MPXV: Update on Morphological and Morphogenesis Aspects Through Transmission and Scanning Electron Microscopies and 3D Reconstruction.

An unprecedented global outbreak caused by the monkeypox virus (MPXV) prompted the World Health Organization to declare a public health emergency of international concern on July 23, 2022. Therapeutics and vaccines for MPXV are not widely available, necessitating further studies, particularly in drug repurposing area. To this end, the standardization of in vitro infection systems is essential.

Testicular damage without clinical manifestations in BALB/c mice experimentally infected with Zika virus.

In 2015-2016, the Zika virus (ZIKV) caused a major epidemic in the Americas, increasing cases of microcephaly and Guillain-Barré syndrome. During this period, the discovery of ZIKV sexual transmission intensified studies on the impact of this virus on the reproductive organs. For this study, 2-month-old male BALB/c mice were infected with 1.

Inhibition of the SREBP pathway prevents SARS-CoV-2 replication and inflammasome activation.

SARS-CoV-2 induces major cellular lipid rearrangements, exploiting the host's metabolic pathways to replicate. Sterol regulatory element binding proteins (SREBPs) are a family of transcription factors that control lipid metabolism. SREBP1 is associated with the regulation of fatty acids, whereas SREBP2 controls cholesterol metabolism, and both isoforms are associated with lipid droplet (LD) biogenesis.

Monkeypox (Mpox) virus isolation and ultrastructural characterisation from a Brazilian human sample case.

Background: According to the last 2023 Monkeypox (Mpox) Outbreak Global Map from the Centres for Disease Control and Prevention (CDC), more than 100 countries with no Mpox infection report cases. Brazil stands out in this group and is the second country with the highest number of cases in the last outbreak.

Objective: To contribute to knowledge of the virus infection effects in a cellular model, which is important for diagnosis infections not yet included in a provider´s differential diagnosis and for developing viral inhibition strategies.

Inactivated and Immunogenic SARS-CoV-2 for Safe Use in Immunoassays and as an Immunization Control for Non-Clinical Trials.

Successful SARS-CoV-2 inactivation allows its safe use in Biosafety Level 2 facilities, and the use of the whole viral particle helps in the development of analytical methods and a more reliable immune response, contributing to the development and improvement of in vitro and in vivo assays. In order to obtain a functional product, we evaluated several inactivation protocols and observed that 0.03% beta-propiolactone for 24 h was the best condition tested, as it promoted SARS-CoV-2 inactivation above 99.

Inactivation of SARS-CoV-2 by a chitosan/α-AgWO composite generated by femtosecond laser irradiation.

In the current COVID-19 pandemic, the next generation of innovative materials with enhanced anti-SARS-CoV-2 activity is urgently needed to prevent the spread of this virus within the community. Herein, we report the synthesis of chitosan/α-AgWO composites synthetized by femtosecond laser irradiation. The antimicrobial activity against Escherichia coli, Methicilin-susceptible Staphylococcus aureus (MSSA), and Candida albicans was determined by estimating the minimum inhibitory concentration (MIC) and minimal bactericidal/fungicidal concentration (MBC/MFC).

Unlike Chloroquine, Mefloquine Inhibits SARS-CoV-2 Infection in Physiologically Relevant Cells.

Despite the development of specific therapies against severe acute respiratory coronavirus 2 (SARS-CoV-2), the continuous investigation of the mechanism of action of clinically approved drugs could provide new information on the druggable steps of virus-host interaction. For example, chloroquine (CQ)/hydroxychloroquine (HCQ) lacks in vitro activity against SARS-CoV-2 in TMPRSS2-expressing cells, such as human pneumocyte cell line Calu-3, and likewise, failed to show clinical benefit in the Solidarity and Recovery clinical trials. Another antimalarial drug, mefloquine, which is not a 4-aminoquinoline like CQ/HCQ, has emerged as a potential anti-SARS-CoV-2 antiviral in vitro and has also been previously repurposed for respiratory diseases.

SARS-CoV-2: Ultrastructural Characterization of Morphogenesis in an In Vitro System.

The pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has impacted public health and the world economy and fueled a worldwide race to approve therapeutic and prophylactic agents, but so far there are no specific antiviral drugs. Understanding the biology of the virus is the first step in structuring strategies to combat it, and in this context several studies have been conducted with the aim of understanding the replication mechanism of SARS-CoV-2 in vitro systems. In this work, studies using transmission and scanning electron microscopy and 3D electron microscopy modeling were performed with the goal of characterizing the morphogenesis of SARS-CoV-2 in Vero-E6 cells.

Immunocompetent Mice Infected by Two Lineages of Dengue Virus Type 2: Observations on the Pathology of the Lung, Heart and Skeletal Muscle.

Dengue virus (DENV) infection by one of the four serotypes (DENV-1 to 4) may result in a wide spectrum of clinical manifestations, with unpredictable evolution and organ involvement. Due to its association with severe epidemics and clinical manifestations, DENV-2 has been substantially investigated. In fact, the first emergence of a new lineage of the DENV-2 Asian/American genotype in Brazil (Lineage II) in 2008 was associated with severe cases and increased mortality related to organ involvement.

Transmission Electron Microscopy Studies of Dengue Viruses.

Despite the advancement of molecular biology techniques, morphological studies using transmission electron microscopy (TEM) are still being of great importance to elucidate some aspects of viral structures, morphogenesis, and pathogenesis. In relation to dengue viruses (DENV), several studies report the use of TEM to obtain a clearer definition of viral morphology, the events involved in its morphogenesis, aspects of pathogenesis, and cell tropism. In this chapter, the main technical protocols and their respective reagents for studies of DENV infection by TEM are described, both in cell culture and in biological tissue samples.

Brazilian Dengue Virus Type 2-Associated Renal Involvement in a Murine Model: Outcomes after Infection by Two Lineages of the Asian/American Genotype.

Dengue virus type 2 (DENV-2) is, traditionally, the most studied serotype due to its association with explosive outbreaks and severe cases. In Brazil, almost 20 years after the first introduction in the 1990s, a new lineage (Lineage II) of the DENV-2 Asian/American genotype emerged and caused an epidemic with severe cases and hospitalizations. Severe dengue includes multiple organ failure, and renal involvement can be potentially related to increased mortality.

Comparative analysis of liver involvement caused by two DENV-2 lineages using an immunocompetent murine model.

Dengue (DEN) is the most prevalent arbovirus among humans, and four billion people live at risk of infection. The clinical manifestations of DEN are variable, and the disease may present subclinically or asymptomatically. A quarter of patients develop classical dengue (CD) or severe dengue (SD), which is potentially lethal and involves vascular permeability changes, severe hemorrhage and organ damage.

Dengue, Yellow Fever, Zika and Chikungunya epidemic arboviruses in Brazil: ultrastructural aspects.

Background: The impact of arbovirus cocirculation in Brazil is unknown. Dengue virus (DENV) reinfection may result in more intense viraemia or immunopathology, leading to more severe disease. The Zika virus (ZIKV) epidemic in the Americas provided pathogenicity evidence that had not been previously observed in flavivirus infections.

Different aspects of platelet evaluation in dengue: Measurement of circulating mediators, ability to interact with the virus, the degree of activation and quantification of intraplatelet protein content.

Platelets play a role in hemostasis, coagulation, angiogenesis, inflammation and immune response is one of the most affected cells in dengue. Here we describe some aspects of platelets by observing their specific circulating mediators, the ability to interact with the virus and morphological consequences of this interaction, activation markers and intraplatelet protein contents in dengue. We conducted this study using dengue-patients as well as healthy donors.

Structural investigation of C6/36 and Vero cell cultures infected with a Brazilian Zika virus.

Zika virus (ZIKV) is a member of the flavivirus genus, and its genome is approximately 10.8 kilobases of positive-strand RNA enclosed in a capsid and surrounded by a membrane. Studies on the replication dynamics of ZIKV are scarce, which limits the development of antiviral agents and vaccines directed against ZIKV.

Ultrastructure of Zika virus particles in cell cultures.

Zika virus (ZIKV) has infected thousands of Brazilian people and spread to other American countries since 2015. The introduction of ZIKV brought a strong impact to public health in Brazil. It is of utmost importance to identify a susceptible cell line that will enable the isolation and identification of the virus from patient samples, viral mass production, and testing of drug and vaccine candidates.

Low impact to fixed cell processing aiming transmission electron microscopy.

In cell culture, cell structures suffer strong impact due to centrifugation during processing for electron microscope observation. In order to minimise this effect, a new protocol was successfully developed. Using conventional reagents and equipments, it took over one week, but cell compression was reduced to none or the lowest deformation possible.