Severe acute respiratory syndrome coronavirus 2 infection among healthcare workers in a tertiary public hospital in Curitiba, Brazil

ABSTRACT BACKGROUND: We aimed to describe the clinical characteristics of coronavirus disease 2019 (COVID-19) among healthcare workers (HCWs) in Curitiba, Brazil. METHODS: Upper respiratory samples from 1077 HCWs were tested for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) using reverse transcription polymerase chain reaction from June 16, 2020 to December 9, 2020. RESULTS: Overall, 32.7% of HCWs were infected. The positivity rates in symptomatic and asymptomatic HCWs were 39.2% and 15.9%, respectively. Hospital departments categorized as high-risk for exposure had the highest number of infected HCWs. CONCLUSIONS: Early diagnosis and isolation of infected HCWs remain key in controlling SARS-CoV-2 transmission because HCWs in close contact with COVID-19 patients are more likely to be infected than those who are not.

SARS-CoV-2 in saliva, viremia and seroprevalence for COVID-19 surveillance at a single hematopoietic stem cell transplantation center: a prospective cohort study

ABSTRACT This prospective cohort study aims to analyze the surveillance of COVID-19 at a single hematopoietic stem cell transplantation (HSCT) center in Brazil, in 29 patients undergoing allogeneic HSCT and 57 healthcare workers (nurses and dentists), through viral shedding of SARS-CoV-2 in saliva and plasma and seroprevalence of anti-SARS-CoV-2 IgG. In addition, we report two cases with prolonged persistent detection of SARS-CoV-2 without seroconversion. The sample collection was performed seven times for patients and five times for healthcare workers. Only two patients tested positive for SARS-CoV-2 in their saliva and plasma samples (6.9%) without seroconversion. All healthcare workers were asymptomatic and none tested positive. Two patients (6.9%) and four nurses (8%) had positive serology. No dentists had positive viral detection or positive serology. Our results reflect a low prevalence of positive RT-PCR and seroprevalence of SARS-CoV-2 in patients and healthcare workers at a single HSCT center. Results have also corroborated how the rigorous protocols adopted in transplant centers were even more strengthened in this pandemic scenario.

The zinc finger protein TcZFP2 binds target mRNAs enriched during Trypanosoma cruzi metacyclogenesis

Trypanosomes are parasitic protozoa in which gene expression is primarily controlled through the regulation of mRNA stability and translation. This post-transcriptional control is mediated by various families of RNA-binding proteins, including those with zinc finger CCCH motifs. CCCH zinc finger proteins have been shown to be essential to differentiation events in trypanosomatid parasites. Here, we functionally characterise TcZFP2 as a predicted post-transcriptional regulator of differentiation in Trypanosoma cruzi. This protein was detected in cell culture-derived amastigotes and trypomastigotes, but it was present in smaller amounts in metacyclic trypomastigote forms of T. cruzi. We use an optimised recombinant RNA immunopreciptation followed by microarray analysis assay to identify TcZFP2 target mRNAs. We further demonstrate that TcZFP2 binds an A-rich sequence in which the adenosine residue repeats are essential for high-affinity recognition. An analysis of the expression profiles of the genes encoding the TcZFP2-associated mRNAs throughout the parasite life cycle by microarray hybridisation showed that most of the associated mRNAs were upregulated in the metacyclic trypomastigote forms, also suggesting a role for TcZFP2 in metacyclic trypomastigote differentiation. Knockdown of the orthologous Trypanosoma brucei protein levels showed ZFP2 to be a positive regulator of specific target mRNA abundance.

TcYchF - uma nova ATPase associada à maquinaria de tradução do protozoário Trypanosoma cruzi / TcYchF - a new ATPase associated with the machinery of translation of the protozoa Trypanosoma cruzi

Muitos processos celulares, incluindo síntese de proteínas, tráfego vesicular, transporte intracelular, sinalização e diferenciação celular, envolvem um importante grupo de proteínas da superfamília das P-loop GTPases. Algumas dessas GTPases, embora ubíquas, não tem função conhecida. Dentro desse último grupo está a subfamília de GTPases conhecida como YchF. A subfamília das GTPases YchF pertence a família das Obg GTPases, é ubíqua em bactérias e eucariotos e apresenta uma notável conservação de seqüência. Nós caracterizamos o ortólogo da YchF em Trypanosoma cruzi, TcYchF, potencialmente associada com a maquinaria de tradução. TcYchF é uma proteína de 44,3 kDa e possui grande percentagem de similaridade com seus ortólogos eucarióticos (45 a 86%), bem como com os ortólogos bacterianos (38 a 43%). Algumas das mais importantes características do domínio G, responsável pelo reconhecimento e hidrólise do GTP e interação com outras proteínas, são cnservadas em TcYchF. Apesar da sua classificação como uma GTPase, verificamos que a TcYchF hidrolisa preferencialmente ATP em relação à GTP. Embora a função das proteínas da subfamília YchF seja desconhecida, outros membros da família Obg, a qual YchF pertence, estão involvidos na biogênese das subunidades ribossomais. Algumas delas foram encontradas em associação com ribossomos, sugerindo que possam ser fatores envolvidos no processo de tradução. De fato, a análise por western blot do fracionamento de polissomos por gradiente de sacarose mostrou que TcYchF estava associada tanto com subunidades ribossomais quanto com polissomos, sugerindo o seu envolvimento com a maquinaria de tradução de T. cruzi. A análise proteômica desses imunocomplexos mostra a associação da TcYchF não só com proteínas ribossomais, mas com diversos fatores de tradução e com a proteína RPN7 da subunidade regulatória do proteassomo. Esses resultados foram corroborados pela análise de imunoprecipitação, que mostrou que TcYchF...