In this trial involving more than 24,000 participants, the efficacy of two doses of a viruslike-particle, plant-based vaccine with adjuvant was 69.5% against symptomatic Covid-19 and 78.8% against ...moderate-to-severe disease. More than 80% of vaccine recipients had local or systemic adverse effects, which were generally mild and short-lived.
As the SARS-CoV-2 pandemic evolves, vaccine evaluation needs to include consideration of both durability and cross-reactivity. This report expands on previously reported results from a Phase 1 trial ...of an AS03-adjuvanted, plant-based coronavirus-like particle (CoVLP) displaying the spike (S) glycoprotein of the ancestral SARS-CoV-2 virus in healthy adults (NCT04450004). Humoral and cellular responses against the ancestral strain were evaluated 6 months post-second dose (D201) as secondary outcomes. Independent of dose, all vaccinated individuals retain binding antibodies, and ~95% retain neutralizing antibodies (NAb). Interferon gamma and interleukin-4 responses remain detectable in ~94% and ~92% of vaccinees respectively. In post-hoc analyses, variant-specific (Alpha, Beta, Delta, Gamma and Omicron) NAb were assessed at D42 and D201. Using a live virus neutralization assay, broad cross-reactivity is detectable against all variants at D42. At D201, cross-reactive antibodies are detectable in almost all participants against Alpha, Gamma and Delta variants (94%) and the Beta variant (83%) and in a smaller proportion against Omicron (44%). Results are similar with the pseudovirion assay. These data suggest that two doses of 3.75 µg CoVLP+AS03 elicit a durable and cross-reactive response that persists for at least 6 months post-vaccination.
To date, five members of the downstream of tyrosine kinase (Dok) family have been characterized. In T cells, two members, Dok-1 and Dok-2, are expressed. CD2 or CD28 stimulation, but not CD3/TCR ...stimulation, induces Dok phosphorylation. Recent evidence suggests that they act as negative regulators of the CD2 and CD28 signaling pathways. To identify the molecular mechanisms involved in Dok-mediated inhibition, we have identified proteins that bind to the phosphotyrosine-binding (PTB) domain of Dok-1 and Dok-2. We showed that the Dok PTB domain mediates phosphotyrosine-dependent homotypic and heterotypic interactions of Dok-1 and Dok-2. Moreover, in CD2-stimulated Jurkat cells, Dok-1 coimmunoprecipitates with tyrosine-phosphorylated Dok-2. To study the involvement of PTB-mediated oligomerization in Dok function, we have generated Jurkat clones overexpressing Dok-1 or Dok-2 with a mutation that prevents oligomerization (in either the PTB domain or Tyr146 of Dok-1 and Tyr139 of Dok-2). These mutations abrogate CD2-induced phosphorylation and the ability of Dok-1 or Dok-2 to inhibit CD2-induced ERK1/2 and NFAT activation. Moreover, overexpression of Dok-1Y146F or Dok-2Y139F interferes with CD2-induced phosphorylation of endogenous Dok, whereas overexpression of PTB mutant or wild-type Dok does not. Taken together, these data indicate that PTB-mediated oligomerization of Dok-1 and Dok-2 represents an essential step for Dok phosphorylation and function.
Abstract
The rapid spread of SARS-CoV-2 continues to impact humanity on a global scale with rising total morbidity and mortality. Despite the development of several effective vaccines, new products ...are needed to supply ongoing demand and to fight variants. We report herein a pre-specified interim analysis of the phase 2 portion of a Phase 2/3, randomized, placebo-controlled trial of a coronavirus virus-like particle (CoVLP) vaccine candidate, produced in plants that displays the SARS-CoV-2 spike glycoprotein, adjuvanted with AS03 (NCT04636697). A total of 753 participants were recruited between 25th November 2020 and 24th March 2021 into three groups: Healthy Adults (18–64 years:
N
= 306), Older Adults (≥65 years:
N
= 282) and Adults with Comorbidities (≥18 years:
N
= 165) and randomized 5:1 to receive two intramuscular doses of either vaccine (3.75 µg CoVLP/dose+AS03) or placebo, 21 days apart. This report presents safety, tolerability and immunogenicity data up to 6 months post-vaccination. The immune outcomes presented include neutralizing antibody (NAb) titres as measured by pseudovirion assay at days 21 and 42 as well as neutralizing antibody cross-reactivity to several variants of concern (VOCs): Alpha, Beta, Gamma, Delta, and Omicron (BA.1), up to 201 days post-immunization. Cellular (IFN-γ and IL-4 ELISpot) response data in day 21 and 42 peripheral blood are also presented. In this study, CoVLP+AS03 was well-tolerated and adverse events (AE) after each dose were generally mild to moderate and transient. Solicited AEs in Older Adults and Adults with Comorbidities were generally less frequent than in Healthy Adults and the reactogenicity was higher after the second dose. CoVLP+AS03 induced seroconversion in >35% of participants in each group after the first dose and in ~98% of participants, 21 days after the second dose. In all cohorts, 21-days after the second dose, NAb levels in sera against the vaccine strain were ~10-times those in a panel of convalescent sera. Cross-reactivity to Alpha, Beta and Delta variants was generally retained to day 201 (>80%) while cross-reactivity to the Gamma variant was reduced but still substantial at day 201 (73%). Cross-reactivity to the Omicron variant fell from 72% at day 42 to 20% at day 201. Almost all participants in all groups (>88%) had detectable cellular responses (IFN-γ, IL-4 or both) at 21 days after the second dose. A Th1-biased response was most evident after the first dose and was still present after the second dose. These data demonstrated that CoVLP+AS03 is well-tolerated and highly immunogenic, generating a durable (at least 6 months) immune response against different VOCs, in adults ≥18 years of age, with and without comorbidities.
The 12th GCC Closed Forum was held in Philadelphia, PA, USA, on 9 April 2018. Representatives from international bioanalytical Contract Research Organizations were in attendance in order to discuss ...scientific and regulatory issues specific to bioanalysis. The issues discussed at the meeting included: critical reagents; oligonucleotides; certificates of analysis; method transfer; high resolution mass spectrometry; flow cytometry; recent regulatory findings and case studies involving stability and nonclinical immunogenicity. Conclusions and consensus from discussions of these topics are included in this article.
Summary
Numerous pre-clinical and clinical studies on reovirus have generated valuable information which supports the use of this orphan virus as an investigational drug for cancer treatment. ...Reolysin® (pelareorep) is a clinical formulation of the human Reovirus Type 3 Dearing strain. The clinical safety and efficacy of Reolysin® in humans is being tested on an assortment of cancer indications as a mono and/or combination therapy. Reovirus has many inherent characteristics that make it a potential candidate for virotherapy, including: the rapid and natural spread through the haematogenous route, the ability to overcome immunological barriers thereby reaching tumor sites, and being replication-competent. The purpose of this study was to elucidate the bio-distribution pattern of Reolysin® in healthy Sprague-Dawley rats. Following a single 15-min intravenous infusion via the tail vein in Sprague-Dawley rats, the levels of virus genome were determined in 16 organs/tissues by RT-qPCR (Reverse Transcriptase- Quantitative Polymerase Chain Reaction) over a 336 h (Day 15) incubation regime. Consistent with previous studies, maximal reovirus RNA levels were observed in the spleen; indicating its involvement in viral uptake and clearance, followed by heart, ovaries, tail (infusion site), liver and lungs. All the organs/tissues demonstrated unquantifiable levels of reovirus genome at the end of incubation, suggesting substantial to complete viral clearance. Several studies in the last decade have described the use of reovirus for treating ovarian cancers. An increase of reovirus genome in ovaries at 24 h post infection was noted. The results will aid in the design of additional exploratory clinical trials for Reolysin®.
Les protéines Dok-1 et Dok-2 sont deux membres d'une nouvelle famille de protéines adaptatrices regroupées sous le nom Dok (Downstream of tyrosine kinase) et sont fortement exprimées dans le ...lymphocyte T. Ces protéines agissent, suite à leur phosphorylation par diverses tyrosine kinases, comme plateforme de liaison à différentes protéines impliquées dans la transduction de signaux intracellulaires. Dans plusieurs systèmes et types cellulaires étudiés, dont le lymphocyte T, Dok-1 et Dok-2 agissent comme régulateur négatif de la transduction de signaux, notamment par l'association avec RasGAP, une protéine inhibant l'activité de la p21 Ras. Pour ce faire, Dok-1 et Dok-2 possèdent toutes deux des domaines structuraux et des motifs de séquences leurs permettant d'interagir spécifiquement avec diverses protéines ou lipides membranaires. Afin de mieux décrire et comprendre le fonctionnement de ces protéines inhibitrices dans le lymphocyte T, nous avons ciblé nos études sur le rôle de certains de ces éléments dans les fonctions de Dok-1 et Dok-2.Dans un premter temps, nous avons tenté de déterminer quels pouvaient être les partenaires d'association du domaine central de liaison à des phosphotyrosines (PTB; phosphotyrosine binding) de Dok-1 et Dok-2 suite à l'engagement du récepteur CD2. Nous avons pu démontrer que ce domaine est impliqué dans des interactions homotypiques et hétérotypiques. La mutation de deux arginines (Arg207-08; Dok-1 et Arg200-01; Dok-2) du domaine PTB, prédites comme étant impliquées dans l'association aux phosphotyrosines, résulte en la perte de ces interactions. La formation d 'hétérodimères entre Dok-1 et Dok-2 a ensuite pu être confirmée in vivo, suite à la phophorylation des protéines Dok induite par 1'engagement du récepteur CD2.Dans un deuxième temps, nous avons étudié l'implication du domaine PTB dans les fonctions des protéines Dok-1 et Dok-2. Il a été précédemment démontré que la tyrosine (Tyrl46) située entre les domaines PH et PTB de Dok-1 est impliquée dans l'oligomérisation de Dok-1 via son domaine PTB. Selon 1'homologie en séquence avec Dok-1, la protéine Dok-2 porte un résidu tyrosine équivalent (Tyr 139). Nous avons donc généré des clones surexprimant les protéines Dok-1 et Dok-2 portant les mutations prévenant la formation d'oligomères (Dok IR207-08A et Y146F; Dok-2R200-0IA et Yl39F). Ces modifications entraînent la perte de phosphorylation induite par CD2. Aussi, la surexpression de ces mutants ne parvient pas à inhiber l'activation des kinases ERK l/2 induite par CD2 comme il est observé lors de la surexpression de la protéine sauvage. De plus, nous avons pu démontrer que la surexpression des mutants Dok-1Y146F et Dok-2Yl39F interfère avec la phosphorylation induite par CD2 des protéines Dok endogènes.L'ensemble de ces résultats nous a permis de proposer un modèle où l'oligomérisation de Dok-1 et Dok-2, médié par leur domaine PTB, est une étape essentielle à la phosphorylation et aux fonctions de ces deux protéines inhibitrices dans la signalisation induite par CD2 chez le lymphocyte T.
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