Memorias do Instituto Oswaldo Cruz最新文献

Free-living amoebas (FLA) are ubiquitous protists found in the environment. They have shown exceptional resistance to environmental challenges and play significant roles in controlling microbial populations through their predatory behaviour and microbicidal activity in both soil and aquatic ecosystems environments. However, although rare, a limited group of FLA can cause serious infections in the central nervous system and other diseases, particularly in immunocompromised individuals with high mortality rates. They can also cause keratitis in otherwise healthy individuals. This review offers a comprehensive overview of freshwater naked amoebae but does not cover all aspects in detail. Its goal is to provide a historical context for our current understanding while addressing the most critical elements of FLA biology, their pathogenic potential, and their interactions with important human pathogens.

Background: Chagas disease (CD) is a neglected tropical disease caused by Trypanosoma cruzi. The current drugs used to treat these diseases have limited efficacy and produce severe side effects. 4-aminoquinoline derivatives were shown to be a promising class of inhibitors of cysteine proteases cruzain and TbrCATL.

Objectives: To evaluate the trypanocidal activity of a new series of aminoquinolines as potential inhibitors of cruzain and TbrCATL.

Methods: Three aminoquinolines were synthesised and their in vitro activity was evaluated against cruzain and TbrCATL as well as against amastigotes and trypomastigotes forms of T. cruzi. In silico studies were also carried out to try to understand the experimental results.

Findings: Compound 5 showed promising activity against cruzain and TbrCATL, with better performance than E60, the reference drug. Compound 5 inhibited cruzain and TbrCATL at IC50 of 23 µM ±3 and 29 µM ±1, respectively, but this inhibition showed characteristics of promiscuous inhibition by colloidal aggregation. On the other hand, the compound 4 showed to be more promising activity against T. cruzi with IC50 2.57 µM ± 0.03 lower than the reference drug benznidazole 3.8 µM.

Main conclusions: The results of this study can guide new drug development for the treatment of trypanosomiasis.

Background: The neglected illness Chagas disease is treated with limited efficacy and adverse effects by old drugs. Due to the low interest of pharmaceutical industry in targeting economically depressed-patients, repurposing is a tool that should be applied because it can introduce new anti-Chagas entities into the clinic at reduced costs.

Objectives: To investigate the repurposing/combination of medicines strategies as anti-Chagas treatment.

Methods: Epimastigotes, trypomastigotes and amastigotes of Trypanosoma cruzi were in vitro exposed to 28 Uruguayan-approved medicines not previously tested, 28 FDA-approved medicines previously evaluated, and three reference agents. Parasite inhibition was assessed and for the best drugs, in pairs-isobolographic studies, looking for synergism/additivity/antagonism, were done. Macrophages were used to study selectivity. For some relevant agents, we analysed whether medicines mammals´ action mechanisms are operative in epimastigotes-T. cruzi.

Findings: From the anti-epimastigotes monotherapy-screening, we found that 18% of them showed better/comparable activities than references. Additionally, for the binary-combinations 8% were additive, 4% were synergic and the rest showed antagonism. Favourably, in macrophages-cytotoxicity four of the binary-combinations were antagonists. Naftazone and pinaverium bromide, not previously tested against T. cruzi, maintained their activity against trypomastigotes and amastigotes. The identified action mechanisms open the door to new strategies designing anti-T. cruzi drugs.

Main conclusions: Using approved-medicines is a good strategy for new anti-Chagas treatments.

Background: The nematode Angiostrongylus cantonensis, which is endemic to Southeast Asia and adjacent Pacific Islands, has already been recorded in more than 30 countries, including Brazil and other South American nations. It is one of the principal etiological agents of the zoonosis Eosinophilic Meningitis (EoM), which has a number of different species of terrestrial gastropods that act as its intermediate hosts.

Objective: The present study investigated the occurrence of the larvae of this nematode in specimens of terrestrial molluscs collected in half of the municipalities of the Brazilian State of Rio de Janeiro.

Methods: The study is based on the surveillance of this nematode in the Brazilian State of Rio de Janeiro, where terrestrial snails and slugs were collected in more than half of the state's municipalities (46 in all), and examined for parasitological infections. The nematode larvae retrieved from these specimens were identified based on their morphology and cytochrome oxidase I (COI) mitochondrial DNA sequences.

Findings: Angiostrongylid larvae were found in 230 (8.8%) of the 2,600 terrestrial molluscs examined, collected from 26 municipalities. Overall, 14 terrestrial gastropod species were identified, including both native and exotic taxa, and six were found to be infected naturally by A. cantonensis. The natural infection rates by Angiostrongylus in the different terrestrial molluscs species were 12.5% in Angustipes erinaceus, 9.7% in Achatina fulica, 6.8% in Bradybaena similaris, 6.3% in Sarasinula linguaeformis, 3.9% in Leptinaria unilamellata, and 4.6% in Subulina octona. A. fulica was the most frequent and extensively distributed species, with infected snails being found in 22 municipalities.

Main conclusions: The data from this first comprehensive survey of A. cantonensis in Rio de Janeiro highlights the potential epidemiological risk of human infection in this state. Mapping the spread of infected molluscs will also provide essential information for the evaluation of the risk of human infection, and should help local health authorities to provide a faster and more accurate diagnosis whenever neuroangiostrongyliasis is suspected.

Background: Non-O1 and non-O139 Vibrio cholerae (NOVC) that cause bacteraemia have attracted the attention of the public health community around the world, mainly due to the prospect of outbreaks and the way to treat such infections.

Objectives: To identify V. cholerae lineages and their antibiotic resistance and virulence factors associated with bacteraemia.

Methods: Vibrio cholerae genomes associated with strains isolated from blood were retrieved and subjected to core genome-based phylogenomic analysis with Roary. The virulome and resistome were searched with abricate using the VFDB and CARD databases.

Findings: Analysis showed that, in addition to V. cholerae, Vibrio paracholerae also causes bacteraemia. The NOVC group was highly diverse, although genomes from different countries were related. Most bacteraemic Vibrios came from countries not affected by epidemic/endemic cholera. The NOVCs virulome presented factors, such as type III and VI secretion systems, HapA, HlyA, RTX, and TLH. Importantly, no resistance to third-generation cephalosporin has been identified in the resistome of NOVCs.

Main conclusions: The presence of multiple NOVC lineages that cause bacteraemia in different parts of the world shows that there is no geographic and socioeconomic restriction for these cases. Therefore, healthcare systems need to be aware of this uncommon but deadly Vibrio infection.

Malaria, caused by Plasmodium spp., remains a major public health problem. Cerebral malaria is its deadliest form, with a 15-25% mortality rate, despite artemisinin-based treatments. In addition, the World Health Organization (WHO) strictly defines cerebral malaria as the presence of coma, 1 h after a seizure or the correction of hypoglycemia, in patients with P. falciparum parasitemia. Consequently, 25% of survivors experience neurocognitive and behavioral sequelae, particularly in children. However, more recently, neurocognitive and behavioral impairments were also reported in severe non-cerebral malaria, non-severe malaria, and even during asymptomatic Plasmodium infection. Such impairments have been observed in school-aged children, the elderly, and in animal models without classic cerebral malaria pathology. Additionally, mild vasogenic edema has been detected in neuroimaging of patients with severe non-cerebral and non-severe P. falciparum malaria. Therefore, given that approximately 98% of malaria cases in the world are non-severe, neurocognitive and behavioral sequelae may account for a significant proportion of global malaria morbidity. Taken together, these observations suggest that systemic inflammation from malaria, even without traditional cerebral malaria signs, can disrupt brain function and lead to long-term sequelae. We propose that the current definition of cerebral malaria may not fully capture the observed evidence and a new conceptualization is necessary to encompass these findings.

Diphtheria, a severe respiratory infection, was a major killer of children until the early years of the 20th century. Although diphtheria is now largely controlled globally thanks to vaccination, it is still endemic in some world regions and large epidemics can occur where vaccination coverage is insufficient. The pathological effects caused by its main virulence factor, diphtheria toxin, can be diminished by passive transfer of antibodies. Equine diphtheria antitoxin (eDAT), the cornerstone of treatment against toxinic complications of diphtheria, was invented more than 130 years ago, in 1890, and is still in use today. A method to concentrate anti-diphtheria antibodies from hyperimmune equine serum was described in the first issue of Memórias do Instituto Oswaldo Cruz in 1909. On this historic occasion, we present recent knowledge on taxonomic, epidemiological and clinical aspects of diphtheria agents that produce diphtheria toxin, and provide a historical perspective on eDAT treatment, adverse effects, threats on its scarce international supply, and current avenues for alternative therapeutic strategies.

Background: Bat-borne hantaviruses have been identified worldwide but little is known about neotropical bats in the megadiverse biomes of the American continent. Although serological evidence has hinted at hantavirus circulation in Brazil, the scarce number of genomic detection represents a gap to understand viral diversity, prevalence, and ecology of bat-borne hantaviruses.

Objective: We aim to investigate and evaluate the presence and prevalence of bat-borne hantavirus in the Brazilian Atlantic Forest.

Methods: Here in, 97 lung and kidney tissue samples from bats captured in the Brazilian Atlantic Rainforest were submitted to hantavirus-specific nested reverse transcription-polymerase chain reaction (RT-PCR) targeted the hantaviral L segment and metagenomic analysis.

Findings: Hantavirus RNA was detected in five tissue fragments of 20 Seba's short-tailed bats (Carollia perspicillata). Phylogenetic analysis, based on partial L-segment sequence using maximum likelihood method, demonstrated that the identified virus formed a monophyletic clade and a highly divergent bat-borne lineage comprising other recent strains found in the genus Carollia from South America.

Main conclusions: Our findings suggest the presence of a novel bat-borne hantavirus in Brazil, tentatively named Mamanguape virus (MGPV). Additional genomic data will help to extend our knowledge about the classification of MGPV within the Hantaviridae family and the evolution origins of new world bat-borne hantaviruses.

Background: Although blood transfusion is an essential therapeutic procedure, it can present risks, including transmitting infectious diseases, such as malaria. In Acre, the thick blood smear microscopic examination (TBS) is used to screen infected malaria blood donors. However, TBS has low sensitivity for detecting Plasmodium in situations of low parasitaemia, such as those presented by asymptomatic clinically healthy individuals.

Objectives: To investigate the pertinence of using polymerase chain reaction (PCR) to detect malarial infection for screening blood donors in Cruzeiro do Sul, Acre, an endemic high-risk malaria area in the Legal Amazon.

Methods: A cross-sectional study was conducted among individuals eligible and ineligible to be blood donors, according to clinical and epidemiological criteria. Besides the mandatory screening of HCV, HBV, and HIV tests, malaria PCR and TBS were also carried out on all blood donor candidates who attended the Cruzeiro do Sul Blood Centre from July to September 2022.

Findings: Of the 230 participants, 209 (91%) were eligible for blood donation by clinical-epidemiological screening. Surprisingly, no blood donor candidate reported a history of malaria. All TBS microscopic tests were negative at the time of recruitment. However, samples from four blood donor candidates (two eligible by clinical and epidemiological malaria criteria and two ineligible by hypertension and recent tattoo) were positive by Plasmodium and P. vivax molecular tests.

Main conclusions: Malaria molecular techniques for screening blood donors should be introduced in the Brazilian Blood Centres to maximise recipient safety. Furthermore, selecting zero-risk donors could pave the way to build a transmissible malaria-free environment in the blood bank context in the near future.

Background: Strigomonas culicis is a monoxenic trypanosomatid parasite of insects that naturally contains an endosymbiotic bacterium. The aposymbiotic strain can be obtained, making this strain a model for evolutive research about organelle origins. In addition, S. culicis contains homologues of virulence factors of pathogenic trypanosomatids, which functions are waiting for further analysis. In this sense, the publication of S. culicis proteome makes feasible additional investigations regarding the differential expression of peptidases from the wild-type (WT) and the aposymbiotic (APO) strains.

Objectives: Here, we analysed two proteomic data from S. culicis WT and APO strains screening for peptidases differentially expressed and assessed the differential expression of cysteine and metallopeptidases.

Methods: A comparative proteomic screening between WT and APO identified 43 modulated peptidases.

Findings: Cysteine and metallopeptidases, such as calpains and GP63, were the major classes, highlighting their significance. GP63 exhibited an increased proteolysis in a specific metallopeptidase substrate, an up-modulation gene expression in RT-PCR, and a higher protein identification by flow cytometry in the aposymbiotic strain. Notwithstanding, the wild-type strain showed enhanced cysteine peptidase activity.

Main conclusion: Our study highlighted the endosymbiont influence in S. culicis peptidase expression, with GP63 expression and activity raised in the aposymbiotic strain, whereas cysteine peptidase levels were reduced.