Neutralizing antibody levels are highly predictive of immune protection from symptomatic SARS-CoV-2 infection

Predictive models of immune protection from COVID-19 are urgently needed to identify correlates of protection to assist in the future deployment of vaccines. To address this, we analyzed the relationship between in vitro neutralization levels and the observed protection from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection using data from seven current vaccines and from convalescent cohorts. We estimated the neutralization level for 50% protection against detectable SARS-CoV-2 infection to be 20.2% of the mean convalescent level (95% confidence interval (CI) = 14.4-28.4%). The estimated neutralization level required for 50% protection from severe infection was significantly lower (3% of the mean convalescent level; 95% CI = 0.7-13%, P = 0.0004). Modeling of the decay of the neutralization titer over the first 250 d after immunization predicts that a significant loss in protection from SARS-CoV-2 infection will occur, although protection from severe disease should be largely retained. Neutralization titers against some SARS-CoV-2 variants of concern are reduced compared with the vaccine strain, and our model predicts the relationship between neutralization and efficacy against viral variants. Here, we show that neutralization level is highly predictive of immune protection, and provide an evidence-based model of SARS-CoV-2 immune protection that will assist in developing vaccine strategies to control the future trajectory of the pandemic

Phylogeny with introgression in Habronattus jumping spiders (Araneae: Salticidae)

Background: Habronattus is a diverse clade of jumping spiders with complex courtship displays and repeated evolution of Y chromosomes. A well-resolved species phylogeny would provide an important framework to study these traits, but has not yet been achieved, in part because the few genes available in past studies gave conflicting signals. Such discordant gene trees could be the result of incomplete lineage sorting (ILS) in recently diverged parts of the phylogeny, but there are indications that introgression could be a source of conflict. Results: To infer Habronattus phylogeny and investigate the cause of gene tree discordance, we assembled transcriptomes for 34 Habronattus species and 2 outgroups. The concatenated 2.41 Mb of nuclear data (1877 loci) resolved phylogeny by Maximum Likelihood (ML) with high bootstrap support (95-100%) at most nodes, with some uncertainty surrounding the relationships of H. icenoglei, H. cambridgei, H. oregonensis, and Pellenes canadensis. Species tree analyses by ASTRAL and SVDQuartets gave almost completely congruent results. Several nodes in the ML phylogeny from 12.33 kb of mitochondrial data are incongruent with the nuclear phylogeny and indicate possible mitochondrial introgression: the internal relationships of the americanus and the coecatus groups, the relationship between the altanus, decorus, banksi, and americanus group, and between H. clypeatus and the coecatus group. To determine the relative contributions of ILS and introgression, we analyzed gene tree discordance for nuclear loci longer than 1 kb using Bayesian Concordance Analysis (BCA) for the americanus group (679 loci) and the VCCR clade (viridipes/clypeatus/coecatus/roberti groups) (517 loci) and found signals of introgression in both. Finally, we tested specifically for introgression in the concatenated nuclear matrix with Patterson’s D statistics and DFOIL. We found nuclear introgression resulting in substantial admixture between americanus group species, between H. roberti and the clypeatus group, and between the clypeatus and coecatus groups. Conclusions: Our results indicate that the phylogenetic history of Habronattus is predominantly a diverging tree, but that hybridization may have been common between phylogenetically distant species, especially in subgroups with complex courtship displays.Science, Faculty ofBotany, Department ofZoology, Department ofReviewedFacult

Size-Dependent Optical Properties of Metallic Nanostructures

Metallic nanostructures are a key component of current and future nanotechnology devices since their individual properties convey the appropriate characteristics for applications in several fields of science and technology. At the nanoscale size, optical properties of metal structures depend not only on the type of material but also on the dimensions and geometry of the structure, suggesting the possibility of tuning optical resonances through appropriate engineering. In this chapter, we will describe methods for calculation of size-dependent optical properties of metal nanostructures and show the successful use of extinction spectroscopy technique to determine the size of nanoparticles (Nps).Fil: Scaffardi, Lucia Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil; ArgentinaFil: Schinca, Daniel Carlos. No especifíca;Fil: Lester, Marcelo Fabian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil; ArgentinaFil: Videla, Fabian Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil; ArgentinaFil: Santillán, Jesica María José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil; ArgentinaFil: Abraham, Ricardo Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil; Argentin