The 3' Untranslated Regions of Ebola Virus mRNAs Contain AU-Rich Elements Involved in Posttranscriptional Stabilization and Decay

The 3' untranslated regions (UTRs) of Ebola virus (EBOV) mRNAs are enriched in their AU content and therefore represent potential targets for RNA binding proteins targeting AU-rich elements (ARE-BPs). ARE-BPs are known to fine-tune RNA turnover and translational activity. We identified putative AREs within EBOV mRNA 3' UTRs and assessed whether they might modulate mRNA stability. Using mammalian and zebrafish embryo reporter assays, we show a conserved, ARE-BP-mediated stabilizing effect and increased reporter activity with the tested EBOV 3' UTRs. When coexpressed with the prototypic ARE-BP tristetraprolin (TTP, ZFP36) that mainly destabilizes its target mRNAs, the EBOV nucleoprotein (NP) 3' UTR resulted in decreased reporter gene activity. Coexpression of NP with TTP led to reduced NP protein expression and diminished EBOV minigenome activity. In conclusion, the enrichment of AU residues in EBOV 3' UTRs makes them possible targets for cellular ARE-BPs, leading to modulation of RNA stability and translational activity.

An introduction to the Marburg virus vaccine consortium, MARVAC

The emergence of Marburg virus (MARV) in Guinea and Ghana triggered the assembly of the MARV vaccine "MARVAC" consortium representing leaders in the field of vaccine research and development aiming to facilitate a rapid response to this infectious disease threat. Here, we discuss current progress, challenges, and future directions for MARV vaccines.

Chikungunya Outbreak in the Republic of the Congo, 2019-Epidemiological, Virological and Entomological Findings of a South-North Multidisciplinary Taskforce Investigation

The Republic of Congo (RoC) declared a chikungunya (CHIK) outbreak on 9 February 2019. We conducted a ONE-Human-Animal HEALTH epidemiological, virological and entomological investigation. Methods: We collected national surveillance and epidemiological data. CHIK diagnosis was based on RT-PCR and CHIKV-specific antibodies. Full CHIKV genome sequences were obtained by Sanger and MinION approaches and Bayesian tree phylogenetic analysis was performed. Mosquito larvae and 215 adult mosquitoes were collected in different villages of Kouilou and Pointe-Noire districts and estimates of Aedes (Ae.) mosquitos' CHIKV-infectious bites obtained. We found two new CHIKV sequences of the East/Central/South African (ECSA) lineage, clustering with the recent enzootic sub-clade 2, showing the A226V mutation. The RoC 2019 CHIKV strain has two novel mutations, E2-T126M and E2-H351N. Phylogenetic suggests a common origin from 2016 Angola strain, from which it diverged around 1989 (95% HPD 1985-1994). The infectious bite pattern was similar for 2017, 2018 and early 2019. One Ae. albopictus pool was RT-PCR positive. The 2019 RoC CHIKV strain seems to be recently introduced or be endemic in sylvatic cycle. Distinct from the contemporary Indian CHIKV isolates and in contrast to the original Central-African strains (transmitted by Ae. aegypti), it carries the A226V mutation, indicating an independent adaptive mutation in response to vector replacement (Ae. albopictus vs Ae. aegypti).

Comparative pathogenesis of Ebola virus and Reston virus infection in humanized mice

Filoviruses of the genus Ebolavirus include 6 species with marked differences in their ability to cause disease in humans. From the highly virulent Ebola virus to the seemingly nonpathogenic Reston virus, case fatality rates can range between 0% and 90%. In order to understand the molecular basis of these differences, it is imperative to establish disease models that recapitulate human disease as faithfully as possible. Nonhuman primates (NHPs) are the gold-standard models for filovirus pathogenesis, but comparative studies are skewed by the fact that Reston virus infection can be lethal for NHPs. Here we used HLA-A2-transgenic, NOD-scid-IL-2γ receptor-knockout (NSG-A2) mice reconstituted with human hematopoiesis to compare Ebola virus and Reston virus pathogenesis in a human-like environment. While markedly less pathogenic than Ebola virus, Reston virus killed 20% of infected mice, a finding that was linked to exacerbated inflammation and viral replication in the liver. In addition, the case fatality ratios of different Ebolavirus species in humans were recapitulated in the humanized mice. Our findings point to humanized mice as a putative model to test the pathogenicity of newly discovered filoviruses, and suggest that further investigations on Reston virus pathogenesis in humans are warranted.

First Report of the Armillaria Root Disease Pathogen, Armillaria gallica, on Douglas-fir (Pseudotsuga menziesii) in Arizona

In August 2010, a mycelial fan (isolate AZ32F) of Armillaria sp. was collected from the root collar of a living Douglas-fir tree on the Mogollon Rim within the Coconino National Forest (approximate location 34°25'31.26″N, 111°20'41.04″W, elevation 2,293 m) in central Arizona. Mycelial fans under the bark of living trees are a sign of pathogenicity, and symptoms of the diseased tree included resinosis, sloughing bark, and thinning crown. The infected tree was located on a south-facing slope with approximately 30% tree cover, dominated by ponderosa pine (Pinus ponderosa), with lesser components of Douglas-fir and Gambel oak (Quercus gambelii). Based on three replications of somatic incompatibility tests against 24 tester isolates representing seven North American Armillaria spp., isolate AZ32F showed 100% intraspecific compatibility (colorless antagonism) with all four A. gallica isolates, 22% compatibility with A. calvescens, and 0% compatibility with the remaining Armillaria spp. Based on GenBank BLASTn of isolate AZ32F sequences, the partial LSU-IGS1 (GenBank Accession No. KF186682) showed 99 to 100% similarity to A. gallica and two other related Armillaria spp. with 99 to 100% coverage, and translation elongation factor-1 alpha (tef-1α) sequences (KC525954) showed 96% similarity to A. gallica (JF895844) with 100% coverage. Thus, isolate AZ32F was identified as A. gallica, based on somatic incompatibility tests and DNA sequences (partial LSU-IGS1 and tef-1α). Although the isolate is identified as A. gallica with similarities to other North American isolates, evidence is mounting that currently recognized A. gallica likely represents a species complex that comprises multiple phylogenetic species (4). Previous surveys in Arizona have noted A. mellea and A. solidipes (as A. ostoyae) (3), but A. gallica has never been previously confirmed in this state. Within North America, A. gallica is commonly reported east of the Rocky Mountains and in West Coast states of the United States, where it infects hardwoods and conifers including Douglas-fir (1,2). Its ecological behavior ranges from saprophyte to weak/aggressive pathogen (1,2). Because damage by A. gallica appears to increase on hosts predisposed by stress (1), further surveys are needed to document its distribution, frequency, and ecological behavior in the southwestern United States, where climate change will likely cause tree stress due to maladaptation. Continued surveys for Armillaria spp. will better determine their potential threat within the geologically and ecologically unique Mogollon Rim of Arizona. References: (1) K. Baumgartner and D. M. Rizzo. Plant Dis. 85:947, 2001. (2) N. J. Brazee and R. L. Wick. For. Ecol. Manage. 258:1605, 2009. (3) R. L. Gilbertson and D. M. Bigelow. J. Arizona-Nevada Acad. Sci. 31:13, 1998. (4) M.-S. Kim et al. Phytopathology 102:S4.63, 2012.

A method for thin sectioning heavily sclerotized cuticle of Odontotaenius disjunctus

Elytra of the bessbeetle, Odontotaenius disjunctus were thin sectioned after embedding in epoxy resin. Sections were cut with a diamond saw, ground to the desired thickness on a rotary grinder and polished. Tearing and distortion were reduced when compared to knifecut sections of heavily sclerotized cuticle.