmodium falciparum

Artemisinin (ART) and its derivatives form the mainstay of antimalarial therapy. Emergence of resistance to them poses a potential threat to future malaria control and elimination on a global level. It is important to know the mechanism of action of drug and development of drug resistance. We put forwards probable correlation between the mode of action of chloroquine (CQ) and ART. Modified trophozoite maturation inhibition assay, WHO Mark III assay and molecular marker study for CQ resistance at K76T codon in Plasmodium falciparum CQ-resistant transporter gene were carried out on cultured P. falciparum. On comparing trophozoite and schizont growth for both CQ-sensitive (MRC-2) and CQ-resistant (RKL-9) culture isolates, it was observed that the clearance of trophozoites and schizonts was similar with both drugs. The experiment supports that CQ interferes with heme detoxification pathway in food vacuoles of parasite, and this may be correlated as one of the plausible mechanisms of ART.

Emerging polymorphisms in falciparum Kelch 13 gene in Northeastern region of India

Background

Recent reports of emergence and spread of artemisinin resistance in the Southeast Asia region, including Myanmar, pose a greater threat to malaria control and elimination in India. Whole genome sequencing studies have associated mutations in the K13 propeller gene (k13), PF3D7_1343700 with artemisinin resistance both in vitro and in vivo. The aim of the present study was to find the k13 gene polymorphisms in Plasmodium falciparum parasites from the three sites in the Northeast region of India, bordering Bangladesh and Myanmar.

Methods

A total of 254 samples collected during 2014–2015 from Tripura, Mizoram and Arunachal Pradesh states in the Northeast region of India were used to obtain the full-length k13 gene sequences.

Results

Three non-synonymous (NS) mutations: two in the propeller region, namely at codon 446 and 578, were observed besides one at codon 189 in the non-propeller region. The treatment outcome was not affected by these mutations at any of the sites. In addition, microsatellite variation in the N-terminus of the k13 protein was observed at all the study sites.

Conclusion

This is the first study to document the presence of F446I NS mutation in the k13 propeller region from Changlang district, Arunachal Pradesh, a site adjoining the Indo-Myanmar border region, where this mutation is highly prevalent. In addition, NS mutation A578S has been observed only at Lunglei district, Mizoram, a site bordering Bangladesh and K189T mutation with relatively higher frequency in Mizoram and Tripura states. The presence of F446I mutation in a region close to the Myanmar border is notable. Considering the spread of anti-malarial drug resistance from Southeast Asia to the Northeast region of India in the past, there is an urgent need to undertake systematic mapping studies to ascertain the role and extent of this mutation in artemisinin resistance in this region of country.

Comparison of WHO Mark III and HRP II ELISA for in vitro sensitivity of Plasmodium falciparum

BACKGROUND & OBJECTIVES

Antimalarial drug resistance is a serious challenge to malaria control worldwide. In vitro sensitivity assays provide an early indication of emerging drug resistance. In vitro susceptibility of field and culture adapted Plasmodium falciparum isolates to different antimalarials was compared using two Methods: World Health Organization (WHO) micro-test (MARK III) and histidine rich protein II (HRP II) based enzyme- linked immunosorbent assay (ELISA).

METHODS

In total, 50 P. falciparum isolates were collected from five states, viz. Chhattisgarh, Meghalaya, Mizoram, Tripura and Odisha of India during December 2011-September 2014. The isolates were revived and evaluated for their susceptibility to chloroquine (CQ), monodesethylamodiaquine (AQ), mefloquine (MQ), quinine (QN) and artemisinin (ART) using the WHO micro-test (Mark III) and HRP II ELISA. The data were analyzed using non- linear regression analysis.

RESULTS

The geometric mean (GM) IC50 values of different antimalarials for WHO Mark III assay were comparatively lower than HRP II ELISA assay. The GM IC50 value for CQ was 59.5 nM (95% confidence interval [CI]: 49.35-71.73 nM) and 78.34 nM (95% CI: 64.57-95.03 nM) for Mark III and HRP II ELISA, respectively. Similarly, the values of GM IC50 for AQ, MQ, QN and ART by Mark III and HRP II ELISA were 13.31, 7.07, 146.4, 0.43 nM and 22.02, 11.46, 258.7, 1.00 nM, respectively. On analyzing statistically, the results of both assays were comparable (R2 = 0.96, p < 0.001; mean log difference at IC50= 0.037).

INTERPRETATION & CONCLUSION

The HRP II ELISA assay showed a reliable sensitivity in comparison to WHO Mark III micro-test complemented with distinguishing features such as high specificity, ease of performance, and notable consistency.

Syncytial Hepatitis of Tilapia ( Oreochromis niloticus L.) is Associated With Orthomyxovirus-Like Virions in Hepatocytes

Using transmission electron microscopy (TEM), the presented work expands on the ultrastructural findings of an earlier report on "syncytial hepatitis," a novel disease of tilapia (SHT). Briefly, TEM confirmed the presence of an orthomyxovirus-like virus within the diseased hepatocytes but not within the endothelium. This was supported by observing extracellular and intracellular (mostly intraendosomal), 60-100 nm round virions with a trilaminar capsid containing up to 7 electron-dense aggregates. Other patterns noted included enveloped or filamentous virions and virion-containing cytoplasmic membrane folds, suggestive of endocytosis. Patterns atypical for orthymyxovirus included the formation of syncytia and the presence of virions within the perinuclear cisternae (suspected to be the Golgi apparatus). The ultrastructural morphology of SHT-associated virions is similar to that previously reported for tilapia lake virus (TiLV). A genetic homology was investigated using the available reverse transcriptase polymerase chain reaction (RT-PCR) probes for TiLV and comparing clinically sick with clinically normal fish and negative controls. By RT-PCR analysis, viral nucleic acid was detected only in diseased fish. Taken together, these findings strongly suggest that a virus is causally associated with SHT, that this virus shares ultrastructural features with orthomyxoviruses, and it presents with partial genetic homology with TiLV (190 nucleotides).

Cation exchange synthesis of uniform PbSe/PbS core/shell tetra-pods and their use as near-infrared photodetectors

In this work we explore the preparation of complex-shaped semiconductor nanostructures composed of different materials via a cationic exchange process in which the cations of the original semiconductor nanostructure are replaced by cations of different metals with preservation of the shape and the anionic framework of the nanocrystals. Utilizing this cation exchange method, we synthesized two new tetrapods for the first time: Cu2-xSe/Cu2-xS and PbSe/PbS, both prepared from CdSe/CdS tetrapods as 'templates'. We also fabricated near-infrared (NIR) photodetectors with a very simple architecture comprising a PbSe/PbS tetrapod layer between two Au electrodes on a glass substrate. When illuminated by a NIR laser, these devices are capable of achieving a responsivity of 11.9 A W(-1) without the use of ligand-exchange processes, thermal annealing or hybrid device architecture. Transient absorption spectroscopy was carried out on these PbSe/PbS tetrapods, the results of which suggest that the branched morphology contributes in part to device performance. Investigation of the charge dynamics of the PbSe/PbS tetrapods revealed an extremely long-lived exciton recombination lifetime of ∼17 ms, which can result in enhanced photoconductive gain. Overall, these heterostructured tetrapods showcase simultaneously the importance of nanoparticle shape, band structure, and surface chemistry in the attainment of NIR photodetection.

Monitoring the efficacy of antimalarial medicines in India via sentinel sites: Outcomes and risk factors for treatment failure

BACKGROUND & OBJECTIVES

To combat the problem of antimalarial drug resistance, monitoring the changes in drug efficacy over time through periodic surveillance is essential. Since 2009, systematic and continuous monitoring is being done through nationwide sentinel site system. Potential early warning signs like partner drug resistance markers were also monitored in the clinical samples from the study areas.

METHODS

A total of 1864 patients with acute uncomplicated malaria were enrolled in therapeutic efficacy studies of artesunate plus sulphadoxine-pyrimethamine (AS+SP) for Plasmodium falciparum; those infected with P. vivax were given chloroquine (CQ). Polymerase chain reaction (PCR) was used to distinguish post-treatment reinfection from treatment failures. Isolates of P. falciparum were also analysed for dihydropteroate synthase (dhps) and dihydrofolate reductase (dhfr) gene mutations.

RESULTS

Overall, 1687 (91.7%) patients completed the follow-up. In most of the falciparum patients the parasitaemia was cleared within 24 h of treatment, except 12 patients who remained parasite positive after 72 h. Presence of dhfr and dhps quintuple mutation was observed predominantly in treatment failure samples. A daily dose of artesunate of < 3 mg/kg of body weight, age of <5 yr, and fever at enrolment were associated with an increased risk of treatment failure. The AS+SP in P. falciparum was effective in > 95% cases in all the sentinel sites except in Northeastern region (NE). Chloroquine remained 100% efficacious in case of P. vivax infections.

INTERPRETATION & CONCLUSION

Till 2012, India's national antimalarial drug resistance monitoring system proved highly efficacious and safe towards first-line antimalarials used in the country, except in Northeastern region where a decline in efficacy of AS+SP has been observed. This led to change in first-line treatment for P. falciparum to artemether-lumefantrine in Northeastern region.

Computer-vision-based technology for fast, accurate and cost effective diagnosis of malaria

Background

Microscopy has long been considered to be the gold standard for diagnosis of malaria despite the introduction of newer assays. However, it has many challenges like requirement of trained microscopists and logistic issues. A vision based device that can diagnose malaria, provide speciation and estimate parasitaemia was evaluated.

Methods

The device was evaluated using samples from 431 consented patients, 361 of which were initially screened by RDT and microscopy and later analysed by PCR. It was a prospective, non-randomized, blinded trial. Quantification of parasitaemia was performed by two experienced technicians. Samples were subjected to diagnosis by Sight Dx digital imaging scanning.

Results

The sensitivity and specificity of the SightDx P1 device for analysed samples were found to be 97.05 and 96.33 %, respectively, when compared to PCR. When compared to microscopy, sensitivity and specificity were found to be 94.4 and 95.6 %, respectively. The device was able to speciate 73.3 % of the PCR Plasmodium falciparum positive samples and 91.4 % of PCR Plasmodium vivax positive samples.

Conclusion

The ability of the device to detect parasitaemia as compared with microscopy, was within 50 % in 71.3 % of cases and demonstrated a correlation coefficient of 0.89.

Comparative assessment of genomic DNA extraction processes for Plasmodium: Identifying the appropriate method

Plasmodium DNA, in addition to being used for molecular diagnosis of malaria, find utility in monitoring patient responses to antimalarial drugs, drug resistance studies, genotyping and sequencing purposes. Over the years, numerous protocols have been proposed for extracting Plasmodium DNA from a variety of sources. Given that DNA isolation is fundamental to successful molecular studies, here we review the most commonly used methods for Plasmodium genomic DNA isolation, emphasizing their pros and cons. A comparison of these existing methods has been made, to evaluate their appropriateness for use in different applications and identify the method suitable for a particular laboratory based study. Selection of a suitable and accessible DNA extraction method for Plasmodium requires consideration of many factors, the most important being sensitivity, cost-effectiveness and, purity and stability of isolated DNA. Need of the hour is to accentuate on the development of a method that upholds well on all these parameters.

Molecular mechanism of in vitro transformation of mammalian cells by chemical carcinogens

BHK21 clone 13 cells transformed by dimethylnitrosamine (DMN) or nitrosomethylurea (NMU) ("alkylating" chemical carcinogens) appear to be restricted by temperature in the expression of their transformed phenotype. When grown at 38.5 degrees C, they exhibit a transformed phenotype (clonal morphology and ability to plate in agar), when grown at 32 degrees C, their phenotype is normal. Conversion from the normal to the transformed phenotype and the reverse is possible by temperature shifts. Conversely of the BHK21 clone 13 cells, of the rat fibroblasts (R111) transformed by 4-nitroquinoline-N-oxide (NQN), some exhibit a transformed phenotype restricted by temperature while others are not restricted by temperature in the expression of transformation. A working hypothesis is proposed suggesting that the phenotype of cells transformed by chemical carcinogens may be determined by the nature of the chemical reaction with the cell DNA. "Alkylating" carcinogens cause prevalently point mutation in bacteria (of the base substitution kind); in the case of transformation of mammalian cells temperature-sensitive phenotypes will be obtained. "Frameshift" carcinogens cause frameshift mutation in bacteria and cells transformed by this class of carcinogens will exhibit a transformed phenotype unrestricted by temperature.

Microwave assisted synthesis, characterization and biocidal activities of some new chelates of carbazole derived Schiff bases of cadmium and tin metals

This study is planned to report the advancement of green microwave approach in the fabrication of a new series of biologically potent (N^X, where X=O/S) donor Schiff bases and their cadmium(II) and tin(II) complexes. The ligands and their metal complexes have been characterized in terms of elemental analysis, molar ionic conductance, magnetic moment and spectral (IR, UV-Vis, NMR ((1)H, (119)Sn), FAB-mass, thermal and XRD) data. The data revealed that the ligands coordinated to the metal center via nitrogen and oxygen/sulfur atoms and form an octahedral arrangement of the ligands around central metal atom. All compounds were evaluated for their in vitro antimicrobial activities against two pathogenic bacteria Bacillus subtilis and Escherichia coli and two fungi Aspergillus niger and Aspergillus flavus by standard disc diffusion method. The discs were stored in an incubator at 37°C. The compounds were dissolved in DMF at 500 and 1000 ppm concentrations for screening biocidal activity. The compounds were dissolved in DMF to get the 100 and 200 ppm concentration of test solutions for screening fungicidal activity. The inhibition zone around each disc was measured (in mm) after 24 h and 96 h for biocidal and fungicidal activities respectively.