First International External Quality Assessment Study on Molecular and Serological Methods for Yellow Fever Diagnosis

Objective: We describe an external quality assurance (EQA) study designed to assess the efficiency and accurateness of molecular and serological methods used by expert laboratories performing YF diagnosis. Study Design: For molecular diagnosis evaluation, a panel was prepared of 14 human plasma samples containing specific RNA of different YFV strains (YFV-17D, YFV South American strain [Brazil], YFV IvoryC1999 strain), and specificity samples containing other flaviviruses and negative controls. For the serological panel, 13 human plasma samples with anti-YFVspecific antibodies against different strains of YFV (YFV-17D strain, YFV IvoryC1999 strain, and YFV Brazilian strain), as well as specificity and negative controls, were included. Results: Thirty-six laboratories from Europe, the Americas, Middle East, and Africa participated in these EQA activities. Only 16% of the analyses reported met all evaluation criteria with optimal performance. Serial dilutions of YFV-17D showed that in general the methodologies reported provided a suitable sensitivity. Failures were mainly due to the inability to detect wild-type strains or the presence of false positives. Performance in the serological diagnosis varied, mainly depending on the methodology used. Anti-YFV IgM detection was not performed in 16% of the reports using IIF or ELISA techniques, although it is preferable for the diagnosis of YFV acute infections. A good sensitivity profile was achieved in general; however, in the detection of IgM antibodies a lack of sensitivity of anti-YFV antibodies against the vaccine strain 17D was observed, and of the anti-YFV IgG antibodies against a West African strain. Neutralization assays showed a very good performance; however, the unexpected presence of false positives underlined the need of improving the running protocols. Conclusion: This EQA provides information on each laboratory’s efficacy of RT-PCR and serological YFV diagnosis techniques. The results indicate the need for improving serological and molecular diagnosis techniques and provide a follow-up of the diagnostic profiles

Phylogenetic history demonstrates two different lineages of dengue type 1 virus in Colombia

Background: Dengue Fever is one of the most important viral re-emergent diseases affecting about 50 million people around the world especially in tropical and sub-tropical countries. In Colombia, the virus was first detected in the earliest 70′s when the disease became a major public health concern. Since then, all four serotypes of the virus have been reported. Although most of the huge outbreaks reported in this country have involved dengue virus serotype 1 (DENV-1), there are not studies about its origin, genetic diversity and distribution. Results: We used 224 bp corresponding to the carboxyl terminus of envelope (E) gene from 74 Colombian isolates in order to reconstruct phylogenetic relationships and to estimate time divergences. Analyzed DENV-1 Colombian isolates belonged to the formerly defined genotype V. Only one virus isolate was clasified in the genotype I, likely representing a sole introduction that did not spread. The oldest strains were closely related to those detected for the first time in America in 1977 from the Caribbean and were detected for two years until their disappearance about six years later. Around 1987, a split up generated 2 lineages that have been evolving separately, although not major aminoacid changes in the analyzed region were found. Conclusion: DENV-1 has been circulating since 1978 in Colombia. Yet, the phylogenetic relationships between strains isolated along the covered period of time suggests that viral strains detected in some years, although belonging to the same genotype V, have different recent origins corresponding to multiple re-introduction events of viral strains that were circulating in neighbor countries. Viral strains used in the present study did not form a monophyletic group, which is evidence of a polyphyletic origin. We report the rapid spread patterns and high evolution rate of the different DENV-1 lineages

Spread of a SARS-CoV-2 variant through Europe in the summer of 2020.

Following its emergence in late 2019, the spread of SARS-CoV-21,2 has been tracked by phylogenetic analysis of viral genome sequences in unprecedented detail3–5. Although the virus spread globally in early 2020 before borders closed, intercontinental travel has since been greatly reduced. However, travel within Europe resumed in the summer of 2020. Here we report on a SARS-CoV-2 variant, 20E (EU1), that was identified in Spain in early summer 2020 and subsequently spread across Europe. We find no evidence that this variant has increased transmissibility, but instead demonstrate how rising incidence in Spain, resumption of travel, and lack of effective screening and containment may explain the variant’s success. Despite travel restrictions, we estimate that 20E (EU1) was introduced hundreds of times to European countries by summertime travellers, which is likely to have undermined local efforts to minimize infection with SARS-CoV-2. Our results illustrate how a variant can rapidly become dominant even in the absence of a substantial transmission advantage in favourable epidemiological settings. Genomic surveillance is critical for understanding how travel can affect transmission of SARS-CoV-2, and thus for informing future containment strategies as travel resumes. © 2021, The Author(s), under exclusive licence to Springer Nature Limited

Measurement of the Double-Differential Muon-neutrino Charged-Current Inclusive Cross Section in the NOvA Near Detector

We report cross-section measurements of the final-state muon kinematics for \numu charged-current interactions in the NOvA near detector using an accumulated 8.09$\times10^{20}$ protons-on-target (POT) in the NuMI beam. We present the results as a double-differential cross section in the observed outgoing muon energy and angle, as well as single-differential cross sections in the derived neutrino energy, $E_\nu$, and square of the four-momentum transfer, $Q^2$. We compare the results to inclusive cross-section predictions from various neutrino event generators via $\chi^2$ calculations using a covariance matrix that accounts for bin-to-bin correlations of systematic uncertainties. These comparisons show a clear discrepancy between the data and each of the tested predictions at forward muon angle and low $Q^2$, indicating a missing suppression of the cross section in current neutrino-nucleus scattering models

The Large Observatory For X-ray Timing: LOFT

LOFT, the Large Observatory for X-ray Timing, is a new space mission concept devoted to observations of Galactic and extra-Galactic sources in the X-ray domain with the main goals of probing gravity theory in the very strong field environment of black holes and other compact objects, and investigating the state of matter at supra-nuclear densities in neutron stars. The instruments on-board LOFT, the Large area detector and the Wide Field Monitor combine for the first time an unprecedented large effective area (~10 m2 at 8 keV) sensitive to X-ray photons mainly in the 2-30 keV energy range and a spectral resolution approaching that of CCD-based telescopes (down to 200 eV at 6 keV). LOFT is currently competing for a launch of opportunity in 2022 together with the other M3 mission candidates of the ESA Cosmic Vision Progra

Measurement of neutrino-induced neutral-current coherent π⁰ production in the NOvA near detector

The cross section of neutrino-induced neutral-current coherent π⁰ production on a carbon-dominated target is measured in the NOvA near detector. This measurement uses a narrow-band neutrino beam with an average neutrino energy of 2.7 GeV, which is of interest to ongoing and future long-baseline neutrino oscillation experiments. The measured, flux-averaged cross section is σ = 13.8±0.9(stat)±2.3(syst)×10⁻⁴⁰ cm²/nucleus, consistent with model prediction. This result is the most precise measurement of neutral-current coherent π⁰ production in the few-GeV neutrino energy region

Search for multimessenger signals in NOvA coincident with LIGO/Virgo detections

Using the NOvA neutrino detectors, a broad search has been performed for any signal coincident with 28 gravitational wave events detected by the LIGO/Virgo Collaboration between September 2015 and July 2019. For all of these events, NOvA is sensitive to possible arrival of neutrinos and cosmic rays of GeV and higher energies. For five (seven) events in the NOvA Far (Near) Detector, timely public alerts from the LIGO/Virgo Collaboration allowed recording of MeV-scale events. No signal candidates were found