Ecological host fitting of Trypanosoma cruzi TcI in Bolivia: mosaic population structure, hybridization and a role for humans in Andean parasite dispersal.

An improved understanding of how a parasite species exploits its genetic repertoire to colonize novel hosts and environmental niches is crucial to establish the epidemiological risk associated with emergent pathogenic genotypes. Trypanosoma cruzi, a genetically heterogeneous, multi-host zoonosis, provides an ideal system to examine the sylvatic diversification of parasitic protozoa. In Bolivia, T. cruzi I, the oldest and most widespread genetic lineage, is pervasive across a range of ecological clines. High-resolution nuclear (26 loci) and mitochondrial (10 loci) genotyping of 199 contemporaneous sylvatic TcI clones was undertaken to provide insights into the biogeographical basis of T. cruzi evolution. Three distinct sylvatic parasite transmission cycles were identified: one highland population among terrestrial rodent and triatomine species, composed of genetically homogenous strains (Ar = 2.95; PA/L = 0.61; DAS = 0.151), and two highly diverse, parasite assemblages circulating among predominantly arboreal mammals and vectors in the lowlands (Ar = 3.40 and 3.93; PA/L = 1.12 and 0.60; DAS = 0.425 and 0.311, respectively). Very limited gene flow between neighbouring terrestrial highland and arboreal lowland areas (distance ~220 km; FST = 0.42 and 0.35) but strong connectivity between ecologically similar but geographically disparate terrestrial highland ecotopes (distance >465 km; FST = 0.016-0.084) strongly supports ecological host fitting as the predominant mechanism of parasite diversification. Dissimilar heterozygosity estimates (excess in highlands, deficit in lowlands) and mitochondrial introgression among lowland strains may indicate fundamental differences in mating strategies between populations. Finally, accelerated parasite dissemination between densely populated, highland areas, compared to uninhabited lowland foci, likely reflects passive, long-range anthroponotic dispersal. The impact of humans on the risk of epizootic Chagas disease transmission in Bolivia is discussed

Development of peptide-based lineage-specific serology for chronic Chagas disease: geographical and clinical distribution of epitope recognition.

BACKGROUND: Chagas disease, caused by infection with the protozoan Trypanosoma cruzi, remains a serious public health issue in Latin America. Genetically diverse, the species is sub-divided into six lineages, known as TcI-TcVI, which have disparate geographical and ecological distributions. TcII, TcV, and TcVI are associated with severe human disease in the Southern Cone countries, whereas TcI is associated with cardiomyopathy north of the Amazon. T. cruzi persists as a chronic infection, with cardiac and/or gastrointestinal symptoms developing years or decades after initial infection. Identifying an individual's history of T. cruzi lineage infection directly by genotyping of the parasite is complicated by the low parasitaemia and sequestration in the host tissues. METHODOLOGY/PRINCIPAL FINDINGS: We have applied here serology against lineage-specific epitopes of the T. cruzi surface antigen TSSA, as an indirect approach to allow identification of infecting lineage. Chagasic sera from chronic patients from a range of endemic countries were tested by ELISA against synthetic peptides representing lineage-specific TSSA epitopes bound to avidin-coated ELISA plates via a biotin labelled polyethylene glycol-glycine spacer to increase rotation and ensure each amino acid side chain could freely interact with their antibodies. 79/113 (70%) of samples from Brazil, Bolivia, and Argentina recognised the TSSA epitope common to lineages TcII/TcV/TcVI. Comparison with clinical information showed that a higher proportion of Brazilian TSSApep-II/V/VI responders had ECG abnormalities than non-responders (38% vs 17%; p<0.0001). Among northern chagasic sera 4/20 (20%) from Ecuador reacted with this peptide; 1/12 Venezuelan and 1/34 Colombian samples reacted with TSSApep-IV. In addition, a proposed TcI-specific epitope, described elsewhere, was demonstrated here to be highly conserved across lineages and therefore not applicable to lineage-specific serology. CONCLUSIONS/SIGNIFICANCE: These results demonstrate the considerable potential for synthetic peptide serology to investigate the infection history of individuals, geographical and clinical associations of T. cruzi lineages

First external quality assurance program for bloodstream Real-Time PCR monitoring of treatment response in clinical trials of Chagas disease

Real-Time PCR (qPCR) testing is recommended as both a diagnostic and outcome measurement of etiological treatment in clinical practice and clinical trials of Chagas disease (CD), but no external quality assurance (EQA) program provides performance assessment of the assays in use. We implemented an EQA system to evaluate the performance of molecular biology laboratories involved in qPCR based follow-up in clinical trials of CD. An EQA program was devised for three clinical trials of CD: the E1224 (NCT01489228), a pro-drug of ravuconazole; the Sampling Study (NCT01678599), that used benznidazole, both conducted in Bolivia; and the CHAGASAZOL (NCT01162967), that tested posaconazole, conducted in Spain. Four proficiency testing panels containing negative controls and seronegative blood samples spiked with 1, 10 and 100 parasite equivalents (par. eq.)/mL of four Trypanosoma cruzi stocks, were sent from the Core Lab in Argentina to the participating laboratories located in Bolivia and Spain. Panels were analyzed simultaneously, blinded to sample allocation, at 4-month intervals. In addition, 302 random blood samples from both trials carried out in Bolivia were sent to Core Lab for retesting analysis. The analysis of proficiency testing panels gave 100% of accordance (within laboratory agreement) and concordance (between laboratory agreement) for all T. cruzi stocks at 100 par. eq./mL; whereas their values ranged from 71 to 100% and from 62 to 100% at 1 and 10 par. eq./mL, respectively, depending on the T. cruzi stock. The results obtained after twelve months of preparation confirmed the stability of blood samples in guanidine-EDTA buffer. No significant differences were found between qPCR results from Bolivian laboratory and Core Lab for retested clinical samples. This EQA program for qPCR analysis of CD patient samples may significantly contribute to ensuring the quality of laboratory data generated in clinical trials and molecular diagnostics laboratories of CD

Defective formation of IgA memory B cells, Th1 and Th17 cells in symptomatic patients with selective IgA deficiency

Objective: Selective IgA deficiency (sIgAD) is the most common primary immunodeficiency in Western countries. Patients can suffer from recurrent infections and autoimmune diseases because of a largely unknown aetiology. To increase insights into the pathophysiology of the disease, we studied memory B and T cells and cytokine concentrations in peripheral blood. Methods: We analysed 30 sIgAD patients (12 children, 18 adults) through detailed phenotyping of peripheral B-cell, CD8+ T-cell and CD4+ T-cell subsets, sequence analysis of IGA and IGG transcripts, in vitro B-cell activation and blood cytokine measurements. Results: All patients had significantly decreased numbers of T-cell-dependent (TD; CD27+) and T-cell-independent (TI; CD27−) IgA memory B cells and increased CD21low B-cell numbers. IgM+IgD− memory B cells were decreased in children and normal in adult patients. IGA and IGG transcripts contained normal SHM levels. In sIgAD children, IGA transcripts more frequently used IGA2 than controls (58.5% vs. 25.1%), but not in adult patients. B-cell activation after in vitro stimulation was normal. However, adult sIgAD patients exhibited increased blood levels of TGF-β1, BAFF and APRIL, whereas they had decreased Th1 and Th17 cell numbers. Conclusion: Impaired IgA memory formation in sIgAD patients is not due to a B-cell activation defect. Instead, decreased Th1 and Th17 cell numbers and high blood levels of BAFF, APRIL and TGF-β1 might reflect disturbed regulation of IgA responses in vivo. These insights into B-cell extrinsic immune defects suggest the need for a broader immunological focus on genomics and functional analyses to unravel the pathogenesis of sIgAD

Genome analysis of triploid hybrid Leishmania parasite from the Neotropics

We discovered a hybrid Leishmania parasite in Costa Rica that is genetically similar to hybrids from Panama. Genome analyses demonstrated the hybrid is triploid and identified L. braziliensis and L. guyanensis-related strains as parents. Our findings highlight the existence of poorly sampled Leishmania (Viannia) variants infectious to humans

El impacto social de las enfermedades degenerativas en adultos mayores: Análisis desde la perspectiva del trabajador social

From the perspective of the social worker, the social impact on the incidence of degenerative diseases in older adults in recent years 2020-2022 is notable. What can be projected is an increase in demand for health care and long-term care services. The aging of the Panamanian population and the prevalence of these conditions bring with them high budgets to cover these health requirements as well as specialized services. Additionally, these diseases can generate significant economic costs for older adults and their families. Expenses on medications, medical treatments and specialized care can be overwhelming, causing additional financial pressure on the families of older adults as in many cases this can lead to financial difficulties and strains on family relationships.Desde la perspectiva del trabajador social, es notorio el impacto social en la incidencia de las enfermedades degenerativas en los adultos mayores en los últimos años 2020-2022. Lo que puede proyectarse un aumento en la demanda de servicios de atención médica y cuidado a largo plazo. El envejecimiento de la población panameña y la prevalencia de estos padecimientos traen consigo altos presupuestos y así poder cubrir estos requerimientos sanitarios como los servicios especializados. Además, estas enfermedades pueden generar costos económicos significativos para los adultos mayores y sus familias. Los gastos en medicamentos, tratamientos médicos y cuidados especializados pueden ser abrumadores, lo que provoca una presión financiera adicional en las familias de los adultos mayores ya que en muchos casos esto puede llevar a dificultades económicas y tensiones en las relaciones familiares

Phylogenetic Analysis of Bolivian Bat Trypanosomes of the Subgenus Schizotrypanum Based on Cytochrome b Sequence and Minicircle Analyses

The aim of this study was to establish the phylogenetic relationships of trypanosomes present in blood samples of Bolivian Carollia bats. Eighteen cloned stocks were isolated from 115 bats belonging to Carollia perspicillata (Phyllostomidae) from three Amazonian areas of the Chapare Province of Bolivia and studied by xenodiagnosis using the vectors Rhodnius robustus and Triatoma infestans (Trypanosoma cruzi marenkellei) or haemoculture (Trypanosoma dionisii). The PCR DNA amplified was analyzed by nucleotide sequences of maxicircles encoding cytochrome b and by means of the molecular size of hyper variable regions of minicircles. Ten samples were classified as Trypanosoma cruzi marinkellei and 8 samples as Trypanosoma dionisii. The two species have a different molecular size profile with respect to the amplified regions of minicircles and also with respect to Trypanosoma cruzi and Trypanosoma rangeli used for comparative purpose. We conclude the presence of two species of bat trypanosomes in these samples, which can clearly be identified by the methods used in this study. The presence of these trypanosomes in Amazonian bats is discussed

Evaluation of the humoral and mucosal immune response of a multiepitope vaccine against COVID-19 in pigs

IntroductionThis study evaluated the immune response to a multiepitope recombinant chimeric protein (CHIVAX) containing B- and T-cell epitopes of the SARS-CoV-2 spike’s receptor binding domain (RBD) in a translational porcine model for pre-clinical studies.MethodsWe generated a multiepitope recombinant protein engineered to include six coding conserved epitopes from the RBD domain of the SARS-CoV-2 S protein. Pigs were divided into groups and immunized with different doses of the protein, with serum samples collected over time to determine antibody responses by indirect ELISA and antibody titration. Peptide recognition was also analyzed by Western blotting. A surrogate neutralization assay with recombinant ACE2 and RBDs was performed. Intranasal doses of the immunogen were also prepared and tested on Vietnamese minipigs.ResultsWhen the immunogen was administered subcutaneously, it induced specific IgG antibodies in pigs, and higher doses correlated with higher antibody levels. Antibodies from immunized pigs recognized individual peptides in the multiepitope vaccine and inhibited RBD-ACE2 binding for five variants of concern (VOC). Comparative antigen delivery methods showed that both, subcutaneous and combined subcutaneous/intranasal approaches, induced specific IgG and IgA antibodies, with the subcutaneous approach having superior neutralizing activity. CHIVAX elicited systemic immunity, evidenced by specific IgG antibodies in the serum, and local mucosal immunity, indicated by IgA antibodies in saliva, nasal, and bronchoalveolar lavage secretions. Importantly, these antibodies demonstrated neutralizing activity against SARS-CoV-2 in vitro.DiscussionThe elicited antibodies recognized individual epitopes on the chimeric protein and demonstrated the capacity to block RBD-ACE2 binding of the ancestral SARS-CoV-2 strain and four VOCs. The findings provide proof of concept for using multiepitope recombinant antigens and a combined immunization protocol to induce a neutralizing immune response against SARS-CoV-2 in the pig translational model for preclinical studies