Hepatobiliary organoids derived from leporids support the replication of hepatotropic lagoviruses.

The genus Lagovirus of the family Caliciviridae contains some of the most virulent vertebrate viruses known. Lagoviruses infect leporids, such as rabbits, hares and cottontails. Highly pathogenic viruses such as Rabbit haemorrhagic disease virus 1 (RHDV1) cause a fulminant hepatitis that typically leads to disseminated intravascular coagulation within 24-72 h of infection, killing over 95 % of susceptible animals. Research into the pathophysiological mechanisms that are responsible for this extreme phenotype has been hampered by the lack of a reliable culture system. Here, we report on a new ex vivo model for the cultivation of lagoviruses in cells derived from the European rabbit (Oryctolagus cuniculus) and European brown hare (Lepus europaeus). We show that three different lagoviruses, RHDV1, RHDV2 and RHDVa-K5, replicate in monolayer cultures derived from rabbit hepatobiliary organoids, but not in monolayer cultures derived from cat (Felis catus) or mouse (Mus musculus) organoids. Virus multiplication was demonstrated by (i) an increase in viral RNA levels, (ii) the accumulation of dsRNA viral replication intermediates and (iii) the expression of viral structural and non-structural proteins. The establishment of an organoid culture system for lagoviruses will facilitate studies with considerable implications for the conservation of endangered leporid species in Europe and North America, and the biocontrol of overabundant rabbit populations in Australia and New Zealand.

Inhibition of Pol I transcription treats murine and human AML by targeting the leukemia-initiating cell population.

Despite the development of novel drugs, the prospects for many patients with acute myeloid leukemia (AML) remain dismal. This study reveals that the selective inhibitor of RNA polymerase I (Pol I) transcription, CX-5461, effectively treats aggressive AML, including mixed-lineage leukemia-driven AML, and outperforms standard chemotherapies. In addition to the previously characterized mechanism of action of CX-5461 (ie, the induction of p53-dependent apoptotic cell death), the inhibition of Pol I transcription also demonstrates potent efficacy in p53null AML in vivo. This significant survival advantage in both p53WT and p53null leukemic mice treated with CX-5461 is associated with activation of the checkpoint kinases 1/2, an aberrant G2/M cell-cycle progression and induction of myeloid differentiation of the leukemic blasts. The ability to target the leukemic-initiating cell population is thought to be essential for lasting therapeutic benefit. Most strikingly, the acute inhibition of Pol I transcription reduces both the leukemic granulocyte-macrophage progenitor and leukemia-initiating cell (LIC) populations, and suppresses their clonogenic capacity. This suggests that dysregulated Pol I transcription is essential for the maintenance of their leukemia-initiating potential. Together, these findings demonstrate the therapeutic utility of this new class of inhibitors to treat highly aggressive AML by targeting LICs.

Marketing claims on websites of brick-and-mortar vape shops in the Greater Los Angeles area.

INTRODUCTION: Brick-and-mortar vape shops have increased in recent years, but there is limited research on the types of marketing claims consumers are exposed to on their websites - a dominant channel for marketing electronic nicotine delivery systems (ENDS). We investigated the websites of vape shop retailers in the Greater Los Angeles Area to describe their ENDS marketing claims. METHODS: Data collection occurred between 25 March and 20 June 2020. Of the 104 brick-and-mortar vape shops identified, 37 were found to have active websites. Rules were established to analyze website content. ENDS Marketing Claims were coded as the presence or absence of: 1) a direct claim of ENDS as a quitting aid; 2) a disclaimer that ENDS are not approved as smoking cessation devices (i.e. ENDS products are not FDA-approved for smoking cessation); 3) a direct claim of ENDS as healthier/safer than combustible cigarettes; and 4) direct claims regarding social benefits, including that ENDS are less expensive, can be used in more places, are cleaner or less messy/smelly, and are more socially accepted than combustible cigarettes. RESULTS: Smoking cessation-related benefits were claimed most frequently (43%), followed by health-related claims (30%), and disclaimers that ENDS are not approved as smoking cessation devices (24%). More than half (56.4%) of websites had an age restriction, requiring the user to click on a box to state that they were aged ≥21 years to view the site. None required proof or outside verification of age. CONCLUSIONS: Brick-and-mortar vape shops in the Greater Los Angeles Area are marketing ENDS on their websites as a healthier alternative to smoking cigarettes. Although half of the websites had an age gate popup that consumers see when they enter the website, action is needed to better enforce age restriction on access to vape shop websites. Utility for smoking cessation was claimed most frequently, followed by the claims of healthier alternatives to smoking cigarettes, and disclaimers that ENDS are not approved as smoking cessation devices. We discuss implications for tobacco regulatory policy.

Nuclear stabilization of p53 requires a functional nucleolar surveillance pathway.

The nucleolar surveillance pathway monitors nucleolar integrity and responds to nucleolar stress by mediating binding of ribosomal proteins to MDM2, resulting in p53 accumulation. Inappropriate pathway activation is implicated in the pathogenesis of ribosomopathies, while drugs selectively activating the pathway are in trials for cancer. Despite this, the molecular mechanism(s) regulating this process are poorly understood. Using genome-wide loss-of-function screens, we demonstrate the ribosome biogenesis axis as the most potent class of genes whose disruption stabilizes p53. Mechanistically, we identify genes critical for regulation of this pathway, including HEATR3. By selectively disabling the nucleolar surveillance pathway, we demonstrate that it is essential for the ability of all nuclear-acting stresses, including DNA damage, to induce p53 accumulation. Our data support a paradigm whereby the nucleolar surveillance pathway is the central integrator of stresses that regulate nuclear p53 abundance, ensuring that ribosome biogenesis is hardwired to cellular proliferative capacity.

An inactivated Vero cell-grown Japanese encephalitis vaccine formulated with Advax, a novel inulin-based adjuvant, induces protective neutralizing antibody against homologous and heterologous flaviviruses.

Advax is a polysaccharide-based adjuvant that potently stimulates vaccine immunogenicity without the increased reactogenicity seen with other adjuvants. This study investigated the immunogenicity of a novel Advax-adjuvanted Vero cell culture candidate vaccine against Japanese encephalitis virus (JEV) in mice and horses. The results showed that, in mice, a two-immunization, low-dose (50 ng JEV antigen) regimen with adjuvanted vaccine produced solid neutralizing immunity comparable to that elicited with live ChimeriVax-JE immunization and superior to that elicited with tenfold higher doses of a traditional non-adjuvanted JEV vaccine (JE-VAX; Biken Institute) or a newly approved alum-adjuvanted vaccine (Jespect; Novartis). Mice vaccinated with the Advax-adjuvanted, but not the unadjuvanted vaccine, were protected against live JEV challenge. Equine immunizations against JEV with Advax-formulated vaccine similarly showed enhanced vaccine immunogenicity, confirming that the adjuvant effects of Advax are not restricted to rodent models. Advax-adjuvanted JEV vaccine elicited a balanced T-helper 1 (Th1)/Th2 immune response against JEV with protective levels of cross-neutralizing antibody against other viruses belonging to the JEV serocomplex, including Murray Valley encephalitis virus (MVEV). The adjuvanted JEV vaccine was well tolerated with minimal reactogenicity and no systemic toxicity in immunized animals. The cessation of manufacture of traditional mouse brain-derived unadjuvanted JEV vaccine in Japan has resulted in a JEV vaccine shortage internationally. There is also an ongoing lack of human vaccines against other JEV serocomplex flaviviruses, such as MVEV, making this adjuvanted, cell culture-grown JEV vaccine a promising candidate to address both needs with one vaccine.

Live chimeric and inactivated Japanese encephalitis virus vaccines differ in their cross-protective values against Murray Valley encephalitis virus.

The Japanese encephalitis virus (JEV) serocomplex, which also includes Murray Valley encephalitis virus (MVEV), is a group of antigenically closely related, mosquito-borne flaviviruses that are responsible for severe encephalitic disease in humans. While vaccines against the prominent members of this serocomplex are available or under development, it is unlikely that they will be produced specifically against those viruses which cause less-frequent disease, such as MVEV. Here we have evaluated the cross-protective values of an inactivated JEV vaccine (JE-VAX) and a live chimeric JEV vaccine (ChimeriVax-JE) against MVEV in two mouse models of flaviviral encephalitis. We show that (i) a three-dose vaccination schedule with JE-VAX provides cross-protective immunity, albeit only partial in the more severe challenge model; (ii) a single dose of ChimeriVax-JE gives complete protection in both challenge models; (iii) the cross-protective immunity elicited with ChimeriVax-JE is durable (>or=5 months) and broad (also giving protection against West Nile virus); (iv) humoral and cellular immunities elicited with ChimeriVax-JE contribute to protection against lethal challenge with MVEV; (v) ChimeriVax-JE remains fully attenuated in immunodeficient mice lacking type I and type II interferon responses; and (vi) immunization with JE-VAX, but not ChimeriVax-JE, can prime heterologous infection enhancement in recipients of vaccination on a low-dose schedule, designed to mimic vaccine failure or waning of vaccine-induced immunity. Our results suggest that the live chimeric JEV vaccine will protect against other viruses belonging to the JEV serocomplex, consistent with the observation of cross-protection following live virus infections.

PGRMC1 phosphorylation affects cell shape, motility, glycolysis, mitochondrial form and function, and tumor growth.

BACKGROUND: Progesterone Receptor Membrane Component 1 (PGRMC1) is expressed in many cancer cells, where it is associated with detrimental patient outcomes. It contains phosphorylated tyrosines which evolutionarily preceded deuterostome gastrulation and tissue differentiation mechanisms. RESULTS: We demonstrate that manipulating PGRMC1 phosphorylation status in MIA PaCa-2 (MP) cells imposes broad pleiotropic effects. Relative to parental cells over-expressing hemagglutinin-tagged wild-type (WT) PGRMC1-HA, cells expressing a PGRMC1-HA-S57A/S181A double mutant (DM) exhibited reduced levels of proteins involved in energy metabolism and mitochondrial function, and altered glucose metabolism suggesting modulation of the Warburg effect. This was associated with increased PI3K/AKT activity, altered cell shape, actin cytoskeleton, motility, and mitochondrial properties. An S57A/Y180F/S181A triple mutant (TM) indicated the involvement of Y180 in PI3K/AKT activation. Mutation of Y180F strongly attenuated subcutaneous xenograft tumor growth in NOD-SCID gamma mice. Elsewhere we demonstrate altered metabolism, mutation incidence, and epigenetic status in these cells. CONCLUSIONS: Altogether, these results indicate that mutational manipulation of PGRMC1 phosphorylation status exerts broad pleiotropic effects relevant to cancer and other cell biology.

Location of contact residues in pharmacologically distinct drug binding sites on P-glycoprotein.

The multidrug resistance P-glycoprotein (P-gp) is characterised by the ability to bind and/or transport an astonishing array of drugs. This poly-specificity is imparted by at least four pharmacologically distinct binding sites within the transmembrane domain. Whether or not these sites are spatially distinct has remained unclear. Biochemical and structural investigations have implicated a central cavity as the likely location for the binding sites. In the present investigation, a number of contact residues that are involved in drug binding were identified through biochemical assays using purified, reconstituted P-gp. Drugs were selected to represent each of the four pharmacologically distinct sites. Contact residues important in rhodamine123 binding were identified in the central cavity of P-gp. However, contact residues for the binding of vinblastine, paclitaxel and nicardipine were located at the lipid-protein interface rather than the central cavity. A key residue (F978) within the central cavity is believed to be involved in coupling drug binding to nucleotide hydrolysis. Data observed in this investigation suggest the presence of spatially distinct drug binding sites connecting through to a single translocation pore in the central cavity.

Antiviral effect of the heparan sulfate mimetic, PI-88, against dengue and encephalitic flaviviruses.

Many viruses, including flaviviruses, display affinity for cell surface heparan sulfate (HS) proteoglycans with biological relevance in virus attachment/entry. This raises the possibility of the application of HS mimetics in antiviral therapy. We have evaluated the antiviral effect of the sulfated polysaccharides, suramin, pentosan polysulfate (PPS) and PI-88, which are currently approved or in trial for clinical use, against dengue virus (DEN) and the encephalitic flaviviruses, Japanese encephalitis virus, West Nile virus, and Murray Valley encephalitis virus. A flow cytometry-based method for the measurement of inhibition of virus infectivity was developed, which showed the in vitro antiviral activity of the three compounds, albeit with differences in efficiency which were virus-dependent. The 50% effective concentration (EC(50)) values for DEN inhibition were in the order: PPS

A flavivirus signal peptide balances the catalytic activity of two proteases and thereby facilitates virus morphogenesis.

Two cleavages on either side of a signal peptide separating capsid and prM on the nascent flavivirus polyprotein are uniquely regulated, such that cytosolic capsid cleavage triggers signalase cleavage of prM. Here, we show, using two experimental approaches, that this sequential order of cleavages facilitates virus morphogenesis: (i) A Murray Valley encephalitis virus (MVEV) variant, in which both cleavages occurred efficiently and independently of each other, displayed an assembly defect. (ii) Replicon particle assembly was assayed in packaging cells encoding the MVEV structural proteins; bicistronic expression of either mature or membrane-anchored capsid in addition to that of the prM and E proteins showed enhanced particle production in the latter cell line. Taken together, this study demonstrates that efficient flavivirus assembly requires a cleavable transmembrane anchor of C protein and an obligatory order of cleavages at the C-prM junction, both controlled by sequence elements in the prM signal peptide.

Cross-protective and infection-enhancing immunity in mice vaccinated against flaviviruses belonging to the Japanese encephalitis virus serocomplex.

The Japanese encephalitis virus serocomplex is a group of mosquito-borne flaviviruses that cause severe encephalitic disease in humans. The recent emergence of several members of this serocomplex in geographic regions where other closely related flaviviruses are endemic has raised urgent human health issues. Thus, the impact of vaccination against one of these neurotropic virus on the outcome of infection with a second, serologically related virus is unknown. We show here that immunity against Murray Valley encephalitis virus in vaccinated mice can cross-protect but also augment disease severity following challenge with Japanese encephalitis virus. Immunepotentiation of heterologous flavivirus disease was apparent in animals immunized with a 'killed' virus preparation when humoral antiviral immunity of low magnitude was elicited.

Role of type I and type II interferon responses in recovery from infection with an encephalitic flavivirus.

We have investigated the contribution of the interferon (IFN)-alpha/beta system, IFN-gamma and nitric oxide to recovery from infection with Murray Valley encephalitis virus, using a mouse model for flaviviral encephalitis where a small dose of virus was administered to 6-week-old wild-type and gene knockout animals by the intravenous route. We show that a defect in the IFN-alpha/beta responses results in uncontrolled extraneural virus growth, rapid virus entry into the brain and 100 % mortality. In contrast, mice deficient in IFN-gamma or nitric oxide production display an only marginally increased susceptibility to infection with the neurotropic virus.