RESUMO
Chikungunya virus (CHIKV) belongs to the genus Alphaviridae, with a single-stranded positive-sense RNA genome of 11.8 kbp encoding a polyprotein that generates both non-structural proteins and structural proteins. The virus is transmitted by the Aedes aegypti and A. albopictus mosquitoes, depending on the location. CHIKV infection leads to dengue-like musculoskeletal symptoms and has been responsible for several outbreaks worldwide since its discovery in 1952. Patients often experience fever, headache, muscle pain, joint swelling, and skin rashes. However, the ultrastructural and mechanical properties of CHIKV have not been fully characterized. Thus, this study aims to apply a physical approach to investigate CHIKV's ultrastructural morphology and mechanical properties, using atomic force microscopy and Raman spectroscopy as the main tools. Using nanomechanical assays of AFM and a gold nanoparticles substrate for Raman signal enhancement, we explored the conformational plasticity, morphology, vibrational signature, and nanomechanical properties of the chikungunya virus, providing new information on its ultrastructure at the nanoscale and offering a novel understanding of the virus' behavior upon mechanical disruptions besides its molecular composition.
Assuntos
Aedes , Febre de Chikungunya , Vírus Chikungunya , Nanopartículas Metálicas , Animais , Humanos , Ouro , Vírus Chikungunya/genética , RNA , VírionRESUMO
Zika virus (ZIKV) is an arthropod-borne virus (arbovirus) from Flavivirus. In 2015, Brazil and other Latin American countries experienced an outbreak of ZIKV infections associated with severe neurological disorders such as Guillain-Barre syndrome (GBS), encephalopathy, and encephalitis. Here, a complete mechanical and structural analysis of the ZIKV has been performed using Atomic Force Microscopy (AFM). AFM analysis corroborated the virus mean size (~50 nm) and icosahedral geometry and revealed high mechanical resistance of both: the viral surface particle (~200 kPa) and its internal content (~800 kPa). The analysis demonstrated the detailed organization of the nucleocapsid structure (such as RNA strips). An interesting finding was the discovery that ZIKV has no surface self-assembling property. These results can contribute to the development of future treatment candidates and circumscribe the magnitude of viral transmission.
Assuntos
Infecção por Zika virus , Zika virus , Brasil/epidemiologia , Surtos de Doenças , Humanos , Microscopia de Força Atômica , Zika virus/genética , Infecção por Zika virus/epidemiologiaRESUMO
The ongoing outbreak of the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) started in late 2019 and spread across the world, infecting millions of people, with over 3.3 million deaths worldwide. To fight back the virus, it is necessary to understand how the main structures work, especially those responsible for the virus infectivity pathogenicity. Here, using the most advanced atomic force microscopy techniques, SARS-CoV-2 viral particles were analyzed, with a special focus on their ultrastructure, adsorption conformation, and nanomechanical behavior. The results uncovered the aspects of the organization and the spatial distribution of the proteins on the surface of the viral particles. It also showed the compliant behavior of the membrane and ability to recover from mechanical injuries. At least three layers composing the membrane and their thickness were measured, protecting the virus from external stress. This study provides new insight into the ultrastructure of SARS-CoV-2 particles at the nanoscale, offering new prospects that could be employed for mapping viral surfaces. The understanding of the viruses' capacity to survive mechanical disruptions at any level and their ability to recover from such injuries can shed a light on the structure-function relationship and help us to find targets for drug action, especially for this virus that, to this day, has no course of treatment approved.