Memorias do Instituto Oswaldo Cruz最新文献

Background: The outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections was a serious disease that spread rapidly around the world and led to a state of global health emergency. During the pandemic, millions of deaths were notified as result of the progression of the disease to a serious condition. Research into the development of diagnostic tests was very important for the identification and control of new cases.

Objectives: In this work a label-free electrochemical platform was developed for sensing of SARS-CoV-2 S-protein.

Methods: The S- antibodies (IgY type) from egg yolk were immobilised though stable bonding onto screen-printed gold electrodes surface, which was previously modified with self-assembled monolayers of cysteamine (Cys). The analytical performance of the devices was followed by differential pulse voltammetry after incubation in various concentrations of S-protein.

Findings: The electrical response exhibited a linear behaviour from 10 to 1000 ng mL-1 [with limit of detection (LOD) of 6.2 ng mL-1]. Also, we confirmed that our method is more sensitive than an enzyme-linked immuno-sorbent assay (ELISA), which was conducted with the same molecules (antibody and antigen) (500-4000 ng mL-1, with LOD = 235 ng mL-1). The immunosensor was selective for S-protein detection, and no significative changes were registered by differential pulse voltammetry in presence of SARS-CoV-2 N-protein. Tests on saliva samples recorded similar results to S protein standards.

Main conclusions: The developed immunosensor showed good performance and selectivity, therefore, it can be an alternative method for coronavirus disease 2019 (Covid-19) detecting in saliva samples.

Background: Through coevolution, helminths have developed immunomodulatory mechanisms that regulate exaggerated host immune responses and may influence immune responses to coinfections or vaccines. The coronavirus disease 19 (COVID-19) pandemic has raised concerns about how such infections might affect vaccine-triggered immune responses.

Objectives: The aim of the study was to investigate how ongoing Trichinella spiralis infection affects the immune response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), in individuals already vaccinated or virus-primed, during Trichinella outbreak in Serbia.

Methods: Among 21 individuals who tested positive for anti-Trichinella antibodies, 15 were included in the study, which allowed for the first time to examine the impact of Trichinella infection on the humoral and cellular immune response to the SARS-CoV-2 using flow cytometry.

Findings: The results showed that Trichinella infection did not impair antibody production or cellular responses to SARS-CoV-2. Specifically, anti-SARS-CoV-2 antibodies and memory B cells remain unaffected, and T cells (CD4+ and CD8+) responded to SARS-CoV-2 antigens by generating pro-inflammatory cytokines.

Main conclusions: Trichinella spiralis infection does not disrupt the host's humoral or cellular immune response to SARS-CoV-2, suggesting that the use of Trichinella antigens for the treatment of chronic inflammatory disorders, which is promising, will not affect the host's ability to respond to future viral challenges.

Background: The Institute of Cancer Research (ICR) mouse-Echinostoma caproni model is used to study mechanisms generating resistance against intestinal helminths due to the development chronic primary infections with Th1 responses, and partial resistance to secondary infections.

Objectives: This study aimed to evaluate the generation of concomitant immunity against superimposed homologous E. caproni infection.

Methods: Changes in cytokine expression and macrophages markers as a consequence of primary infection, superimposed infection and superimposed infection in anti (α)-interleuquin(IL)-25-treated mice were investigated by real-time polymerase chain reaction (PCR). Translocation and phosphorylation of STAT6 were studied by indirect immunofluorescence (IIF) on intestinal tissue sections. The IIF technique was also used to label M1 and M2 macrophages to confirm the activation pathways.

Findings: Primary E. caproni infections elicit partial resistance against homologous superimposed infections. The animal groups displayed distinct patterns in the expression of cytokines, macrophages markers and IL-13Rα2 as well as STAT6 phosphorylation in a process mediated by IL-25. Resistance appears to rely on the ability of to induce IL-13Rα2 upregulation.

Main conclusions: The concomitant immunity is based the production of IL-25, rather than in the development of Th2 responses. Regarding the IL-25-dependent mechanisms responsible for concomitant immunity, the ability of IL-25 to induce IL-13Rα2 upregulation which serves to limit the production of other regulatory proteins such as Ym1 affecting the maintenance of mucosal homeostasis appears to be critical.

Epitranscriptomics, the study of post-transcriptional chemical base modifications of RNAs, has become a crucial area of research for understanding the complex interactions between viruses and their hosts. These RNA modifications significantly impact both viral and host RNA functions, influencing viral replication, transcription, translation, and immune evasion. The advancement of high-throughput technologies, such as mass spectrometry-based techniques and next-generation sequencing, has enabled researchers to investigate epitranscriptomic modifications and their roles in gene regulation in greater depth. Viral RNAs often carry various epitranscriptomic modifications that facilitate their stability and translation, enabling viruses to hijack the host environment, enhance replication, and evade immune defences. Conversely, host epitranscriptomic modifications can enhance antiviral responses by regulating gene expression and promoting the degradation of viral RNAs. This dual role underscores the complexity of virus-host dynamics, where epitranscriptomic modifications can be both beneficial and detrimental. This review aims to provide an overview of current knowledge on epitranscriptomic modifications in viral infections, focusing on their roles in viral replication and immune interactions, while considering their potential as targets for antiviral therapeutic intervention.

Background: The microbiome is fundamental in the host's immunobiology and dysbiosis leads to pathological conditions, potentially affecting parasitic diseases.

Objectives: To investigate how oral probiotics affect infection and antiparasitic treatment of Leishmania in macrophages.

Methods: Swiss mice were orally treated with 109 colony forming units (CFU) multi- or single-strain probiotic formulations (PB8, Bifilac), their peritoneal mouse macrophages (PMMs) were obtained and infected ex vivo with L. amazonensis amastigotes. The effects of prior probiotic administration on ex vivo infection and treatment responses to 1 µM miltefosine and N 6-methyltubercidin were evaluated. Flow cytometry measured the inflammatory mediator release in the supernatant of the PMMs.

Findings and main conclusions: PB8 or Bifilac administration significantly reduced (p < 0.05) ex vivo infection of PMMs from male mice by 27% and 12%, respectively. No gender-dependent effect of probiotics was observed. No improved antiparasitic activity of 1 µM miltefosine or N 6-methyltubercidin was observed in probiotic-treated PMMs. Ex vivo Leishmania infection stimulated tumour necrosis factor (TNF), MCP-1, and interleukin-6 (IL-6) production by PMMs (p < 0.05). A trend of increase was recorded with elevated levels of TNF and IL-6 in PB8-treated male groups (around 43 and 52%, respectively) but were not statistically significant. Collectively, probiotic treatment of mice influences Leishmania infection in PMMs. Clinical applications in leishmaniasis warrant further studies.

Background: Trypanosoma cruzi, causative agent of Chagas disease (CD), remains a public health problem in Latin America and is emerging in non-endemic areas. Phospholipids (PL) are essential components of biomembranes and their enzymatic modification by phospholipases yields bioactive lipids that modulate immune responses. Anti-PL antibodies have been associated with autoimmune diseases and inflammation, potentially influencing CD pathology by recognising PL and PL-binding proteins. T. cruzi Phospholipase A1 (TcPLA1) hydrolyses membrane PL and participates in parasite-host cell interactions.

Objectives: This study evaluated IgM and IgG antibody responses against phosphatidylcholine, phosphatidylethanolamine, and their derived lysophospholipids (LPL), as well as recombinant TcPLA1, during experimental T. cruzi infection with two strains: RA (high virulence) and K98 (low virulence). It also aimed to predict the recognition capacity of TcPLA1 by CD patients using in silico analysis.

Methods: Antibody responses were analysed by enzyme-linked immunosorbent assay (ELISA) using different PL and recombinant TcPLA1 as antigens. Lytic activity assays were performed to evaluate the functional impact of anti-PL antibodies. The CHAGASTOPE resource was used to predict TcPLA1 antigenicity.

Findings: This study identified IgM and IgG antibodies against PL, LPL and TcPLA1 during experimental T. cruzi infection. Different amino acid sequences of TcPLA1 showed stronger antigenic recognition by CD patient's sera.

Main conclusions: The presence of these antibodies suggests their involvement in the pathogenesis of CD and their potential as markers for disease monitoring and prognosis.

Background: Parasite antigens and plasma lipopolysaccharide (LPS) levels from luminal origin in visceral leishmaniasis (VL) patients are correlated with cellular activation and low CD4+T cell counts.

Objectives: Our aim was to verify whether Leishmania infantum infection damages the intestinal barrier and whether combination antimonial/antibiotic contributes to the reduction of LPS levels and immune activation.

Methods: Golden hamsters were grouped in: G1-uninfected; G2-infected with L. infantum; and G3/G4 and G5-infected, treated with antimonial, antibiotic or both drugs, respectively. The treatment initiated 45 days post infection (dpi), daily by 10 days.

Findings: G2, G3, and G4 animals showed a significant increase in spleen weight compared to G1. An elevated parasite load was observed in G2, unlike the G3, G4, and especially, G5, whose decrease was significant at 120 dpi. Intestinal mucosal alterations and elevated LPS levels were observed in G2 group. However, G3, G4 and G5 animals showed lower LPS levels than G2. Moreover, G4 and G5 presented higher CD4+T-cell percentages and lower activation levels than G2 and G3, either at 60 or 101-120 dpi.

Main conclusions: Our results showed evidence of bacterial translocation in experimental VL and that the concomitant use of antimonial and antibiotic may reduce LPS levels, along with an improvement of the immunosuppression and reduction of lymphocyte activation.

Background: The performance of serological tests for Trypanosoma cruzi diagnosis in Mexico has not included discordant control sera nor has it evaluated the role of immune response specificities, patient infection history or clinical status.

Objectives: The performance of commercial serological and molecular diagnostic tests and diagnostic algorithms was analysed in Mixtecan and Zapotecan ethnic populations having recent and long-term infection history.

Methods: An amplified global gold standard for T. cruzi infection included serological (≥ 2 conventional tests positive) and molecular (sequence identity of any of five genes using end point polymerase chain reaction (epPCR) or any positive using quantitative polymerase chain reaction (qPCR) diagnostic test results.

Findings: Only 81% of previously diagnosed untreated infections were reconfirmed using serology, while an additional 14% only using PCR. Serological diagnosis sensitivity (≥ 2 tests positive) in the primary diagnosis cohort was 8%, while specificity was 16%. Diagnosis sensitivity was similar using epPCR and qPCR only in primary diagnoses and all identified using the satellite (SAT) gene. The 18S ribosomal DNA identified T. cruzi and T. dionisii co-infections from Pacific coast sites.

Main conclusions: The current study provides evidence for inadequate diagnostic performance of conventional serological tests and the need to develop appropriate antigenic tools and use molecular testing of seronegatives to ascertain absence of infection.

Here, we review the key findings on the genetic characterisation of Berenice strains of Trypanosoma cruzi isolated from a 2-year-old child, Berenice, the first patient with Chagas disease described in the literature in 1909. Be-62 and Be-78 strains were isolated from Berenice when she was 55 and 71 years old, respectively. They were comparatively studied, revealing several important genetic differences that indicated the presence of heterogeneous T. cruzi populations within the infection of patient Berenice. Recently, a high-quality whole-genome assembly was generated using the strain Be-62, which was isolated in 1962. Even after decades-long persistence in the patient, there is a high level of conservation in synteny between Be-62 and different T. cruzi lineages. It has been suggested that T. cruzi diversity is driven by the evolution of multigene families encoding target antigens of anti-parasite immune responses, located in disruptive regions of the genome. Most studies of Berenice have been conducted on genomic bulk samples, resulting in a biased analysis that favours the dominant genotype. Single-cell omics technologies enable us to study the genetic diversity within an infection caused by protozoan parasites in detail. Sequencing individual genomes of Berenice strains will be the key to elucidating the population structure of individual infections, the dynamics of parasite populations, and adaptive mechanisms.