Genomic Analysis Illustrated a Single Introduction and Evolution of Israeli Bluetongue Serotype 8 Virus Population 2008–2019

Outbreaks of the European Bluetongue virus (BTV) serotype 8 (BTV-8), which are characterized by activity cycles separated by years of inactivity, may be influenced by genetic changes of the virus or by herd immunity. BTV activity in Israel is characterized by similar dynamics, but differs from European countries in its vector population, environmental conditions, and lack of cattle vaccination against this serotype. Comparison of these two geographical systems and characterization of their epidemiological connection is therefore of high interest in-order to better understand the factors influencing BTV-8 evolution. BTV-8, closely related to the European strain, was introduced to Israel in 2008. It was at the center of BT outbreaks in 2010 and 2015–2016 and thereafter was lastly isolated in Israel in 2019. We performed genetic analyses of twelve BTV-8 Israeli strains isolated between 2008 and 2019 and compared them with published sequences of BTV-8 isolated in other countries. The analysis revealed a single introduction of BTV-8 into Israel and thereafter extensive occurrence of genomic drifts and multiple reassortments with local BTV strains. Comparison of the Israeli and Cypriot BTV-8 from 2015 to 2016 suggests transmission of the virus between the two countries and a separate and parallel development from European or other Israeli BTV-8 strains. The parallel development of other BTV-8 strains was demonstrated by the identification of the Israeli BTV-8 ISR-1194/1/19 strain, which exhibited common origin with reassorted Israeli BTV-8 strains from 2010 and additional reassortment of seven segments. In order to reveal the source of BTV-8 introduction into Israel we performed BEAST analysis which showed that a probable common ancestor for both European and Israeli BTV-8 presumably existed in 2003–2004. In 2019, a possible new introduction occurred in Israel, where a novel BTV-8 strain was detected, sharing ~95% identity by segments 2 and 6 with Nigerian BTV-8NIG1982/07 and European–Middle Eastern strains. The results of the study indicate that Israel and neighboring countries consist a separate environmental and evolutionary system, distinct from European ones.

Phylogeographic analysis of Pseudogymnoascus destructans partitivirus-pa explains the spread dynamics of white-nose syndrome in North America

Understanding the dynamics of white-nose syndrome spread in time and space is an important component for the disease epidemiology and control. We reported earlier that a novel partitivirus, Pseudogymnoascus destructans partitivirus-pa, had infected the North American isolates of Pseudogymnoascus destructans, the fungal pathogen that causes white-nose syndrome in bats. We showed that the diversity of the viral coat protein sequences is correlated to their geographical origin. Here we hypothesize that the geographical adaptation of the virus could be used as a proxy to characterize the spread of white-nose syndrome. We used over 100 virus isolates from diverse locations in North America and applied the phylogeographic analysis tool BEAST to characterize the spread of the disease. The strict clock phylogeographic analysis under the coalescent model in BEAST showed a patchy spread pattern of white-nose syndrome driven from a few source locations including Connecticut, New York, West Virginia, and Kentucky. The source states had significant support in the maximum clade credibility tree and Bayesian stochastic search variable selection analysis. Although the geographic origin of the virus is not definite, it is likely the virus infected the fungus prior to the spread of white-nose syndrome in North America. We also inferred from the BEAST analysis that the recent long-distance spread of the fungus to Washington had its root in Kentucky, likely from the Mammoth cave area and most probably mediated by a human. The time to the most recent common ancestor of the virus is estimated somewhere between the late 1990s to early 2000s. We found the mean substitution rate of 2 X 10−3 substitutions per site per year for the virus which is higher than expected given the persistent lifestyle of the virus, and the stamping-machine mode of replication. Our approach of using the virus as a proxy to understand the spread of white-nose syndrome could be an important tool for the study and management of other infectious diseases.

Biosystematic study of the genus Lallemantia (Lamiaceae): species delimitation and relationship

Lallemantia (Lamiaceae) is a small genus with 5 species. In general, little biosystematics and molecular study has been performed on the genus Lallemantia. Moreover, the studies used only some of the species; none of them has considered all 5 species as a whole in one specific approach. Therefore, the species inter-relationship or nexus in the genus is not thoroughly probed. The present study investigated the molecular phylogeny and species relationship of all five species in the genus Lallemantia, using ribosomal protein L16 and the multilocus ISSR markers. It also compared their morphometric, anatomical and seed results. The species were efficaciously delimited by the morphological, anatomical and seed characters, as well as by ISSR and cpDNA markers. The PCA (Principal components analysis) plot of the species based upon the morphological characters, the MDS (Multidimensional Scaling) plot of the species based on the nutlet and anatomical characters, the NJ (neighbor joining) tree plot of ISSR dataand the ML tree of cpDNA revealed closer affinity between L. iberica and L. canescens and L. peltata was placed at some distance from these species. The phylogenetic trees displayed monophyly of the genus Lallemantia. The Bayesian Evolutionary Analysis by Sampling Trees (BEAST) analysis unveiled that the studied Lallemantia species started to diverge about 25 million years ago.

Genotypic Characterization of Livestock-Associated Methicillin-Resistant Staphylococcus aureus Isolates of Clonal Complex 398 in Pigsty Visitors: Transient Carriage or Persistence?

ABSTRACT Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) of clonal complex (CC) 398 has become a rising issue for public health. While it is known that >80% of pig farmers are colonized with LA-MRSA, only a few studies have assessed the situation for humans with occasional livestock contact. Recently it was shown that over 75% of scientific fieldworkers visiting pigsties were temporarily carrying LA-MRSA. To find out whether they were transiently or permanently colonized, we used whole-genome sequencing (WGS) data to analyze the relatedness of isolates from these recurrently LA-MRSA-positive fieldworkers and from corresponding pigsties. Sequences were analyzed using in silico typing (spa and core genomic multilocus sequence typing [cgMLST]), and the BEAST software package was used to examine phylogeny. In total, 81 samples from three fieldworkers on eight different pigsties over a period of 2.5 years were sequenced. All isolates belonged to spa type t011, t034, or t2011, with different types found in the same fieldworker at different time points. Analysis of cgMLST revealed nine genotypic clusters, mostly correlating with the pigsty on which they were sampled. Fieldworker isolates clustered with the samples from farms that were visited on the same day. BEAST analysis corroborated the cgMLST-based clustering and suggests an origin of the lineage about 22 years ago. We conclude that nasal LA-MRSA colonization among humans with occasional livestock contact is common but most likely only temporary. Furthermore, we showed that the Western German LA-MRSA CC398 originated in the late 1990s and diversified into farm-specific genotypes, which stay relatively consistent over time.

Evolutionary history of the tribe Astereae in the Flora Iranica area: Systematic implications

The present study reconstructs the phylogenetic relationships of the tribe with emphasis on Psychrogeton using both nuclear (ITS, ETS) and chloroplast (trnL intron and trnL-trnF intergenic spacer) markers. Divergence times for main lineages were estimated using BEAST analysis. Based on results of molecular analyses, tribe Astereae is circumscribed here as containing 16 genera and 38 species and comprising strongly supported five major clades: Aster, Chamaegeron, Erigeron, Galatella and Psychrogeton. Among the Eurasian asteroid taxa, Aster bachtiaricus formed the basal most diverging lineage far distantly from the Aster s.str. clade. Lachnophllum and Chamaegeron are sister taxa in nuclear tree, although weakly united in plastid topology. Galatella with the inclusion of Crinitina (= Crinitaria) constitutes a well-supported clade, which along with Tripolium forms the Galatella group. Eurasian Erigeron species were derived within the Erigeron clade. Erigeron uniflorus subsp. daenensis and subsp. elborsensis are distinct from the type subspecies and are resurrected here as species in their own right. Our analyses of the datasets revealed that all examined species of Psychrogeton, except P. obovatus, emerged in a single clade comprising four distinct subclades. Molecular dating analyses indicate that tribe Astereae originated in the Late Eocene at 38.6 Ma. The most genera of Astereae diverged during the Middle Miocene whereas the diversification of lineages began mostly through the Pliocene and Pleistocene. On the basis of the molecular data as well as the morphological characteristics, Aster bachtiaricus was elevated to the generic rank and this new monospecific genus was named Iranoaster. Psychrogeton obovatus was treated as a member of the recently established genus Neobrachyactis. The conflicting position of some taxa including Lachnophyllum gossypinum, Dichrocephala, Myriactis and Asterothamnus in nuclear and plastid trees might be the result of ancient hybridization/introgression events.

DISSECT: an assignment-free Bayesian discovery method for species delimitation under the multispecies coalescent

Motivation: The multispecies coalescent model provides a formal framework for the assignment of individual organisms to species, where the species are modeled as the branches of the species tree. None of the available approaches so far have simultaneously co-estimated all the relevant parameters in the model, without restricting the parameter space by requiring a guide tree and/or prior assignment of individuals to clusters or species. Results: We present DISSECT, which explores the full space of possible clusterings of individuals and species tree topologies in a Bayesian framework. It uses an approximation to avoid the need for reversible-jump MCMC, in the form of a prior that is a modification of the birth-death prior for the species tree. It incorporates a spike near zero in the density for node heights. The model has two extra parameters: one controls the degree of approximation, and the second controls the prior distribution on the numbers of species. It is implemented as part of BEAST and requires only a few changes from a standard *BEAST analysis. The method is evaluated on simulated data and demonstrated on an empirical data set. The method is shown to be insensitive to the degree of approximation, but quite sensitive to the second parameter, suggesting that large numbers of sequences are needed to draw firm conclusions. Availability:http://code.google.com/p/beast-mcmc/, http://www.indriid.com/dissectinbeast.html Contact:[email protected], www.indriid.com Supplementary information: Supplementary material is available.

Revisiting the Clinal Concept of Evolution and Dispersal for the Tick-Borne Flaviviruses by Using Phylogenetic and Biogeographic Analyses

Tick-borne flaviviruses (TBF) are widely dispersed across Africa, Europe, Asia, Oceania, and North America, and some present a significant threat to human health. Seminal studies on tick-borne encephalitis viruses (TBEV), based on partial envelope gene sequences, predicted a westward clinal pattern of evolution and dispersal across northern Eurasia, terminating in the British Isles. We tested this hypothesis using all available full-length open reading frame (ORF) TBF sequences. Phylogenetic analysis was consistent with current reports. However, linear and nonlinear regression analysis of genetic versus geographic distance combined with BEAST analysis identified two separate clines, suggesting that TBEV spread both east and west from a central point. In addition, BEAST analysis suggested that TBF emerged and dispersed more than 16,000 years ago, significantly earlier than previously predicted. Thus, climatic and ecological changes may have played a greater role in TBF dispersal than humans.