DSpace Collection:

Própolis Brasileira Frente a Patógenos Associados às Infecções Neonatais: Abordagem Antibacteriana e Antiviral

2026-04-06T00:00:00Z

Title: Própolis Brasileira Frente a Patógenos Associados às Infecções Neonatais: Abordagem Antibacteriana e Antiviral Abstract: Neonatal infections represent a major global public health challenge due to high morbidity and mortality, particularly in neonatal intensive care units (NICUs). In this context, bacteria associated with sepsis and biofilm formation, opportunistic yeasts, and viruses such as Zika virus (ZIKV), which causes congenital infections and neurological alterations, stand out as clinically relevant pathogens. Accordingly, this study evaluated the in vitro antimicrobial, antibiofilm, anti–quorum sensing, and antiviral activities of the hydroethanolic extract of Brazilian red propolis (BRP) and the hydromethanolic extract of Caatinga green propolis (BGP-C) against microorganisms associated with neonatal infections. The strains evaluated included Staphylococcus epidermidis (ATCC 12228 and ATCC 14990), Staphylococcus aureus (ATCC 29213), Streptococcus pneumoniae (ATCC 6305), Streptococcus agalactiae (ATCC 13813), Streptococcus pyogenes (ATCC 19015), Enterococcus faecalis (ATCC 29212 and ATCC 51299), Listeria monocytogenes (ATCC 15313), Neisseria gonorrhoeae (ATCC 43069), Escherichia coli (ATCC BAA-198), Enterobacter cloacae (clinical isolate IAL 124), Candida albicans (ATCC 90028), and Zika virus (ZIKV), clinical isolate PE243. Antimicrobial activity was assessed by determining the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and minimum fungicidal concentration (MFC). Antibiofilm activity was analyzed by determining the minimum biofilm inhibitory concentration required to inhibit 50% of biofilm formation (MBIC₅₀) and the concentration that inhibited 50% of biofilm metabolic activity (IC₅₀). Morphological alterations and membrane integrity were investigated by scanning electron microscopy (SEM) and by staining with 4’,6-diamidino-2-phenylindole (DAPI) and propidium iodide (PI). Interference with quorum sensing systems was investigated using the biosensor strain Chromobacterium violaceum CV026. Antiviral activity was evaluated in Vero E6 cells and, additionally, in human trophoblast BeWo cells. Both extracts exhibited activity against Gram-positive bacteria, with MIC values ranging from 6.25 to 400 µg/mL, highlighting Streptococcus pneumoniae and Streptococcus agalactiae (6.25 µg/mL) and Listeria monocytogenes (50 µg/mL), whereas no antibacterial activity was observed against Gram-negative species. For Candida albicans, both extracts exhibited MIC and MFC values of 200 µg/mL. BRP and BGP-C reduced biofilm biomass and metabolic activity, with evidence of impaired cellular integrity and no detectable interference with AHL-dependent quorum sensing. In antiviral assays, BRP and BGP-C reduced ZIKV infectivity by approximately 34% and 40%, respectively, under non-cytotoxic conditions, with dose-dependent antiviral activity observed in BeWo cells. Overall, these findings indicate that BRP and, particularly, BGP-C represent biologically relevant natural sources with in vitro activity against pathogens associated with neonatal infections.

Identificação e caracterização funcional de uma nova proteína de grânulos densos em Neospora caninum por meio de edição gênica mediada por CRISPR/Cas9

2026-02-24T00:00:00Z

Title: Identificação e caracterização funcional de uma nova proteína de grânulos densos em Neospora caninum por meio de edição gênica mediada por CRISPR/Cas9 Abstract: Across apicomplexan parasites, dense granule proteins are key effectors that play essential roles in intracellular parasite survival and host immune modulation, although many remain uncharacterized in Neospora caninum. In this study, we identify and characterize a novel dense granule protein of N. caninum, designated as GRA90, through integrated bioinformatic and experimental approaches. Orthology and synteny analyses demonstrated approximately 50% sequence identity with the corresponding Toxoplasma gondii orthologue, with partial conservation of structural features, indicating evolutionary relatedness with potential functional divergence. CRISPR/Cas9-mediated epitope tagging localized GRA90 to the lumen of the parasitophorous vacuole. Disruption of GRA90 significantly reduced plaque formation, reflecting compromised intracellular replication and/or survival. In a murine model, infection with Δgra90 parasites was associated with greater weight loss and decreased IFN-γ levels during the acute phase, alongside a tendency toward increased parasite burden in the brain during chronic infection. Altogether, these data identify GRA90 as a pro-host effector contributing to parasite fitness and expand current understanding of dense granule protein function in N. caninum.

Caracterização molecular e funcional da proteína micronema 10 de Neospora caninum

2026-02-23T00:00:00Z

Title: Caracterização molecular e funcional da proteína micronema 10 de Neospora caninum Abstract: Neospora caninum is an obligate intracellular protozoan of the phylum Apicomplexa and the etiological agent of neosporosis, a disease of worldwide distribution that primarily affects dogs and cattle, causing significant economic losses. Parasites of this phylum possess a specialized apical complex composed of secretory organelles such as micronemes, which are essential for host cell adhesion and invasion. Microneme proteins (MICs) play a central role in the early stages of infection by mediating specific interactions between the parasite and the host. Among them, MIC10 stands out as a protein located in the apical region and is potentially involved in parasite adhesion and invasion; however, its function in N. caninum remains poorly characterized. This study aimed to evaluate the role of microneme protein 10 (MIC10) during N. caninum infection. Using CRISPR-Cas9-mediated genome editing, we fused an epitope tag to the C-terminal region of the protein, which allowed us to confirm the predicted subcellular localization of MIC10. We also generated a MIC10-deficient parasite line (Δmic10) and observed a reduction in host cell invasion, associated with a significant decrease in intracellular replication capacity. In vivo assays using a murine experimental model demonstrated that animals infected with Δmic10 knockout parasites exhibited a higher parasite burden during the acute phase of infection (24 hours), whereas parasite load was significantly reduced in brain tissue during the chronic phase (30 days) compared to mice infected with the parental strain. In conclusion, this study describes the molecular and functional characteristics of MIC10 in N. caninum and highlights its relevance in the host cell invasion process, making it a potential target for studies aimed at the prophylaxis and control of infection.

Avaliação do papel do fator de inibição da migração de macrófagos de Toxoplasma gondii (TgMIF) na infecção crônica pelo parasito

2025-08-04T00:00:00Z

Title: Avaliação do papel do fator de inibição da migração de macrófagos de Toxoplasma gondii (TgMIF) na infecção crônica pelo parasito Abstract: Toxoplasma gondii is an obligate intracellular protozoan with marked tropism for the central nervous system and the ability to establish chronic infection associated with neuroinflammatory alterations. This parasite expresses a homolog of the Macrophage Migration Inhibitory Factor (TgMIF), a bioactive protein with immunomodulatory potential that remains poorly characterized. This study aimed to evaluate the role of TgMIF in the chronicity of T.gondii infection using female C57BL/6 mice infected intraperitoneally with 10⁴ tachyzoites of either the wild-type PRU strain (WT) or a TgMIF-deficient strain (ΔTgmif), the latter genetically modified by targeted gene deletion. Clinical parameters (survival, morbidity score, and weight variation) were monitored, along with brain parasite burden assessed by quantitative PCR targeting the Tg529 gene, and histopathological and neurodegenerative changes analyzed through hematoxylin-eosin and cresyl violet staining. Mice infected with the ΔTgmif strain exhibited more pronounced and sustained weight loss, significantly increased brain parasite burden (p < 0.01), and extensive inflammatory infiltrates, especially in the meninges and brain parenchyma. A lower density of Nissl bodies was also observed, indicating more severe neuronal damage. Although no statistically significant difference in survival rates was detected between groups, histological data revealed an exacerbated inflammatory profile in the absence of TgMIF, suggesting that this molecule actively participates in regulating the immune response within neural tissue. It is concluded that TgMIF may play a relevant role in modulating chronic infection by the parasite, favoring the control of neuroinflammation and contributing to the balance between parasite persistence and immunopathology. These findings open new perspectives for the investigation of TgMIF as a potential immunotherapeutic target in chronic cerebral toxoplasmosis.