An ACE2 decamer viral trap as a durable intervention solution for current and future SARS-CoV

The capacity of SARS-CoV-2 to evolve poses challenges to conventional prevention and treatment options such as vaccination and monoclonal antibodies, as they rely on viral receptor binding domain (RBD) sequences from previous strains. Additionally, animal CoVs, especially those of the SARS family, are now appreciated as a constant pandemic threat. We present here a new antiviral approach featuring inhalation delivery of a recombinant viral trap composed of ten copies of angiotensin-converting enzyme 2 (ACE2) fused to the IgM Fc. This ACE2 decamer viral trap is designed to inhibit SARS-CoV-2 entry function, regardless of viral RBD sequence variations as shown by its high neutralization potency against all known SARS-CoV-2 variants, including Omicron BQ.1, BQ.1.1, XBB.1 and XBB.1.5. In addition, it demonstrates potency against SARS-CoV-1, human NL63, as well as bat and pangolin CoVs. The multivalent trap is effective in both prophylactic and therapeutic settings since a single intranasal dosing confers protection in human ACE2 transgenic mice against viral challenges. Lastly, this molecule is stable at ambient temperature for more than twelve weeks and can sustain physical stress from aerosolization. These results demonstrate the potential of a decameric ACE2 viral trap as an inhalation solution for ACE2-dependent coronaviruses of current and future pandemic concerns.

Stimulation of B Cell Immunity in Flavivirus-Naive Individuals by the Tetravalent Live Attenuated Dengue Vaccine TV003

The tetravalent live attenuated dengue vaccine candidate TV003 induces neutralizing antibodies against all four dengue virus serotypes (DENV1–DENV4) and protects against experimental challenge with DENV2 in humans. Here, we track vaccine viremia and B and T cell responses to this vaccination/challenge model to understand how vaccine viremia links adaptive immunity and development of protective antibody responses. TV003 viremia triggers an acute plasmablast response that, in combination with DENV-specific CD4⁺ T cells, correlates with serum neutralizing antibodies. TV003 vaccinees develop DENV2-reactive memory B cells, including serotype-specific and multivalent specificities in line with the composition of serum antibodies. There is no post-challenge plasmablast response in vaccinees, although stronger and earlier post-TV003 plasmablast responses associate with sterile humoral protection from DENV2 challenge. TV003 vaccine triggers plasmablasts and memory B cells, which, with support from CD4⁺ T cells, functionally link early vaccine viremia and the serum antibody responses.

The tetravalent live attenuated dengue vaccine TV003 stimulates plasmablasts

Robust plasmablast response is associated with sterile protection from challenge

DENV-specific memory B cells persist 6 months after vaccination

DENV-specific CD4⁺ T cells correlate with neutralizing antibodies

Comparison of VSV Pseudovirus and Focus Reduction Neutralization Assays for Measurement of Anti-Andes orthohantavirus Neutralizing Antibodies in Patient Samples

Andes orthohantavirus (ANDV) is the etiologic agent of hantavirus cardiopulmonary syndrome (HCPS), which has a case fatality rate around 35%, with no effective treatment or vaccine available. ANDV neutralizing antibody (NAb) measurements are important for the evaluation of the immune response following infection, vaccination, or passive administration of investigational monoclonal or polyclonal antibodies. The standard assay for NAb measurement is a focus reduction neutralization test (FRNT) featuring live ANDV and must be completed under biosafety level (BSL)-3 conditions. In this study, we compared neutralization assays featuring infectious ANDV or vesicular stomatitis virus (VSV) pseudovirions decorated with ANDV glycoproteins for their ability to measure anti-ANDV NAbs from patient samples. Our studies demonstrate that VSV pseudovirions effectively measure NAb from clinical samples and have greater sensitivity compared to FRNT with live ANDV. Importantly, the pseudovirus assay requires less labor and sample materials and can be conducted at BSL-2.

NEDD4 family ubiquitin ligases associate with LCMV Z's PPXY domain and are required for virus budding, but not via direct ubiquitination of Z

Viral late domains are used by many viruses to recruit the cellular endosomal sorting complex required for transport (ESCRT) to mediate membrane scission during viral budding. Unlike the P(S/T)AP and YPX_(1–3)L late domains, which interact directly with the ESCRT proteins Tsg101 and ALIX, the molecular linkage connecting the PPXY late domain to ESCRT proteins is unclear. The mammarenavirus lymphocytic choriomeningitis virus (LCMV) matrix protein, Z, contains only one late domain, PPXY. We previously found that this domain in LCMV Z, as well as the ESCRT pathway, are required for the release of defective interfering (DI) particles but not infectious virus. To better understand the molecular mechanism of ESCRT recruitment by the PPXY late domain, affinity purification-mass spectrometry was used to identify host proteins that interact with the Z proteins of the Old World mammarenaviruses LCMV and Lassa virus. Several Nedd4 family E3 ubiquitin ligases interact with these matrix proteins and in the case of LCMV Z, the interaction was PPXY-dependent. We demonstrated that these ligases directly ubiquitinate LCMV Z and mapped the specific lysine residues modified. A recombinant LCMV containing a Z that cannot be ubiquitinated maintained its ability to produce both infectious virus and DI particles, suggesting that direct ubiquitination of LCMV Z alone is insufficient for recruiting ESCRT proteins to mediate virus release. However, Nedd4 ligases appear to be important for DI particle release suggesting that ubiquitination of targets other than the Z protein itself is required for efficient viral ESCRT recruitment.

Enveloped viruses derive their lipid bilayer from either the cellular plasma membrane or an intracellular organelle during the process of viral budding in which a virus particle is formed at a membrane. Many enveloped viruses recruit the cellular endosomal sorting complex required for transport (ESCRT) in order to efficiently cut the membrane that connects a newly budded, but not released, virus particle from its parent membrane. Late domains, which are short protein motifs found in numerous enveloped viruses, specifically recruit ESCRT for this process. Two types of late domains accomplish this by binding directly to ESCRT proteins. A third late domain, PPXY, recruits ESCRT proteins through an unknown, indirect linkage. In this study, we sought to identify proteins that may bridge the PPXY late domain and ESCRT proteins. We found that Nedd4 family ubiquitin ligases interact with the PPXY domain in the mammarenavirus Z protein resulting in ubiquitination of Z at two lysine residues. However, Z ubiquitination was largely dispensable for the virus. Conversely, Nedd4 ubiquitin ligases were critical during infection suggesting that the most important contribution made to virus release by Nedd4 ligases is not direct ubiquitination of the viral matrix protein, but possibly the ubiquitination of cellular proteins or other viral proteins.

Host-Driven Phosphorylation Appears to Regulate the Budding Activity of the Lassa Virus Matrix Protein

Lassa mammarenavirus (LASV) is an enveloped RNA virus that can cause Lassa fever, an acute hemorrhagic fever syndrome associated with significant morbidity and high rates of fatality in endemic regions of western Africa. The arenavirus matrix protein Z has several functions during the virus life cycle, including coordinating viral assembly, driving the release of new virus particles, regulating viral polymerase activity, and antagonizing the host antiviral response. There is limited knowledge regarding how the various functions of Z are regulated. To investigate possible means of regulation, mass spectrometry was used to identify potential sites of phosphorylation in the LASV Z protein. This analysis revealed that two serines (S18, S98) and one tyrosine (Y97) are phosphorylated in the flexible N- and C-terminal regions of the protein. Notably, two of these sites, Y97 and S98, are located in (Y97) or directly adjacent to (S98) the PPXY late domain, an important motif for virus release. Studies with non-phosphorylatable and phosphomimetic Z proteins revealed that these sites are important regulators of the release of LASV particles and that host-driven, reversible phosphorylation may play an important role in the regulation of LASV Z protein function.

Anschluß und On-line-Betrieb eines Szintiscanners an einem Digitalrechner

Das Betriebssystem BSC 1 steuert sowohl die Übernahme der Scanner-Informationen und die Eingaben vom Teletype als auch die verschiedenen Wiedergabemöglichkeiten eines Szintigramms. Bei der Aufnahme werden zunächst Patientennamen und verschiedene Scan-Parameter eingegeben. Vor Beginn des übemahmeprogramms errechnet das Programm Größen für eine möglichst optimale Ausnutzung des Speichers. Nach der Scan-Aufnahme werden Parameter für die Wiedergabeprogramme bestimmt. Danach geht der Rechner in die Warteschleife, in der er auf Wiedergabekommandos wartet. Das Betriebssystem enthält weiter Programmteile, mit denen der Inhalt des Datenspeichers als Lochstreifen ausgegeben, ein solcher Lochstreifen wieder eingelesen werden kann und Möglichkeiten zur zusätzlichen Beschriftung der Sichtgerätausgaben.

Anschluß und On-line-Betrieb eines Szintiscanners an einem Digitalrechner

Zur möglichst vollständigen Übernahme und Speicherung der bei der Aufnahme eines Szintigramms gewinnbaren Basis-Informationen wird ein Digitalrechner eingesetzt. Die Anlage besteht aus einem Picker Magnascanner und einem Rechner PDP 8/S als Grundeinheiten und einem Fernschreiber, einem Sichtgerät und einem x-y-Schreiber als Ausgabeeinheiten. Interface-Elektroniken dienen dazu, die Scanner-Informationen in den Rechner zu übernehmen und die Ausgabegeräte softwaremäßig vom Rechner her zu steuern. Das “Übernahme-Interface enthält ein eigenes Zählregister, Dadurch und durch die Bedienung des Interface über den Programm-Interrupt wurde erreicht, daß der Rechner während der Szintigramm-Aufnahme nur einen kleinen Prozentsatz der Zeit beansprucht wird und in der übrigen Zeit für die Auswertung der Datenmatrix oder für die Bedienung weiterer Geräte zur Verfügung steht.

Anschluß und On-line-Betrieb eines Szintiscanners an einem Digitalrechner

Das Betriebssystem enthält 2 Arten von Wiedergabeprogrammen: Wiedergaben am Sichtgerät und Druckausgaben. Beide werden durch ein Codewort vom Teletype aus aufgerufen.

Bei dem Programm SSWE werden auf dem Sichtgerät alle Werte dargestellt, die über einer bestimmten Schwelle liegen. Diese Schwelle wird bei diesem Programm mit der Hand eingestellt, während sie bei dem Programm SASW automatisch angehoben wird und so einen Bilderzyklus liefert. Weitere Programme zeichnen die Höhenschichtlinien und liefern eine perspektivische Darstellung des Aktivitätsgebirges.

Bei den Druckausgaben liefert das Programm FSWE eine Schwellendarstellung, während das Programm FVZE eine Darstellung der verschiedenen Niveaus mit verschiedenen Druckzeichen ausgibt. Ein ähnliches Programm ergibt eine Darstellung in mehrfachen Niveaugruppen. Außerdem ist in dem Betriebssystem noch ein Programm zur Druckausgabe von Höhenschichtlinien enthalten.

A novel phosphoserine motif in the LCMV matrix protein Z regulates the release of infectious virus and defective interfering particles

We report that the lymphocytic choriomeningitis virus (LCMV) matrix protein, which drives viral budding, is phosphorylated at serine 41 (S41). A recombinant (r)LCMV bearing a phosphomimetic mutation (S41D) was impaired in infectious and defective interfering (DI) particle release, while a non-phosphorylatable mutant (S41A) was not. The S41D mutant was disproportionately impaired in its ability to release DI particles relative to infectious particles. Thus, DI particle production by LCMV may be dynamically regulated via phosphorylation of S41.

The intracellular cargo receptor ERGIC-53 is required for the production of infectious arenavirus, coronavirus, and filovirus particles

Arenaviruses and hantaviruses cause severe human disease. Little is known regarding host proteins required for their propagation. We identified human proteins that interact with the glycoproteins (GPs) of a prototypic arenavirus and hantavirus and show that the lectin endoplasmic reticulum (ER)-Golgi intermediate compartment 53 kDa protein (ERGIC-53), a cargo receptor required for glycoprotein trafficking within the early exocytic pathway, associates with arenavirus, hantavirus, coronavirus, orthomyxovirus, and filovirus GPs. ERGIC-53 binds to arenavirus GPs through a lectin-independent mechanism, traffics to arenavirus budding sites, and is incorporated into virions. ERGIC-53 is required for arenavirus, coronavirus, and filovirus propagation; in its absence, GP-containing virus particles form but are noninfectious, due in part to their inability to attach to host cells. Thus, we have identified a class of pathogen-derived ERGIC-53 ligands, a lectin-independent basis for their association with ERGIC-53, and a role for ERGIC-53 in the propagation of several highly pathogenic RNA virus families.

Endogenous distal airway progenitor cells, lung mechanics, and disproportionate lobar growth following long-term postpneumonectomy in mice

Using a model of postpneumonectomy (PNY) compensatory lung growth in mice, we previously observed an increase in numbers of a putative endogenous distal airway progenitor cell population (CCSP(pos) /pro-SPC(pos) cells located at bronchoalveolar duct junctions [BADJs]), at 3, 7, and 14 days after pneumonectomy, returning to baseline at 28 days post-PNY. As the origin of these cells is poorly understood, we evaluated whether bone marrow cells contributed to the pool of these or other cells during prolonged post-PNY lung regrowth. Naïve and sex-mismatched chimeric mice underwent left PNY and were evaluated at 1, 2, and 3 months for numbers of BADJ CCSP(pos) /pro-SPC(pos) cells and presence of donor-derived marrow cells engrafted as airway or alveolar epithelium. Nonchimeric mice were also examined at 12 months after PNY for numbers of BADJ CCSP(pos) /pro-SPC(pos) cells. Notably, the right accessory lobe (RAL) continued to grow disproportionately over 12 months, a novel finding not previously described. Assessment of lung mechanics demonstrated an increase in lung stiffness following PNY, which significantly diminished over 1 year, but remained elevated relative to 1-year-old naïve controls. However, the number of CCSP(pos) /pro-SPC(pos) BADJ cells ≥1-month following PNY was equivalent to that found in naïve controls even after 12 months of continued RAL growth. Notably, no donor bone marrow-derived cells engrafted as airway or alveolar epithelial cells, including those at the BADJ, up to 3 months after PNY. These studies suggest that lung epithelial cells, including CCSP(pos) /pro-SPC(pos) cells, are not replenished from marrow-derived cells during post-PNY lung growth in mice.

Bone marrow-derived mesenchymal stromal cells inhibit Th2-mediated allergic airways inflammation in mice

Bone marrow-derived mesenchymal stromal cells (BMSCs) mitigate inflammation in mouse models of acute lung injury. However, specific mechanisms of BMSC actions on CD4 T lymphocyte-mediated inflammation in vivo remain poorly understood. Limited data suggests promotion of Th2 phenotype in models of Th1-mediated diseases. However, whether this might alleviate or worsen Th2-mediated diseases such as allergic asthma is unknown. To ascertain the effects of systemic administration of BMSCs in a mouse model of Th2-mediated allergic airways inflammation, ovalbumin (OVA)-induced allergic airways inflammation was induced in wild-type C57BL/6 and BALB/c mice as well as in interferon-γ (IFNγ) receptor null mice. Effects of systemic administration during antigen sensitization of either syngeneic or allogeneic BMSC on airways hyperreactivity, lung inflammation, antigen-specific CD4 T lymphocytes, and serum immunoglobulins were assessed. Both syngeneic and allogeneic BMSCs inhibited airways hyperreactivity and lung inflammation through a mechanism partly dependent on IFNγ. However, contrary to existing data, BMSCs did not affect antigen-specific CD4 T lymphocyte proliferation but rather promoted Th1 phenotype in vivo as assessed by both OVA-specific CD4 T lymphocyte cytokine production and OVA-specific circulating immunoglobulins. BMSCs treated to prevent release of soluble mediators and a control cell population of primary dermal skin fibroblasts only partly mimicked the BMSC effects and in some cases worsened inflammation. In conclusion, BMSCs inhibit Th2-mediated allergic airways inflammation by influencing antigen-specific CD4 T lymphocyte differentiation. Promotion of a Th1 phenotype in antigen-specific CD4 T lymphocytes by BMSCs is sufficient to inhibit Th2-mediated allergic airways inflammation through an IFNγ-dependent process.

Blood brain barrier endothelial cells express candidate amyloid precursor protein-cleaving secretases

Proteolytic cleavage of the amyloid precursor protein (A beta PP) results in the generation of the amyloidogenic fragment known as amyloid beta peptide (A beta). Deposition of A beta in the brain parenchyma and cerebrovasculature is a feature of Alzheimer's disease (AD). To date, the process whereby A beta is generated and deposited remains unclear. We have previously established that activated platelets from AD patients retain more A beta PP on their surface than control platelets. We report here that an endothelial cell-derived enzyme can cleave this surface platelet A beta PP. Human blood brain barrier endothelial cells from brains of AD patients were assayed for potential A beta PP-cleaving enzymes using synthetic peptide substrates encompassing the A beta N-terminus cleavage site. A protease activity capable of cleaving A beta PP on the surface of AD platelets was noted. The A beta PP cleavage is partially inhibited by EDTA, by ZincOV, as well as by a specific inhibitor of the Zn metalloprotease E.C.3.4.24.15. Furthermore, the protease is recognized by an antibody directed against it, using immunohistochemistry, Western blot analysis and flow cytometry. The protease is not secreted, but rather resides intracellularly as well as on the surface of the endothelial cells. The data suggest that E.C.3.4.24.15 synthesized by brain endothelial cells may process the platelet-derived A beta PP, yielding fragments which could contribute to cerebrovascular A beta deposits.

Ultrasensitive assays for endogenous antimicrobial polypeptides

We developed two sensitive methods for identifying antimicrobial molecules in leukocytes and other tissues. One method uses a gel overlay technique and was designed to identify antimicrobial polypeptides in samples subjected to polyacrylamide gel electrophoresis. The other, a radial diffusion assay, allows multiple fractions obtained by chromatographic procedures to be tested for antimicrobial activity conveniently. When we used E. coli ML-35p or Salmonella typhimurium 14028S as test organisms in the radial diffusion assay, we routinely detected 5-10 ng of rabbit defensin NP-1 in 5 microliters of sample. With minor modifications, both methods can be applied to other organisms, including Gram-positive bacteria, several Candida species and Cryptococcus neoformans.

Polymorphic expression of defensins in neutrophils from outbred rats

We isolated and characterized a rat neutrophil defensin, RatNP-2, that differs from the previously described defensin RatNP-1 by containing Ser-7 in place of Arg-7. Although the resulting charge difference rendered RatNP-2 easily distinguishable from RatNP-1 on polyacrylamide gel electrophoresis gels, the two defensins exhibited very similar antimicrobial efficacies against Salmonella typhimurium, Staphylococcus aureus, and Candida albicans. The polymorphonuclear leukocytes of Sprague-Dawley rats obtained from one of two breeders also showed a marked polymorphism for defensin RatNP-4. This defensin was absent in two of seven animals and present in 1x or 2x relative amounts in the others. These observations indicate that a striking degree of defensin polymorphism exists in the polymorphonuclear leukocytes of outbred rodents.

Immune responses associated with early survival after peroral infection with Toxoplasma gondii

After peroral infection with cysts of Toxoplasma gondii, C57BL/6 mice died and A/J mice survived. To better understand the reasons for this difference in survival, host defenses during acute infection were studied: initial portal of entry of T. gondii contributed to susceptibility as more C57BL/6 mice survived after i.p. than peroral infection (p less than 0.001). Susceptible (C57BL/6) mice had more necrosis and inflammation in their brains, livers, and mesenteric lymph nodes than resistant (A/J) mice. Susceptible mice had less IgM antibody to T. gondii (p less than 0.0005) than resistant mice 7 days after infection, but amounts of IgG antibody to T. gondii were similar. Infection reduced percentages of spleen cells with the Lyt-2+ phenotype in susceptible (p less than 0.02) but not resistant mice; infection decreased percentages of spleen cells with the L3T4+ phenotype similarly in both strains of mice. Spleen cells from infected susceptible mice had greater depression in their blastogenic response to Con A (p less than 0.05) and produced significantly more IFN-gamma in culture with (p = 0.009) or without (p less than 0.05) Toxoplasma Ag than spleen cells from infected resistant mice. Infection increased serum levels of IFN-gamma substantially in susceptible but not resistant mice. Lymphocyte IL-2 production was similar in both groups of mice. Peritoneal macrophages from both strains of mice became activated to inhibit or kill T. gondii by 7 days after infection, but Kupffer cells became activated only in susceptible mice. These results indicate that increased resistance to peroral Toxoplasma infection is likely to be mediated by a number of immune responses acting together. They suggest that increased susceptibility may result from inadequately regulated inflammatory responses that increase tissue destruction.

Immune responses associated with early survival after peroral infection with Toxoplasma gondii

After peroral infection with cysts of Toxoplasma gondii, C57BL/6 mice died and A/J mice survived. To better understand the reasons for this difference in survival, host defenses during acute infection were studied: initial portal of entry of T. gondii contributed to susceptibility as more C57BL/6 mice survived after i.p. than peroral infection (p less than 0.001). Susceptible (C57BL/6) mice had more necrosis and inflammation in their brains, livers, and mesenteric lymph nodes than resistant (A/J) mice. Susceptible mice had less IgM antibody to T. gondii (p less than 0.0005) than resistant mice 7 days after infection, but amounts of IgG antibody to T. gondii were similar. Infection reduced percentages of spleen cells with the Lyt-2+ phenotype in susceptible (p less than 0.02) but not resistant mice; infection decreased percentages of spleen cells with the L3T4+ phenotype similarly in both strains of mice. Spleen cells from infected susceptible mice had greater depression in their blastogenic response to Con A (p less than 0.05) and produced significantly more IFN-gamma in culture with (p = 0.009) or without (p less than 0.05) Toxoplasma Ag than spleen cells from infected resistant mice. Infection increased serum levels of IFN-gamma substantially in susceptible but not resistant mice. Lymphocyte IL-2 production was similar in both groups of mice. Peritoneal macrophages from both strains of mice became activated to inhibit or kill T. gondii by 7 days after infection, but Kupffer cells became activated only in susceptible mice. These results indicate that increased resistance to peroral Toxoplasma infection is likely to be mediated by a number of immune responses acting together. They suggest that increased susceptibility may result from inadequately regulated inflammatory responses that increase tissue destruction.

Prevention of peroral and congenital acquisition of Toxoplasma gondii by antibody and activated macrophages

Intramuscular administration of Toxoplasma gondii lysate antigens to mice produced titers of T. gondii-specific antibody (measured by Sabin-Feldman dye test) greater than or equal to 1:1,024 in their sera. Intravenous administration of heat-killed Propionibacterium acnes to mice produced peritoneal macrophages with enhanced microbicidal capacity against T. gondii. Mice with high antibody titers or activated peritoneal macrophages or both had reduced numbers of Toxoplasma cysts in their brains 30 days after peroral challenge. Specific antibody and activated macrophages appeared to act together to significantly (P = 0.01) reduce the numbers of Toxoplasma cysts. A reduction in tissue infection as a result of these treatments was also demonstrated by subinoculation of brain tissue. A high antibody titer alone did not protect against congenital infection. Mice treated with P. acnes delivered reduced numbers of T. gondii-infected pups (P greater than 0.05). Treatment that produced high titers of Toxoplasma antibody and activated macrophages provided significant protection against congenital infection (P less than 0.05).