Presence Of Structural Proteins Research Articles

The Antiviral Activity of the Lectin Griffithsin against SARS-CoV-2 Is Enhanced by the Presence of Structural Proteins.

Although COVID-19 transmission has been reduced by the advent of vaccinations and a variety of rapid monitoring techniques, the SARS-CoV-2 virus itself has shown a remarkable ability to mutate and persist. With this long track record of immune escape, researchers are still exploring prophylactic treatments to curtail future SARS-CoV-2 variants. Specifically, much focus has been placed on the antiviral lectin Griffithsin in preventing spike protein-mediated infection via the hACE2 receptor (direct infection). However, an oft-overlooked aspect of SARS-CoV-2 infection is viral capture by attachment receptors such as DC-SIGN, which is thought to facilitate the initial stages of COVID-19 infection in the lung tissue (called trans-infection). In addition, while immune escape is dictated by mutations in the spike protein, coronaviral virions also incorporate M, N, and E structural proteins within the particle. In this paper, we explored how several structural facets of both the SARS-CoV-2 virion and the antiviral lectin Griffithsin can affect and attenuate the infectivity of SARS-CoV-2 pseudovirus. We found that Griffithsin was a better inhibitor of hACE2-mediated direct infection when the coronaviral M protein is present compared to when it is absent (possibly providing an explanation regarding why Griffithsin shows better inhibition against authentic SARS-CoV-2 as opposed to pseudotyped viruses, which generally do not contain M) and that Griffithsin was not an effective inhibitor of DC-SIGN-mediated trans-infection. Furthermore, we found that DC-SIGN appeared to mediate trans-infection exclusively via binding to the SARS-CoV-2 spike protein, with no significant effect observed when other viral proteins (M, N, and/or E) were present. These results provide etiological data that may help to direct the development of novel antiviral treatments, either by leveraging Griffithsin binding to the M protein as a novel strategy to prevent SARS-CoV-2 infection or by narrowing efforts to inhibit trans-infection to focus on DC-SIGN binding to SARS-CoV-2 spike protein.

P.169: Decellularized Cotyledons Isolated From Human Placenta Used Like a Scaffold for the Generation of a Human Bioartificial Pancreas

Background: Replacing damaged organs with biological substitutes capable of protecting the islets and facilitating vascularization is a great objective in the field of islet transplantation. A decellularized placenta includes a large number of cotyledons with a conserved vessel structure of the native organ. Our goal is to obtain a perfect decellularization protocol to generate pre-vascularized organoids by recellularizing this ECM with HUVECs and pancreatic islets. Methods: After blood removal, cotyledons were dissected from the placentas and decellularized using a bioreactor. Cell removal was assessed by histology and quantification of residual DNA. Presence of structural proteins and ECM structure were analyzed using SEM, CT scan and mass spectrometry. Recellularization protocols were conducted, with HUVECs or BOECs as endothelial cell sources, and with Ins-1E cells or rat islets as insulin secreting cell sources. Function of recellularized cotyledons was assessed in vitro with glucose stimulated insulin secretion tests (GSIS). To assess in vivo biocompatibility and function of the scaffolds, we transplanted in diabetic NSG mice. Glycaemia was measured every day to monitor normalization of blood glucose levels. Results: Our protocol led to successful decellularization, as evidenced by the absence of cells and the preserved ECM structure. Moreover, DNA quantification did not reveal any residual DNA. Quantification of GAG and hydroxyproline, and mass spectrometry analysis show that structural proteins are conserved. SEM and CT scan images revealed that the ECM structure was preserved after the decellularization protocol. Cells after recellularization showed a good vascularization after 7 days. The GSIS test shows a perfect organ response in the production of insulin. Conclusions: The decellularized cotyledon is the perfect scaffold to reproduce a prevascularized insulin-producing organ, which allows transplanted cells to survive during the peri-transplantation period.

SenSARS: A Low-Cost Portable Electrochemical System for Ultra-Sensitive, Near Real-Time, Diagnostics of SARS-CoV-2 Infections.

A critical path to solving the SARS-CoV-2 pandemic, without further socioeconomic impact, is to stop its spread. For this to happen, pre- or asymptomatic individuals infected with the virus need to be detected and isolated opportunely. Unfortunately, there are no current ubiquitous (i.e., ultra-sensitive, cheap, and widely available) rapid testing tools capable of early detection of SARS-CoV-2 infections. In this article, we introduce an accurate, portable, and low-cost medical device and bio-nanosensing electrode dubbed SenSARS and its experimental validation. SenSARS’ device measures the electrochemical impedance spectra of a disposable bio-modified screen-printed carbon-based working electrode (SPCE) to the changes in the concentration of SARS-CoV-2 antigen molecules (“S” spike proteins) contained within a sub-microliter fluid sample deposited on its surface. SenSARS offers real-time diagnostics and viral load tracking capabilities. Positive and negative control tests were performed in phosphate-buffered saline (PBS) at different concentrations (between 1 and 50 fg/mL) of SARS-CoV-2(S), Epstein–Barr virus (EBV) glycoprotein gp350, and Influenza H1N1 M1 recombinant viral proteins. We demonstrate that SenSARS is easy to use, with a portable and lightweight (< 200 g) instrument and disposable test electrodes (<U.S. n}{} n5), capable of fast diagnosis (~10 min), with high analytical sensitivity (low limits of detection, LOD = 1.065 fg/mL, and quantitation, LOQ = 3.6 fg/mL) and selectivity to SARS-CoV-2(S) antigens, even in the presence of structural proteins from the other pathogens tested. SenSARS provides a potential path to pervasive rapid diagnostics of SARS-CoV-2 in clinical, point-of-care, and home-care settings, and to breaking the transmission chain of this virus. Medical device compliance testing of SenSARS to EIC-60601 technical standards is underway.

Aspectos Estruturais e Fitoquímicos de partes vegetativas de Costus spicatus (Jacq.) Sw. (Costaceae)

As folhas de Costus spicatus são amplamente empregadas na medicina popular para o tratamento de várias doenças entre elas: malária, hepatite e doença do aparelho urinário. O objetivo deste trabalho foi identificar aspectos da anatomia dos órgãos vegetativos (folhas, caules, raízes e rizomas) associados à triagem fitoquímica visando contribuir com informações relevantes para o desenvolvimento de estudos taxonômicos e farmacológicos. A análise anatômica por meio da microscopia óptica e de varredura evidenciou folha anfi-hipoestomática, com estômatos e tricomas tectores filamentosos simples. O mesofilo é constituído por parênquima clorofiliano, que se divide em duas regiões intercaladas por cordão de fibras e feixes vasculares. O caule é do tipo atactostélico como no rizoma. A raiz é poliarca. Os testes histoquímicos indicaram a presença de amido, proteínas estruturais, alcaloides, cristais de oxalato de cálcio. A prospecção química com extratos hidroalcoólico e aquoso constatou a presença de saponinas, taninos, alcaloides, compostos fenólicos e heterosídeos cianogênicos.

Rubella virus capsid protein modulates viral genome replication and virus infectivity.

The structural proteins (SP) of the Togaviridae can be deleted in defective interfering RNAs. The dispensability of viral SP has allowed construction of noninfectious viral expression vectors and replicons from viruses of the Alphavirus and Rubivirus genera. Nevertheless, in this study, we found that the SP of rubella virus (RUB) could enhance expression of reporter genes from RUB replicons in trans. SP enhancement required capsid protein (CP) expression and was not due to RNA-RNA recombination. Accumulation of minus- and plus-strand RNAs from replicons was observed in the presence of SP, suggesting that SP specifically affects RNA synthesis. By using replicons containing an antibiotic resistance gene, we found 2- to 50-fold increases in the number of cells surviving selection in the presence of SP. The increases depended significantly on the amount of transfected RNA. Small amounts of RNA or templates that replicated inefficiently showed more enhancement. The infectivity of infectious RNA was increased by at least 10-fold in cells expressing CP. Moreover, virus infectivity was greatly enhanced in such cells. In other cells that expressed higher levels of CP, RNA replication of replicons was inhibited. Thus, depending on conditions, CP can markedly enhance or inhibit RUB RNA replication.

Antigen Distribution in Organs of Mink with Aleutian Disease Parvovirus Infection

On tissues from naturally infected non-Aleutian mink an immunohistological study was performed using monoclonal antibodies and the immunoperoxidase method. Structural proteins of ADV were demonstrated in cryosections and in ethanol-fixed and paraffin-embedded material which provide antigen detection in a similar amount together with good histological structure. In lymphoid organs viral antigen was restricted to B-cell areas, particularly lymphoid follicles. The pattern of antigen distribution was typical for follicular dendritic cells which are capable to retain immune complexes. Beside macrophages in the interior of lymphoid follicles most likely proliferating B-lymphoblasts reveal nuclear and cytoplasmatic presence of structural proteins indicating viral replication. Cells of the mononuclear phagocyte system such as cells of lymphatic sinuses and hepatic Kupffer cells harbor viral protein in the cytoplasm, probably resulting from phagocytosis of immune complexes. Renal glomeruli were consistently negative for virus antigen whereas in interstitial infiltrates cells resembling macrophages stained positive for ADV structural proteins.