The evolutionary history of Senna ser. Aphyllae (Leguminosae–Caesalpinioideae), an endemic clade of southern South America

In the legume genus Senna, series Aphyllae includes seven species of leafless shrubs and subshrubs from arid, semiarid and xerophilous areas of three different biogeographic subregions in southern South America. In this study, we investigated the evolutionary history of Aphyllae in a molecular phylogenetic framework. We reconstructed phylogenetic relationships among Aphyllae species based on DNA sequence data of four plastid (rpS16, rpL16, matK, trnL-F) and one nuclear (ITS) region from 23 accessions, analyzed with parsimony, Bayesian and maximum likelihood methods. We inferred the evolutionary and biogeographic history estimating divergence times and reconstructing ancestral character states and ancestral areas of distribution. Series Aphyllae was found to be monophyletic, and the taxa formed two main clades: Clade A gathering S. aphylla var. aphylla, S. crassiramea, S. rigidicaulis and S. spiniflora; and Clade B grouping S. acanthoclada, S. aphylla var. divaricata, S. aphylla var. pendula and S. pachyrrhiza. The morphologically complex S. aphylla appears thus polyphyletic. Molecular dating and ancestral area reconstructions suggest that the Aphyllae clade started to diversify in the South American Transition Zone in the Late Pliocene. Based on these results, we hypothesize that this diversification occurred during the last period of Andean uplift with the aridification in South America. The ancestral character state reconstructions suggest that, in addition to the loss of leaves in adult plants, series Aphyllae evolved various morphological features, such as fastigiate, thickened or decumbent–subdecumbent branches during the colonization and establishment in different arid and semiarid lands in South America.EEA SaltaFil: Robbiati, Federico Omar. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Salta; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Anton, Ana Maria Ramona. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Marazzi, Brigitte. Natural History Museum of Cantone Ticino; SuizaFil: Vásquez-Cruz, Marilyn. Instituto de Ecología. Biología Evolutiva; MéxicoFil: Fortunato, Renee Hersilia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Recursos Biológicos; Argentina. Universidad de Morón. Facultad de Agronomía y Ciencias Agroalimentarias; Argentin

Preclinical development of a molecular clamp-stabilised subunit vaccine for severe acute respiratory syndrome coronavirus 2

Objectives: Efforts to develop and deploy effective vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continue at pace. Here, we describe rational antigen design through to manufacturability and vaccine efficacy of a prefusion-stabilised spike (S) protein, Sclamp, in combination with the licensed adjuvant MF59 'MF59C.1' (Seqirus, Parkville, Australia). Methods: A panel recombinant Sclamp proteins were produced in Chinese hamster ovary and screened in vitro to select a lead vaccine candidate. The structure of this antigen was determined by cryo-electron microscopy and assessed in mouse immunogenicity studies, hamster challenge studies and safety and toxicology studies in rat. Results: In mice, the Sclamp vaccine elicits high levels of neutralising antibodies, as well as broadly reactive and polyfunctional S-specific CD4+ and cytotoxic CD8+ T cells in vivo. In the Syrian hamster challenge model (n = 70), vaccination results in reduced viral load within the lung, protection from pulmonary disease and decreased viral shedding in daily throat swabs which correlated strongly with the neutralising antibody level. Conclusion: The SARS-CoV-2 Sclamp vaccine candidate is compatible with large-scale commercial manufacture, stable at 2-8°C. When formulated with MF59 adjuvant, it elicits neutralising antibodies and T-cell responses and provides protection in animal challenge models

Preclinical development of a molecular clamp-stabilised subunit vaccine for severe acute respiratory syndrome coronavirus 2

Objectives: Efforts to develop and deploy effective vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continue at pace. Here, we describe rational antigen design through to manufacturability and vaccine efficacy of a prefusion-stabilised spike (S) protein, Sclamp, in combination with the licensed adjuvant MF59 'MF59C.1' (Seqirus, Parkville, Australia). Methods: A panel recombinant Sclamp proteins were produced in Chinese hamster ovary and screened in vitro to select a lead vaccine candidate. The structure of this antigen was determined by cryo-electron microscopy and assessed in mouse immunogenicity studies, hamster challenge studies and safety and toxicology studies in rat. Results: In mice, the Sclamp vaccine elicits high levels of neutralising antibodies, as well as broadly reactive and polyfunctional S-specific CD4+ and cytotoxic CD8+ T cells in vivo. In the Syrian hamster challenge model (n = 70), vaccination results in reduced viral load within the lung, protection from pulmonary disease and decreased viral shedding in daily throat swabs which correlated strongly with the neutralising antibody level. Conclusion: The SARS-CoV-2 Sclamp vaccine candidate is compatible with large-scale commercial manufacture, stable at 2-8°C. When formulated with MF59 adjuvant, it elicits neutralising antibodies and T-cell responses and provides protection in animal challenge models