Enhanced Assessment of Cross-Reactive Antigenic Determinants within the Spike Protein.

Despite successful vaccination efforts, the emergence of new SARS-CoV-2 variants poses ongoing challenges to control COVID-19. Understanding humoral responses regarding SARS-CoV-2 infections and their impact is crucial for developing future vaccines that are effective worldwide. Here, we identified 41 immunodominant linear B-cell epitopes in its spike glycoprotein with an SPOT synthesis peptide array probed with a pool of serum from hospitalized COVID-19 patients. The bioinformatics showed a restricted set of epitopes unique to SARS-CoV-2 compared to other coronavirus family members. Potential crosstalk was also detected with Dengue virus (DENV), which was confirmed by screening individuals infected with DENV before the COVID-19 pandemic in a commercial ELISA for anti-SARS-CoV-2 antibodies. A high-resolution evaluation of antibody reactivity against peptides representing epitopes in the spike protein identified ten sequences in the NTD, RBD, and S2 domains. Functionally, antibody-dependent enhancement (ADE) in SARS-CoV-2 infections of monocytes was observed in vitro with pre-pandemic Dengue-positive sera. A significant increase in viral load was measured compared to that of the controls, with no detectable neutralization or considerable cell death, suggesting its role in viral entry. Cross-reactivity against peptides from spike proteins was observed for the pre-pandemic sera. This study highlights the importance of identifying specific epitopes generated during the humoral response to a pathogenic infection to understand the potential interplay of previous and future infections on diseases and their impact on vaccinations and immunodiagnostics.

Extracellular vesicles from primary human macrophages stimulated with VIP or PACAP mediate anti-SARS-CoV-2 activities in monocytes through NF-κB signaling pathway.

Infection by SARS-CoV-2 is associated with uncontrolled inflammatory response during COVID-19 severe disease, in which monocytes are one of the main sources of pro-inflammatory mediators leading to acute respiratory distress syndrome. Extracellular vesicles (EVs) from different cells play important roles during SARS-CoV-2 infection, but investigations describing the involvement of EVs from primary human monocyte-derived macrophages (MDM) on the regulation of this infection are not available. Here, we describe the effects of EVs released by MDM stimulated with the neuropeptides VIP and PACAP on SARS-CoV-2-infected monocytes. MDM-derived EVs were isolated by differential centrifugation of medium collected from cells cultured for 24 h in serum-reduced conditions. Based on morphological properties, we distinguished two subpopulations of MDM-EVs, namely large (LEV) and small EVs (SEV). We found that MDM-derived EVs stimulated with the neuropeptides inhibited SARS-CoV-2 RNA synthesis/replication in monocytes, protected these cells from virus-induced cytopathic effects and reduced the production of pro-inflammatory mediators. In addition, EVs derived from VIP- and PACAP-treated MDM prevented the SARS-CoV-2-induced NF-κB activation. Overall, our findings suggest that MDM-EVs are endowed with immunoregulatory properties that might contribute to the antiviral and anti-inflammatory responses in SARS-CoV-2-infected monocytes and expand our knowledge of EV effects during COVID-19 pathogenesis.

Diminazene aceturate inhibits the SARS-CoV-2 spike protein-induced inflammation involving leukocyte migration and DNA extracellular traps formation.

AIMS: To investigate the SARS-CoV-2 Spike protein (Spk)-induced inflammatory response and its downmodulation by diminazene aceturate (DIZE). MATERIALS AND METHODS: Through inducing Spk inflammation in murine models, leukocyte migration to the peritoneum, levels of myeloperoxidase (MPO), malondialdehyde (MDA), rolling and adhesion of mesenteric leukocytes, and vascular permeability were investigated. Extracellular DNA traps (DETs) induced by Spk and the production of IL-6 and TNF-α were analyzed using human neutrophils, monocytes, and macrophages. In silico assays assessed the molecular interaction between DIZE and molecules related to leukocyte migration and DETs induction. KEY FINDINGS: Spk triggered acute inflammation, demonstrated by increasing leukocyte migration. Oxidative stress was evidenced by elevated levels of MPO and MDA in the peritoneal liquid. DIZE attenuated cell migration, rolling, and leukocyte adhesion, improved vascular barrier function, mitigated DETs, and reduced the production of Spk-induced pro-inflammatory cytokines. Computational studies supported our findings, showing the molecular interaction of DIZE with targets such as ß2 integrin, PI3K, and PAD2 due to its intermolecular coupling. SIGNIFICANCE: Our results outline a novel role of DIZE as a potential therapeutic agent for mitigating Spk-induced inflammation.

Isolation and antigenic characterization of human immunodeficiency virus (HIV) in Brazil

Isolamento e caracterizaçäo antigênica do vírus da imunodeficiência humana (VIH/HIV) no Brasil - Um retrovírus foi isolado de um paciente brasileiro com "Síndrome de Imunodeficiência Adquirida" (SIDA/AIDS) e caracterizado em termos de sua reatividade com soros de indivíduos infectados com vírus da imunodeficiência humana dos tipos 1 e 2 (HIV-1 e HIV-2). A análise antigênica por "Western blot" revelou que o isolado brasileiro é bastante similar a uma cepa de HIV-1 bem caracterizada. A identificaçäo do retrovírus como HIV-1 e näo HIV-2 é reforçada pelo fato dos anticorpos do paciente do qual foi isolado o vírus näo terem reagido com a glicoproteínas de envelope de 140 kDa, específica para HIV-2

Melhora importante nos resultados de transplantes renais após transfusöes sanguíneas específicas do doador: experiência pessoal e revisäo da literatura / Important improvement of renal transplantation results after donor-specific blood transfusion: personal experience and literature review

Demonstramos importante melhora nos resultados de transplantes renais (TR) após transfusöes sanguíneas específicas do doador (TSED), com e sem cobertura de droga imunodepressora (TSEDI ou TSEDS) quando comparados aos alcançados em TR realizados em pacientes com doadores HLA näo-idênticos (HLANI). De 39 pacientes que participaram do protocolo de TSED (20 TSEDS e 19 TSEDI) entre 1982 e 1985, 28 receberam rins de seus doadores prospectivos (14 TSEDS e 14 TSEDI) e os resultados säo comparados com 9 TR realizados entre pares HLA idênticos (HLAI) e 43 entre pares HLANI sem TSED, transolantados após 1980. Oitenta TR foram comparados, näo havendo diferenças significativas em faixa etária (6 a 60 anos, média 31), número de transfusöes sanguíneas inespecíficas (TSI), causas de insuficiência renal crônica terminal (IRCT) e parentesco com os doadores (exceto por terem sido realizados 5 TR com doadores vivos näo-relacionados - DVNR - no grupo TSED). O seguimento dos pacientes variou de 3 a 63 meses, embora tenha sido considerado 21 meses o limite por ter sido o período máximo de seguimento dos pacientes com TSEDI. A medicaçäo imunodepressora de rotina pós-operatória (prednisona e azatioprina) e a terapêutica para episódios