Publications by authors named "Myriam Arevalo-Herrera"

A total of 5011 adult volunteers attending vaccination centers in different regions of Colombia were enrolled in a 1-year prospective observational cohort study to evaluate the immunogenicity and effectiveness of SARS-CoV-2-based vaccines as part of a National Vaccine Program established to contain the COVID-19 pandemic. Following informed consent, 5,011 participants underwent a sociodemographic survey and PCR testing to assess SARS-CoV-2 infection. Blood samples were collected, and serum fractions were obtained from a participant subsample (n = 3441) at six-time points to assess virus-specific IgG responses to the Spike protein, its Receptor Binding Domain, and the Nucleoprotein by ELISA.

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Background: 48/45, a gametocyte surface protein, is a promising candidate for malaria transmission-blocking (TB) vaccine. Due to its relevance for a multispecies vaccine, we explored the cross-reactivity and TB activity of a recombinant 48/45 protein (r48/45) with sera from -exposed African donors.

Methods: r48/45 was produced in Chinese hamster ovary cell lines and tested by ELISA for its cross-reactivity with sera from Burkina Faso, Tanzania, Mali, and Nigeria - In addition, BALB/c mice were immunized with the r48/45 protein formulated in Montanide ISA-51 and inoculated with a crude extract of NF-54 gametocytes to evaluate the parasite-boosting effect on r48/45 antibody titers.

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Malaria sterile immunity has been reproducibly induced by immunization with Plasmodium radiation-attenuated sporozoites (RAS). Analyses of sera from RAS-immunized individuals allowed the identification of P. falciparum antigens, such as the circumsporozoite protein (CSP), the basis for the RTS, S and R21Matrix-M vaccines.

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Colombia aims to eliminate malaria by 2030 but remains one of the highest burden countries in the Americas. Plasmodium vivax contributes half of all malaria cases, with its control challenged by relapsing parasitaemia, drug resistance and cross-border spread. Using 64 Colombian P.

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Article Synopsis
  • Malaria is a significant global health issue, particularly in Venezuela, where co-infections with other viral and bacterial pathogens complicate malaria diagnosis and treatment, leading to higher mortality rates.
  • A study was conducted on 161 malaria patients to assess the prevalence of co-infections with pathogens like dengue virus and hepatitis viruses, using specific laboratory tests for diagnosis.
  • Results showed that 34% of the malaria patients had co-infections, with a higher incidence in those infected with the Plasmodium falciparum strain compared to Plasmodium vivax, highlighting the need for improved diagnostic methods in endemic areas.
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The currently devastating pandemic of severe acute respiratory syndrome known as coronavirus disease 2019 or COVID-19 is caused by the coronavirus SARS-CoV-2. Both the virus and the disease have been extensively studied worldwide. A trimeric spike (S) protein expressed on the virus outer bilayer leaflet has been identified as a ligand that allows the virus to penetrate human host cells and cause infection.

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Despite the global interest and the unprecedented number of scientific studies triggered by the COVID-19 pandemic, few data are available from developing and low-income countries. In these regions, communities live under the threat of various transmissible diseases aside from COVID-19, including malaria. This study aims to determine the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) seroreactivity of antibodies from COVID-19 and pre-COVID-19 samples of individuals in Mali (West Africa).

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A randomized, double-blind, controlled vaccine clinical trial was conducted to assess, as the primary outcome, the safety and protective efficacy of the Plasmodium vivax circumsporozoite (CS) protein in healthy malaria-naïve (phase IIa) and semi-immune (phase IIb) volunteers. Participants (n = 35) were randomly selected from a larger group (n = 121) and further divided into naïve (n = 17) and semi-immune (n = 18) groups and were immunized at months 0, 2, and 6 with PvCS formulated in Montanide ISA-51 adjuvant or placebo (adjuvant alone). Specific antibodies and IFN-γ responses to PvCS were determined as secondary outcome; all experimental volunteers developed specific IgG and IFN-γ.

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Article Synopsis
  • Pvs48/45 is a Plasmodium vivax protein linked to parasite fertilization, and previous studies found it to be immunogenic in animal models; this study compares its immunogenicity in different vaccine formulations.
  • Recombinant Pvs48/45 proteins were produced in E. coli and CHO cells, combined with various adjuvants to immunize mice, and serum was analyzed for antibody responses and effectiveness in blocking parasite transmission.
  • Results indicated that while all adjuvants elicited antibody responses, Montanide ISA-51 with CHO-rPvs48/45 produced the strongest and most durable antibody levels, demonstrating the best transmission-blocking capability against the malaria parasite.
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Article Synopsis
  • P48/45 is a key gametocyte antigen related to malaria parasite fertilization, and a recombinant version of the protein expressed in CHO cells was tested for its immunogenic properties.
  • In studies with plasma from individuals in Colombia and Guatemala, the CHO-48/45 protein showed higher seroprevalence and stronger immune responses compared to another recombinant protein.
  • The research indicated that antibodies generated from CHO-48/45 could effectively block malaria transmission, suggesting its potential as a candidate for a malaria vaccine.
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, the most widely distributed human malaria parasite, causes severe clinical syndromes despite low peripheral blood parasitemia. This conundrum is further complicated as cytoadherence in the microvasculature is still a matter of investigations. Previous reports in , another parasite species shown to infect humans, demonstrated that variant genes involved in cytoadherence were dependent on the spleen for their expression.

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Plasmodium vivax malaria is a neglected disease, particularly during pregnancy. Severe vivax malaria is associated with inflammatory responses but in pregnancy immune alterations make it uncertain as to what cytokine signatures predominate, and how the type and quantity of blood immune mediators influence delivery outcomes. We measured the plasma concentrations of a set of thirty-one biomarkers, comprising cytokines, chemokines and growth factors, in 987 plasma samples from a cohort of 572 pregnant women from five malaria-endemic tropical countries and related these concentrations to delivery outcomes (birth weight and hemoglobin levels) and malaria infection.

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Article Synopsis
  • * A total of 1,318 blood samples were taken, revealing high seroprevalence rates: 85% for children and over 90% for adults, along with notable rates of IgM positivity and recent infections.
  • * The findings highlight the widespread circulation of dengue virus (DENV) in Colombia, suggesting a need for enhanced vector control measures and adjustments in vaccine policies and clinical management practices.
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The immune status of women changes during and after pregnancy, differs between blood compartments at delivery and is affected by environmental factors particularly in tropical areas endemic for multiple infections. We quantified the plasma concentration of a set of thirty-one T1, T2, T17 and regulatory cytokines, pro-inflammatory and anti-inflammatory cytokines and chemokines, and growth factors (altogether biomarkers), in a cohort of 540 pregnant women from five malaria-endemic tropical countries. Samples were collected at recruitment (first antenatal visit), delivery (periphery, cord and placenta) and postpartum, allowing a longitudinal analysis.

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Malaria control and interventions including long-lasting insecticide-treated nets, indoor residual spraying, and intermittent preventative treatment in pregnancy have resulted in a significant reduction in the number of cases. Considerable efforts have been devoted to vaccines development with much less to . Transmission-blocking vaccines, which can elicit antibodies targeting antigens expressed during sexual stage development and interrupt transmission, offer an alternative strategy to achieve malaria control.

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Background: Malaria remains endemic in several countries of South America with low to moderate transmission intensity. Regional human migration through underserved endemic areas may be responsible for significant parasite dispersion making the disease resilient to interventions. Thus, the genetic characterization of malarial parasites is an important tool to assess how endemic areas may connect via the movement of infected individuals.

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Objectives: To dissect the transcriptional networks underpinning immune cells responses during primary Plasmodium vivax infection of healthy human adults.

Methods: We conducted network co-expression analysis of next-generation RNA sequencing data from whole blood from P. vivax and P.

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Article Synopsis
  • The study aimed to determine if recovery from complicated malaria follows a similar immunological pattern or is unique to each patient, using RNA sequencing on blood samples from eight patients over four days.
  • Findings showed significant variability in gene activity related to immune responses among patients, with limited correlations to specific malaria symptoms like jaundice or anemia.
  • The pilot study concluded that there's no single immune process to target for treatment, but suggests larger studies could help classify patient responses and develop new treatment strategies.
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  • Clinical immunity to malaria in pregnant women is linked to the presence of IgG antibodies targeting VAR2CSA, a specific subtype of the PfEMP1 family found on infected blood cells.* -
  • Recent findings in Colombia showed high levels of VAR2CSA-specific IgG in men and children, challenging established views about the immunity development during pregnancy.* -
  • A study revealed that while Colombian individuals produce IgG against certain PfEMP1 proteins, this reactivity is not specific to malaria, suggesting that the development of VAR2CSA-specific IgG may primarily occur during pregnancy.*
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Malaria in pregnancy threatens birth outcomes and the health of women and their newborns. This is also the case in low transmission areas, such as Colombia, where Plasmodium vivax is the dominant parasite species. Within the Colombian health system, which underwent major reforms in the 90s, malaria treatment is provided free of charge to patients.

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Almost invariably, humans become ill during primary infections with malaria parasites which is a pathology associated with oxidative stress and perturbations in metabolism. Importantly, repetitive exposure to Plasmodium results in asymptomatic infections, which is a condition defined as clinical tolerance. Integration of transcriptomics and metabolomics data provides a powerful way to investigate complex disease processes involving oxidative stress, energy metabolism and immune cell activation.

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Introduction: Inborn errors of metabolism (IEM) represent an important public health problem due to current diagnosis and treatment limitations, poor life quality of affected patients, and consequent untimely child death. In contrast to classical methods, tandem mass spectrometry (MS/MS) has allowed simultaneous evaluation of multiple metabolites associated with IEM offering higher sensitivity, low false positive rates and high throughput.

Aims: Determine concentration levels for amino acids and acylcarnitines in blood of newborns from Colombia, to establish reference values for further use in diagnosis of IEM.

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Article Synopsis
  • Rapid urbanization in Pereira, Colombia, has created conditions favorable for mosquito breeding and malaria transmission, exacerbated by inadequate housing and sanitation.
  • A retrospective analysis of malaria cases from 2008 to 2015 revealed 214 reported cases, predominantly affecting men and children under 15, primarily caused by Plasmodium vivax.
  • Findings indicated ongoing local malaria transmission, particularly between 2008 and 2009, with a noted decrease in reported cases over the study period and insufficient use of protective measures among the affected population.
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Background: Complicated malaria remains an important public health problem, particularly in endemic settings where access to health services is limited and consequently malaria fatal outcomes occur. Few publications describing the clinical course and outcomes of complicated malaria in Latin America are found in the literature. This prospective study approached the clinical and laboratory characteristics of hospitalized patients with complicated malaria in different endemic areas of the Colombian Pacific Coast with the aim to provide epidemiological knowledge and guide to further reducing malaria severity and mortality.

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