Memorias Do Instituto Oswaldo Cruz[JOURNAL]
Sun
200 papers
Novel epitope-based diagnostic probes selected by phage display for the serological detection of HDV.
Costa MA, de Souza RC, Roca TP … +17 more , Araújo A, de Souza LFA, Souza RB, Sabatini R, Andrade BS, Soares IP, Caixeta DC, Guevara-Vega M, Lima IMS, Passos-Silva AM, Martins MM, Rayashi AD, da Matta DA, Vieira D, Goulart LR, Sabino-Silva R, Santos FAA
Mem Inst Oswaldo Cruz · 2026 · PMID 42307405 · Full text
BACKGROUND: Hepatitis delta virus (HDV) is associated with the worst prognosis among viral hepatitis infections; however, it remains largely underdiagnosed, particularly in endemic developing regions, underscoring the ne...
BACKGROUND: Hepatitis delta virus (HDV) is associated with the worst prognosis among viral hepatitis infections; however, it remains largely underdiagnosed, particularly in endemic developing regions, underscoring the need for new, accessible serological methods for large-scale screening. OBJECTIVES: To develop HDV-mimetic molecules using phage display for application in immunodiagnostic platforms. METHODS: HDV-mimetic peptides were selected via phage display biopanning, sequenced and screened by phage-enzyme-linked immunosorbent assay (ELISA). Based on the sequences of these peptides, a recombinant protein (rHDV) was constructed and employed in an ELISA. The test was validated using 87 anti-HDV-positive samples and 93 hepatitis B virus (HBV) control samples collected from a public diagnostic laboratory in the Amazon region. Statistical analyses were performed to evaluate the diagnostic performance of the synthetic peptides and the recombinant protein. FINDINGS: Overall, rHDV exhibits a sensitivity of 74.71%, specificity of 97.85%, and area under the curve (AUC) of 0.8906. In HDV ribonucleic acid (HDV RNA)-positive patients, diagnostic performance improved, with a sensitivity of 88.0%, specificity of 98.92%, and AUC of 0.96. MAIN CONCLUSIONS: These findings highlight that the rHDV protein used in ELISA effectively discriminated HDV-infected individuals from patients monoinfected with hepatitis B. This demonstrates the potential of rHDV as an effective, rapid, and low-cost tool for HDV detection for broader HDV screening.
Coexistence of monogamy and polygyny in Triatoma infestans: fine-scale genealogical structure reveals complex social structures within domestic colonies in the Bolivian Chaco.
Cornejo Pinto AJ, Sánchez R, Lardeux F
Mem Inst Oswaldo Cruz · 2026 · PMID 42307292 · Full text
BACKGROUND: Persistent reinfestation of Triatoma infestans in the Gran Chaco undermines Chagas disease (CD) control. While insecticide resistance is a known factor, the fine-scale social and demographic structure of vect...
BACKGROUND: Persistent reinfestation of Triatoma infestans in the Gran Chaco undermines Chagas disease (CD) control. While insecticide resistance is a known factor, the fine-scale social and demographic structure of vector colonies remains poorly understood. OBJECTIVES: To analyse the micro-geographic genetic structure, mating systems, and demographic history of T. infestans in a rural community in the Bolivian Chaco. METHODS: We genotyped 381 individuals from three neighbouring structures (domiciliary and peridomestic) using eight highly polymorphic microsatellite loci (expected heterozygosity, HE = 0.675). Genealogical relationships were reconstructed using maximum likelihood (ML) analysis (COLONY), and demographic history was inferred through heterozygosity tests. FINDINGS: The infestation comprised 42 distinct full-sibling families nested within a single colony. We observed a stark dichotomy: two dominant families (> 80 individuals) exhibited monogamy and signs of distinct demographic histories (one in expansion, one recovering from a bottleneck), while 40 minor families showed high promiscuity (polygyny/polyandry). Finite growth rates varied significantly (λ = 1.03 vs 1.22), evidencing active intra-colonial competition. MAIN CONCLUSIONS: Domestic populations are not random aggregates, but complex mosaics of coexisting lineages with different adaptive strategies. The dominance of monogamous families suggests a priority effect advantage, while the "tail" of promiscuous minor families represents a cryptic reservoir. Effective control must account for this structural resilience, as surviving minor lineages could rapidly recolonise the niche.
Evaluation of a new rapid diagnostic test, based on the chimeric protein Q5, for the diagnosis of human and canine forms of visceral leishmaniasis.
Dos Santos WJT, Nadaes NR, Dutra AKO … +16 more , da Silva A, da Silva HRF, de Castro Neto AL, de Lorena VMB, Pereira VRA, Pereira AMS, de Brito MEF, Cavalcanti MP, Medeiros ZM, Pussi KF, Neitzke-Abreu HC, de Lima VMF, Costa CHN, Dos Santos KGAF, da Silva ED, de Melo Neto OP
Mem Inst Oswaldo Cruz · 2026 · PMID 42207130 · Full text
BACKGROUND: Visceral leishmaniasis (VL), caused by Leishmania infantum, is the most severe form of leishmaniasis, prevalent in many countries, but still with limitations in diagnosis for both human and canine hosts. Sero...
BACKGROUND: Visceral leishmaniasis (VL), caused by Leishmania infantum, is the most severe form of leishmaniasis, prevalent in many countries, but still with limitations in diagnosis for both human and canine hosts. Serological assays based on recombinant proteins are the most efficient diagnostic alternatives, with the rapid diagnostic test (RDT) being the most cost-effective. The previously described chimeric Q5 is a recombinant protein derived from three native L. infantum antigens, which is potentially useful for both human and canine VL diagnosis, through preliminary enzyme-linked immunosorbent assay (ELISA), but which was not evaluated within an RDT setting. OBJECTIVES: To evaluate the diagnostic performance of the chimeric recombinant protein Q5 in both ELISA and RDT formats for the detection of human and canine VL, and to compare its performance with RDTs based on Lci2 and Lci13 antigens. METHODS: Here, we first expanded the Q5 evaluation through ELISA with a larger set of human and canine VL-positive sera from multiple origins. We confirmed a sensitivity ranging between 80% and 90% for the human VL and greater than 90% with the canine VL sera. A new RDT-Q5 was then set up and tested with multiple batches of human and canine sera. FINDINGS: An improved performance was seen for the human VL diagnosis (94% sensitivity), but it was reduced with canine sera (86% sensitivity). Specificity values for both the ELISA-Q5 and RDT-Q5 were generally greater than 95%, with limited (8%) or no false-positive results with human sera from individuals with cutaneous leishmaniasis (CL) and Chagas disease (CD), respectively. The RDT-Q5 performance was compared with RDTs based on two other recombinant proteins, Lci2 and Lci13, tested respectively for the human and canine VL diagnosis. MAIN CONCLUSIONS: Despite an equivalent performance for the human VL diagnosis, the RDT-Lci2 led to a much greater incidence of false-positive results with the CL and CD sera. In contrast, no setup for the RDT-Lci13 was effective with the canine sera. Our results confirm the RDT-Q5 as an efficient alternative for the VL diagnosis in the field, particularly for the human form of the disease.
Five times a quarter of a century at Instituto Oswaldo Cruz.
Brandão AA
Mem Inst Oswaldo Cruz · 2026 · PMID 42207087 · Full text
The pathway of Instituto Oswaldo Cruz (IOC) runs parallel with the astonishing series of events in the 20th century, which might be viewed as a dispute between hope and ideological belief. As a centennial organisation th...
The pathway of Instituto Oswaldo Cruz (IOC) runs parallel with the astonishing series of events in the 20th century, which might be viewed as a dispute between hope and ideological belief. As a centennial organisation the IOC has witnessed the same set of events and perhaps experienced some of them, but in most cases, it has been unable to influence or deter them. Since its beginnings the IOC has been engaged in addressing public health challenges and either by serendipitous findings or by the scientific inquiry it has brought some Res Novae and ignited sparks of hope that one day most of the infectious diseases that proliferate in Brazil might be controlled. In this perspective essay to introduce the series of articles in celebration of the 125th Anniversary of the IOC I will sketch an overview of its journey in the context of some 20th century events through a quarter of a century time frame.
Aedes aegypti salivary gland extract enhances Zika virus replication through immune modulation.
Hilario G, Dorneles GP, Freitas DN … +9 more , Silva OSD, Prophiro JS, Fazolo T, Machado RRG, Bonorino C, Oliveira DBL, Fonseca SGD, Romão PRT, Rodrigues LC
Mem Inst Oswaldo Cruz · 2026 · PMID 42090697 · Full text
BACKGROUND: Mosquito saliva contains bioactive molecules that modulate host immunity and may influence arboviral infection. The contribution of Aedes aegypti salivary gland extract (SGE) to viral replication and immune r...
BACKGROUND: Mosquito saliva contains bioactive molecules that modulate host immunity and may influence arboviral infection. The contribution of Aedes aegypti salivary gland extract (SGE) to viral replication and immune regulation during Zika virus (ZIKV) infection remains poorly understood. OBJECTIVES: To investigate the immunomodulatory effects of Ae. aegypti SGE during ZIKV infection. METHODS: Peripheral blood mononuclear cells (PBMCs) and murine antigen-presenting cell lines were exposed to ZIKV with or without SGE. Viral replication was measured by quantitative polymerase chain reaction (qPCR), cell death and immune subsets by flow cytometry, oxidative stress markers by biochemical assays, and cytokine production by enzyme-linked immunosorbent assay (ELISA). FINDINGS: SGE enhanced ZIKV replication, particularly in PBMCs, with increased RNA copies (median Δ = +1,779), reduced late apoptosis of CD4⁺ T cells (p = 0.0055), dendritic cell death (p < 0.01), and impaired T-cell proliferation. SGE attenuated ZIKV-induced oxidative damage by restoring glutathione levels, reducing lipid and protein oxidation (p < 0.001), and increasing nitric oxide (NO) production. Cytokine profiling revealed suppression of interferon-y (IFN-γ) (p < 0.001) and induction of interleukin-4 (IL-4) (p < 0.0001), indicating a Th2-skewed response. Murine cell lines confirmed SGE-driven cytokine modulation. MAIN CONCLUSIONS: Ae. aegypti SGE alters host immune homeostasis, favouring ZIKV infection by weakening antiviral defences and redirecting immune and redox pathways, thereby facilitating viral expansion.
Beyond Leishmania: hidden trypanosomatid diversity reveals complex parasite-sand fly networks in southeastern Brazil.
Isnard AP, Madureira ACC, Carvalho GML … +5 more , Freire ML, Avelar DM, Diotaiuti LG, Andrade Filho JD, Dutra-Rêgo F
Mem Inst Oswaldo Cruz · 2026 · PMID 42090696 · Full text
BACKGROUND: Sand flies (Diptera: Psychodidae) are well-known vectors of Leishmania, yet their associations with other trypanosomatids remain poorly understood. Expanding knowledge on these interactions is essential to el...
BACKGROUND: Sand flies (Diptera: Psychodidae) are well-known vectors of Leishmania, yet their associations with other trypanosomatids remain poorly understood. Expanding knowledge on these interactions is essential to elucidate the ecological diversity of parasites circulating in natural and periurban environments. OBJECTIVE: To characterise sand fly species composition and assess the diversity of trypanosomatids naturally infecting sand flies in the Serra do Cipó district, Minas Gerais, Brazil. METHODS: Sand flies were collected between 2023 and 2025 in the Mata da Tapera and nine surrounding peridomestic sites using Centre for Disease Control light trap (CDC-LT) and a Shannon trap. Females were examined by midgut dissection and screened individually for trypanosomatids using nested polymerase chain reaction (PCR) targeting the 18S rRNA V7-V8 region, followed by sequencing and phylogenetic analyses. FINDINGS: A total of 1,460 sand flies representing 21 species were collected, with Pintomyia pessoai (35.5%) being the most abundant. No flagellates were observed in 105 dissected females. Molecular screening of 730 females revealed 12 positives (overall positivity = 1.6%), including Leishmania infantum in Pi. pessoai, Pi. christenseni, and Pa. barretoi; L. braziliensis in Pi. monticola; and non-Leishmania taxa such as Herpetomonas samuelpessoai, Novymonas esmeraldas, a representative of Strigomonadinae, Trypanosoma sp. (Anura clade), and a lineage related to Sergeia. MAIN CONCLUSION: These findings confirm the circulation of Leishmania in Serra do Cipó while revealing hidden trypanosomatid diversity spanning at least five genera. The results suggest that sand flies may act as ecological "hubs", transiently interacting with multiple parasite lineages beyond the classical Leishmania cycle, highlighting the need to broaden the ecological perspective in sand fly-parasite studies.
A non-destructive image-based approach to quantify blood meal size in Lutzomyia longipalpis (Diptera: Psychodidae).
Costa LMD, Sant'Anna MRV, Generoso LA … +5 more , Cruz GPD, Pessoa GCD, Araujo RN, Gontijo NF, Pereira MH
Mem Inst Oswaldo Cruz · 2026 · PMID 42090695 · Full text
BACKGROUND: Phlebotomine sand flies are hematophagous vectors of major human pathogens, including Leishmania spp., with blood ingestion essential for reproduction and vector competence. Accurate quantification of blood m...
BACKGROUND: Phlebotomine sand flies are hematophagous vectors of major human pathogens, including Leishmania spp., with blood ingestion essential for reproduction and vector competence. Accurate quantification of blood meal volume is crucial for understanding physiological processes and transmission dynamics. OBJECTIVES: Here, we introduce a novel, non-destructive image-based method to estimate blood intake in Lutzomyia longipalpis, the principal vector of Leishmania infantum in the Americas. METHODS: High-resolution images of unfed and blood-fed females were analysed using Fiji ImageJ (open-source software) when several morphometric parameters were measured and validated against biochemical haemoglobin (Hb) quantification. FINDINGS: Blood-fed females exhibited a 56.6% increase in abdominal width and a shift toward a rounded body shape, which was strongly correlated with a visible transilluminated abdominal area (R² = 0.92). Some parameters, such as mean grey value and abdominal length, showed a low to moderate correlation with Hb content (R < 0.60). However, the correlation with abdominal area and width was R ≈ 0.90, indicating those are reliable parameters that can be used to estimate blood intake by Lu. longipalpis females. MAIN CONCLUSIONS: Unlike spectrophotometric methods, this approach preserves specimen integrity, which, in theory, enables longitudinal studies on physiology and host-parasite interactions. This methodology offers a reliable, scalable, and cost-effective alternative for estimating blood meal.
Mitochondrial genome refinement and comparative phylogenetics of Parastrongyloides trichosuri (KNP strain; Nematoda: Strongyloididae) from South Africa.
Cho K, Kim M, Park JW … +2 more , Choi YK, Yoo WG
Mem Inst Oswaldo Cruz · 2026 · PMID 42054167 · Full text
BACKGROUND: Parastrongyloides trichosuri Mackerras, 1959 (Nematoda: Strongyloididae) is a facultatively parasitic nematode infecting the common brushtail possum. A previously reported mitochondrial genome (mitogenome) fr...
BACKGROUND: Parastrongyloides trichosuri Mackerras, 1959 (Nematoda: Strongyloididae) is a facultatively parasitic nematode infecting the common brushtail possum. A previously reported mitochondrial genome (mitogenome) from a Kruger National Park (KNP) isolate (GenBank: NC_028620) is incomplete, lacking the nad3 gene and the noncoding region (NCR), limiting its utility for comparative and phylogenetic studies. OBJECTIVES: This study aimed to reconstruct, annotate, and validate a complete mitogenome of P. trichosuri (KNP strain) to enhance genomic accuracy and phylogenetic resolution within Strongyloididae. METHODS: Whole-genome sequencing data (SRA: ERS056619) were reanalysed. Missing genes, including tRNA-Glu and atp6, were manually curated using BLASTn searches against Rfam v15, while cox3 and nad3 were confirmed through transmembrane topology analysis. FINDINGS: The reconstructed mitogenome was 13,809 bp long, comprising 12 protein-coding genes, 22 tRNAs, 2 rRNAs, and a 539-bp tandem-repeat NCR. Gene order and structure were consistent with other Strongyloididae mitogenomes. Phylogenetic analysis supported P. trichosuri as a distinct lineage within the family. The annotated sequence has been deposited in the Third Party Annotation database in GenBank (accession No. BK075097). MAIN CONCLUSIONS: This improved mitogenome fills an existing genomic gaps and provides a reliable reference for future comparative, phylogenetic, and evolutionary studies of Strongyloididae.
Immunoinformatic analysis for identifying immunogenic antigens from the complete proteome of Giardia lamblia.
Ortega-Tirado D, Velazquez-Valdez CA, Garzon T … +3 more , Bracamontes-Picos L, Lopez-Romero G, Velazquez C
Mem Inst Oswaldo Cruz · 2026 · PMID 42018797 · Full text
BACKGROUND: Giardia lamblia is a parasite that infects humans. To date, there is no vaccine available for human giardiasis. Thus, discovering new immunogenic antigens is crucial for the rational design of a vaccine. OBJE...
BACKGROUND: Giardia lamblia is a parasite that infects humans. To date, there is no vaccine available for human giardiasis. Thus, discovering new immunogenic antigens is crucial for the rational design of a vaccine. OBJECTIVES: This study aimed to identify the main immunogenic antigens of G. lamblia from its entire proteome using immunoinformatic and data science techniques. To our knowledge, this is the first study to systematically identify immunogenic antigens of G. lamblia across its complete proteome, providing a comprehensive map of potential immunogenic antigens. METHODS: Briefly, FASTA sequences of G. lamblia isolates WB and GS were submitted to the NetMHCII 2.3 predictor. The analysis was conducted for five murine major histocompatibility complex (MHC)-II molecules: I-Ab, I-Ad, I-Ed, I-Ak, and I-Ek. Python 3.9 was used to develop custom code for data processing and analysis. FINDINGS: We identified 414 potential immunogenic polypeptides for isolate WB and 350 for isolate GS. For both isolates, most polypeptides contained peptides with high affinity for I-Ab and I-Ek. Notably, no polypeptides with high affinity for I-Ak were detected. Homologous potential immunogenic antigens (129 polypeptides) were identified in both isolates. The analysis revealed that 12 potential immunogenic polypeptides from isolate WB and 10 from isolate GS are part of the Giardia secretome. Additionally, promiscuous polypeptides that bind to at least two different MHC-II molecules were found in both isolates. MAIN CONCLUSIONS: These findings lay a valuable foundation for the rational development of a vaccine against human giardiasis and show a computational strategy that can be applied to the study of other pathogens.
Coxiella burnetii in free-living feral pigs (Sus scrofa) in Brazil.
Fernandes J, Santos WGD, Assis MRDS … +7 more , Brandão ML, Oliveira MB, Barreira JD, Freitas DES, Cordeiro JLP, Oliveira LFB, Lemos ERS
Mem Inst Oswaldo Cruz · 2026 · PMID 42018786 · Full text
BACKGROUND: Coxiella burnetii, the etiological agent of coxiellosis in animals and Q fever in humans, is a zoonotic pathogen of global relevance that can infect a wide range of species. Although several domestic and wild...
BACKGROUND: Coxiella burnetii, the etiological agent of coxiellosis in animals and Q fever in humans, is a zoonotic pathogen of global relevance that can infect a wide range of species. Although several domestic and wild animals are involved in the natural cycle, the role of wildlife hosts remains poorly understood. OBJECTIVES: Our study aimed to investigate the presence of C. burnetii in feral pigs hunted in Brazilian Pantanal wetland. METHODS: In this study, 36 free-living feral pigs legally hunted in Mato Grosso State, Brazil, were sampled. Sera were tested by enzyme-linked immunosorbent assay (ELISA), and spleen, liver, sera and tick samples were analysed by polymerase chain reaction (PCR). FINDINGS: Serological evidence of exposure was detected in 22.2% [8/36; 95% confidence interval (CI): 11.7% - 38.1%], while C. burnetii DNA was found in one spleen sample (1/36 - 2.8%; 95% CI: 0.1% - 14.5%). Only Coxiella-like endosymbiont was detected in Amblyomma sculptum ticks (9/23 - 39.13%; 95% CI: 22.2% - 59.2%). MAIN CONCLUSIONS: These results represent the first detection of C. burnetii in free-living feral pigs in Brazil and suggest potential exposure of this invasive mammal species to the pathogen. The findings underscore the need for broader surveillance of C. burnetii at the wildlife-livestock-human interface in Brazil.
Retinal pigment epithelium drives macrophage migration during Toxoplasma gondii infection in vitro.
Nasaré AM, Tedesco RC, Waziry PAF … +5 more , Pantaleon LP, Ricci EL, Leoni LAB, Fukushima AR, Galisteo Junior AJ
Mem Inst Oswaldo Cruz · 2026 · PMID 41983790 · Full text
BACKGROUND: Ocular toxoplasmosis is a leading cause of infectious posterior uveitis worldwide. The retinal pigment epithelium (RPE), a key barrier and immunomodulatory layer in the eye, is directly targeted by Toxoplasma...
BACKGROUND: Ocular toxoplasmosis is a leading cause of infectious posterior uveitis worldwide. The retinal pigment epithelium (RPE), a key barrier and immunomodulatory layer in the eye, is directly targeted by Toxoplasma gondii during infection. However, its role in orchestrating the local immune response remains unclear. OBJECTIVES: To investigate whether RPE cells actively drive macrophage migration during T. gondii infection in vitro, and to identify associated cytokine profiles. METHODS: Adult retinal pigment epithelial cells (ARPE)-19 and primary RPE cells were exposed to tachyzoites, soluble antigens or conditioned supernatants. Macrophage migration was assessed using Transwell® and under-agar assays. Cytokines were quantified by cytometric bead array. FINDINGS: Both ARPE-19 and primary RPE exhibited chemotaxis toward parasite antigens (0.12 - 0.5 μg), and enhanced interleukin-6 (IL-6), IL-10 and tumor necrosis factor-α (TNF-α) secretion. Co-culture with RAW 264.7 macrophages further amplified cytokine production. Primary RPE from infected animals occluded 90% of Transwell® pores within 24h. IL-6 and IL-10 levels strongly correlated with migratory activity (r = 0.82 and 0.77, respectively). MAIN CONCLUSIONS: RPE cells are not passive targets but active participants in the ocular immune response to T. gondii. By secreting IL-6 and IL-10, they establish a chemotactic environment that recruits macrophages. These insights identify the RPE-cytokine-macrophage axis as a potential therapeutic target in ocular toxoplasmosis.
Sustained Oropouche virus transmission in Rio de Janeiro's Atlantic Forest: genomic evidence over a two-year period.
Arantes I, Bruycker-Nogueira F, Oliveira C … +24 more , Sequeira PC, Lupi O, Borges M, Melo CL, Brendolin M, Braga A, Velasque LS, Cavalcanti AC, Camargo AC, Costa FBD, Moreira CGC, Dias VZ, Sousa TJ, Gatti FD, Mendonça GC, Nodari JZ, Ribeiro-Rodrigues R, Delatorre E, Calvet G, Naveca FG, Brasil P, Filippis AMB, Bello G, OROV-Rio de Janeiro Outbreak Response Working Group
Mem Inst Oswaldo Cruz · 2026 · PMID 41919903 · Full text
BACKGROUND: Oropouche virus (OROV), an arbovirus endemic to the Amazon region, has recently expanded into non-endemic areas including Rio de Janeiro State, Brazil. OBJECTIVE: To characterise the spatio-temporal dynamics...
BACKGROUND: Oropouche virus (OROV), an arbovirus endemic to the Amazon region, has recently expanded into non-endemic areas including Rio de Janeiro State, Brazil. OBJECTIVE: To characterise the spatio-temporal dynamics and ecological factors associated with OROV transmission in Rio de Janeiro during 2024-2025. METHODS: We analysed OROV case-associated ecological factors and performed a phylodynamic analysis on 40 viral genomes, comprising 35 new and five published sequences, sampled from 15 municipalities across the state during 2024-2025. FINDINGS: OROV cases showed significant positive correlations with forest area (r = 0.50, p < 0.0001), banana harvest area (r = 0.39, p < 0.01), and cassava harvest area (r = 0.29, p < 0.05); but these factors were autocorrelated, suggesting a confounded relationship. We identified two OROV sub-clades circulating in the Rio de Janeiro State. The OROVRJ/ES sub-clade was likely introduced into the Southern Fluminense region around January 2024, spread primarily by short (> 2 km, 50% of events) and mid-distance movements (2-9 km; 30%) with a mean dispersal rate of 0.3 km/day, and seed outbreaks in Metropolitan and Northwest Fluminense regions in 2025. The OROVES-I clade was likely introduced into Central Fluminense and Coastal Lowlands regions, later spreading to the Northern Fluminense region. MAIN CONCLUSIONS: Following its introduction in early 2024, OROV persisted in Rio de Janeiro State by spreading through short-distance movements among municipalities with high forest cover and agricultural areas. The sustained multi-year OROV transmission in the Atlantic Forest biome highlights the potential for establishment of endemic cycles beyond the Amazon region and the need for enhanced surveillance in extra-Amazonian areas, where OROV will evolve in a different ecosystem.
The complexity of the population dynamics of Triatoma brasiliensis in rural north-east Brazil indicated by genetic characterisation.
Silva LOR, Belisário CJ, Ferreira FC … +3 more , Heukelbach J, Diotaiuti L, Bezerra CM
Mem Inst Oswaldo Cruz · 2026 · PMID 41919902 · Full text
BACKGROUND: Triatoma brasiliensis, the primary Chagas disease (CD) vector in the north-east of Brazil, poses a significant challenge for control due to its adaptability and ability to colonise anthropic environments. The...
BACKGROUND: Triatoma brasiliensis, the primary Chagas disease (CD) vector in the north-east of Brazil, poses a significant challenge for control due to its adaptability and ability to colonise anthropic environments. The limited number of previous studies on the population dynamics of T. brasiliensis hinders the development of effective control strategies. OBJECTIVES: This study characterises the genetic variability of T. brasiliensis populations in Jaguaruana using microsatellite markers, in order to understand the population processes of triatomine infestation and reinfestation. METHODS: We analysed the genetic structure of 229 T. brasiliensis specimens collected in the municipality of Jaguaruana in the north-east Brazilian State of Ceará using microsatellite markers. FINDINGS: Hardy-Weinberg disequilibrium prevailed, with substantial genetic variability (67.2%) among individuals and inbreeding, but genetic differentiation lacked correlation with geographical distance (Mantel's test). MAIN CONCLUSIONS: The complex population dynamics in Jaguaruana revealed diverse sources of anthropogenic colonisation, impacting regional control. This study underscores the necessity of comprehending intricate infestation processes for planning effective vector surveillance and control strategies.
Giardia duodenalis assemblage A: new genotype in non-human primates from the Brazilian Amazon region revealed by high-resolution MLST.
Dos Reis LL, de Souza LSS, Antunes MGR … +2 more , Nava AFD, Vicente ACP
Mem Inst Oswaldo Cruz · 2026 · PMID 41880478 · Publisher ↗
BACKGROUND: Giardia duodenalis is an intestinal protozoan parasite that infects a wide range of vertebrate hosts, including humans, and is the etiological agent of giardiasis. Within this species, assemblage A is further...
BACKGROUND: Giardia duodenalis is an intestinal protozoan parasite that infects a wide range of vertebrate hosts, including humans, and is the etiological agent of giardiasis. Within this species, assemblage A is further subdivided into three sub-assemblages: AI, AII, and AIII. OBJECTIVES: To apply the high-resolution multilocus sequence typing (MLST) to perform molecular epidemiology of G. duodenalis assemblage A in humans and animals in the State of Amazonas, Brazil. METHODS: We performed parasitological analyses of faecal samples from animals and collected Giardia-positive samples from humans in the State of Amazonas, Brazil. Giardia genotyping was carried out using an MLST scheme based on six genes (CID1, NEK15411, DIS3, HCMP22547, HCMP6372, RHP26), as well as the three conventional loci (tpi, bg and gdh), followed by phylogenetic analysis. FINDINGS: Using an extended MLST scheme for assemblage A, we identified a new genotype infecting two non-human primate (NHP) species from the Amazon region. Additionally, Giardia from sub-assemblage AII infecting humans in this region shows a close phylogenetic relationship with isolates from other countries. Furthermore, a sub-assemblage AI isolate from an anteater (Tamandua tetradactyla) belongs to a lineage infecting diverse animals and humans, highlighting its zoonotic and cosmopolitan nature. MAIN CONCLUSIONS: These findings reveal a new, genetically distinct lineage within G. duodenalis assemblage A, likely representing a new sub-assemblage (AIV) associated with NHPs in the Amazon region, and reinforce the usefulness of high-resolution MLST for detecting fine-scale genetic diversity and potential zoonotic transmission pathways.
Effects of exposure to Rickettsia bellii on reservoir competence of guinea pigs for Rickettsia rickettsii.
Binder LC, Fanchini CEC, Soares HS … +7 more , Santos TBSD, Taniwaki SA, Nassar MB, Fogaça AC, Serpa MCA, Martins MP, Labruna MB
Mem Inst Oswaldo Cruz · 2026 · PMID 41880477 · Full text
BACKGROUND: Amblyomma sculptum is the main vector implicated in the transmission of Rickettsia rickettsii in southeastern Brazil, where capybaras are known to be the main amplifying hosts of this pathogen. Interestingly,...
BACKGROUND: Amblyomma sculptum is the main vector implicated in the transmission of Rickettsia rickettsii in southeastern Brazil, where capybaras are known to be the main amplifying hosts of this pathogen. Interestingly, many areas inhabited by large populations of capybaras and A. sculptum remain free of R. rickettsii, suggesting that other drivers may be involved in the pathogen perpetuation. A. sculptum frequently occurs in sympatry with Amblyomma dubitatum ticks, sharing the same hosts with them. Considering that A. dubitatum ticks are frequently infected with Rickettsia bellii, a possible interference of R. bellii in the reservoir competence of capybaras for R. rickettsii could explain the heterogeneous distribution of R. rickettsii in A. sculptum populations in southeastern Brazil. OBJECTIVES: The present study aimed to evaluate the effect of primary exposure to R. bellii-infected A. dubitatum on the reservoir competence for R. rickettsii using guinea pigs as experimental models. METHODS: Three guinea pigs were infested with R. bellii-infected A. dubitatum (Group GB), four guinea pigs with uninfected A. dubitatum (Group GD), and three guinea pigs were not exposed to A. dubitatum (Group GC). After infestation with A. dubitatum, all guinea pigs were exposed to one single R. rickettsii-infected A. sculptum female and then were infested with uninfected A. sculptum larvae. After ecdysis, nymphs were tested for detection of spotted fever group rickettsiae. FINDINGS: Five out of six guinea pigs from GD and GC groups died, while one out of three guinea pigs in the GB group had a fatal outcome. R. rickettsii infection rate among ticks fed on animals from GB group was 21% (17/80), significantly lower than the rate of 54% (60/111) recorded in ticks fed on animals from GD and GC groups. MAIN CONCLUSIONS: Prior exposure of guinea pigs to R. bellii-infected A. dubitatum ticks reduced their reservoir competence for R. rickettsii.
Reframing vector control: land use and climate shape malaria risk in Amazonian communities.
Acosta AL, Bergo ES, Figueira EAG … +2 more , Conn JE, Sallum MAM
Mem Inst Oswaldo Cruz · 2026 · PMID 41880475 · Publisher ↗
BACKGROUND: Malaria remains a major public health challenge in the Brazilian Amazon, where ecological heterogeneity and socio-economic vulnerability hinder the effectiveness of vector elimination. The primary vector, Nys...
BACKGROUND: Malaria remains a major public health challenge in the Brazilian Amazon, where ecological heterogeneity and socio-economic vulnerability hinder the effectiveness of vector elimination. The primary vector, Nyssorhynchus darlingi, shows substantial spatiotemporal variation influenced by land-use changes and local microclimates. OBJECTIVES: Investigate how land cover and microclimatic factors affect Ny. darlingi human biting rate (HBR) across different Amazonian ecoregions. METHODS: HBR was measured through human landing catches at 70 sites in four ecoregions, with simultaneous temperature and humidity recordings. Landscape composition was quantified within 100-, 250-, and 500-m buffers. Data were analyzed using linear regressions, mixed-effects models, and principal component analysis. FINDINGS: We recorded 14,689 mosquito bites across 384 events. HBR was highest in areas with intermediate forest degradation and was positively associated with temperature and negatively with humidity. Floodable vegetation was the strongest land cover predictor, especially at the 500-m scale. Intrazonal variation exceeded interzonal differences. MAIN CONCLUSIONS: Local environmental conditions, particularly floodable vegetation near human settlements, strongly influence Ny. darlingi activity. Vector elimination in the Amazon should adopt climate-sensitive, spatially targeted strategies informed by land cover and microclimate data.
Immune dysregulation, apoptosis impairment, and enhanced seroreactivity to Anisakis simplex in Crohn's disease: interplay of IL-7/IL-7R signalling and CD132 deficiency.
Cuéllar C, Hurtado-Marcos C, Valdivieso E … +10 more , Vaccaro L, González-Fernández J, Jiménez AI, Pérez-Griera J, Benlloch S, Amorós C, Gil-Borrás R, Sorando-Serra R, Cano-Cano MJ, Andreu-Ballester JC
Mem Inst Oswaldo Cruz · 2026 · PMID 41880474 · Full text
BACKGROUND: In previous studies, we identified a deficiency of γδ T cells and an increased prevalence of anti-Anisakis simplex antibodies in patients with Crohn's disease (CD). Additionally, decreased gene expression of...
BACKGROUND: In previous studies, we identified a deficiency of γδ T cells and an increased prevalence of anti-Anisakis simplex antibodies in patients with Crohn's disease (CD). Additionally, decreased gene expression of the interleukin 2 (IL-2) receptor γ subunit (CD132) was observed in tissues from CD patients. OBJECTIVE: To analyse the gene expression of IL-7 and its receptors in tissues from CD patients and to explore its relationship with anti-A. simplex antibodies. METHODS: 52 patients diagnosed with CD were compared with a control group of 52 healthy individuals. Peripheral blood samples were analysed to assess levels of anti-A. simplex antibodies and IL-7. In addition, intestinal tissue samples from 20 subjects in each group were examined to evaluate IL-7 gene expression, IL-7 protein levels, the IL-2 receptor γ subunit (CD132), the IL-7 receptor α subunit (CD127), and caspase-3 expression. FINDINGS: Anti-A. simplex antibody levels were elevated in patients with CD. Caspase-3 expression was significantly reduced in the tissues of CD patients with anti-A. simplex IgA, and this reduction extended to IgG and IgE in healthy individuals. A negative correlation was observed between caspase-3 levels and serum anti-A. simplex IgA, as well as IL-7 levels in the tissues of CD patients. In healthy subjects, tissue IL-7 levels were lower in those positive for anti-A. simplex IgA, while serum IL-7 levels were higher in individuals positive for anti-A. simplex IgG. MAIN CONCLUSIONS: This study revealed the interplay between IL-7 signalling, γδ T cell deficiency, and immune responses to A. simplex in CD. Our findings underscored a cause-effect relationship between CD132 deficiency, γδ T cell depletion, and defective mucosal immunity, which may drive both CD inflammation and susceptibility to parasitic infections like A. simplex.
Investigation of neurotropic arboviruses in wild and domestic animals in Amazon region, 2023-2024.
Hayashi DJ, Nunes BTD, Silva SPD … +13 more , Cunha TCADSD, Paiva FADS, Prazeres ITE, Santos ADCM, Barros LJL, Ribeiro ACDS, Sobral FB, Fernandes LM, Coelho TFSB, Carvalho VL, Cruz ACR, Medeiros DBA, Casseb LMN
Mem Inst Oswaldo Cruz · 2026 · PMID 41849539 · Full text
BACKGROUND: Arboviruses represent a potential threat to global public health due to their ability to infect various vertebrate hosts and vectors, as well as their adaptability to diverse ecosystems, allowing them to expa...
BACKGROUND: Arboviruses represent a potential threat to global public health due to their ability to infect various vertebrate hosts and vectors, as well as their adaptability to diverse ecosystems, allowing them to expand geographically across continents. OBJECTIVE: The present study aimed to describe the molecular epidemiology of encephalitic arboviruses, including Venezuelan equine encephalitis virus (VEEV), Eastern equine encephalitis virus (EEEV), Western equine encephalitis virus (WEEV), West Nile virus (WNV), Saint Louis encephalitis virus (SLEV), Toscana virus (TOSV), and Rift Valley fever virus (RVFV) in nervous tissue samples from domestic and wild animals from the Northern region of Brazil, between February 2023 and June 2024. METHODS: Samples negative for rabies virus were analysed by reverse transcription real-time polymerase chain reaction (RT-qPCR) targeting Alphavirus, Orthoflavivirus and Phlebovirus species.Positive samples were subjected to viral isolation in cell culture and whole-genome sequencing using next-generation sequencing.Phylogenetic and molecular clock analyses were performed to characterise viral lineages and evolutionary relationships. FINDINGS: Two samples tested positive for arboviruses by RT-qPCR: one SLEV sample from the state of Amazonas, which showed a low viral load, preventing virus isolation and sequencing, and one Madariaga virus (MADV) sample from the state of Pará, which could be isolated and sequenced.The isolated agent belongs to lineage III of EEEV, showing most similarity to strains from Guyana and Argentina. MAIN CONCLUSIONS: The present study detected two arboviruses in animals, suggesting its circulation in the study area.
Differential expression of miRNAs in Vero cells after Mayaro virus infection.
Curcio JS, Silva LDC, Novaes E … +1 more , Silveira-Lacerda EP
Mem Inst Oswaldo Cruz · 2026 · PMID 41849537 · Full text
BACKGROUND: The Mayaro virus (MAYV) is an alphavirus endemic to Central and South America, primarily transmitted by mosquitoes of the Haemagogus genus. Human infection causes "Mayaro fever," characterized by symptoms sim...
BACKGROUND: The Mayaro virus (MAYV) is an alphavirus endemic to Central and South America, primarily transmitted by mosquitoes of the Haemagogus genus. Human infection causes "Mayaro fever," characterized by symptoms similar to dengue and chikungunya, including debilitating arthralgia. Despite its potential for urbanisation, many aspects of MAYV-host interactions, particularly the role of host microRNAs (miRNAs), remain poorly understood. OBJECTIVES: This study aimed to investigate the expression profile of miRNAs in Vero cells infected with MAYV and to predict their potential biological targets and associated pathways. METHODS: Infection was performed using the MAYV strain (BeAr 20290), and small RNA libraries were prepared from infected and control cells. Initial experiments were conducted to evaluate viral replication, cell viability, and small RNA expression. Based on these parameters, the 24-h post-infection time point was selected for small RNA sequencing. Bioinformatic tools were used to identify differentially expressed miRNAs and predict their targets in Homo sapiens and the MAYV genome. FINDINGS: Among the 348 miRNAs identified, 46 were differentially expressed at 24 h (42 upregulated and four downregulated). Principal component analysis (PCA) indicated a clear separation between infected and control groups. In silico predictions of the targets of these miRNAs suggest potential associations with biological processes that may be relevant to virus-host interactions, such as immune response, programmed cell death pathways, viral replication, and persistence. Additionally, one miRNA detected in Vero cells was predicted to target a viral non-structural protein. MAIN CONCLUSIONS: Our findings indicate a potential dual role for host miRNAs during MAYV infection, involving both the modulation of host responses by the virus to enhance replication and a possible antiviral effect. While these interactions underscore the prospective relevance of miRNAs as biomarkers and therapeutic targets in arboviral infections, it is important to note that these conclusions are based solely on computational analyses. Therefore, they should be interpreted with caution until they are supported by further experimental validation.
Genome mining and characterisation of biosynthetic clusters in Aspergillus japonicus isolated from the Amazon rainforest.
Rodrigues JC, Grisolia ME, Queiroz ADS … +4 more , Lima ALR, Goiabeira CVS, Lima LM, Fernandes OCC
Mem Inst Oswaldo Cruz · 2026 · PMID 41849536 · Full text
BACKGROUND: In light of the biotechnological potential demonstrated by Aspergillus species and, considering the great need for further research into the search for new sources of active molecules and the biodiversity of...
BACKGROUND: In light of the biotechnological potential demonstrated by Aspergillus species and, considering the great need for further research into the search for new sources of active molecules and the biodiversity of these microorganisms occurring in the Amazon region. OBJECTIVES: This research aimed to investigate the biotechnological potential of the fungus Aspergillus japonicus Amazon Fungi Collection (CFAM) 0234, a fungal strain isolated from Amazonian soil and stored in the CFAM. METHODS: For this purpose, the Aspergillus species was investigated through comparative genomic analysis and antimicrobial activity assays. FINDINGS: Genome sequencing revealed a fragmented assembly (72.67 Mbp, N50 = 152 kbp) containing 106 biosynthetic clusters (BGCs), surpassing the reference strain CBS 114.51 (57 BGCs). Among the clusters identified, NRPS, PKS type I and hybrid NRPS-PKS systems stood out, including clusters exclusive to betalactones and isocyanides, potentially involved in the synthesis of β-lactam antibiotics and innovative metabolites. BiG-SCAPE analysis identified 63 BGC families unique to CFAM 0234, suggesting evolutionary adaptations to the competitive environment of the Amazon. Biological assays demonstrated selective antimicrobial activity of the ethyl acetate extract against Escherichia coli, Shigella sonnei and Sthapylococcus aureus (MRSA), with inhibition halos ranging from 8 mm to 6 mm in diameter, pathogens classified as priorities for research into new antibiotics. The correlation between predicted BGCs and antimicrobial activity reinforces the strain's biotechnological potential. Despite the fragmentation of the genome, the high completeness assessed by BUSCO (98.5%) confirms the quality of the assembly, while the detection of single nucleotide polymorphisms (SNPs) in regulatory regions and rearrangements close to BGCs suggests evolutionary pressure for metabolic diversification. The lack of correspondence with the minimum information about a biosynthetic gene cluster (MIBiG) bank and the limitations of crude extracts highlight the need for complementary techniques, such as long-read sequencing (Oxford Nanopore) and metabolomic analysis [liquid chromatography-mass espectrometry (LC-MS)], to link clusters to active metabolites. MAIN CONCLUSIONS: Aspergillus japonicus CFAM 0234 represents a promising microbial resource for bioprospecting in the Amazon, offering relevant genomic and chemical insights for the development of new antimicrobial agents. Future studies will focus on the purification of compounds and activation of silent BGCs, aiming at sustainable pharmaceutical applications.
About
- Frequency
- Sun
- Papers found
- 200
- RSS feed
- Subscribe