Parasite Genotype Is a Major Predictor of Mortality from Visceral Leishmaniasis.

Visceral leishmaniasis (VL) is a potentially fatal disease caused mainly by Leishmania infantum in South America and Leishmania donovani in Asia and Africa. Disease outcomes have been associated with patient genotype, nutrition, age, sex, comorbidities, and coinfections. In this study, we examine the effects of parasite genetic variation on VL disease severity in Brazil. We collected and sequenced the genomes of 109 L. infantum isolates from patients in northeastern Brazil and retrieved matching patient clinical data from medical records, including mortality, sex, HIV coinfection, and laboratory data (creatinine, hemoglobin, and leukocyte and platelet counts). We identified genetic differences between parasite isolates, including single nucleotide polymorphisms (SNPs), small insertions/deletions (indels), and variations in genic, intergenic, and chromosome copy numbers (copy number variants [CNVs]). To describe associations between the parasite genotypes and clinical outcomes, we applied quantitative genetics methods of heritability and genome-wide association studies (GWAS), treating clinical outcomes as traits that may be influenced by parasite genotype. Multiple aspects of the genetic analysis indicate that parasite genotype affects clinical outcomes. We estimate that parasite genotype explains 83% chance of mortality (narrow-sense heritability [h2] = 0.83 ± 0.17) and has a significant relationship with patient sex (h2 = 0.60 ± 0.27). Impacts of parasite genotype on other clinical traits are lower (h2 ≤ 0.34). GWAS analysis identified multiple parasite genetic loci that were significantly associated with clinical outcomes; 17 CNVs were significantly associated with mortality, two with creatinine, and one with bacterial coinfection, jaundice, and HIV coinfection, and two SNPs/indels and six CNVs were associated with age, jaundice, HIV and bacterial coinfections, creatinine, and/or bleeding sites. Parasite genotype is an important factor in VL disease severity in Brazil. Our analysis indicates that specific genetic differences between parasites act as virulence factors, enhancing risks of severe disease and mortality. More detailed understanding of these virulence factors could be exploited for novel therapies. IMPORTANCE Multiple factors contribute to the risk of mortality from visceral leishmaniasis (VL), including, patient genotype, comorbidities, and nutrition. Many of these factors are influenced by socioeconomic biases. Our work suggests that the virulence of the infecting parasite is an important risk factor for mortality. We pinpoint some specific genomic markers that are associated with mortality, which can lead to a greater understanding of the molecular mechanisms that cause severe VL disease, to the identification of genetic markers for virulent parasites, and to the development of drug and vaccine therapies.

Interaction between Benzo[a]anthracene 7,2-dione 7-oxime (BZA) and calf thymus dsDNA using electroanalytical genosensor.

In the present study, the objective was to evaluate in situ interaction between Benzo[a]anthracene 7,2-dione 7-oxime (BZA) and calf thymus dsDNA (ct-dsDNA) using electroanalytical genosensor. Analytical techniques based on Ultraviolet/Visible (UV-Vis) spectroscopy and electroanalytical were used to investigate the interaction processes in solution and immobilized on carbon screen-printed electrodes modified with electrochemical mediator Meldola blue. In addition, was possible to evaluate the degree of damage caused to the genetic material by the analyte through of toxicity estimate (S%). The interaction evaluated by genosensor showed processes of intercalation, degradation, and breaks of the double strand of ct-dsDNA, suggesting that the interaction simulates highly toxic (values varying from 0.6 to 0.8 µA in 48 h of interaction), such as 8-oxoguanine (+0.48 V), which is a by-product of guanine oxidation. Furthermore, monitoring A (+1.10 V) after 1 h showed an S% value between 50 and 90%, indicative of high toxicity, and monitoring G (+0.85 V), which showed S>90%, indicated no toxicity after 10 min. Overall, the electroanalytical genosensor developed in a miniaturized system displayed good reproducibility and stability over time being a quick alternative for assesses the degree of toxicity between toxic xenobiotics and biologically electroactive molecules, such as DNA.

Immunodiagnostic of leprosy exploiting a photoelectrochemical platform based on a recombinant peptide mimetic of a Mycobacterium leprae antigen.

The first serum diagnosis of leprosy based on the detection of antibodies of patients using a recombinant mimetic peptide (PGL1M3R) as recognition element and exploiting a photoelectrochemical sensor is presented in this work. The photoeletrochemical platform consists of cadmium sulphide and nickel hydroxide electrodeposited on fluorine-doped tin oxide coated glass slide (CdS/Ni(OH)2/FTO). The optical band gap and flat band potential of the photoelectroactive materials were evaluated by UV-Vis spectroscopy and electrochemical impedance spectroscopy. The spatial photoelectrochemical response of the platform was evaluated by Scanning Electrochemical Microscopy and the morphology of the films was investigated by Scanning Electron Microscopy (SEM). The photoelectrochemical response of the CdS/Ni(OH)2/FTO platform was optimized by evaluating the effects of the kind, concentration, and pH of the buffer. Furthermore, the applied potential to the CdS/Ni(OH)2/FTO platform was also investigated. The CdS/Ni(OH)2/FTO photoelectrochemical platform was modified with a synthetic peptide by using glutaraldehyde as cross-linking reagent and chitosan (CS) for the covalent coupling of the peptide to the photoelectrochemical platform (PGL1M3R/CdS/Ni(OH)2/FTO). The photoelectrochemical immunosensor is able to distinguishing between positive and negative leprosy human sera samples diluted from 1:640 up to 1:10240. Furthermore, to test the specificity of the sensor, samples from tuberculosis and leishmaniasis patients were analyzed using the proposed photoelectrochemical immunosensor.