Advances and gaps in SARS-CoV-2 infection models

The global response to Coronavirus Disease 2019 (COVID-19) is now facing new challenges such as vaccine inequity and the emergence of SARS-CoV-2 variants of concern (VOCs). Preclinical models of disease, in particular animal models, are essential to investigate VOC pathogenesis, vaccine correlates of protection and postexposure therapies. Here, we provide an update from the World Health Organization (WHO) COVID-19 modeling expert group (WHO-COM) assembled by WHO, regarding advances in preclinical models. In particular, we discuss how animal model research is playing a key role to evaluate VOC virulence, transmission and immune escape, and how animal models are being refined to recapitulate COVID-19 demographic variables such as comorbidities and age

Transcriptional role of p53 in interferon-mediated antiviral immunity

Tumor suppressor p53 is activated by several stimuli, including DNA damage and oncogenic stress. Previous studies (Takaoka, A., S. Hayakawa, H. Yanai, D. Stoiber, H. Negishi, H. Kikuchi, S. Sasaki, K. Imai, T. Shibue, K. Honda, and T. Taniguchi. 2003. Nature. 424:516–523) have shown that p53 is also induced in response to viral infections as a downstream transcriptional target of type I interferon (IFN) signaling. Moreover, many viruses, including SV40, human papillomavirus, Kaposi's sarcoma herpesvirus, adenoviruses, and even RNA viruses such as polioviruses, have evolved mechanisms designated to abrogate p53 responses. We describe a novel p53 function in the activation of the IFN pathway. We observed that infected mouse and human cells with functional p53 exhibited markedly decreased viral replication early after infection. This early inhibition of viral replication was mediated both in vitro and in vivo by a p53-dependent enhancement of IFN signaling, specifically the induction of genes containing IFN-stimulated response elements. Of note, p53 also contributed to an increase in IFN release from infected cells. We established that this p53-dependent enhancement of IFN signaling is dependent to a great extent on the ability of p53 to activate the transcription of IFN regulatory factor 9, a central component of the IFN-stimulated gene factor 3 complex. Our results demonstrate that p53 contributes to innate immunity by enhancing IFN-dependent antiviral activity independent of its functions as a proapoptotic and tumor suppressor gene

Regulation of Ebola virus VP40 matrix protein by SUMO

The matrix protein of Ebola virus (EBOV) VP40 regulates viral budding, nucleocapsid recruitment, virus structure and stability, viral genome replication and transcription, and has an intrinsic ability to form virus-like particles. The elucidation of the regulation of VP40 functions is essential to identify mechanisms to inhibit viral replication and spread. Post-translational modifications of proteins with ubiquitin-like family members are common mechanisms for the regulation of host and virus multifunctional proteins. Thus far, no SUMOylation of VP40 has been described. Here we demonstrate that VP40 is modified by SUMO and that SUMO is included into the viral like particles (VLPs). We demonstrate that lysine residue 326 in VP40 is involved in SUMOylation, and by analyzing a mutant in this residue we show that SUMO conjugation regulates the stability of VP40 and the incorporation of SUMO into the VLPs. Our study indicates for the first time, to the best of our knowledge, that EBOV hijacks the cellular SUMOylation system in order to modify its own proteins. Modulation of the VP40-SUMO interaction may represent a novel target for the therapy of Ebola virus infectionWe thank Sergio Gomez-Medina for excellent technical assistance. Funding at the laboratory of CR is provided by BFU-2014-58530. Work at the laboratory of CSM is supported by BFU2013-41249-P. This work was partially funded by the Lebniz Association (Prämie ERC Starting Grant 2013 to CM-F). The Heinrich-Pette-Institute is financed by the German Federal Ministry of Health and the Freie und Hansestadt Hamburg. AEM is supported by the Spanish Ministry of Economy and Competitiveness (FPI Fellowship). CFC-H is supported by CONACYT. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscriptS

Transcriptomic signatures differentiate survival from fatal outcomes in humans infected with Ebola virus

Background In 2014, Western Africa experienced an unanticipated explosion of Ebola virus infections. What distinguishes fatal from non-fatal outcomes remains largely unknown, yet is key to optimising personalised treatment strategies. We used transcriptome data for peripheral blood taken from infected and convalescent recovering patients to identify early stage host factors that are associated with acute illness and those that differentiate patient survival from fatality. Results The data demonstrate that individuals who succumbed to the disease show stronger upregulation of interferon signalling and acute phase responses compared to survivors during the acute phase of infection. Particularly notable is the strong upregulation of albumin and fibrinogen genes, which suggest significant liver pathology. Cell subtype prediction using messenger RNA expression patterns indicated that NK-cell populations increase in patients who survive infection. By selecting genes whose expression properties discriminated between fatal cases and survivors, we identify a small panel of responding genes that act as strong predictors of patient outcome, independent of viral load. Conclusions Transcriptomic analysis of the host response to pathogen infection using blood samples taken during an outbreak situation can provide multiple levels of information on both disease state and mechanisms of pathogenesis. Host biomarkers were identified that provide high predictive value under conditions where other predictors, such as viral load, are poor prognostic indicators. The data suggested that rapid analysis of the host response to infection in an outbreak situation can provide valuable information to guide an understanding of disease outcome and mechanisms of disease

Influenza A viruses alter the stability and antiviral contribution of host E3-ubiquitin ligase Mdm2 during the time-course of infection

International audienceThe interplay between influenza A viruses (IAV) and the p53 pathway has been reported in several studies, highlighting the antiviral contribution of p53. Here, we investigated the impact of IAV on the E3-ubiquitin ligase Mdm2, a major regulator of p53, and observed that IAV targets Mdm2, notably via its non-structural protein (NS1), therefore altering Mdm2 stability, p53/Mdm2 interaction and regulatory loop during the time-course of infection. This study also highlights a new antiviral facet of Mdm2 possibly increasing the list of its many p53-independent functions. Altogether, our work contributes to better understand the mechanisms underlining the complex interactions between IAV and the p53 pathway, for which both NS1 and Mdm2 arise as key players

Chikungunya Outbreak in the Republic of the Congo, 2019—Epidemiological, Virological and Entomological Findings of a South-North Multidisciplinary Taskforce Investigation

The Republic of Congo (RoC) declared a chikungunya (CHIK) outbreak on 9 February 2019. We conducted a ONE-Human-Animal HEALTH epidemiological, virological and entomological investigation. Methods: We collected national surveillance and epidemiological data. CHIK diagnosis was based on RT-PCR and CHIKV-specific antibodies. Full CHIKV genome sequences were obtained by Sanger and MinION approaches and Bayesian tree phylogenetic analysis was performed. Mosquito larvae and 215 adult mosquitoes were collected in different villages of Kouilou and Pointe-Noire districts and estimates of Aedes (Ae.) mosquitos’ CHIKV-infectious bites obtained. We found two new CHIKV sequences of the East/Central/South African (ECSA) lineage, clustering with the recent enzootic sub-clade 2, showing the A226V mutation. The RoC 2019 CHIKV strain has two novel mutations, E2-T126M and E2-H351N. Phylogenetic suggests a common origin from 2016 Angola strain, from which it diverged around 1989 (95% HPD 1985–1994). The infectious bite pattern was similar for 2017, 2018 and early 2019. One Ae. albopictus pool was RT-PCR positive. The 2019 RoC CHIKV strain seems to be recently introduced or be endemic in sylvatic cycle. Distinct from the contemporary Indian CHIKV isolates and in contrast to the original Central-African strains (transmitted by Ae. aegypti), it carries the A226V mutation, indicating an independent adaptive mutation in response to vector replacement (Ae. albopictus vs Ae. aegypti)

N′-phenylacetohydrazide derivatives as potent Ebola virus entry inhibitors with an improved pharmacokinetic profile

19 p.-6 fig.-7 tab.-1 graph. abst.Ebola virus (EBOV) is a single-strand RNA virus belonging to the Filoviridae family, which has been associated to most Ebola virus disease outbreaks to date, including the West African and the North Kivu epidemics between 2013 and 2022. This unprecedented health emergency prompted the search for effective medical countermeasures. Following up on the carbazole hit identified in our previous studies, we synthetized a new series of compounds, which demonstrated to prevent EBOV infection in cells by acting as virus entry inhibitors. The in vitro inhibitory activity was evaluated through the screening against surrogate models based on viral pseudotypes and further confirmed using replicative EBOV. Docking and molecular dynamics simulations joined to saturation transfer difference–nuclear magnetic resonance (STD–NMR) and mutagenesis experiments to elucidate the biological target of the most potent compounds. Finally, in vitro metabolic stability and in vivo pharmacokinetic studies were performed to confirm their therapeutic potential.The project leading to these results has received funding from “la Caixa” Foundation under the project code LCF/PR/HR19/52160012. This research was partially supported through ERA-NET-2021-862605. Cofounded by AEI, Spain (PCI2021-121939 (C.A.), PID2019-105237GB-I00 (A.C.), PID2021-122825OB (C.A.), and PID2021-122223OB-I00 (C.G.)), Instituto de Salud Carlos III (CIBERINFEC and FIS PI2100989), and the European Commission Horizon 2020 Framework Programme (Project VIRUSCAN FETPROACT-2016: 731868 and Project EPIC-CROWN-2 ID: 101046084). This research work was also funded by the European Commission–NextGenerationEU (Regulation EU 2020/2094), through CSIC’s Global Health Platform (PTI Salud Global). M.M.-T holds a predoctoral FPU grant (FPU18/03493) from MICINNPeer reviewe

Experimental Evolution of an Oncolytic Vesicular Stomatitis Virus with Increased Selectivity for p53-Deficient Cells

Experimental evolution has been used for various biotechnological applications including protein and microbial cell engineering, but less commonly in the field of oncolytic virotherapy. Here, we sought to adapt a rapidly evolving RNA virus to cells deficient for the tumor suppressor gene p53, a hallmark of cancer cells. To achieve this goal, we established four independent evolution lines of the vesicular stomatitis virus (VSV) in p53-knockout mouse embryonic fibroblasts (p53−/− MEFs) under conditions favoring the action of natural selection. We found that some evolved viruses showed increased fitness and cytotoxicity in p53−/− cells but not in isogenic p53+/+ cells, indicating gene-specific adaptation. However, full-length sequencing revealed no obvious or previously described genetic changes associated with oncolytic activity. Half-maximal effective dose (EC50) assays in mouse p53-positive colon cancer (CT26) and p53-deficient breast cancer (4T1) cells indicated that the evolved viruses were more effective against 4T1 cells than the parental virus or a reference oncolytic VSV (MΔ51), but showed no increased efficacy against CT26 cells. In vivo assays using 4T1 syngeneic tumor models showed that one of the evolved lines significantly delayed tumor growth compared to mice treated with the parental virus or untreated controls, and was able to induce transient tumor suppression. Our results show that RNA viruses can be specifically adapted typical cancer features such as p53 inactivation, and illustrate the usefulness of experimental evolution for oncolytic virotherapy

SARS-CoV-2 Variants and Vaccines.

Viral variants of concern may emerge with dangerous resistance to the immunity generated by the current vaccines to prevent coronavirus disease 2019 (Covid-19). Moreover, if some variants of concern have increased transmissibility or virulence, the importance of efficient public health measures and vaccination programs will increase. The global response must be both timely and science based