A hybrid soluble gp130/spike-nanobody fusion protein simultaneously blocks IL-6 trans-signaling and cellular infection with SARS-CoV2

SARS-CoV2 infection can induce mild to life threatening symptoms. Especially individuals over 60 years of age or with underlying co-morbidities including heart or lung disease, and diabetes or immune compromised patients are at higher risk. Fatal multi-organ damage in COVID19 patients can be attributed to Interleukin (IL-)6 dominated cytokine storm. Consequently, IL-6R monoclonal antibody treatment for severe COVID19 cases has been approved for therapy. High concentrations of soluble IL-6R were found in COVID19 intensive care unit patients suggesting the involvement of IL-6 trans-signaling in disease pathology. Here, in analogy to bispecific antibodies (bsAbs), we developed the first bispecific IL-6 trans-signaling inhibitor c19s130Fc which blocks viral infection and IL-6 trans-signaling. c19s130Fc is a designer protein of the IL-6 trans-signaling inhibitor cs130 fused to a single domain nanobody directed against the receptor binding domain (RBD) of the SARS-CoV2 spike protein. c19s130Fc binds with high affinity to IL-6:sIL6R complexes as well as the spike protein of SARS-CoV2 as shown by surface plasmon resonance. Using cell-based assays, we demonstrate that c19s130Fc blocks IL-6 trans-signaling-induced proliferation and STAT3 phosphorylation of Ba/F3-gp130 cells as well as SARS-CoV2 infection and STAT3 phosphorylation in Vero cells. Taken together, c19s130Fc represents a new class of bispecific inhibitors consisting of a soluble cytokine receptor fused to anti-viral nanobodies and principally demonstrates the multi-functionalization of trans-signaling inhibitors. Importance The availability of effective SARS-CoV2 vaccines is a big step forward in managing the pandemic situation. In addition, therapeutic options e.g. monoclonal antibodies to prevent viral cell entry and anti-inflammatory therapies including glucocorticoid treatment are currently developed or in clinical use utilized to treat already infected patients. Here we report a novel dual-specific inhibitor to simultaneously target SARS-Cov2 infection and virus induced hyper-inflammation. This was achieved by fusing an inhibitor of viral cell entry with a molecule blocking IL-6, a key mediator of SARS-CoV2 induced hyper-inflammation. Through this dual action, this molecule may have the potential to efficiently ameliorate symptoms of COVID19 in infected individuals.

Peptides derived from the SARS-CoV-2 receptor binding motif bind to ACE2 but do not block ACE2-mediated host cell entry or pro-inflammatory cytokine induction

SARS-CoV-2 viral attachment and entry into host cells is mediated by a direct interaction between viral spike glycoproteins and membrane bound angiotensin-converting enzyme 2 (ACE2). The receptor binding motif (RBM), located within the S1 subunit of the spike protein, incorporates the majority of known ACE2 contact residues responsible for high affinity binding and associated virulence. Observation of existing crystal structures of the SARS-CoV-2 receptor binding domain (SRBD)–ACE2 interface, combined with peptide array screening, allowed us to define a series of linear native RBM-derived peptides that were selected as potential antiviral decoy sequences with the aim of directly binding ACE2 and attenuating viral cell entry. RBM1 (16mer): S443KVGGNYNYLYRLFRK458, RBM2A (25mer): E484GFNCYFPLQSYGFQPTNGVGYQPY508, RBM2B (20mer): F456NCYFPLQSYGFQPTNGVGY505 and RBM2A-Sc (25mer): NYGLQGSPFGYQETPYPFCNFVQYG. Data from fluorescence polarisation experiments suggested direct binding between RBM peptides and ACE2, with binding affinities ranging from the high nM to low μM range (Kd = 0.207–1.206 μM). However, the RBM peptides demonstrated only modest effects in preventing SRBD internalisation and showed no antiviral activity in a spike protein trimer neutralisation assay. The RBM peptides also failed to suppress S1-protein mediated inflammation in an endogenously expressing ACE2 human cell line. We conclude that linear native RBM-derived peptides are unable to outcompete viral spike protein for binding to ACE2 and therefore represent a suboptimal approach to inhibiting SARS-CoV-2 viral cell entry. These findings reinforce the notion that larger biologics (such as soluble ACE2, ‘miniproteins’, nanobodies and antibodies) are likely better suited as SARS-CoV-2 cell-entry inhibitors than short-sequence linear peptides.

LectinOracle – A Generalizable Deep Learning Model for Lectin-Glycan Binding Prediction

Ranging from bacterial cell adhesion over viral cell entry to human innate immunity, glycan-binding proteins or lectins abound in nature. Widely used as staining and characterization reagents in cell biology, and crucial for understanding the interactions in biological systems, lectins are a focal point of study in glycobiology. Yet the sheer breadth and depth of specificity for diverse oligosaccharide motifs has made studying lectins a largely piecemeal approach, with few options to generalize. Here, we present LectinOracle, a model combining transformer-based representations for proteins and graph convolutional neural networks for glycans to predict their interaction. Using a curated dataset of 564,647 unique protein-glycan interactions, we show that LectinOracle predictions agree with literature-annotated specificities for a wide range of lectins. We further identify clusters of lectins with related binding specificity that are not clustered based on sequence similarity. Using a range of specialized glycan arrays, we show that LectinOracle predictions generalize to new glycans and lectins, with qualitative and quantitative agreement with experimental data. We further demonstrate that LectinOracle can analyze whole lectomes and their role in host-microbe interactions. We envision that the herein presented platform will advance both the study of lectins and their role in (glyco)biology.

Drugs Shown to Inhibit SARS-CoV-2 in COVID-19 Disease: Comparative Basic and Clinical Pharmacology of Molnupiravir and Ivermectin

The pharmacology of anti-SARS-CoV-2 drugs, Molnupiravir (M) and repurposed Ivermectin (IV) were compared. The IC50 for the inhibition of viral replication were 0.3μM for M and 2.8μM for IV. Both drugs have good oral absorption, with M achieving peak plasma concentrations by 2 hours and IV by 5 hours. The plasma half life were 7 hours for M and 81-91 hours for IV. M inhibits viral replication inducing viral mutagenesis in RdRp, causing viral error catastrophe and viral extinction. IV affects viral cell entry, nuclear transport and inhibits replication via RdRp. IV has additional effect to suppress cytokine production through STAT-3 inhibition. M is a more potent antiviral drug and IV has a longer residence in the body. Their effects on RdRp and cytokine inhibition are potentially complimentary for anti-COVID-19 activity. Both IV and M should be compared in randomized controlled clinical trials, and the possibility of their combination for anti-SARS-CoV-2 antiviral actions, explored further.

SARS-CoV-2 variants of concern have acquired mutations associated with an increased spike cleavage

For efficient cell entry and membrane fusion, SARS-CoV-2 spike (S) protein needs to be cleaved at two different sites, S1/S2 and S2 by different cellular proteases such as furin and TMPRSS2. Polymorphisms in the S protein can affect cleavage, viral transmission, and pathogenesis. Here, we investigated the role of arising S polymorphisms in vitro and in vivo to understand the emergence of SARS-CoV-2 variants. First, we showed that the S:655Y is selected after in vivo replication in the mink model. This mutation is present in the Gamma Variant Of Concern (VOC) but it also occurred sporadically in early SARS-CoV-2 human isolates. To better understand the impact of this polymorphism, we analyzed the in vitro properties of a panel of SARS-CoV-2 isolates containing S:655Y in different lineage backgrounds. Results demonstrated that this mutation enhances viral replication and spike protein cleavage. Viral competition experiments using hamsters infected with WA1 and WA1-655Y isolates showed that the variant with 655Y became dominant in both direct infected and direct contact animals. Finally, we investigated the cleavage efficiency and fusogenic properties of the spike protein of selected VOCs containing different mutations in their spike proteins. Results showed that all VOCs have evolved to acquire an increased spike cleavage and fusogenic capacity despite having different sets of mutations in the S protein. Our study demonstrates that the S:655Y is an important adaptative mutation that increases viral cell entry, transmission, and host susceptibility. Moreover, SARS-COV-2 VOCs showed a convergent evolution that promotes the S protein processing.

Structural basis for genome packaging, retention, and ejection in human cytomegalovirus

How the human cytomegalovirus (HCMV) genome—the largest among human herpesviruses—is packaged, retained, and ejected remains unclear. We present the in situ structures of the symmetry-mismatched portal and the capsid vertex-specific components (CVSCs) of HCMV. The 5-fold symmetric 10-helix anchor—uncommon among known portals—contacts the portal-encircling DNA, which is presumed to squeeze the portal as the genome packaging proceeds. We surmise that the 10-helix anchor dampens this action to delay the portal reaching a “head-full” packaging state, thus facilitating the large genome to be packaged. The 6-fold symmetric turret, latched via a coiled coil to a helix from a major capsid protein, supports the portal to retain the packaged genome. CVSCs at the penton vertices—presumed to increase inner capsid pressure—display a low stoichiometry, which would aid genome retention. We also demonstrate that the portal and capsid undergo conformational changes to facilitate genome ejection after viral cell entry.

Dynamic causal modelling of immune heterogeneity

An interesting inference drawn by some COVID-19 epidemiological models is that there exists a proportion of the population who are not susceptible to infection—even at the start of the current pandemic. This paper introduces a model of the immune response to a virus. This is based upon the same sort of mean-field dynamics as used in epidemiology. However, in place of the location, clinical status, and other attributes of people in an epidemiological model, we consider the state of a virus, B and T-lymphocytes, and the antibodies they generate. Our aim is to formalise some key hypotheses as to the mechanism of resistance. We present a series of simple simulations illustrating changes to the dynamics of the immune response under these hypotheses. These include attenuated viral cell entry, pre-existing cross-reactive humoral (antibody-mediated) immunity, and enhanced T-cell dependent immunity. Finally, we illustrate the potential application of this sort of model by illustrating variational inversion (using simulated data) of this model to illustrate its use in testing hypotheses. In principle, this furnishes a fast and efficient immunological assay—based on sequential serology—that provides a (1) quantitative measure of latent immunological responses and (2) a Bayes optimal classification of the different kinds of immunological response (c.f., glucose tolerance tests used to test for insulin resistance). This may be especially useful in assessing SARS-CoV-2 vaccines.

When Off Target Effects Are On Target: The Role Of Spironolactone In Patients With COVID-19

Aims: Spironolactone is a steroidal mineralocoricosteroid receptor antagonist (MRA) used for treatment of resistant hypertension, heart failure and edema. It exerts class specific adverse effects that are shared by other MRAs. Additionally, it exerts unique “off target” steroidal effects that include gynecomastia, impotence and loss of libido in males and menstrual irregularity in females. Together, these have led to a poor tolerability and limited use despite positive results in many randomized, controlled clinical trials. We review the off-target effects of spironolactone that may summate with its MRA action to provide an advantageous profile for prevention or treatment of patients with COVID-19. Methods: Literature review using PubMed Central. Results: The blockade by spironolactone of the androgen receptor should diminish the expression of transmembrane protease serine 2 (TMPRSS2) that has an androgen promoter while its MRA action should enhance the expression of protease nexin1 (PN1) that inhibits furin and plasmin. TMPRSS2, furin and plasmin cooperated to process the SARS-CoV-2 spike protein to increase its high affinity binding to the angiotensin converting enzyme 2 (ACE2) and thereby promote viral cell entry. Its actions as an MRA may reduce inflammation and preserve pulmonary, cardiac and vascular functions. Its anti-plasmin action may combat hemostatic dysfunction. Conclusion: The hypothesis that the off-target effects of spironolactone summate with its MRA actions to provide special benefits for COVID-19 is worthy of direct investigation and clinical trial.

Predicting the zoonotic capacity of mammal species for SARS-CoV-2

Spillback transmission from humans to animals, and secondary spillover from animal hosts back into humans, have now been documented for SARS-CoV-2. In addition to threatening animal health, virus variants arising from novel animal hosts have the potential to undermine global COVID-19 mitigation efforts. Numerous studies have therefore investigated the zoonotic capacity of various animal species for SARS-CoV-2, including predicting both species’ susceptibility to infection and their capacities for onward transmission. A major bottleneck to these studies is the limited number of sequences for ACE2, a key cellular receptor in chordates that is required for viral cell entry. Here, we combined protein structure modeling with machine learning of species’ traits to predict zoonotic capacity of SARS-CoV-2 across 5,400 mammals. High accuracy model predictions were strongly corroborated by in vivo empirical studies, and identify numerous mammal species across global COVID-19 hotspots that should be prioritized for surveillance and experimental validation.