Memorias do Instituto Oswaldo Cruz最新文献

Background: Mosquito-disseminated pyriproxyfen (MD-PPF) is a promising novel tool for urban-mosquito control, yet resistance to PPF (a juvenile-hormone analogue) may arise in exposed mosquito populations. Alternative larvicide/pupicide molecules suitable for mosquito-driven dissemination, but with distinct modes of action, are therefore needed.

Objectives: To provide a proof-of-concept evaluation of mosquito-disseminated diflubenzuron (MD-DFB, a chitin-synthesis inhibitor) and spinosad (MD-SPN, a biological neurotoxin composite) as potential alternatives to MD-PPF.

Methods: We studied Aedes aegypti-driven dissemination in 20 blind, controlled experiments run in 110 × 90 × 30-cm cages. Of primary interest was whether and how (a) mosquito-driven dissemination affected adult-mosquito emergence (1705 larvae in 40 open and 20 closed cups set inside cages; generalised linear mixed models) and (b) exposure to larvicide/pupicide-treated dissemination stations affected adult-female lifespan (400 females released inside cages; proportional-hazards mixed models).

Findings: Adult-mosquito emergence was similar across treatments in closed cups. In open cups, average emergence fell from ~90% [95% confidence interval (CI), 84-95%] in control cages to ~30% (20-43%), ~56% (42-69%), and ~75% (63-85%) in, respectively, MD-PPF, MD-DFB, and MD-SPN cages. Exposure to SPN, but not to DFB or PPF, clearly reduced adult-female lifespan (SPN death-hazard ratio 2.4; 1.2-5.0).

Conclusion: Mosquito-disseminated diflubenzuron holds promise as a potential alternative to MD-PPF; further testing in field settings seems warranted.

Background: It is known that host sex can influence the immune response to administration of Mycobacterium bovis Bacillus Calmette-Guérin (BCG). However, the effect of BCG or BCG-derived vaccines cultured as biofilms on development of T cell responses in both sexes remains unclear.

Objectives: To compare the influence of sex and vaccine strain (BCG Pasteur vs. BCGΔBCG1419c) on ex vivo T cell responses against mycobacterial purified protein derivative (PPD) stimulation in lung and spleen cells of mice vaccinated with bacteria grown as biofilms.

Methods: Male and female BALB/c mice were subcutaneously vaccinated with disaggregated, biofilm-derived BCG Pasteur or BCGΔBCG1419c. Sixty days later, lung and spleen cells were collected and stimulated ex vivo with PPD. Flow cytometry was used to quantify frequencies of mono- and bi-functional CD4⁺ and CD8a⁺ T cells expressing interferon gamma (IFN-γ) and tumour necrosis factor alpha (TNF-α) or interleukin-2 (IL-2), as well as frequencies of tissue-resident memory CD4⁺ T cells.

Findings: Sex influenced T cell responses in both organs. Lungs of female mice vaccinated with BCGΔBCG1419c showed reduced frequencies of CD8a⁺ IFN-γ⁺, and reduced frequency of CD4⁺ IFN-γ⁺ in spleen, compared with males. On the other hand, female mice vaccinated with BCG produced higher IL-2+ and IL-2+TNF-α+ T cells in spleen than paired males. Vaccine strain alone had limited effects, but sex-strain interactions shaped distinct immune profiles.

Main conclusions: Sex modulates the immunogenicity of BCG-based vaccines grown as biofilms. Our results underscore the importance of considering host sex and vaccine preparation in tuberculosis preclinical research.

Malaria was one of the main research themes of Leônidas de Mello Deane (1914-1993) and Maria José von Paumgartten Deane (1916-1995), a couple of parasitologists - known among their peers as "the Deanes" - who in the late 1930s and 1940s ventured into areas of the Amazon, where the disease was endemic, and of the northeastern Brazil, where an important epidemic outbreak ecloded. Despite their knowledge of the disease and the adoption of preventive measures, both contracted malaria, he the malignant tertian fever (Plasmodium falciparum) and she the benign form of the disease (Plasmodium vivax). This article describes the circumstances in which they became infected and the evolution and outcome of their malaria. The years subsequent to the period in which they became ill witnessed extraordinary progress in the pharmacological treatment of malaria. The Deanes' two episodes of malaria are contextualised in relation to the treatment alternatives available at the time and the couple's suspicions regarding the development of resistance to existing antimalarial drugs in view of the persistence of recurrences of the disease despite treatment.

Chagas disease (CD), caused by Trypanosoma (Schizotrypanum) cruzi, remains a major global health concern, particularly in Latin America, where millions are at risk. To mark five decades of Chagas research, the Brazilian Society of Protozoology (SBPz) hosted a four-day conference held in Caxambu, Minas Gerais, Brazil, from November 3 to 7, 2024. The meeting brought together world-renowned experts from diverse disciplines whose work has significantly advanced the boundaries of CD studies. Key discussions focused on the parasite's genetic and metabolic adaptability, with special emphasis on genomic compartmentalisation, RNA processing, and metabolic flexibility essential for survival and pathogenesis. New insights into host-parasite interactions highlighted inflammatory and vascular remodelling processes that drive parasite dissemination and disease progression, especially in cardiac tissue. In the area of drug development, researchers noted treatment limitations, the urgency for novel therapeutic candidates, and ongoing clinical trials assessing alternative regimens of benznidazole (BZN) and nifurtimox (NFX). Progress in biomarker discovery and vaccine development was also discussed as pivotal to improving disease diagnosis, prognosis, and prevention. Beyond laboratory research, the meeting highlighted the importance of science communication and public health engagement. Outreach initiatives and educational exhibitions were showcased as tools to raise awareness and enhance access to disease diagnosis and treatment. Altogether the integration of multidisciplinary approaches from molecular biology to public policy underscores the enduring commitment to combating CD through research, collaboration, and innovation.

Background: The protozoan Trypanosoma cruzi causes Chagas disease (CD). There are two drugs available for the treatment with limited efficacy, especially in the later stage. Focusing on drug repurposing by virtual screening of chemical databases, butoconazole (BTZ) was identified as promising hit.

Objectives: Our aim was to explore the trypanosomicidal effect of BTZ alone or in combination with benznidazole (BZ) against T. cruzi.

Methods and findings: Our in vitro assays validated the low cytotoxicity of BTZ and high potency on amastigotes (EC50 = 0.07 μM), being 24-fold more potent than BZ. Washout assays demonstrated the sterilisation capacity of BTZ, whereas its combination with BZ gave an additive interaction (xƩFICI = 0.66). In a mouse model of acute T. cruzi infection, BTZ was unable to suppress parasitaemia but ensured the animal survival. BTZ plus BZ reduced parasitaemia and provided higher survival rates than monotherapies. However, quantitative polymerase chain reaction (qPCR) revealed that BTZ + BZ protocol gave 100% of lack of parasitological cure, as parasite satDNA was amplified in the heart of all surviving animals.

Main conclusions: Our dataset reinforces the relevance of drug repurposing and combination strategies to advance into the development of novel therapeutic approaches for CD.

Background: Streptococcus agalactiae is responsible for sepsis and meningitis, and the major cause of neonatal morbidity and mortality. However, how S. agalactiae disrupts endothelial barriers is poorly understood.

Objectives: Analyse the influence of endothelial cell (HUVECs) growth under static and shear stress conditions during infection with S. agalactiae, and the role of pilus PI-2b during endothelial barrier disruption and increased endothelial permeability.

Methods: HUVECs under static and shear conditions were infected by S. agalactiae (GBS90356 and GBS90356Δpilus2b) strains in the presence and absence of fibrinogen. VE-cadherin was evaluated by immunofluorescence and RT-PCR assays, and the endothelial permeability by transwell assay.

Finds: Shear stress induced the alignment of HUVECs and increased the adherence of S. agalactiae strains (GBS90356 and GBS90356Δpilus2b), mainly in the presence of fibrinogen, in addition to greater peripheral localisation of VE-cadherin. Rupture points and damage to endothelial integrity was visualised after infection with the GBS90356WT strain, mainly in the presence of fibrinogen. RT-PCR analyses identified increase in VE-cadherin expression in HUVECs under shear stress and a decrease in VE-cadherin after infection, with increased levels of endothelial permeability.

Main conclusion: Data demonstrate for the first time the dysfunction of the adhesive barrier induced by the S. agalactiae ST-17 strain, mainly in HUVECs under shear stress, where PI-2b expression was essential to optimise the damage to endothelial integrity.

Background: Norovirus is a major cause of acute gastroenteritis (AGE) outbreaks worldwide. On 1 August 2023, the health surveillance agency of Espírito Santo received a notification of a set cases of AGE from patients who attended an event organised by the Municipal Health Department. A local catering company provided lunch on 30 July (30 lunch boxes). The menu provided included macaroni, rice, tropeiro beans and cooked potatoes. The ingredients used in the preparation of tropeiro beans were beans, banana, cabbage, sausage and cassava flour. Diarrhoea, nausea, vomiting, abdominal pain, headache and weakness were the main reported symptoms peaking between 30 and 31 July.

Objectives: In the present study, we aimed to establish the agent responsible for a gastroenteritis outbreak during a lunch event in Espírito Santo State, Brazil.

Methods: Stool samples (n = 5) of AGE patients were analysed by real-time quantitative polymerase chain reaction (RT-qPCR) to detect rotavirus A (RVA) and norovirus GI/GII. For norovirus molecular characterisation an open reading frame (ORF)1-2 junction region was used.

Findings: All samples tested positive for norovirus GII, showing high viral loads. Rotavirus and norovirus GI were not detected in any of the samples. Norovirus sequencing identified a rare recombinant genotype GII.10[P16] as the cause of the outbreak. Norovirus sequences from specimens from five individuals shared 100% of nucleotide (nt) identity and had the highest nt similarity with a South Africa GII.10 strain detected in 2020.

Main conclusion: This is the first report of a rare GII.10[P16] recombinant norovirus strain in Brazil.

Background: Leishmaniasis, caused by the protozoan Leishmania, is a neglected tropical disease (NTD) with diverse clinical forms, the most common being cutaneous leishmaniasis (CL). Antileishmanial treatments rely on a small arsenal of chemoherapeutic agents, which are outdated, toxic, and increasingly ineffective due to drug resistance. New antileishmanial treatments and/or adjunctive therapies are warranted.

Objectives: Given the role of microbiota in modulating host immunity, we explored whether probiotics (PB8-multistrain probiotic blend, or Lactobacillus rhamnosus GG, LGG-single strain) alone or in combination with the reference drug miltefosine (ML) could improve clinical outcomes against Leishmania amazonensis infection in a BALB/c mouse model for CL.

Methods: Mice were administered probiotics [gavage, 109 colony-forming units (CFU)] for a 7-day pre-treatment before infection, followed by another 14-day probiotic treatment with ML co-administration. Paw lesions were measured using a digital calliper, and parasite loads were determined through lesion imprinting and quantitative polymerase chain reaction (qPCR). The potential immunoregulatory effects of probiotic administration on the mouse serum cytokine profiles were investigated via flow cytometry.

Findings and main conclusions: Probiotics alone reduced lesion size slightly, with PB8 achieving a 32% and LGG a 10% reduction at the endpoint (47-50 days post-infection, dpi). The combination of PB8 with a suboptimal ML dose (4 mg/kg/day) reduced the lesion size by 74% compared to the vehicle-treated mice, while ML alone achieved 53%. These findings were corroborated by amastigote quantification via imprinting (light microscopy) and qPCR: PB8 plus ML reduced parasite load by 76% and 87%, respectively. Multiplex cytokine analysis [interferon (IFN)-γ, interleukin (IL)-6, IL-10, IL-12p70, tumour necrosis factor (TNF) and chemokine CCL2] showed reduced serum CCL2 in PB8-cotreated groups. This suggests that PB8 could modulate serum cytokine levels to mitigate the risk of excessive inflammation, as elevated CCL2 is linked to disease exacerbation through monocyte recruitment. Our findings demonstrate the potential effect of probiotic administration to enhance antileishmanial efficacy of antiparasitic drugs.

Background: Mycobacterium brisbanense is a rare nontuberculous mycobacteria and was for the first time detected in the Americas in humans. However, this, like several other species of mycobacteria, may be underreported worldwide. Therefore, their study is increasingly important.

Objectives: The aim of this article is to report and analyse the first seven human isolates of M. brisbanense in the Americas, derived from six Brazilian patients.

Methods: We sequenced the genes hsp65, rpoB and 16s rRNA, of seven mycobacterial clinical isolates, constructed a phylogenetic tree, and determined their drug susceptibility profile.

Findings: The regions sequenced were highly similar between the M. brisbanense type strain and the Brazilian strains. Similarly, their susceptibility profiles were similar to that of M. brisbanense type strain, except for two antibiotics tested, cefoxitin and doxycycline.

Main conclusions: All studied strains were identified at the species level by a concatenated tree as M. brisbanense.

Background: Chagas disease (CD) caused by Trypanosoma cruzi has limited therapy. Probiotics sustain healthy microbiota, playing roles in biological events.

Objectives: Our aim was to determine the impact of probiotics on T. cruzi infection in vitro and in mouse acute experimental models.

Methods: The multi strain - PB8 and the Lactobacillus rhamnosus (LR) were orally administered [106-109 colony-forming units (CFU)] for seven days prior to mice infection followed for 14 daily administrations. Peritoneal mouse macrophages (PMM) were obtained from mice treated with 109 probiotics one day before collection and infected in vitro with or not benznidazole (BZ).

Findings: LR and PB8 reduced by 44-87% and 23-16% the parasitaemia peak in male and female mice, respectively, but did not protect against mortality. Histopathology showed mild reduction in cardiac nests due to probiotics' administration. PB8 and LR suppressed the parasite infection of PMM by 24 and 26%, reaching 65 and 42% of declines, respectively when 3% thioglycolate was performed. PB8 increased BZ activity at 1 µM, reaching 40% of parasitism' declines compared to BZ alone (25%). No gender difference was noticed during probiotic in vivo administration.

Main conclusions: The results point to the potential of a combined therapeutic approach for CD, using probiotics and BZ.