Alzheimer's Associated β-Amyloid Protein Inhibits Influenza A Virus and Modulates Viral Interactions with Phagocytes

Accumulation of β-Amyloid (βA) is a key pathogenetic factor in Alzheimer's disease; however, the normal function of βA is unknown. Recent studies have shown that βA can inhibit growth of bacteria and fungi. In this paper we show that βA also inhibits replication of seasonal and pandemic strains of H3N2 and H1N1 influenza A virus (IAV) in vitro. The 42 amino acid fragment of βA (βA42) had greater activity than the 40 amino acid fragment. Direct incubation of the virus with βA42 was needed to achieve optimal inhibition. Using quantitative PCR assays βA42 was shown to reduce viral uptake by epithelial cells after 45 minutes and to reduce supernatant virus at 24 hours post infection. βA42 caused aggregation of IAV particles as detected by light transmission assays and electron and confocal microscopy. βA42 did not stimulate neutrophil H2O2 production or extracellular trap formation on its own, but it increased both responses stimulated by IAV. In addition, βA42 increased uptake of IAV by neutrophils. βA42 reduced viral protein synthesis in monocytes and reduced IAV-induced interleukin-6 production by these cells. Hence, we demonstrate for the first time that βA has antiviral activity and modulates viral interactions with phagocytes

Carbon Detection in Early-Time Optical Spectra of Type Ia Supernovae

While O is often seen in spectra of Type Ia supernovae (SNe Ia) as both unburned fuel and a product of C burning, C is only occasionally seen at the earliest times, and it represents the most direct way of investigating primordial white dwarf material and its relation to SN Ia explosion scenarios and mechanisms. In this paper, we search for C absorption features in 188 optical spectra of 144 low-redshift (z < 0.1) SNe Ia with ages <3.6 d after maximum brightness. These data were obtained as part of the Berkeley SN Ia Program (BSNIP; Silverman et al. 2012) and represent the largest set of SNe Ia in which C has ever been searched. We find that ~11 per cent of the SNe studied show definite C absorption features while ~25 per cent show some evidence for C II in their spectra. Also, if one obtains a spectrum at t < -5 d, then there is a better than 30 per cent chance of detecting a distinct absorption feature from C II. SNe Ia that show C are found to resemble those without C in many respects, but objects with C tend to have bluer optical colours than those without C. The typical expansion velocity of the C II {\lambda}6580 feature is measured to be 12,000-13,000 km/s, and the ratio of the C II {\lambda}6580 to Si II {\lambda}6355 velocities is remarkably constant with time and among different objects with a median value of ~1.05. While the pseudo-equivalent widths (pEWs) of the C II {\lambda}6580 and C II {\lambda}7234 features are found mostly to decrease with time, we see evidence of a significant increase in pEW between ~12 and 11 d before maximum brightness, which is actually predicted by some theoretical models. The range of pEWs measured from the BSNIP data implies a range of C mass in SN Ia ejecta of about (2-30) * 10^-3 M_Sun.Comment: 20 pages, 11 figures, 4 tables, revised version re-submitted to MNRA

THE FIRST MAXIMUM-LIGHT ULTRAVIOLET THROUGH NEAR-INFRARED SPECTRUM OF A TYPE Ia SUPERNOVA

We present the first maximum-light ultraviolet (UV) through near-infrared (NIR) Type Ia supernova (SN Ia) spectrum. This spectrum of SN 2011iv was obtained nearly simultaneously by the Hubble Space Telescope at UV/optical wavelengths and the Magellan Baade telescope at NIR wavelengths. These data provide the opportunity to examine the entire maximum-light SN Ia spectral energy distribution. Since the UV region of an SN Ia spectrum is extremely sensitive to the composition of the outer layers of the explosion, which are transparent at longer wavelengths, this unprecedented spectrum can provide strong constraints on the composition of the SN ejecta, and similarly the SN explosion and progenitor system. SN 2011iv is spectroscopically normal, but has a relatively fast decline (Δm [subscript 15](B) = 1.69 ± 0.05 mag). We compare SN 2011iv to other SNe Ia with UV spectra near maximum light and examine trends between UV spectral properties, light-curve shape, and ejecta velocity. We tentatively find that SNe with similar light-curve shapes but different ejecta velocities have similar UV spectra, while those with similar ejecta velocities but different light-curve shapes have very different UV spectra. Through a comparison with explosion models, we find that both a solar-metallicity W7 and a zero-metallicity delayed-detonation model provide a reasonable fit to the spectrum of SN 2011iv from the UV to the NIR

Novel Pandemic Influenza A(H1N1) Viruses Are Potently Inhibited by DAS181, a Sialidase Fusion Protein

Background: The recent emergence of a novel pandemic influenza A(H1N1) strain in humans exemplifies the rapid and unpredictable nature of influenza virus evolution and the need for effective therapeutics and vaccines to control such outbreaks. However, resistance to antivirals can be a formidable problem as evidenced by the currently widespread oseltamivir- and adamantane-resistant seasonal influenza A viruses (IFV). Additional antiviral approaches with novel mechanisms of action are needed to combat novel and resistant influenza strains. DAS181 (Fludase)™) is a sialidase fusion protein in early clinical development with in vitro and in vivo preclinical activity against a variety of seasonal influenza strains and highly pathogenic avian influenza strains (A/H5N1). Here, we use in vitro, ex vivo, and in vivo models to evaluate the activity of DAS181 against several pandemic influenza A(H1N1) viruses. Methods and Findings: The activity of DAS181 against several pandemic influenza A(H1N1) virus isolates was examined in MDCK cells, differentiated primary human respiratory tract culture, ex-vivo human bronchi tissue and mice. DAS181 efficiently inhibited viral replication in each of these models and against all tested pandemic influenza A(H1N1) strains. DAS181 treatment also protected mice from pandemic influenza A(H1N1)-induced pathogenesis. Furthermore, DAS181 antiviral activity against pandemic influenza A(H1N1) strains was comparable to that observed against seasonal influenza virus including the H274Y oseltamivir-resistant influenza virus. Conclusions: The sialidase fusion protein DAS181 exhibits potent inhibitory activity against pandemic influenza A(H1N1) viruses. As inhibition was also observed with oseltamivir-resistant IFV (H274Y), DAS181 may be active against the antigenically novel pandemic influenza A(H1N1) virus should it acquire the H274Y mutation. Based on these and previous results demonstrating DAS181 broad-spectrum anti-IFV activity, DAS181 represents a potential therapeutic agent for prevention and treatment of infections by both emerging and seasonal strains of IFV.published_or_final_versio

Effects of βA42 on viral internalization and viral replication in MDCK cells as determined by quantitative RT-PCR.

<p>In panels A, Phil82 IAV was pre-incubated with the indicated concentrations of βA42, followed by incubation of these samples for 45 min with MDCK cells as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0101364#pone-0101364-g001" target="_blank">figure 1</a>. The cell supernatant and cell pellets were then harvested and viral RNA was extracted followed by PCR assay to determine the amount of virus present in cells and supernatant. βA42 significantly reduced the amount of virus taken up by cells after 45 min of infection. There was a trend to increased virus in the supernatant after 45 min of infection but this was not significant. Panel B shows the results of cell and supernatant assays after 24 hrs of infection. βA42 significantly reduced the amount of virus in both cell and supernatant at this time. * indicates p<0.05 compared with control. Results are mean±SEM of three experiments.</p

Neutrophil H₂O₂ responses to IAV alone or IAV treated with βA42 or βA40.

<p>Human neutrophils were treated with buffer alone (PBS), IAV alone (Phil82) or IAV that had been pre-treated with βA42 or scrambled βA42 (panel A) or βA40 (panel B) (all at 16 µg/ml). βA42 caused a significant increase in H₂O₂ response compared to IAV alone or IAV pre-treated with the scrambled peptide of βA40 (indicated by **). Note that the latter two proteins did not increase the response compared to IAV alone. Results are mean±SEM from 5 experiments (each with a separate neutrophil donor).</p

Effects of βA42 on interactions of IAV with monocytes: viral protein synthesis (panel A), viral uptake (panel B) and virus-induced cytokine generation (panel C).

<p>Adherent peripheral blood monocytes were infected with Phil82 IAV alone or Phil82 IAV treated with the indicated doses of βA42. In panel A the presence of viral nucleoprotein in the cells was tested as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0101364#pone-0101364-g001" target="_blank">figure 1</a> after 24 hours of incubation. * indicates significant reduction compared to virus alone (p<0.03; n = 4 separate blood donors). In panel B the ability of monocytes to take up fluorescently labeled IAV after a 45 min incubation was tested. Increased uptake (p<0.05; n = 4) is indicated by *. In panel C the monocytes were incubated with IAV+/−peptide for 24 hrs and then TNF or IL-6 release into the supernatant was measured by ELISA. IAV alone stimulated increased cytokine production by the cells (see Results section). IL-6 production was significantly reduced by pre-incubation of the virus with βA42 (p<0.02; n = 4; indicated by *). TNF production was not reduced by βA42 (n = 8).</p

Viral neutralizing activity of βA42 and 40 for seasonal H3N2 and pandemic H1N1 strains of IAV.

<p>Aliquots of the Phil82 H3N2 (panel A) or Cal09 H1N1 (panel B) viral strains were incubated with the indicated concentrations of βA42 or 40 or a scrambled version of βA42 and then these samples were used to infect HBTE cell monolayers and tested for infectious foci 7 hrs later using anti-nucleoprotein antibodies and fluorescence detection. * indicates significant reduction in infectivity compared to control (p<0.05; n = 4 experiments) ** indicates p<0.02 compared with βA40, scrambled βA42 and control (ANOVA analysis) # indicates increased infectivity compared to control.</p

Fluorescent micrographs of NET formation in response to IAV and/or βA42.

<p>Panel A: Results are representative of 4 experiments using different neutrophil donors. The figures to the left show Sytox green fluorescence and those to the right in this panel show the same fields under phase contrast microscopy to illustrate how many neutrophils were present. These pictures were taken at 40× and enlarged to match the size of the cells in panel B. Panel B are representative of another set of 3 experiments using Phil82 or Aichi68 viral strains as indicated phase and show Sytox green fluorescence taken at 100× magnification.</p