Influenza, evolution, and the next pandemic

SARS-CoV-2 and oncolytic EV-D68-encoded proteases differentially regulate pyroptosis

Pyroptosis, a pro-inflammatory programmed cell death, has been implicated in the pathogenesis of coronavirus disease 2019 and other viral diseases. Gasdermin family proteins (GSDMs), including GSDMD and GSDME, are key regulators of pyroptotic cell death. However, the mechanisms by which virus infection modulates pyroptosis remain unclear. Here, we employed a mCherry-GSDMD fluorescent reporter assay to screen for viral proteins that impede the localization and function of GSDMD in living cells. Our data indicated that the main protease NSP5 of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) blocked GSDMD-mediated pyroptosis via cleaving residues Q29 and Q193 of GSDMD. While another SARS-CoV-2 protease, NSP3, cleaved GSDME at residue G370 but activated GSDME-mediated pyroptosis. Interestingly, respiratory enterovirus EV-D68-encoded proteases 3C and 2A also exhibit similar differential regulation on the functions of GSDMs by inactivating GSDMD but initiating GSDME-mediated pyroptosis. EV-D68 infection exerted oncolytic effects on human cancer cells by inducing pyroptotic cell death. Our findings provide insights into how respiratory viruses manipulate host cell pyroptosis and suggest potential targets for antiviral therapy as well as cancer treatment.IMPORTANCEPyroptosis plays a crucial role in the pathogenesis of coronavirus disease 2019, and comprehending its function may facilitate the development of novel therapeutic strategies. This study aims to explore how viral-encoded proteases modulate pyroptosis. We investigated the impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and respiratory enterovirus D68 (EV-D68) proteases on host cell pyroptosis. We found that SARS-CoV-2-encoded proteases NSP5 and NSP3 inactivate gasdermin D (GSDMD) but initiate gasdermin E (GSDME)-mediated pyroptosis, respectively. We also discovered that another respiratory virus EV-D68 encodes two distinct proteases 2A and 3C that selectively trigger GSDME-mediated pyroptosis while suppressing the function of GSDMD. Based on these findings, we further noted that EV-D68 infection triggers pyroptosis and produces oncolytic effects in human carcinoma cells. Our study provides new insights into the molecular mechanisms underlying virus-modulated pyroptosis and identifies potential targets for the development of antiviral and cancer therapeutics.

Influenza virus replication in cardiomyocytes drives heart dysfunction and fibrosis

Cardiac dysfunction is a common complication of severe influenza virus infection, but whether this occurs due to direct infection of cardiac tissue or indirectly through systemic lung inflammation remains unclear. To test the etiology of this aspect of influenza disease, we generated a novel recombinant heart-attenuated influenza virus via genome incorporation of target sequences for miRNAs expressed in cardiomyocytes. Compared with control virus, mice infected with miR-targeted virus had significantly reduced heart viral titers, confirming cardiac attenuation of viral replication. However, this virus was fully replicative in the lungs and induced similar systemic inflammation and weight loss compared to control virus. The miR-targeted virus induced fewer cardiac conduction irregularities and significantly less fibrosis in mice lacking interferon-induced transmembrane protein 3 (IFITM3), which serve as a model for influenza-associated cardiac pathology. We conclude that robust virus replication in the heart is required for pathology, even when lung inflammation is severe.

COVID-19, host response treatment, and the need for political leadership

Health officials and scientists have warned that we face the threat of a potentially devastating influenza pandemic. Instead, we are now in the midst of a global coronavirus (COVID-19) pandemic. National and international pandemic preparedness plans have focused on developing vaccines and antiviral treatments. Another way to confront the COVID-19 pandemic (and future pandemics) might be to treat patients with inexpensive and widely available generic drugs that target the host response to infection, not the virus itself. The feasibility of this idea was tested during the Ebola outbreak in West Africa in 2014. This experience should inform our approach to treating COVID-19 patients. It could also save lives during outbreaks of other emerging infectious diseases and episodes of everyday acute critical illness. If this "bottom up" syndromic approach to treating acute critical illness were shown to be effective, it could have a dramatic impact on health, equity and security throughout the world. HIGHLIGHTS: Uncertainty about the outcome of COVID-19 is driving the social, economic and political distress associated with the pandemic. Treating the host response to COVID-19 with inexpensive and widely available generic drugs might save lives and mitigate this distress. Undertaking research on this idea will require political leadership.

A conserved multi-epitope-based vaccine designed by targeting hemagglutinin protein of highly pathogenic avian H5 influenza viruses

The highly pathogenic avian H5N1 influenza viruses have been recognized as a potential pandemic threat to humans, and to the poultry industry since 1997. H5 viruses consist of a high mutation rate, so universal vaccine designing is very challenging. Here, we describe a vaccinomics approach to design a novel multi-epitope influenza vaccine, based on the highly conserved regions of surface glycoprotein, Hemagglutinin (HA). Initially, the HA protein sequences from Bangladeshi origin were retrieved and aligned by ClustalW. The sequences of 100% conserved regions extracted and analyzed to select the highest potential T-cell and B-cell epitope. The HTL and CTL analyses using IEDB tools showed that DVWTYNAELLVLMEN possesses the highest affinity with MHC class I and II alleles, and it has the highest population coverage. The docking simulation study suggests that this epitope has the potential to interact with both MHC class I and MHC class II. The B-cell epitope prediction provides a potential peptide, GAIAGFIEGGWQGM. We further retrieved HA sequences of 3950 avian and 250 human H5 isolates from several populations of the world, where H5 was an epidemic. Surprisingly, these epitopes are more than 98% conserved in those regions which indicate their potentiality as a conserved vaccine. We have proposed a multi-epitope vaccine using these sequences and assess its stability and potentiality to induce B-cell immunity. In vivo study is necessary to corroborate this epitope as a vaccine, however, setting forth groundwork for wet-lab studies essential to mitigate pandemic threats and provide cross-protection of both avian and humans against H5 influenza viruses.

What do differences in case fatality ratios between children and adults tell us about COVID-19?

We thank S. Ebmeier and A.J. Cunnington for their commentary on our editorial [1], providing another point of view on such a controversial topic. In their letter, S. Ebmeier and A.J. Cunnington assume that the greater burden of coronavirus disease 19 (COVID-19) in adults may be related to the absence in the population of prior immunity to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), as occurred in fully susceptible populations during previous viral epidemics. In particular, Shankset al. [2] report that the measles mortality rate in a fully susceptible population during the 1846 measles epidemic was higher in adults and in children aged <2 years. However, nowadays, children younger than 5 years and adults older than 20 years are still more likely to suffer from measles complications, despite not being fully susceptible [3]. Moreover, Strebelet al. [4] reported that the case fatality ratio is still high in children aged <1 year, lower in children aged 1–9 years, and then rises again in teenagers and adults. The reported data suggest that greater morbidity and mortality in adults is not a unique feature of first-contact measles epidemics.

Other reasons, rather than absence of prior immunity, could play a crucial role in the coronavirus dilemma that surrounds childrenhttps://bit.ly/36BzTaD

Pathogen Lists Do Not Tell Us What We Need to Do

Brett-Major and others remind us that pathogen lists for emerging infectious diseases aid in the development of tools that target specific pathogens (e.g., vaccines) and help attract financial support. These lists tell us what we need to have, not what we need to do. The authors call for more research on ways to prevent these diseases (e.g., platform technologies for vaccines) and mitigate disease impact. Vaccines and new treatments that target individual pathogens have many limitations. However, we might save lives by treating patients with inexpensive generic drugs that target common features of the host response to infection. Undertaking research on this approach to treatment is what we need to do.

Catalytic inactivation of influenza virus by iron oxide nanozyme

Influenza poses a severe threat to human health in the world. However, developing a universal anti-viral strategy has remained challenging due to the presence of diverse subtypes as well as its high mutation rate, resulting in antigenic shift and drift. Here we developed an antiviral strategy using iron oxide nanozymes (IONzymes) to target the lipid envelope of the influenza virus. Methods: We evaluated the antiviral activities of our IONzymes using a hemagglutination assay, together with a 50% tissue culture infectious doses (TCID₅₀) method. Lipid peroxidation of the viral envelope was analyzed using a maleic dialdehyde (MDA) assay and transmission electron microscopy (TEM). The neighboring viral proteins were detected by western blotting. Results: We show that IONzymes induce envelope lipid peroxidation and destroy the integrity of neighboring proteins, including hemagglutinin, neuraminidase, and matrix protein 1, causing the inactivation of influenza A viruses (IAVs). Furthermore, we show that our IONzymes possess a broad-spectrum antiviral activity on 12 subtypes of IAVs (H1~H12). Lastly, we demonstrate that applying IONzymes to a facemask improves the ability of virus protection against 3 important subtypes that pose a threat to human, including H1N1, H5N1, and H7N9 subtype. Conclusion: Together, our results clearly demonstrate that IONzymes can catalyze lipid peroxidation of the viral lipid envelope to inactivate enveloped viruses and provide protection from viral transmission and infection.

MultiBac: Baculovirus-Mediated Multigene DNA Cargo Delivery in Insect and Mammalian Cells

The baculovirus/insect cell system (BICS) is widely used in academia and industry to produce eukaryotic proteins for many applications, ranging from structure analysis to drug screening and the provision of protein biologics and therapeutics. Multi-protein complexes have emerged as vital catalysts of cellular function. In order to unlock the structure and mechanism of these essential molecular machines and decipher their function, we developed MultiBac, a BICS particularly tailored for heterologous multigene transfer and multi-protein complex production. Baculovirus is unique among common viral vectors in its capacity to accommodate very large quantities of heterologous DNA and to faithfully deliver this cargo to a host cell of choice. We exploited this beneficial feature to outfit insect cells with synthetic DNA circuitry conferring new functionality during heterologous protein expression, and developing customized MultiBac baculovirus variants in the process. By altering its tropism, recombinant baculovirions can be used for the highly efficient delivery of a customized DNA cargo in mammalian cells and tissues. Current advances in synthetic biology greatly facilitate the construction or recombinant baculoviral genomes for gene editing and genome engineering, mediated by a MultiBac baculovirus tailored to this purpose. Here, recent developments and exploits of the MultiBac system are presented and discussed.

The influenza of 1918: Evolutionary perspectives in a historical context

The 1918 influenza pandemic was the deadliest in known human history. It spread globally to the most isolated of human communities, causing clinical disease in a third of the world's population, and infecting nearly every human alive at the time. Determination of mortality numbers is complicated by weak contemporary surveillance in the developing world, but recent estimates put the death toll at 50 million or even higher. This outbreak is of great interest to modern day epidemiologists, virologists, global health researchers and evolutionary biologists. They ask: Where did it come from? And if it happened once, could it happen again? Understanding how such a virulent epidemic emerged and spread offers hope for prevention and strategies of response. This review uses historical methodology and evolutionary perspectives to revisit the 1918 outbreak. Using the American military experience as a case study, it investigates the emergence of virulence in 1918 by focusing on key susceptibility factors that favored both the influenza virus and the subsequent pneumococcal invasion that took so many lives. This article explores the history of the epidemic and contemporary measures against it, surveys modern research on the virus, and considers what aspects of 1918 human and animal ecology most contributed to the emergence of this pandemic.