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Uncertainty remains about how long the protective immune responses against severe acute respiratory syndrome coronavirus 2 persists, and suspected reinfection in recovered patients has been reported. We describe a case of reinfection from distinct virus lineages in Brazil harboring the E484K mutation, a variant associated with escape from neutralizing antibodies.

Ipecac alkaloids are secondary metabolites produced in the medicinal plant Psychotria ipecacuanha. Emetine is the main alkaloid of ipecac and one of the active compounds in syrup of Ipecac with emetic property. Here we evaluated emetine’s potential as an antiviral agent against Human Immunodeficiency Virus. We performed in vitro Reverse Transcriptase (RT) Assay and Natural Endogenous Reverse Transcriptase Activity Assay (NERT) to evaluate HIV RT inhibition. Emetine molecular docking on HIV-1 RT was also analyzed. Phenotypic assays were performed in non-lymphocytic and in Peripheral Blood Mononuclear Cells (PBMC) with HIV-1 wild-type and HIV-harboring RT-resistant mutation to Nucleoside Reverse Transcriptase Inhibitors (M184V). Our results showed that HIV-1 RT was blocked in the presence of emetine in both models: in vitro reactions with isolated HIV-1 RT and intravirion, measured by NERT. Emetine revealed a strong potential of inhibiting HIV-1 replication in both cellular models, reaching 80% of reduction in HIV-1 infection, with low cytotoxic effect. Emetine also blocked HIV-1 infection of RT M184V mutant. These results suggest that emetine is able to penetrate in intact HIV particles, and bind and block reverse transcription reaction, suggesting that it can be used as anti-HIV microbicide. Taken together, our findings provide additional pharmacological information on the potential therapeutic effects of emetine.

The introduction of SARS-CoV-2 variants of concern (VOCs) in Brazil has been associated with major impacts on the epidemiological and public health scenario. In this study, 291,571 samples were investigated for SARS-CoV-2 variants from August 2021 to March 2022 (the highest peak of positive cases) in four geographical regions of Brazil. To identify the frequency, introduction, and dispersion of SARS-CoV-2 variants in 12 Brazilian capitals, VOCs defining spike mutations were identified in 35,735 samples through genotyping and viral genome sequencing. Omicron VOC was detected in late November 2021 and replaced the Delta VOC in approximately 3.5 weeks. We estimated viral load differences between SARS-CoV-2 Delta and Omicron through the evaluation of the RT-qPCR cycle threshold (Ct) score in 77,262 samples. The analysis demonstrated that the Omicron VOC has a lower viral load in infected patients than the Delta VOC. Analyses of clinical outcomes in 17,586 patients across the country indicated that individuals infected with Omicron were less likely to need ventilatory support. The results of our study reinforce the importance of surveillance programs at the national level and showed the introduction and faster dispersion of Omicron over Delta VOC in Brazil without increasing the numbers of severe cases of COVID-19.

Abstract Zika virus is an arthropod-borne flavivirus mainly transmitted by the bite of infected mosquitoes. However, alternative transmission routes can occur. In this study, we show the accidental transmission of virus from an infected mouse to a human during the experimental manipulation. This study describes the patient clinical manifestations and virus genome identification. We describe a new route of transmission of Zika virus from an infected mouse to human during experimental manipulation.

Zika virus (ZIKV) infection in utero might lead to microcephaly and other congenital defects. Since no specific therapy is available thus far, there is an urgent need for the discovery of agents capable of inhibiting its viral replication and deleterious effects. Chloroquine is widely used as an antimalarial drug, anti-inflammatory agent, and it also shows antiviral activity against several viruses. Here we show that chloroquine exhibits antiviral activity against ZIKV in Vero cells, human brain microvascular endothelial cells, human neural stem cells, and mouse neurospheres. We demonstrate that chloroquine reduces the number of ZIKV-infected cells in vitro, and inhibits virus production and cell death promoted by ZIKV infection without cytotoxic effects. In addition, chloroquine treatment partially reveres morphological changes induced by ZIKV infection in mouse neurospheres.

A genomic investigation revealed that these outbreaks were driven by a novel reassortant virus, with genomic segments of different viruses that are classified in the species Orthobunyavirus oropoucheense.4 Although the medium segment of circulating viruses was more related to the OROV prototype, the small and large segments were related to the Iquitos virus (IQTV), a closely related virus detected in outbreaks in Peru.5 In 2024, central reference laboratories in several states across Brazil detected OROV circulation through molecular diagnosis.6 By July 4, 2024, 6976 laboratory-confirmed cases were documented in the country, with 21·6% occurring outside of the endemic region. Several factors contribute to the emergence of arboviruses, including highly connected air-travel networks, deforestation, and climate change.7 Specifically, for orthobunyaviruses, reassortment has also been associated with human outbreaks.8,9 Accordingly, viruses endemic to north Brazil have been increasingly detected in other regions of the country, such as yellow fever virus10 and Mayaro virus.11 OROV has been previously detected in zoonotic reservoirs outside of its recognised endemic region (Minas Gerais state, southeast Brazil).12 2024 was marked by a substantial increase of arboviruses cases across the world, with 7·6 million suspected cases, 90% of which were registered in Brazil. [...]how do climatic, entomological, demographic, immunological, and evolutionary factors contribute to OROV emergence?

ACE2 and TMPRSS2 are key players on SARS-CoV-2 entry into host cells. However, it is still unclear whether expression levels of these factors could reflect disease severity. Here, a case–control study was conducted with 213 SARS-CoV-2 positive individuals where cases were defined as COVID-19 patients with respiratory distress requiring oxygen support (N = 38) and controls were those with mild to moderate symptoms of the disease who did not need oxygen therapy along the entire clinical course (N = 175). ACE2 and TMPRSS2 mRNA levels were evaluated in nasopharyngeal swab samples by RT-qPCR and logistic regression analyzes were applied to estimate associations with respiratory outcomes. ACE2 and TMPRSS2 levels positively correlated with age, which was also strongly associated with respiratory distress. Increased nasopharyngeal ACE2 levels showed a protective effect against this outcome ( adj OR = 0.30; 95% CI 0.09–0.91), while TMPRSS2/ACE2 ratio was associated with risk ( adj OR = 4.28; 95% CI 1.36–13.48). On stepwise regression, TMPRSS2/ACE2 ratio outperformed ACE2 to model COVID-19 severity. When nasopharyngeal swabs were compared to bronchoalveolar lavages in an independent cohort of COVID-19 patients under mechanical ventilation, similar expression levels of these genes were observed. These data suggest nasopharyngeal TMPRSS2/ACE2 as a promising candidate for further prediction models on COVID-19.

Neutrophils release extracellular traps (NETs) after interaction with microorganisms and physiological or synthetic products. NETs consist of decondensed chromatin complexed with proteins, some of them with microbicidal properties. Because NETs can modulate the functioning of HIV-1 target cells, we aimed to verify whether they modify HIV-1 replication in macrophages. We found that exposure of HIV-1-infected macrophages to NETs resulted in significant inhibition of viral replication. The NET anti-HIV-1 action was independent of other soluble factors released by the activated neutrophils, but otherwise dependent on the molecular integrity of NETs, since NET-treatment with protease or DNase abolished this effect. NETs induced macrophage production of the anti-HIV-1 β-chemokines Rantes and MIP-1β, and reduced the levels of integrated HIV-1 DNA in the macrophage genome, which may explain the decreased virus production by infected macrophages. Moreover, the residual virions released by NET-treated HIV-1-infected macrophages lost infectivity. In addition, elevated levels of DNA-elastase complexes were detected in the plasma from HIV-1-infected individuals, and neutrophils from these patients released NETs, which also inhibited HIV-1 replication in in vitro infected macrophages. Our results reveal that NETs may function as an innate immunity mechanism able to restrain HIV-1 production in macrophages.

[This corrects the article DOI: 10.3389/fcimb.2025.1726007.].

Background The pandemic caused by SARS-CoV-2 has not only affected humans but also raised concerns about its transmission to wild animals, potentially creating natural reservoirs. Understanding these dynamics is critical for preventing future pandemics and developing control strategies. This study aims to investigate the presence of SARS-CoV-2 in wild mammals at the Belo Horizonte Zoo in Brazil, analyzing the virus's evolution and zoonotic potential. Methods The study was conducted at the Belo Horizonte Zoo, Minas Gerais, Brazil, covering a diverse population of mammals. Oropharyngeal, rectal, and nasal swabs were collected from 47 captive animals between November 2021 and March 2023. SARS-CoV-2 presence was determined using RT-PCR, and positive samples were sequenced for phylogenetic analysis. Consensus genomes were classified using Pangolin and NextClade tools, and a maximum likelihood phylogeny was inferred using IQ-Tree. Results Of the 47 animals tested, nine (19.1%) were positive for SARS-CoV-2. Positive samples included rectal, oropharyngeal, and nasal swabs, with the highest positivity in rectal samples. Three genomes were successfully sequenced, revealing two variants: VOC Alpha in a maned wolf ( Chrysocyon brachyurus ) and a fallow deer ( Dama dama ), and VOC Omicron in a western lowland gorilla ( Gorilla gorilla gorilla ). Phylogenetic analysis indicated potential human-to-animal transmission, with animal genomes clustering close to human samples from the same region. Conclusions This study highlights the presence of SARS-CoV-2 in various wild mammal species at the Belo Horizonte Zoo, emphasizing the virus's zoonotic potential and the complexity of interspecies transmission. The detection of different variants suggests ongoing viral evolution and adaptation in new hosts. Continuous monitoring and genomic surveillance of SARS-CoV-2 in wildlife are essential for understanding its transmission dynamics and preventing future zoonotic outbreaks. These findings underscore the need for integrated public health strategies that include wildlife monitoring to mitigate the risks posed by emerging infectious diseases.