Seroprevalence of IgG and IgM anti-SARS-CoV-2 among voluntary blood donors in Rio de Janeiro, Brazil

Background: In Brazil, mathematical models for deriving estimates and projections of COVID-19 cases have been developed without data on asymptomatic SARS-CoV-2 infection. We estimated the seroprevalence of antibodies to SARS-CoV-2 among blood donors in the State of Rio de Janeiro. Methods: Data were collected on 2,857 blood donors from April 14 to 27, 2020. We report the crude prevalence of antibodies to SARS-CoV-2, the weighted prevalence by the total state population, and adjusted prevalence estimates for test sensitivity and specificity. To establish the correlates of SARS-CoV-2 prevalence, we used logistic regression models. The analysis included period and site of blood collection, sociodemographic characteristics, and place of residence. Results: The proportion of SARS-Cov-2 positive tests without any adjustment was 4.0% (95% CI 3.3-4.7%), and the weighted prevalence was 3.8% (95% CI 3.1-4.5%). Further adjustment by test sensitivity and specificity produced lower estimates, 3.6% (95% CI 2.7-4.4%) and 3.3% (95% CI 2.6-4.1%), respectively. The variable most significantly associated with the crude prevalence was the period of blood collection: the later the period, the higher the prevalence. Regarding socio-demographic characteristics, the younger the blood donors, the higher the prevalence, and the lower the educational level, the higher the odds of a positive SARS-Cov-2 antibody. Similar results were found for the weighted prevalence. Discussion: Although our findings resulted from a convenience sample, they match some basic premises: the increasing trend over time, since the epidemic curve in the state is still on the rise; the higher prevalence among the youngest who are more likely to circulate; and the higher prevalence among the less educated as they have more difficulties in following the social distancing recommendations. Despite the study limitations, it is possible to infer that protective levels of natural herd immunity to SARS-CoV-2 are far from being reached in Rio de Janeiro

Roflumilast n-oxide associated with PGE2 prevents the neutrophil elastase-induced production of chemokines by epithelial cells

International audienceNeutrophil chemotaxis is involved in the lung inflammatory process in conditions such as chronic obstructive pulmonary disease (COPD). Neutrophil elastase (NE), one of the main proteases produced by neutrophils, has an important role in the inflammatory process via the release of chemokines from airway epithelial cells. It was recently shown that roflumilast N-oxide has therapeutic potential in COPD. The aim of the present study was to investigate roflumilast N-oxide's effect on NE-induced chemokine production and signaling pathways in A549 epithelial cells. A549 cells were incubated with NE for 30min, washed with PBS and then cultured for 2h (for measurement of mRNA expression) and 24h (for chemokine release) or for 5 to 30min (for protein phosphorylation assays). Prior to the addition of NE, cells were also pre-incubated with prostaglandin E2 (PGE2), alone and in combination with roflumilast N-oxide. Addition of NE was associated with elevated chemokine production by A549 cells and induction of the p38α pathway. In contrast when combined with PGE2, the roflumilast N-oxide had an additive effect on the inhibition of NE-induced chemokine release and p38α and other kinases activation. In conclusion, we demonstrated that NE is able to increase the release of chemokines from epithelial cells via the activation of p38α MAP-kinase and that roflumilast N-oxide when combined with PGE2 lowers NE-induced kinase activation and chemokine productio

Effects of CSE and LPS alone or in combination in ERK1/2, p38 and JNK activation.

<p>Serum-starved A549 cells were incubated with serum free medium alone (control, Ctrl), LPS 0.1 µg/ml, CSE 4% or CSE 4% associated with LPS 0.1 µg/ml for 5, 15, 30, 60 or 120 min. Total cell lysates were immunoblotted with antibodies specific for phospho-p38 kinase and total p38 kinase (<i>A</i>), phospho-JNK and total JNK (<i>B</i>) or phospho ERK1/2 and total ERK1/2 (<i>C</i>). A549 cells stimulated with IL-1β (7 ng/ml) were used as positive controls. The data represent the mean ± SEM of 3 experiments. * p<0.05 compared to control; α p<0.05 compared to LPS 0.1 µg/ml.</p

Roflumilast N-oxide associated with PGE₂ partly inhibits chemokines release from A549 cells stimulated with CSE+LPS.

<p>Cells were preincubated with vehicle (blank bars) or 10 nM PGE₂ with roflumilast N-oxide at 1 nM (A, B and C) or 1 µM (D, E and F) (hatched bars) for 2 h and then stimulated or not with CSE at 2% or 4% in combination with LPS at 0.1 µg/ml. After 24 hours cell culture supernatants were collected and chemokines were quantified by ELISA. Results are expressed as means ± SEM of 3 independent experiments. * p<0.05 compared to control (0.01% DMSO); # p<0.05 compared to vehicle.</p

Effects of CSE (0.1%–10%) and LPS (10 ng/ml–10 µg/ml) on chemokine release and cell viability.

<p>Serum-starved A549 cells were incubated with medium alone (control) or with different concentration of CSE (0.1%–10%) and LPS (10 ng/ml–10 µg/ml) for 24 h. The culture supernatants were collected and the concentrations of IL-8/CXCL8, Gro-α/CXCL1 and MCP-1/CCL2 were measured by ELISA (A, B, C and D) and viability was determined by MTT test (E). The data represent the mean ± SEM of 3 experiments. * p<0.05 compared to control.</p

Effects of CSE and LPS alone or in combination on selected phosphoproteins in A549 cells.

<p>Cells were incubated for 40-free medium alone (control), LPS 0.1 µg/ml (A), CSE 4% (B), or CSE 4% and LPS 0.1 µg/ml (C). Then cell extracts were probed on human phosphoprotein arrays. Results representing the signal intensity (AU) were expressed as % of the unstimulated control. Data are expressed as means ± SEM of 3 independent experiments. * p<0.05 compared to control.</p

Effects of roflumilast N-oxide on selected phosphoproteins in A549 cells.

<p>Cells were preincubated for 2(blank bars) or PGE₂ (10 nM) and roflumilast N-oxide (1 nM) (hatched bars) then co-stimulated with CSE (4%) and LPS (0.1 µg/ml). Cell extracts were probed on human phosphoprotein arrays. Results representing the signal intensity (AU) were expressed as % of the unstimulated control. Data are expressed as means ± SEM of 3 independent experiments. * p<0.05 compared to control; # p<0.05 compared to respective vehicle.</p

CSE associated with LPS induced chemokine release from A549 cells and mRNA expression.

<p>Serum-starved A549 cells were incubated with medium alone (control), CSE 2% or 4% (blank bars), LPS 0.1 µg/ml alone or in combination with 2 or 4% of CSE (hatched bars) for 24 h. The culture supernatants were collected and the concentrations of chemokines were measured by ELISA (A, B and C). The data represent the mean ± SEM of 7 experiments. A549 cells were stimulated for 2 h. mRNA expression was then determined by real-time quantitative RT-PCR (D, E and F). The results are normalized to the gene expression of GAPDH. The data represent the mean ± SEM of 4 experiments. * p<0.05 compared to control; α p<0.05 compared to LPS 0.1 µg/ml.</p

Seroprevalence of anti-SARS-CoV-2 among blood donors in Rio de Janeiro, Brazil

OBJECTIVE: To estimate the seroprevalence of antibodies to SARS-CoV-2 among blood donors in the state of Rio de Janeiro, Brazil. METHODS: Data were collected on 2,857 blood donors from April 14 to 27, 2020. This study reports crude prevalence of antibodies to SARS-CoV-2, population weighted prevalence for the state, and prevalence adjusted for test sensitivity and specificity. Logistic regression models were used to establish the correlates of SARS-CoV-2 prevalence. For the analysis, we considered collection period and site, sociodemographic characteristics, and place of residence. RESULTS: The proportion of positive tests for SARS-Cov-2, without any adjustment, was 4.0% (95%CI 3.3–4.7%), and the weighted prevalence was 3.8% (95%CI 3.1–4.5%). We found lower estimates after adjusting for test sensitivity and specificity: 3.6% (95%CI 2.7–4.4%) for the non-weighted prevalence, and 3.3% (95%CI 2.6–4.1%) for the weighted prevalence. Collection period was the variable most significantly associated with crude prevalence: the later the period, the higher the prevalence. Regarding sociodemographic characteristics, the younger the blood donor, the higher the prevalence, and the lower the education level, the higher the odds of testing positive for SARS-Cov-2 antibody. We found similar results for weighted prevalence. CONCLUSIONS: Our findings comply with some basic premises: the increasing trend over time, as the epidemic curve in the state is still on the rise; and the higher prevalence among both the youngest, for moving around more than older age groups, and the less educated, for encountering more difficulties in following social distancing recommendations. Despite the study limitations, we may infer that Rio de Janeiro is far from reaching the required levels of herd immunity against SARS-CoV-2.

Evaluation of Naturally Acquired IgG Antibodies to a Chimeric and Non-Chimeric Recombinant Species of Plasmodium vivax Reticulocyte Binding Protein-1: Lack of Association with HLA-DRB1*/DQB1* in Malaria Exposed Individuals from the Brazilian Amazon

Made available in DSpace on 2015-06-22T12:26:39Z (GMT). No. of bitstreams: 2 license.txt: 1914 bytes, checksum: 7d48279ffeed55da8dfe2f8e81f3b81f (MD5) dalma_banicetal_IOC_2014.pdf: 999806 bytes, checksum: 4c409a84e1fed1f60ad648fcb94d2723 (MD5) Previous issue date: 2014Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Imunoparasitologia. Rio de Janeiro, RJ, Brasil.Emory University. Yerkes National Primate Research Center. Emory Vaccine Center. Atlanta, Geogia, USA.Emory University. Yerkes National Primate Research Center. Emory Vaccine Center. Atlanta, Georgia, USA.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Imunoparasitologia. Rio de Janeiro, RJ, Brasil.Universidade do Estado do Rio de Janeiro. Laboratório de Criopreservação e Histocompatibilidade. Rio de Janeiro, RJ, Brasil.Universidade do Estado do Rio de Janeiro. Laboratório de Criopreservação e Histocompatibilidade. Rio de Janeiro, RJ, Brasil.Fundação Nacional de Saúde. Departamento de Entomologia. Laboratório Central. Porto Velho, RO, Brasil.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Referência Nacional de Simulídeos e Oncocercose. Rio de Janeiro, RJ, Brasil.University of Massachusetts. Medical School. Department of Pathology. Worcester, Massachusetts, USA.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Imunoparasitologia. Rio de Janeiro, RJ, Brasil.Emory University. Yerkes National Primate Research Center. Emory Vaccine Center. Department of Medicine. Division of Infectious Diseases. Atlanta, Geogia, USA.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Imunoparasitologia. Rio de Janeiro, RJ, Brasil.The development of modular constructs that include antigenic regions targeted by protective immune responses is an attractive approach for subunit vaccine development. However, a main concern of using these vaccine platforms is how to preserve the antigenic identity of conformational B cell epitopes. In the present study we evaluated naturally acquired antibody responses to a chimeric protein engineered to contain a previously defined immunodominant domain of the Plasmodium vivax reticulocyte binding protein-1 located between amino acid positions K435-I777. The construct also includes three regions of the cognate protein (F571-D587, I1745-S1786 and L2235-E2263) predicted to contain MHC class II promiscuous T cell epitopes. Plasma samples from 253 naturally exposed individuals were tested against this chimeric protein named PvRMC-RBP1 and a control protein that includes the native sequence PvRBP123-751 in comparative experiments to study the frequency of total IgG and IgG subclass reactivity. HLA-DRB1 and HLA-DQB1 allelic groups were typed by PCR-SSO to evaluate the association between major HLA class II alleles and antibody responses. We found IgG antibodies that recognized the chimeric PvRMC-RBP1 and the PvRBP123-751 in 47.1% and 60% of the studied population, respectively. Moreover, the reactivity index against both proteins were comparable and associated with time of exposure (p,0.0001) and number of previous malaria episodes (p,0.005). IgG subclass profile showed a predominance of cytophilic IgG1 over other subclasses against both proteins tested. Collectively these studies suggest that the chimeric PvRMC-RBP1 protein retained antigenic determinants in the PvRBP1435–777 native sequence. Although 52.9% of the population did not present detectable titers of antibodies to PvRMC-RBP1, genetic restriction to this chimeric protein does not seem to occur, since no association was observed between the HLA-DRB1* or HLA-DQB1* alleles and the antibody responses. This experimental evidence strongly suggests that the identity of the conformational B cell epitopes is preserved in the chimeric protein