Fc-dependent functional activity of ChAdOx1-S and CoronaVac vaccine-induced antibodies to the SARS-CoV-2 spike protein (preprint)

Ongoing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission and COVID-19 disease severity is influenced by immunity acquired by natural exposure and/or vaccination, whereby most vaccines are formulated on the Ancestral strain. However, population-level immunity is complicated by the emergence of variants of concern (VOCs), such as Omicron that is the dominant variant currently in circulation. Antibody Fc-dependent effector functions are being increasingly recognised as important mediators in immunity, especially against VOCs. However, induction of these functions in populations with diverse infection and/or vaccination histories, remains poorly defined. Here, we evaluated Fc-dependent functional antibodies following vaccination with two widely used vaccines: AstraZeneca (AZ; ChAdOx1-S) and Sinovac (SV). We quantified Fc{gamma}R-binding and C1q-fixing antibodies against Ancestral and variant spike (S) proteins in Brazilian adults vaccinated with AZ or SV (n=222), some of which were previously exposed to SARS-CoV-2. AZ induced greater Fc{gamma}R-binding responses to Ancestral S than the SV vaccine. Previously exposed individuals had significantly greater vaccine-induced responses compared to their naive counterparts, with notably high C1q-fixation levels, irrespective of vaccine type. Fc{gamma}R-binding was highest among AZ vaccinated individuals with a prior exposure, and these responses were well retained against the Omicron S protein. Overall, these findings contribute to our understanding of vaccine-induced immunity and its effectiveness against evolving variants.

A theoretical analysis of the putative ORF10 protein in SARS-CoV-2 (preprint)

Found just upstream of the 3'-untranslated region in the SARS-CoV-2 genome is the putative ORF10 which has been proposed to encode for the hypothetical ORF10 protein. Even though current research suggests this protein is not likely to be produced, further investigations into this protein are still warranted. Herein, this study uses multiple bioinformatic programs to theoretically characterize and construct the ORF10 protein in SARS-CoV-2. Results indicate this protein is mostly ordered and hydrophobic with high protein-binding propensity, especially in the N-terminus. Although minimal, an assessment of twenty-two missense mutations for this protein suggest slight changes in protein flexibility and hydrophobicity. When compared against two other protein models, this study's model was found to possess higher quality. As such, this model suggests the ORF10 protein contains a {beta}--{beta} motif with a {beta}-molecular recognition feature occurring as the first {beta}-strand. Furthermore, this protein also shares a strong phylogenetic relationship with other putative ORF10 protein's in closely related coronaviruses. Despite not yielding evidence for the existence of this protein within SARS-CoV-2, this study does present theoretical examinations that can serve as platforms to drive additional experimental work that assess the biological relevance of this hypothetical protein in SARS-CoV-2.

Clinical and laboratory characteristics in outpatient diagnosis of COVID-19 in healthcare professionals in Rio de Janeiro, Brazil (preprint)

AimsThis study aimed to identify the symptoms associated with early stage SARS-CoV-2 (COVID-19) infections in healthcare professionals (HCP) using both clinical and laboratory data. MethodsA total of 1,297 patients, admitted between March 18 and April 8, 2020, were stratified according to their risk of developing COVID-19 using their responses to a questionnaire designed to evaluate symptoms and risk conditions. ResultsAnosmia/hyposmia (p <0.0001), fever (p<0.0001), body pain (p<0.0001), and chills (p=0.001) were all independent predictors for COVID-19, with a 72% estimated probability for detecting COVID-19 in nasopharyngeal swab samples. Leukopenia, relative monocytosis, decreased eosinophil values, CRP, and platelets were also shown to be significant independent predictors for COVID-19. ConclusionsThe significant clinical features for COVID-19 were identified as anosmia, fever, chills, and body pain. Elevated CRP, leukocytes under 5,400 x 109/L, and relative monocytosis (>9%) were common among patients with a confirmed COVID-19 diagnosis. These variables may help, in the absence of RT-PCR tests, to identify possible COVID-19 infections during pandemic outbreaks. SummaryFrom March 19 to April 8 2020, 1,297 patients attended the Polyclinic Piquet Carneiro for COVID-19 detection. Healthcare professional data was analyzed, significant clinical features were anosmia, fever, chills and body pain. Elevated CRP, leukopenia and monocytosis were common in COVID-19.