Central ions and lateral asparagine/glutamine zippers stabilize the post-fusion hairpin conformation of the SARS coronavirus spike glycoprotein

AbstractThe coronavirus spike glycoprotein is a class I membrane fusion protein with two characteristic heptad repeat regions (HR1 and HR2) in its ectodomain. Here, we report the X-ray structure of a previously characterized HR1/HR2 complex of the severe acute respiratory syndrome coronavirus spike protein. As expected, the HR1 and HR2 segments are organized in antiparallel orientations within a rod-like molecule. The HR1 helices form an exceptionally long (120 Å) internal coiled coil stabilized by hydrophobic and polar interactions. A striking arrangement of conserved asparagine and glutamine residues of HR1 propagates from two central chloride ions, providing hydrogen-bonding “zippers” that strongly constrain the path of the HR2 main chain, forcing it to adopt an extended conformation at either end of a short HR2 α-helix

Detection of MERS-CoV antigen on formalin-fixed paraffin-embedded nasal tissue of alpacas by immunohistochemistry using human monoclonal antibodies directed against different epitopes of the spike protein

Middle East respiratory syndrome (MERS) represents an important respiratory disease accompanied by lethal outcome in one third of human patients. In recent years, several investigators developed protective antibodies which could be used as prophylaxis in prospective human epidemics. In the current study, eight human monoclonal antibodies (mAbs) with neutralizing and non-neutralizing capabilities, directed against different epitopes of the MERS-coronavirus (MERS-CoV) spike (MERS-S) protein, were investigated with regard to their ability to immunohistochemically detect respective epitopes on formalin-fixed paraffin-embedded (FFPE) nasal tissue sections of MERS-CoV experimentally infected alpacas. The most intense immunoreaction was detected using a neutralizing antibody directed against the receptor binding domain S1B of the MERS-S protein, which produced an immunosignal in the cytoplasm of ciliated respiratory epithelium and along the apical membranous region. A similar staining was obtained by two other mAbs which recognize the sialic acid-binding domain and the ectodomain of the membrane fusion subunit S2, respectively. Five mAbs lacked immunoreactivity for MERS-CoV antigen on FFPE tissue, even though they belong, at least in part, to the same epitope group. In summary, three tested human mAbs demonstrated capacity for detection of MERS-CoV antigen on FFPE samples and may be implemented in double or triple immunohistochemical methods.info:eu-repo/semantics/acceptedVersio

Genetic analysis of infectious bronchitis virus (IBV) in vaccinated poultry populations over a period of 10 years

Infectious bronchitis virus (IBV) is an avian pathogen from the Coronavirus family causing major health issues in poultry flocks worldwide. Because of its negative impact on health, performance, and bird welfare, commercial poultry are routinely vaccinated by administering live attenuated virus. However, field strains are capable of rapid adaptation and may evade vaccine-induced immunity. We set out to describe dynamics within and between lineages and assess potential escape from vaccine-induced immunity. We investigated a large nucleotide sequence database of over 1700 partial sequences of the S1 spike protein gene collected from clinical samples of Dutch chickens submitted to the laboratory of Royal GD between 2011 and 2020. Relative frequencies of the two major lineages GI-13 (793B) and GI-19 (QX) did not change in the investigated period, but we found a succession of distinct GI-19 sublineages. Analysis of dN/dS ratio over all sequences demonstrated episodic diversifying selection acting on multiple sites, some of which overlap predicted N-glycosylation motifs. We assessed several measures that would indicate divergence from vaccine strains, both in the overall database and in the two major lineages. However, the frequency of vaccine-homologous lineages did not decrease, no increase in genetic variation with time was detected, and the sequences did not grow more divergent from vaccine sequences in the examined time window. Concluding, our results show sublineage turnover within the GI-19 lineage and we demonstrate episodic diversifying selection acting on the partial sequence, but we cannot confirm nor rule out escape from vaccine-induced immunity. RESEARCH HIGHLIGHTS Succession of GI-19 IBV variants in broiler populations. IBV lineages overrepresented in either broiler, or layer production chickens. Ongoing episodic selection at the IBV S1 spike protein gene sequence. Several positively selected codons coincident with N-glycosylation motifs

Blocking transmission of Middle East respiratory syndrome coronavirus (MERS-CoV) in llamas by vaccination with a recombinant spike protein

The ongoing Middle East respiratory syndrome coronavirus (MERS-CoV) outbreaks pose a worldwide public health threat. Blocking MERS-CoV zoonotic transmission from dromedary camels, the animal reservoir, could potentially reduce the number of primary human cases. Here we report MERS-CoV transmission from experimentally infected llamas to naïve animals. Directly inoculated llamas shed virus for at least 6 days and could infect all in-contact naïve animals 4-5 days after exposure. With the aim to block virus transmission, we examined the efficacy of a recombinant spike S1-protein vaccine. In contrast to naïve animals, in-contact vaccinated llamas did not shed infectious virus upon exposure to directly inoculated llamas, consistent with the induction of strong virus neutralizing antibody responses. Our data provide further evidence that vaccination of the reservoir host may impede MERS-CoV zoonotic transmission to humans

Inoperable chronic thromboembolic pulmonary hypertension:Evolution of prognosis over 10 years of new emerging therapies

Therapies for inoperable chronic thromboembolic pulmonary hypertension (CTEPH) include balloon pulmonary angioplasty (BPA) and PH-specific medical therapy. This study compares survival and its predictors before and after the introduction of BPA. BPA was independently associated with survival; however, there was no difference in overall survival between the two cohorts.</p

Взаємодія системи "політика-релігія"

Досліджено феномен суспільних явищ політики і релігії у перерізі їх взаємодії, вивчено історичний досвід такого взаємного впливу. Окреме місце відведено аналізу практичного застосування закону України “Про свободу совісті та релігійні організації”.The article explores the phenomenon of social phenomena politics and religion in the context of their interaction, exploring the historical experience of such mutual influence. A separate analysis is given to the practical application of the Law of Ukraine “On Freedom of Conscience and Religious Organizations”

Sialoglycan binding triggers spike opening in a human coronavirus

Coronavirus spike proteins mediate receptor binding and membrane fusion, making them prime targets for neutralizing antibodies. In the cases of severe acute respiratory syndrome coronavirus, severe acute respiratory syndrome coronavirus 2 and Middle East respiratory syndrome coronavirus, spike proteins transition freely between open and closed conformations to balance host cell attachment and immune evasion 1-5. Spike opening exposes domain S1 B, allowing it to bind to proteinaceous receptors 6,7, and is also thought to enable protein refolding during membrane fusion 4,5. However, with a single exception, the pre-fusion spike proteins of all other coronaviruses studied so far have been observed exclusively in the closed state. This raises the possibility of regulation, with spike proteins more commonly transitioning to open states in response to specific cues, rather than spontaneously. Here, using cryogenic electron microscopy and molecular dynamics simulations, we show that the spike protein of the common cold human coronavirus HKU1 undergoes local and long-range conformational changes after binding a sialoglycan-based primary receptor to domain S1 A. This binding triggers the transition of S1 B domains to the open state through allosteric interdomain crosstalk. Our findings provide detailed insight into coronavirus attachment, with possibilities of dual receptor usage and priming of entry as a means of immune escape

Nanoparticle display of neuraminidase elicits enhanced antibody responses and protection against influenza A virus challenge in mice

Current Influenza virus vaccines primarily induce antibody responses against variable epitopes in hemagglutinin (HA), necessitating frequent updates. However, antibodies against neuraminidase (NA) can also confer protection against influenza, making NA an attractive target for the development of novel vaccines. In this study, we aimed to enhance the immunogenicity of recombinant NA antigens by presenting them multivalently on a nanoparticle carrier. Soluble tetrameric NA antigens of the N1 and N2 subtypes, confirmed to be correctly folded by cryo-electron microscopy structural analysis, were conjugated to Mi3 self-assembling protein nanoparticles using the SpyTag-SpyCatcher system. Immunization of mice with NA-Mi3 nanoparticles induced higher titers of NA-binding and -inhibiting antibodies and improved protection against a lethal challenge compared to unconjugated NA. Additionally, we explored the co-presentation of N1 and N2 antigens on the same Mi3 particles to create a mosaic vaccine candidate. These mosaic nanoparticles elicited antibody titers that were similar or superior to the homotypic nanoparticles and effectively protected against H1N1 and H3N2 challenge viruses. The NA-Mi3 nanoparticles represent a promising vaccine candidate that could complement HA-directed approaches for enhanced potency and broadened protection against influenza A virus

Serological Survey of Retrovirus and Coronavirus Infections, including SARS-CoV-2, in Rural Stray Cats in The Netherlands, 2020–2022

Stray cats can host (zoonotic) viral pathogens and act as a source of infection for domestic cats or humans. In this cross-sectional (sero)prevalence study, sera from 580 stray cats living in 56 different cat groups in rural areas in The Netherlands were collected from October 2020 to July 2022. These were used to investigate the prevalence of the cat-specific feline leukemia virus (FeLV, n = 580), the seroprevalence of the cat-specific feline viruses feline immunodeficiency virus (FIV, n = 580) and feline coronavirus (FCoV, n = 407), and the zoonotic virus severe acute respiratory coronavirus-2 (SARS-CoV-2, n = 407) using enzyme-linked immunosorbent assays (ELISAs). ELISA-positive results were confirmed using Western blot (FIV) or pseudovirus neutralization test (SARS-CoV-2). The FIV seroprevalence was 5.0% (95% CI (Confidence Interval) 3.4–7.1) and ranged from 0–19.0% among groups. FIV-specific antibodies were more often detected in male cats, cats ≥ 3 years and cats with reported health problems. No FeLV-positive cats were found (95% CI 0.0–0.6). The FCoV seroprevalence was 33.7% (95% CI 29.1–38.5) and ranged from 4.7–85.7% among groups. FCoV-specific antibodies were more often detected in cats ≥ 3 years, cats with reported health problems and cats living in industrial areas or countryside residences compared to cats living at holiday parks or campsites. SARS-CoV-2 antibodies against the subunit 1 (S1) and receptor binding domain (RBD) protein were detected in 2.7% (95% CI 1.4–4.8) of stray cats, but sera were negative in the pseudovirus neutralization test and therefore were considered SARS-CoV-2 suspected. Our findings suggest that rural stray cats in The Netherlands can be a source of FIV and FCoV, indicating a potential risk for transmission to other cats, while the risk for FeLV is low. However, suspected SARS-CoV-2 infections in these cats were uncommon. We found no evidence of SARS-CoV-2 cat-to-cat spread in the studied stray cat groups and consider the likelihood of spillover to humans as low