Search

Background: SARS‐CoV2 virus, responsible for the COVID‐19 pandemic, has four structural proteins and 16 nonstructural proteins. S‐protein is one of the structural proteins exposed on the virus surface and is the main target for producing neutralizing antibodies and vaccines. The S‐protein forms a trimer that can bind the angiotensin‐converting enzyme 2 (ACE2) through its receptor binding domain (RBD) for cell entry. Aims: The goal of this study was to express in HEK293 cells a new RBD recombinant protein in a constitutive and stable manner in order to use it as an alternative immunogen and diagnostic tool for COVID‐19. Materials & Methods: The protein was designed to contain an immunoglobulin signal sequence, an explanded C‐terminal section of the RBD, a region responsible for the bacteriophage T4 trimerization inducer, and six histidines in the pCDNA‐3.1 plasmid. Following transformation, the cells were selected with geneticin‐G418 and purified from serum‐fre culture supernatants using Ni2+‐agarand size exclusion chromatography. The protein was structurally identified by cross‐linking and circular dichroism experiments, and utilized to immunize mice in conjuction with AS03 or alum adjuvants. The mice sera were examined for antibody recognition, receptor‐binding inhibition, and virus neutralization, while spleens were evaluated for γ‐interferon production in the presence of RBD. Results: The protein released in the culture supernatant of cells, and exhibited a molecular mass of 135 kDa with a secondary structure like the monomeric and trimeric RBD. After purification, it formed a multimeric structure comprising trimers and hexamers, which were able to bind the ACE2 receptor. It generated high antibody titers in mice when combined with AS03 adjuvant (up to 1:50,000). The sera were capable of inhibiting binding of biotin‐labeled ACE2 to the virus S1 subunit and could neutralize the entry of the Wuhan virus strain into cells at dilutions up to 1:2000. It produced specific IFN‐γ producing cells in immunized mouse splenocytes. Discussion: Our data describe a new RBD containing protein, forming trimers and hexamers, which are able to induce a protective humoral and cellular response against SARS‐CoV2. Conclusion: These results add a new arsenal to combat COVID‐19, as an alternative immunogen or antigen for diagnosis. [ABSTRACT FROM AUTHOR]

Rabies is a fatal viral zoonosis caused by rabies virus (RABV). RABV infects the central nervous system and triggers acute encephalomyelitis in both humans and animals. Endemic in the Brazilian Northeast region, RABV emergence in distinct wildlife species has been identified as a source of human rabies infection and as such, constitutes a public health concern. Here, we performed post‐mortem RABV analyses of 144 encephalic tissues from bats sampled from January to July 2022, belonging to 15 different species. We identified phylogenetically distinct RABV from Phyllostomidae and Molossidae bats circulating in Northeastern Brazil. Phylogenetic clustering revealed the close evolutionary relationship between RABV viruses circulating in bats and variants hosted in white‐tufted marmosets, commonly captured to be kept as pets and linked to human rabies cases and deaths in Brazil. Our findings underline the urgent need to implement a phylogenetic‐scale epidemiological surveillance platform to track multiple RABV variants which may pose a threat to both humans and animals. [ABSTRACT FROM AUTHOR]

The main coronavirus disease 2019 (COVID‐19) vaccine formulations used today are mainly based on the wild‐type severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) spike glycoprotein as an antigen. However, new virus variants capable of escaping neutralization activity of serum antibodies elicited in vaccinated individuals have emerged. The Omicron (B.1.1.529) variant caused epidemics in regions of the world in which most of the population has been vaccinated. In this study, we aimed to understand what determines individual's susceptibility to Omicron in a scenario of extensive vaccination. For that purpose, we collected nasopharynx swab (n = 286) and blood samples (n = 239) from flu‐like symptomatic patients, as well as their vaccination history against COVID‐19. We computed the data regarding vaccine history, COVID‐19 diagnosis, COVID‐19 serology, and viral genome sequencing to evaluate their impact on the number of infections. As main results, we showed that vaccination in general did not reduce the number of individuals infected by Omicron, even with an increased immune response found among vaccinated, noninfected individuals. Nonetheless, we found that individuals who received the third vaccine dose showed significantly reduced susceptibility to Omicron infections. A relevant evidence that support this finding was the higher virus neutralization capacity of serum samples of most patients who received the third vaccine dose. In summary, this study shows that boosting immune responses after a third vaccine dose reduces susceptibility to COVID‐19 caused by the Omicron variant. Results presented in this study are useful for future formulations of COVID‐19 vaccination policies. [ABSTRACT FROM AUTHOR]

The effects of neuroinvasion by severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) become clinically relevant due to the numerous neurological symptoms observed in Corona Virus Disease 2019 (COVID‐19) patients during infection and post‐COVID syndrome or long COVID. This study reports the biofabrication of a 3D bioprinted neural‐like tissue as a proof‐of‐concept platform for a more representative study of SARS‐CoV‐2 brain infection. Bioink is optimized regarding its biophysical properties and is mixed with murine neural cells to construct a 3D model of COVID‐19 infection. Aiming to increase the specificity to murine cells, SARS‐CoV‐2 is mouse‐adapted (MA‐SARS‐CoV‐2) in vitro, in a protocol first reported here. MA‐SARS‐CoV‐2 reveals mutations located at the Orf1a and Orf3a domains and is evolutionarily closer to the original Wuhan SARS‐CoV‐2 strain than SARS‐CoV‐2 used for adaptation. Remarkably, MA‐SARS‐CoV‐2 shows high specificity to murine cells, which present distinct responses when cultured in 2D and 3D systems, regarding cell morphology, neuroinflammation, and virus titration. MA‐SARS‐CoV‐2 represents a valuable tool in studies using animal models, and the 3D neural‐like tissue serves as a powerful in vitro platform for modeling brain infection, contributing to the development of antivirals and new treatments for COVID‐19. [ABSTRACT FROM AUTHOR]

From Alpha to Omicron SARS-CoV-2 variants: What their evolutionary signatures can tell us? Taking into account that SARS-CoV-2 variants carry homoplasy traits from independent evolution,16 where the viral effective population size has earned identical site-specific mutations in the Spike protein (i); assuming that unidentified SARS-CoV-2 variants and sub-lineages carrying new as well as several previously described mutations are very likely to be circulating worldwide (ii) and considering a high vaccine coverage with two/booster-dose schedules (iii): should we expect a high number of severe infections from different SARS-CoV-2 variants? Since the first detection of the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) in 2019, the continuous interest in gaining insights into its epidemiology and evolution is widespread. [Extracted from the article]

The COVID‐19 has originated from Wuhan, China, in December 2019 and has been affecting the public health system, society, and economy in an unheard‐of manner. There is no specific treatment or vaccine available for COVID‐19. Previous data showed that men are more affected than women by COVID‐19, then we hypothesized whether sex hormones could be protecting the female organism against the infection. VERO E6 cells have been commonly used as in vitro model for SARS‐CoV‐2 infection. In our experimental approach, we have treated VERO E6 cells with 17β‐estradiol to evaluate the modulation of SARS‐CoV‐2 infection in this cell line. Here we demonstrated that estrogen protein receptors ERα, ERβ, and GPER1 are expressed by VERO E6 cells and could be used to study the effects of this steroid hormone. Previous and 24‐hours post‐infection, cells treated with 17β‐estradiol revealed a reduction in the viral load. Afterward, we found that SARS‐CoV‐2 infection per se results in ACE2 and TMPRSS2 increased gene expression in VERO E6‐cell, which could be generating a cycle of virus infection in host cells. The estrogen treatment reduces the levels of the TMPRSS2, which are involved with SARS‐CoV‐2 infectiveness capacity, and hence, reducing the pathogenicity/genesis. These data suggest that estrogen could be a potential therapeutic target promoting cell protection against SARS‐CoV‐2. This opens new possibilities for further studies on 17β‐estradiol in human cell lines infected by SARS‐CoV‐2 and at least in part, explain why men developed a more severe COVID‐19 compared to women. [ABSTRACT FROM AUTHOR]

Although interleukin‐24 (IL‐24) has been extensively explored in the immunopathologies of autoimmune diseases, neoplasms, and infections, its role in HIV‐1 infection has not been thoroughly elucidated to date. Therefore, the objective of this study was to evaluate the gene and protein expressions of IL‐24 at the initial moments of HIV infection in PBMCs. Due to the pro‐apoptotic role of IL‐24, we evaluated the protein expression of caspase‐3, as well as Annexin V/Propidium Iodide flow cytometry and phosphorylation of ERK, which may induce an apoptotic signal block when phosphorylated. The results of this study demonstrated that HIV‐1 infection had an impact on the gene and protein expressions of IL‐24 and ERK. Annexin V/Propidium Iodide assay demonstrated decrease in the mechanisms of apoptosis in infected cells after incubation of IL‐24 neutralizing antibody. Studies on how HIV‐1 regulates IL‐24 expression may play a role in characterizing viral persistence mechanisms and designing antiretroviral strategies. [ABSTRACT FROM AUTHOR]

Introduction: In Brazil, the use of antiretrovirals is widespread: more than 260,000 individuals are currently undergoing treatment. We conducted a survey targeting antiretroviral-naı¨ve individuals who were initiating antiretroviral therapy (ART) according to local guidelines. This survey covered five Brazilian regions. Methods: The HIV Threshold Survey methodology (HIV-THS) of the World Health Organization was utilized, and subjects were selected from seven highly populated cities representative of all Brazilian macro-regions. Dried blood spots (DBS) were collected on SS903 collection cards and were transported by regular mail at room temperature to a single central laboratory for genotyping. Results: We analysed samples from 329 individuals initiating highly active antiretroviral therapy (HAART), 39 (11.8%) of whom were harbouring transmitted drug resistance (TDR). The mean CD4 + T cell count was 253 cells/μL, and the mean viral load was 142,044 copies/mL. The regional prevalence of resistance was 17.0% in the Northeast, 12.8% in the Southeast, 10.6% in the Central region, 8.5% in the North and 8.5% in the South. The inhibitor-specific TDR prevalence was 6.9% for nucleoside reverse transcriptase inhibitors, 4.9% for non-nucleoside reverse transcriptase inhibitors and 3.9% for protease inhibitors; 3.6% of individuals presented resistance to more than one class of inhibitors. Overall, there were trends towards higher prevalences of subtype C towards the South and subtype F towards the North. Of the DBS samples collected, 9.3% failed to provide reliable results. Discussion: We identified variable TDR prevalence, ranging from intermediate to high levels, among individuals in whom HIV disease progressed, thus implying that resistance testing before initiating ART could be effective in Brazil. Our results also indicate that the use of DBS might be especially valuable for providing access to testing in resource-limited and remote settings. [ABSTRACT FROM AUTHOR]