Virome release of an invasive exotic plant species in southern France

The increase in human-mediated introduction of plant species to new regions has resulted in a rise of invasive exotic plant species (IEPS) that has had significant effects on biodiversity and ecosystem processes. One commonly accepted mechanism of invasions is that proposed by the enemy release hypothesis (ERH), which states that IEPS free from their native herbivores and natural enemies in new environments can outcompete indigenous species and become invasive. We here propose the virome release hypothesis (VRH) as a virus-centered variant of the conventional ERH that is only focused on enemies. The VRH predicts that vertically transmitted plant-associated viruses (PAV, encompassing phytoviruses and mycoviruses) should be co-introduced during the dissemination of the IEPS, while horizontally transmitted PAV of IEPS should be left behind or should not be locally transmitted in the introduced area due to a maladaptation of local vectors. To document the VRH, virome richness and composition as well as PAV prevalence, co-infection, host range, and transmission modes were compared between indigenous plant species and an invasive grass, cane bluestem (Bothriochloa barbinodis), in both its introduced range (southern France) and one area of its native range (Sonoran Desert, Arizona, USA). Contrary to the VRH, we show that invasive populations of B. barbinodis in France were not associated with a lower PAV prevalence or richness than native populations of B. barbinodis from the USA. However, comparison of virome compositions and network analyses further revealed more diverse and complex plant-virus interactions in the French ecosystem, with a significant richness of mycoviruses. Setting mycoviruses apart, only one putatively vertically transmitted phytovirus (belonging to the Amalgaviridae family) and one putatively horizontally transmitted phytovirus (belonging to the Geminiviridae family) were identified from B. barbinodis plants in the introduced area. Collectively, these characteristics of the B. barbinodis-associated PAV community in southern France suggest that a virome release phase may have immediately followed the introduction of B. barbinodis to France in the 1960s or 1970s, and that, since then, the invasive populations of this IEPS have already transitioned out of this virome release phase, and have started interacting with several local mycoviruses and a few local plant viruses.

An Oxford Nanopore Technology-Based Hepatitis B Virus Sequencing Protocol Suitable For Genomic Surveillance Within Clinical Diagnostic Settings

Chronic hepatitis B virus (HBV) infection remains a significant public health concern, particularly in Africa, where there is a substantial burden. HBV is an enveloped virus, with isolates being classified into ten phylogenetically distinct genotypes (A - J) determined based on full-genome sequence data or reverse hybridization-based diagnostic tests. In practice, limitations are noted in that diagnostic sequencing, generally using Sanger sequencing, tends to focus only on the S-gene, yielding little or no information on intra-patient HBV genetic diversity with very low-frequency variants and reverse hybridization detects only known genotype-specific mutations. To resolve these limitations, we developed an Oxford Nanopore Technology (ONT)-based HBV genotyping protocol suitable for clinical virology, yielding complete HBV genome sequences and extensive data on intra-patient HBV diversity. Specifically, the protocol involves tiling-based PCR amplification of HBV sequences, library preparation using the ONT Rapid Barcoding Kit, ONT GridION sequencing, genotyping using Genome Detective software, recombination analysis using jpHMM and RDP5 software, and drug resistance profiling using Geno2pheno software. We prove the utility of our protocol by efficiently generating and characterizing high-quality near full-length HBV genomes from 148 left-over diagnostic Hepatitis B patient samples obtained in the Western Cape province of South Africa, providing valuable insights into the genetic diversity and epidemiology of HBV in this region of the world.

Rapid dynamic changes of FL.2 variant: A case report of COVID-19 breakthrough infection

We investigated intra-host genetic evolution using two SARS-CoV-2 isolates from a fully vaccinated (primary schedule x2 doses of AstraZeneca plus a booster of Pfizer), >70-year-old woman with a history of lymphoma and hypertension who presented a SARS-CoV-2 infection for 3 weeks prior to death due to COVID-19. Two full genome sequences were determined from samples taken 13 days apart with both belonging to Pango lineage FL.2: the first detection of this Omicron sub-variant in Botswana. FL.2 is a sub-lineage of XBB.1.9.1. The repertoire of mutations and minority variants in the Spike protein differed between the two time points. Notably, we also observed deletions within the ORF1a and Membrane proteins; both regions are associated with high T-cell epitope density. The internal milieu of immune-suppressed individuals may accelerate SARS-CoV-2 evolution; hence, close monitoring is warranted.

Complete genome reconstruction of the global and European regional dispersal history of the lumpy skin disease virus

IMPORTANCE

Lumpy skin disease virus (LSDV) has a complex epidemiology involving multiple strains, recombination, and vaccination. Its DNA genome provides limited genetic variation to trace outbreaks in space and time. Sequencing of LSDV whole genomes has also been patchy at global and regional scales. Here, we provide the first fine-grained whole genome sequence sampling of a constrained LSDV outbreak (southeastern Europe, 2015-2017), which we analyze along with global publicly available genomes. We formally evaluate the past occurrence of recombination events as well as the temporal signal that is required for calibrating molecular clock models and subsequently conduct a time-calibrated spatially explicit phylogeographic reconstruction. Our study further illustrates the importance of accounting for recombination events before reconstructing global and regional dynamics of DNA viruses. More LSDV whole genomes from endemic areas are needed to obtain a comprehensive understanding of global LSDV dispersal dynamics.

Metagenomics reveals the structure of Mastrevirus-host interaction network within an agro-ecosystem

As highly pervasive parasites that sometimes cause disease, viruses are likely major components of all natural ecosystems. An important step towards both understanding the precise ecological roles of viruses and determining how natural communities of viral species are assembled and evolve is obtaining full descriptions of viral diversity and distributions at ecosystem scales. Here, we focused on obtaining such 'community-scale' data for viruses in a single genus. We chose the genus Mastrevirus (family Geminiviridae), members of which have predominantly been found infecting uncultivated grasses (family Poaceae) throughout the tropical and sub-tropical regions of the world. We sampled over 3 years, 2,884 individual Poaceae plants belonging to thirty different species within a 2-ha plot which included cultivated and uncultivated areas on the island of Reunion. Mastreviruses were found in ∼8 per cent of the samples, of which 96 per cent did not have any discernible disease symptoms. The multitude of host-virus associations that we uncovered reveals both the plant species that most commonly host mastreviruses and the mastrevirus species (such as maize streak virus and maize streak Reunion virus) that have especially large host ranges. Our findings are consistent with the hypothesis that perennial plant species capable of hosting years-long mixed mastrevirus infections likely play a disproportionately important role in the generation of inter-species and inter-strain mastrevirus recombinants.

Evolution of anelloviruses from a circovirus-like ancestor through gradual augmentation of the jelly-roll capsid protein

Anelloviruses are highly prevalent in diverse mammals, including humans, but so far have not been linked to any disease and are considered to be part of the 'healthy virome'. These viruses have small circular single-stranded DNA (ssDNA) genomes and encode several proteins with no detectable sequence similarity to proteins of other known viruses. Thus, anelloviruses are the only family of eukaryotic ssDNA viruses currently not included in the realm Monodnaviria. To gain insights into the provenance of these enigmatic viruses, we sequenced more than 250 complete genomes of anelloviruses from nasal and vaginal swab samples of Weddell seal (Leptonychotes weddellii) from Antarctica and a fecal sample of grizzly bear (Ursus arctos horribilis) from the USA and performed a comprehensive family-wide analysis of the signature anellovirus protein ORF1. Using state-of-the-art remote sequence similarity detection approaches and structural modeling with AlphaFold2, we show that ORF1 orthologs from all Anelloviridae genera adopt a jelly-roll fold typical of viral capsid proteins (CPs), establishing an evolutionary link to other eukaryotic ssDNA viruses, specifically, circoviruses. However, unlike CPs of other ssDNA viruses, ORF1 encoded by anelloviruses from different genera display remarkable variation in size, due to insertions into the jelly-roll domain. In particular, the insertion between β-strands H and I forms a projection domain predicted to face away from the capsid surface and function at the interface of virus-host interactions. Consistent with this prediction and supported by recent experimental evidence, the outermost region of the projection domain is a mutational hotspot, where rapid evolution was likely precipitated by the host immune system. Collectively, our findings further expand the known diversity of anelloviruses and explain how anellovirus ORF1 proteins likely diverged from canonical jelly-roll CPs through gradual augmentation of the projection domain. We suggest assigning Anelloviridae to a new phylum, 'Commensaviricota', and including it into the kingdom Shotokuvirae (realm Monodnaviria), alongside Cressdnaviricota and Cossaviricota.

RASCL: Rapid Assessment of Selection in CLades through molecular sequence analysis

An important unmet need revealed by the COVID-19 pandemic is the near-real-time identification of potentially fitness-altering mutations within rapidly growing SARS-CoV-2 lineages. Although powerful molecular sequence analysis methods are available to detect and characterize patterns of natural selection within modestly sized gene-sequence datasets, the computational complexity of these methods and their sensitivity to sequencing errors render them effectively inapplicable in large-scale genomic surveillance contexts. Motivated by the need to analyze new lineage evolution in near-real time using large numbers of genomes, we developed the Rapid Assessment of Selection within CLades (RASCL) pipeline. RASCL applies state of the art phylogenetic comparative methods to evaluate selective processes acting at individual codon sites and across whole genes. RASCL is scalable and produces automatically updated regular lineage-specific selection analysis reports: even for lineages that include tens or hundreds of thousands of sampled genome sequences. Key to this performance is (i) generation of automatically subsampled high quality datasets of gene/ORF sequences drawn from a selected "query" viral lineage; (ii) contextualization of these query sequences in codon alignments that include high-quality "background" sequences representative of global SARS-CoV-2 diversity; and (iii) the extensive parallelization of a suite of computationally intensive selection analysis tests. Within hours of being deployed to analyze a novel rapidly growing lineage of interest, RASCL will begin yielding JavaScript Object Notation (JSON)-formatted reports that can be either imported into third-party analysis software or explored in standard web-browsers using the premade RASCL interactive data visualization dashboard. By enabling the rapid detection of genome sites evolving under different selective regimes, RASCL is well-suited for near-real-time monitoring of the population-level selective processes that will likely underlie the emergence of future variants of concern in measurably evolving pathogens with extensive genomic surveillance.

Virion-Associated Nucleic Acid-Based Metagenomics: A Decade of Advances in Molecular Characterization of Plant Viruses

Over the last decade, viral metagenomic studies have resulted in the discovery of thousands of previously unknown viruses. These studies are likely to play a pivotal role in obtaining an accurate and robust understanding of how viruses affect the stability and productivity of ecosystems. Among the metagenomics-based approaches that have been developed since the beginning of the 21st century, shotgun metagenomics applied specifically to virion-associated nucleic acids (VANA) has been used to disentangle the diversity of the viral world. We summarize herein the results of 24 VANA-based studies, focusing on plant and insect samples conducted over the last decade (2010 to 2020). Collectively, viruses from 85 different families were reliably detected in these studies, including capsidless RNA viruses that replicate in fungi, oomycetes, and plants. Finally, strengths and weaknesses of the VANA approach are summarized and perspectives of applications in detection, epidemiological surveillance, environmental monitoring, and ecology of plant viruses are provided. [Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

Investment in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing in Africa over the past year has led to a major increase in the number of sequences that have been generated and used to track the pandemic on the continent, a number that now exceeds 100,000 genomes. Our results show an increase in the number of African countries that are able to sequence domestically and highlight that local sequencing enables faster turnaround times and more-regular routine surveillance. Despite limitations of low testing proportions, findings from this genomic surveillance study underscore the heterogeneous nature of the pandemic and illuminate the distinct dispersal dynamics of variants of concern-particularly Alpha, Beta, Delta, and Omicron-on the continent. Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve while the continent faces many emerging and reemerging infectious disease threats. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century.

Emergence of SARS-CoV-2 Omicron lineages BA.4 and BA.5 in South Africa

Three lineages (BA.1, BA.2 and BA.3) of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant of concern predominantly drove South Africa's fourth Coronavirus Disease 2019 (COVID-19) wave. We have now identified two new lineages, BA.4 and BA.5, responsible for a fifth wave of infections. The spike proteins of BA.4 and BA.5 are identical, and similar to BA.2 except for the addition of 69-70 deletion (present in the Alpha variant and the BA.1 lineage), L452R (present in the Delta variant), F486V and the wild-type amino acid at Q493. The two lineages differ only outside of the spike region. The 69-70 deletion in spike allows these lineages to be identified by the proxy marker of S-gene target failure, on the background of variants not possessing this feature. BA.4 and BA.5 have rapidly replaced BA.2, reaching more than 50% of sequenced cases in South Africa by the first week of April 2022. Using a multinomial logistic regression model, we estimated growth advantages for BA.4 and BA.5 of 0.08 (95% confidence interval (CI): 0.08-0.09) and 0.10 (95% CI: 0.09-0.11) per day, respectively, over BA.2 in South Africa. The continued discovery of genetically diverse Omicron lineages points to the hypothesis that a discrete reservoir, such as human chronic infections and/or animal hosts, is potentially contributing to further evolution and dispersal of the virus.

HIV-1 Evolutionary Dynamics under Nonsuppressive Antiretroviral Therapy

Prolonged virologic failure on 2nd-line protease inhibitor (PI)-based antiretroviral therapy (ART) without emergence of major protease mutations is well recognized and provides an opportunity to study within-host evolution in long-term viremic individuals. Using next-generation sequencing and in silico haplotype reconstruction, we analyzed whole-genome sequences from longitudinal plasma samples of eight chronically infected HIV-1-positive individuals failing 2nd-line regimens from the French National Agency for AIDS and Viral Hepatitis Research (ANRS) 12249 Treatment as Prevention (TasP) trial. On nonsuppressive ART, there were large fluctuations in synonymous and nonsynonymous variant frequencies despite stable viremia. Reconstructed haplotypes provided evidence for selective sweeps during periods of partial adherence, and viral haplotype competition, during periods of low drug exposure. Drug resistance mutations in reverse transcriptase (RT) were used as markers of viral haplotypes in the reservoir, and their distribution over time indicated recombination. We independently observed linkage disequilibrium decay, indicative of recombination. These data highlight dramatic changes in virus population structure that occur during stable viremia under nonsuppressive ART. IMPORTANCE HIV-1 infections are most commonly initiated with a single founder virus and are characterized by extensive inter- and intraparticipant genetic diversity. However, existing literature on HIV-1 intrahost population dynamics is largely limited to untreated infections, predominantly in subtype B-infected individuals. The manuscript characterizes viral population dynamics in long-term viremic treatment-experienced individuals, which has not been previously characterized. These data are particularly relevant for understanding HIV dynamics but can also be applied to other RNA viruses. With this unique data set we propose that the virus is highly unstable, and we have found compelling evidence of HIV-1 within-host viral diversification, recombination, and haplotype competition during nonsuppressive ART.

Neutralisation sensitivity of the SARS-CoV-2 omicron (B.1.1.529) variant: a cross-sectional study

Background

The SARS-CoV-2 omicron (B.1.1.529) variant, which was first identified in November, 2021, spread rapidly in many countries, with a spike protein highly diverged from previously known variants, and raised concerns that this variant might evade neutralising antibody responses. We therefore aimed to characterise the sensitivity of the omicron variant to neutralisation.

Methods

For this cross-sectional study, we cloned the sequence encoding the omicron spike protein from a diagnostic sample to establish an omicron pseudotyped virus neutralisation assay. We quantified the neutralising antibody ID₅₀ (the reciprocal dilution that produces 50% inhibition) against the omicron spike protein, and the fold-change in ID₅₀ relative to the spike of wild-type SARS-CoV-2 (ie, the pandemic founder variant), for one convalescent reference plasma pool (WHO International Standard for anti-SARS-CoV-2 immunoglobulin [20/136]), three reference serum pools from vaccinated individuals, and two cohorts from Stockholm, Sweden: one comprising previously infected hospital workers (17 sampled in November, 2021, after vaccine rollout and nine in June or July, 2020, before vaccination) and one comprising serum from 40 randomly sampled blood donors donated during week 48 (Nov 29–Dec 5) of 2021. Furthermore, we assessed the neutralisation of omicron by five clinically relevant monoclonal antibodies (mAbs).

Findings

Neutralising antibody responses in reference sample pools sampled shortly after infection or vaccination were substantially less potent against the omicron variant than against wild-type SARS-CoV-2 (seven-fold to 42-fold reduction in ID₅₀ titres). Similarly, for sera obtained before vaccination in 2020 from a cohort of convalescent hospital workers, neutralisation of the omicron variant was low to undetectable (all ID₅₀ titres <20). However, in serum samples obtained in 2021 from two cohorts in Stockholm, substantial cross-neutralisation of the omicron variant was observed. Sera from 17 hospital workers after infection and subsequent vaccination had a reduction in average potency of only five-fold relative to wild-type SARS-CoV-2 (geometric mean ID₅₀ titre 495 vs 105), and two donors had no reduction in potency. A similar pattern was observed in randomly sampled blood donors (n=40), who had an eight-fold reduction in average potency against the omicron variant compared with wild-type SARS-CoV-2 (geometric mean ID₅₀ titre 369 vs 45). We found that the omicron variant was resistant to neutralisation (50% inhibitory concentration [IC₅₀] >10 μg/mL) by mAbs casirivimab (REGN-10933), imdevimab (REGN-10987), etesevimab (Ly-CoV016), and bamlanivimab (Ly-CoV555), which form part of antibody combinations used in the clinic to treat COVID-19. However, S309, the parent of sotrovimab, retained most of its activity, with only an approximately two-fold reduction in potency against the omicron variant compared with ancestral D614G SARS-CoV-2 (IC₅₀ 0·1–0·2 μg/mL).

Interpretation

These data highlight the extensive, but incomplete, evasion of neutralising antibody responses by the omicron variant, and suggest that boosting with licensed vaccines might be sufficient to raise neutralising antibody titres to protective levels.

Funding

European Union Horizon 2020 research and innovation programme, European and Developing Countries Clinical Trials Partnership, SciLifeLab, and the Erling-Persson Foundation.

Recent Zoonotic Spillover and Tropism Shift of a Canine Coronavirus Is Associated with Relaxed Selection and Putative Loss of Function in NTD Subdomain of Spike Protein

A canine coronavirus (CCoV) has now been reported from two independent human samples from Malaysia (respiratory, collected in 2017–2018; CCoV-HuPn-2018) and Haiti (urine, collected in 2017); these two viruses were nearly genetically identical. In an effort to identify any novel adaptations associated with this apparent shift in tropism we carried out detailed evolutionary analyses of the spike gene of this virus in the context of related Alphacoronavirus 1 species. The spike 0-domain retains homology to CCoV2b (enteric infections) and Transmissible Gastroenteritis Virus (TGEV; enteric and respiratory). This domain is subject to relaxed selection pressure and an increased rate of molecular evolution. It contains unique amino acid substitutions, including within a region important for sialic acid binding and pathogenesis in TGEV. Overall, the spike gene is extensively recombinant, with a feline coronavirus type II strain serving a prominent role in the recombinant history of the virus. Molecular divergence time for a segment of the gene where temporal signal could be determined, was estimated at around 60 years ago. We hypothesize that the virus had an enteric origin, but that it may be losing that particular tropism, possibly because of mutations in the sialic acid binding region of the spike 0-domain.

Selection Analysis Identifies Clusters of Unusual Mutational Changes in Omicron Lineage BA.1 That Likely Impact Spike Function

Among the 30 nonsynonymous nucleotide substitutions in the Omicron S-gene are 13 that have only rarely been seen in other SARS-CoV-2 sequences. These mutations cluster within three functionally important regions of the S-gene at sites that will likely impact (1) interactions between subunits of the Spike trimer and the predisposition of subunits to shift from down to up configurations, (2) interactions of Spike with ACE2 receptors, and (3) the priming of Spike for membrane fusion. We show here that, based on both the rarity of these 13 mutations in intrapatient sequencing reads and patterns of selection at the codon sites where the mutations occur in SARS-CoV-2 and related sarbecoviruses, prior to the emergence of Omicron the mutations would have been predicted to decrease the fitness of any virus within which they occurred. We further propose that the mutations in each of the three clusters therefore cooperatively interact to both mitigate their individual fitness costs, and, in combination with other mutations, adaptively alter the function of Spike. Given the evident epidemic growth advantages of Omicron overall previously known SARS-CoV-2 lineages, it is crucial to determine both how such complex and highly adaptive mutation constellations were assembled within the Omicron S-gene, and why, despite unprecedented global genomic surveillance efforts, the early stages of this assembly process went completely undetected.

Rapid epidemic expansion of the SARS-CoV-2 Omicron variant in southern Africa

The SARS-CoV-2 epidemic in southern Africa has been characterized by three distinct waves. The first was associated with a mix of SARS-CoV-2 lineages, while the second and third waves were driven by the Beta (B.1.351) and Delta (B.1.617.2) variants, respectively1-3. In November 2021, genomic surveillance teams in South Africa and Botswana detected a new SARS-CoV-2 variant associated with a rapid resurgence of infections in Gauteng province, South Africa. Within three days of the first genome being uploaded, it was designated a variant of concern (Omicron, B.1.1.529) by the World Health Organization and, within three weeks, had been identified in 87 countries. The Omicron variant is exceptional for carrying over 30 mutations in the spike glycoprotein, which are predicted to influence antibody neutralization and spike function4. Here we describe the genomic profile and early transmission dynamics of Omicron, highlighting the rapid spread in regions with high levels of population immunity.

RASCL: Rapid Assessment Of SARS-CoV-2 Clades Through Molecular Sequence Analysis

An important component of efforts to manage the ongoing COVID19 pandemic is the R apid A ssessment of how natural selection contributes to the emergence and proliferation of potentially dangerous S ARS-CoV-2 lineages and CL ades (RASCL). The RASCL pipeline enables continuous comparative phylogenetics-based selection analyses of rapidly growing clade-focused genome surveillance datasets, such as those produced following the initial detection of potentially dangerous variants. From such datasets RASCL automatically generates down-sampled codon alignments of individual genes/ORFs containing contextualizing background reference sequences, analyzes these with a battery of selection tests, and outputs results as both machine readable JSON files, and interactive notebook-based visualizations.

AVAILABILITY

RASCL is available from a dedicated repository at https://github.com/veg/RASCL and as a Galaxy workflow https://usegalaxy.eu/u/hyphy/w/rascl . Existing clade/variant analysis results are available here: https://observablehq.com/@aglucaci/rascl .

CONTACT

Dr. Sergei L Kosakovsky Pond ( spond@temple.edu ).

SUPPLEMENTARY INFORMATION

N/A.

Selection analysis identifies unusual clustered mutational changes in Omicron lineage BA.1 that likely impact Spike function

Among the 30 non-synonymous nucleotide substitutions in the Omicron S-gene are 13 that have only rarely been seen in other SARS-CoV-2 sequences. These mutations cluster within three functionally important regions of the S-gene at sites that will likely impact (i) interactions between subunits of the Spike trimer and the predisposition of subunits to shift from down to up configurations, (ii) interactions of Spike with ACE2 receptors, and (iii) the priming of Spike for membrane fusion. We show here that, based on both the rarity of these 13 mutations in intrapatient sequencing reads and patterns of selection at the codon sites where the mutations occur in SARS-CoV-2 and related sarbecoviruses, prior to the emergence of Omicron the mutations would have been predicted to decrease the fitness of any genomes within which they occurred. We further propose that the mutations in each of the three clusters therefore cooperatively interact to both mitigate their individual fitness costs, and adaptively alter the function of Spike. Given the evident epidemic growth advantages of Omicron over all previously known SARS-CoV-2 lineages, it is crucial to determine both how such complex and highly adaptive mutation constellations were assembled within the Omicron S-gene, and why, despite unprecedented global genomic surveillance efforts, the early stages of this assembly process went completely undetected.

Conserved recombination patterns across coronavirus subgenera

Recombination contributes to the genetic diversity found in coronaviruses and is known to be a prominent mechanism whereby they evolve. It is apparent, both from controlled experiments and in genome sequences sampled from nature, that patterns of recombination in coronaviruses are non-random and that this is likely attributable to a combination of sequence features that favour the occurrence of recombination break points at specific genomic sites, and selection disfavouring the survival of recombinants within which favourable intra-genome interactions have been disrupted. Here we leverage available whole-genome sequence data for six coronavirus subgenera to identify specific patterns of recombination that are conserved between multiple subgenera and then identify the likely factors that underlie these conserved patterns. Specifically, we confirm the non-randomness of recombination break points across all six tested coronavirus subgenera, locate conserved recombination hot- and cold-spots, and determine that the locations of transcriptional regulatory sequences are likely major determinants of conserved recombination break-point hotspot locations. We find that while the locations of recombination break points are not uniformly associated with degrees of nucleotide sequence conservation, they display significant tendencies in multiple coronavirus subgenera to occur in low guanine-cytosine content genome regions, in non-coding regions, at the edges of genes, and at sites within the Spike gene that are predicted to be minimally disruptive of Spike protein folding. While it is apparent that sequence features such as transcriptional regulatory sequences are likely major determinants of where the template-switching events that yield recombination break points most commonly occur, it is evident that selection against misfolded recombinant proteins also strongly impacts observable recombination break-point distributions in coronavirus genomes sampled from nature.

ICTV Virus Taxonomy Profile: Geminiviridae 2021

The family Geminiviridae includes viruses with mono- or bipartite single-stranded, circular DNA genomes of 2.5–5.2 kb. They cause economically important diseases in most tropical and subtropical regions of the world. Geminiviruses infect dicot and monocot plants and are transmitted by insect vectors. DNA satellites are associated with some geminiviruses. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the family Geminiviridae which is available at ictv.global/report/geminiviridae.

Establishment of five new genera in the family Geminiviridae: Citlodavirus, Maldovirus, Mulcrilevirus, Opunvirus, and Topilevirus

Geminiviruses are plant-infecting, circular single-stranded DNA viruses that have a geminate virion morphology. These viruses infect both cultivated and non-cultivated monocotyledonous and dicotyledonous plants and have a wide geographical distribution. Nine genera had been established within the family Geminiviridae (Becurtovirus, Begomovirus, Capulavirus, Curtovirus, Eragrovirus, Grablovirus, Mastrevirus, Topocuvirus, and Turncurtovirus) as of 2020. In the last decade, metagenomics approaches have facilitated the discovery and identification of many novel viruses, among them numerous highly divergent geminiviruses. Here, we report the establishment of five new genera in the family Geminiviridae (Citlodavirus, Maldovirus, Mulcrilevirus, Opunvirus, and Topilevirus) to formally classify twelve new, divergent geminiviruses.

Novel circular DNA virus identified in Opuntia discolor (Cactaceae) that codes for proteins with similarity to those of geminiviruses

Viral metagenomic studies have enabled the discovery of many unknown viruses and revealed that viral communities are much more diverse and ubiquitous than previously thought. Some viruses have multiple genome components that are encapsidated either in separate virions (multipartite viruses) or in the same virion (segmented viruses). In this study, we identify what is possibly a novel bipartite plant-associated circular single-stranded DNA virus in a wild prickly pear cactus, Opuntia discolor, that is endemic to the Chaco ecoregion in South America. Two ~1.8 kb virus-like circular DNA components were recovered, one encoding a replication-associated protein (Rep) and the other a capsid protein (CP). Both of the inferred protein sequences of the Rep and CP are homologous to those encoded by members of the family Geminiviridae. These two putatively cognate components each have a nonanucleotide sequence within a likely hairpin structure that is homologous to the origins of rolling-circle replication (RCR), found in diverse circular single-stranded DNA viruses. In addition, the two components share similar putative replication-associated iterative sequences (iterons), which in circular single-stranded DNA viruses are important for Rep binding during the initiation of RCR. Such molecular features provide support for the possible bipartite nature of this virus, which we named utkilio virus (common name of the Opuntia discolor in South America) components A and B. In the infectivity assays conducted in Nicotiana benthamiana plants, only the A component of utkilio virus, which encodes the Rep protein, was found to move and replicate systemically in N. benthamiana. This was not true for component B, for which we did not detect replication, which may have been due to this being a defective molecule or because of the model plants (N. benthamiana) used for the infection assays. Future experiments need to be conducted with other plants, including O. discolor, to understand more about the biology of these viral components.

A year of genomic surveillance reveals how the SARS-CoV-2 pandemic unfolded in Africa

The progression of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic in Africa has so far been heterogeneous, and the full impact is not yet well understood. In this study, we describe the genomic epidemiology using a dataset of 8746 genomes from 33 African countries and two overseas territories. We show that the epidemics in most countries were initiated by importations predominantly from Europe, which diminished after the early introduction of international travel restrictions. As the pandemic progressed, ongoing transmission in many countries and increasing mobility led to the emergence and spread within the continent of many variants of concern and interest, such as B.1.351, B.1.525, A.23.1, and C.1.1. Although distorted by low sampling numbers and blind spots, the findings highlight that Africa must not be left behind in the global pandemic response, otherwise it could become a source for new variants.

The emergence and ongoing convergent evolution of the SARS-CoV-2 N501Y lineages

The independent emergence late in 2020 of the B.1.1.7, B.1.351, and P.1 lineages of SARS-CoV-2 prompted renewed concerns about the evolutionary capacity of this virus to overcome public health interventions and rising population immunity. Here, by examining patterns of synonymous and non-synonymous mutations that have accumulated in SARS-CoV-2 genomes since the pandemic began, we find that the emergence of these three "501Y lineages" coincided with a major global shift in the selective forces acting on various SARS-CoV-2 genes. Following their emergence, the adaptive evolution of 501Y lineage viruses has involved repeated selectively favored convergent mutations at 35 genome sites, mutations we refer to as the 501Y meta-signature. The ongoing convergence of viruses in many other lineages on this meta-signature suggests that it includes multiple mutation combinations capable of promoting the persistence of diverse SARS-CoV-2 lineages in the face of mounting host immune recognition.

Taxonomy update for the family Alphasatellitidae: new subfamily, genera, and species

Alphasatellites (family Alphasatellitidae) are circular, single-stranded DNA molecules (~1-1.4 kb) that encode a replication-associated protein and have commonly been associated with some members of the families Geminiviridae, Nanoviridae, and Metaxyviridae (recently established). Here, we provide a taxonomy update for the family Alphasatellitidae following the International Committee on Taxonomy of Viruses (ICTV) Ratification Vote held in March 2021. The taxonomic update includes the establishment of the new subfamily Petromoalphasatellitinae. This new subfamily includes three new genera as well as the genus Babusatellite, which previously belonged to the subfamily Nanoalphasatellitinae. Additionally, three new genera and 14 new species have been established in the subfamily Geminialphasatellitinae, as well as five new species in the subfamily Nanoalphasatellitinae.

Circoviruses and cycloviruses identified in Weddell seal fecal samples from McMurdo Sound, Antarctica

Circoviridae is a family of circular single-stranded DNA viruses whose members infect a wide variety of hosts. While well characterized in avian and mammalian hosts, little is known about circoviruses associated with Antarctic animals. From 48 Weddell seal (Leptonychotes weddellii) fecal samples collected on the sea ice in McMurdo between Nov 2014 and Dec 2014, we identified and determined the genomes of novel viruses that fall within two genera of the family Circoviridae, i.e. Circovirus (n = 7) and Cyclovirus (n = 45). We named these viruses as werosea circovirus (WerCV) and werosea cyclovirus (WerCyV). The genomes of WerCV and WerCyV share ~63-64% genome-wide pairwise identity with classified circoviruses and cycloviruses, respectively. Based on the species demarcation threshold of 80% for members of the Circoviridae, the genomes of WerCV and WerCyV represent new species in their respective genera. Evidence indicated recombination in five of the 45 WerCyV genomes identified in this study. These are the first circoviruses found associated with Antarctic pinnipeds, adding to those recently identified associated with Adélie (Pygoscelis adeliae) and chinstrap penguins (P. antarcticus).

A novel lineage of polyomaviruses identified in bark scorpions

Polyomaviruses are non-enveloped viruses with circular double-stranded DNA genomes (~4-7 kb). Initially identified in mammals, polyomaviruses have now been identified in birds and a few fish species. Although fragmentary polyomavirus-like sequences have been detected as apparent 'hitchhikers' in shotgun genomics datasets of various arthropods, the possible diversity of these viruses in invertebrates remains unclear. Scorpions are predatory arachnids that are among the oldest terrestrial animals. Using high-throughput sequencing and traditional molecular techniques we determine the genome sequences of eight novel polyomaviruses in scorpions (Centruroides sculpturatus) from the greater Phoenix area, Arizona, USA. Analysis of Centruroides transcriptomic datasets elucidated the splicing of the viral late gene array, which is more complex than that of vertebrate polyomaviruses. Phylogenetic analysis provides further evidence of co-divergence of polyomaviruses with their hosts, suggesting that at least one ancestral species of polyomaviruses was circulating amongst the primitive common ancestors of arthropods and chordates.

Complex evolutionary history of felid anelloviruses

Anellovirus infections are highly prevalent in mammals, however, prior to this study only a handful of anellovirus genomes had been identified in members of the Felidae family. Here we characterise anelloviruses in pumas (Puma concolor), bobcats (Lynx rufus), Canada lynx (Lynx canadensis), caracals (Caracal caracal) and domestic cats (Felis catus). The complete anellovirus genomes (n = 220) recovered from 149 individuals were diverse. ORF1 protein sequence similarity network analysis coupled with phylogenetic analysis, revealed two distinct clusters that are populated by felid-derived anellovirus sequences, a pattern mirroring that observed for the porcine anelloviruses. Of the two-felid dominant anellovirus groups, one includes sequences from bobcats, pumas, domestic cats and an ocelot, and the other includes sequences from caracals, Canada lynx, domestic cats and pumas. Coinfections of diverse anelloviruses appear to be common among the felids. Evidence of recombination, both within and between felid-specific anellovirus groups, supports a long coevolution history between host and virus.

The emergence and ongoing convergent evolution of the N501Y lineages coincides with a major global shift in the SARS-CoV-2 selective landscape

The emergence and rapid rise in prevalence of three independent SARS-CoV-2 "501Y lineages", B.1.1.7, B.1.351 and P.1, in the last three months of 2020 prompted renewed concerns about the evolutionary capacity of SARS-CoV-2 to adapt to both rising population immunity, and public health interventions such as vaccines and social distancing. Viruses giving rise to the different 501Y lineages have, presumably under intense natural selection following a shift in host environment, independently acquired multiple unique and convergent mutations. As a consequence, all have gained epidemiological and immunological properties that will likely complicate the control of COVID-19. Here, by examining patterns of mutations that arose in SARSCoV-2 genomes during the pandemic we find evidence of a major change in the selective forces acting on various SARS-CoV-2 genes and gene segments (such as S, nsp2 and nsp6), that likely coincided with the emergence of the 501Y lineages. In addition to involving continuing sequence diversification, we find evidence that a significant portion of the ongoing adaptive evolution of the 501Y lineages also involves further convergence between the lineages. Our findings highlight the importance of monitoring how members of these known 501Y lineages, and others still undiscovered, are convergently evolving similar strategies to ensure their persistence in the face of mounting infection and vaccine induced host immune recognition.

Elucidation of Early Evolution of HIV-1 Group M in the Congo Basin Using Computational Methods

The Congo Basin region is believed to be the site of the cross-species transmission event that yielded HIV-1 group M (HIV-1M). It is thus likely that the virus has been present and evolving in the region since that cross-species transmission. As HIV-1M was only discovered in the early 1980s, our directly observed record of the epidemic is largely limited to the past four decades. Nevertheless, by exploiting the genetic relatedness of contemporary HIV-1M sequences, phylogenetic methods provide a powerful framework for investigating simultaneously the evolutionary and epidemiologic history of the virus. Such an approach has been taken to find that the currently classified HIV-1 M subtypes and Circulating Recombinant Forms (CRFs) do not give a complete view of HIV-1 diversity. In addition, the currently identified major HIV-1M subtypes were likely genetically predisposed to becoming a major component of the present epidemic, even before the events that resulted in the global epidemic. Further efforts have identified statistically significant hot- and cold-spots of HIV-1M subtypes sequence inheritance in genomic regions of recombinant forms. In this review we provide ours and others recent findings on the emergence and spread of HIV-1M variants in the region, which have provided insights into the early evolution of this virus.

Freely accessible ready to use global infrastructure for SARS-CoV-2 monitoring

The COVID-19 pandemic is the first global health crisis to occur in the age of big genomic data.Although data generation capacity is well established and sufficiently standardized, analytical capacity is not. To establish analytical capacity it is necessary to pull together global computational resources and deliver the best open source tools and analysis workflows within a ready to use, universally accessible resource. Such a resource should not be controlled by a single research group, institution, or country. Instead it should be maintained by a community of users and developers who ensure that the system remains operational and populated with current tools. A community is also essential for facilitating the types of discourse needed to establish best analytical practices. Bringing together public computational research infrastructure from the USA, Europe, and Australia, we developed a distributed data analysis platform that accomplishes these goals. It is immediately accessible to anyone in the world and is designed for the analysis of rapidly growing collections of deep sequencing datasets. We demonstrate its utility by detecting allelic variants in high-quality existing SARS-CoV-2 sequencing datasets and by continuous reanalysis of COG-UK data. All workflows, data, and documentation is available at https://covid19.galaxyproject.org .

Transmission dynamics of SARS-CoV-2 within-host diversity in two major hospital outbreaks in South Africa

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes acute, highly transmissible respiratory infection in humans and a wide range of animal species. Its rapid global spread has resulted in a major public health emergency, necessitating commensurately rapid research to improve control strategies. In particular, the ability to effectively retrace transmission chains in outbreaks remains a major challenge, partly due to our limited understanding of the virus' underlying evolutionary dynamics within and between hosts. We used high-throughput sequencing whole-genome data coupled with bottleneck analysis to retrace the pathways of viral transmission in two nosocomial outbreaks that were previously characterised by epidemiological and phylogenetic methods. Additionally, we assessed the mutational landscape, selection pressures, and diversity at the within-host level for both outbreaks. Our findings show evidence of within-host selection and transmission of variants between samples. Both bottleneck and diversity analyses highlight within-host and consensus-level variants shared by putative source-recipient pairs in both outbreaks, suggesting that certain within-host variants in these outbreaks may have been transmitted upon infection rather than arising de novo independently within multiple hosts. Overall, our findings demonstrate the utility of combining within-host diversity and bottleneck estimations for elucidating transmission events in SARS-CoV-2 outbreaks, provide insight into the maintenance of viral genetic diversity, provide a list of candidate targets of positive selection for further investigation, and demonstrate that within-host variants can be transferred between patients. Together these results will help in developing strategies to understand the nature of transmission events and curtail the spread of SARS-CoV-2.

Creating a model to predict time intervals from induction of labor to induction of anesthesia and delivery to coordinate workload

BACKGROUND

Induction of labor continues to become more common. We analyzed induction of labor and timing of obstetric and anesthesia work to create a model to predict the induction-anesthesia interval and the induction-delivery interval in order to co-ordinate workload to occur when staff are most available.

METHODS

Patients who underwent induction of labor at a single medical center were identified and multivariable linear regression was used to model anesthesia and delivery times. Data were collected on date of birth, race/ethnicity, body mass index, gestational age, gravidity, parity, indication for labor induction, number of prior deliveries, time of induction, induction agent, cervical dilation, effacement, and fetal station on admission, date and time of anesthesia administration, date and time of delivery, and delivery type.

RESULTS

A total of 1746 women met inclusion criteria. Associations which significantly influenced time from induction of labor to anesthesia and delivery included maternal age (anesthesia P <0.001, delivery P =0.002), body mass index (both P <0.001), prior vaginal delivery (both P <0.001), gestational age (anesthesia P <0.001, delivery P <0.018), simplified Bishop score (both P <0.001), and first induction agent (both P <0.001). Induction of labor of nulliparous women at 02:00 h and parous women at 04:00 or 05:00 h had the highest estimated probability of the mother having her first anesthesia encounter and delivering during optimally staffed hours when our institution's specialty personnel are most available.

CONCLUSIONS

Time to obstetric and anesthesia tasks can be estimated to optimize induction of labor start times, and shift anesthesia and delivery workload to hours when staff are most available.

Large-scale survey reveals pervasiveness and potential function of endogenous geminiviral sequences in plants

The family Geminiviridae contains viruses with single-stranded DNA genomes that have been found infecting a wide variety of angiosperm species. The discovery within the last 25 years of endogenous geminivirus-like (EGV) elements within the nuclear genomes of several angiosperms has raised questions relating to the pervasiveness of EGVs and their impacts on host biology. Only a few EGVs have currently been characterized and it remains unclear whether any of these have influenced, or are currently influencing, the evolutionary fitness of their hosts. We therefore undertook a large-scale search for evidence of EGVs within 134 genome and 797 transcriptome sequences of green plant species. We detected homologues of geminivirus replication-associated protein (Rep) genes in forty-two angiosperm species, including two monocots, thirty-nine dicots, and one ANITA-grade basal angiosperm species (Amborella trichopoda). While EGVs were present in the members of many different plant orders, they were particularly common within the large and diverse order, Ericales, with the highest copy numbers of EGVs being found in two varieties of tea plant (Camellia sinensis). Phylogenetic and clustering analyses revealed multiple highly divergent previously unknown geminivirus Rep lineages, two of which occur in C.sinensis alone. We find that some of the Camellia EGVs are likely transcriptionally active, sometimes co-transcribed with the same host genes across several Camellia species. Overall, our analyses expand the known breadths of both geminivirus diversity and geminivirus host ranges, and strengthens support for the hypothesis that EGVs impact the biology of their hosts.

Diverse genomoviruses representing twenty-nine species identified associated with plants

Genomoviruses (family Genomoviridae) are circular single-stranded DNA viruses that have been mainly identified through metagenomics studies in a wide variety of samples from various environments. Here, we describe 98 genomes of genomoviruses found associated with members of 19 plant families from Australia, Brazil, France, South Africa and the USA. These 98 genomoviruses represent 29 species, 26 of which are new, in the genera Gemykolovirus (n = 37), Gemyduguivirus (n = 9), Gemygorvirus (n = 8), Gemykroznavirus (n = 6), Gemycircularvirus (n = 21) and Gemykibivirus (n = 17).

Heterogeneity of the rice microbial community of the Chinese centuries-old Honghe Hani rice terraces system

The Honghe Hani rice terraces system (HHRTS) is a traditional rice cultivation system where Hani people cultivate remarkably diverse rice varieties. Recent introductions of modern rice varieties to the HHRTS have significantly increased the severity of rice diseases within the terraces. Here, we determine the impacts of these recent introductions on the composition of the rice-associated microbial communities. We confirm that the HHRTS contains a range of both traditional HHRTS landraces and introduced modern rice varieties and find differences between the microbial communities of these two groups. However, this introduction of modern rice varieties has not strongly impacted the overall diversity of the HHRTS rice microbial community. Furthermore, we find that the rice varieties (i.e. groups of closely related genotypes) have significantly structured the rice microbial community composition (accounting for 15%-22% of the variance) and that the core microbial community of HHRTS rice plants represents less than 3.3% of all the microbial taxa identified. Collectively, our study suggests a highly diverse HHRTS rice holobiont (host with its associated microbes) where the diversity of rice hosts mirrors the diversity of their microbial communities. Further studies will be needed to better determine how such changes might impact the sustainability of the HHRTS.

Sorghum mastrevirus-associated alphasatellites: new geminialphasatellites associated with an African streak mastrevirus infecting wild Poaceae plants on Reunion Island

Nine complete nucleotide sequences of geminialphasatellites (subfamily Geminialphasatellitinae, family Alphasatellitidae) recovered from the wild Poaceae Sorghum arundinaceum collected in Reunion are described and analyzed. While the helper geminivirus was identified as an isolate of maize streak virus (genus Mastrevirus, family Geminiviridae), the geminialphasatellite genomes were most closely related to, and shared ~63% identity with, clecrusatellites. Even though the geminialphasatellite molecules lack an adenine rich-region, they have the typical size of geminialphasatellites, encode a replication-associated protein in the virion sense, and have probable stem-loop structures at their virion-strand origins of replication. According to the proposed geminialphasatellite species and genus demarcation thresholds (88% and 70% nucleotide identity, respectively), the genomes identified here represent a new species (within a new genus) for which we propose the name "Sorghum mastrevirus-associated alphasatellite" (genus "Sorgasalphasatellite").

Compartmentalization and Clonal Amplification of HIV-1 in the Male Genital Tract Characterized Using Next-Generation Sequencing

Compartmentalization of HIV-1 between the systemic circulation and the male genital tract may have a substantial impact on which viruses are available for sexual transmission to new hosts. We studied compartmentalization and clonal amplification of HIV-1 populations between the blood and the genital tract from 10 antiretroviral-naive men using Illumina MiSeq with a PrimerID approach. We found evidence of some degree of compartmentalization in every study participant, unlike previous studies, which collectively showed that only ∼50% of analyzed individuals exhibited compartmentalization of HIV-1 lineages between the male genital tract (MGT) and blood. Using down-sampling simulations, we determined that this disparity can be explained by differences in sampling depth in that had we sequenced to a lower depth, we would also have found compartmentalization in only ∼50% of the study participants. For most study participants, phylogenetic trees were rooted in blood, suggesting that the male genital tract reservoir is seeded by incoming variants from the blood. Clonal amplification was observed in all study participants and was a characteristic of both blood and semen viral populations. We also show evidence for independent viral replication in the genital tract in the individual with the most severely compartmentalized HIV-1 populations. The degree of clonal amplification was not obviously associated with the extent of compartmentalization. We were also unable to detect any association between history of sexually transmitted infections and level of HIV-1 compartmentalization. Overall, our findings contribute to a better understanding of the dynamics that affect the composition of virus populations that are available for transmission.IMPORTANCE Within an individual living with HIV-1, factors that restrict the movement of HIV-1 between different compartments-such as between the blood and the male genital tract-could strongly influence which viruses reach sites in the body from which they can be transmitted. Using deep sequencing, we found strong evidence of restricted HIV-1 movements between the blood and genital tract in all 10 men that we studied. We additionally found that neither the degree to which particular genetic variants of HIV-1 proliferate (in blood or genital tract) nor an individual's history of sexually transmitted infections detectably influenced the degree to which virus movements were restricted between the blood and genital tract. Last, we show evidence that viral replication gave rise to a large clonal amplification in semen in a donor with highly compartmentalized HIV-1 populations, raising the possibility that differential selection of HIV-1 variants in the genital tract may occur.

RDP5: a computer program for analyzing recombination in, and removing signals of recombination from, nucleotide sequence datasets

For the past 20 years, the recombination detection program (RDP) project has focused on the development of a fast, flexible, and easy to use Windows-based recombination analysis tool. Whereas previous versions of this tool have relied on considerable user-mediated verification of detected recombination events, the latest iteration, RDP5, is automated enough that it can be integrated within analysis pipelines and run without any user input. The main innovation enabling this degree of automation is the implementation of statistical tests to identify recombination signals that could be attributable to evolutionary processes other than recombination. The additional analysis time required for these tests has been offset by algorithmic improvements throughout the program such that, relative to RDP4, RDP5 will still run up to five times faster and be capable of analyzing alignments containing twice as many sequences (up to 5000) that are five times longer (up to 50 million sites). For users wanting to remove signals of recombination from their datasets before using them for downstream phylogenetics-based molecular evolution analyses, RDP5 can disassemble detected recombinant sequences into their constituent parts and output a variety of different recombination-free datasets in an array of different alignment formats. For users that are interested in exploring the recombination history of their datasets, all the manual verification, data management and data visualization components of RDP5 have been extensively updated to minimize the amount of time needed by users to individually verify and refine the program's interpretation of each of the individual recombination events that it detects.

A Novel Divergent Geminivirus Identified in Asymptomatic New World Cactaceae Plants

Cactaceae comprise a diverse and iconic group of flowering plants which are almost exclusively indigenous to the New World. The wide variety of growth forms found amongst the cacti have led to the trafficking of many species throughout the world as ornamentals. Despite the evolution and physiological properties of these plants having been extensively studied, little research has focused on cactus-associated viral communities. While only single-stranded RNA viruses had ever been reported in cacti, here we report the discovery of cactus-infecting single-stranded DNA viruses. These viruses all apparently belong to a single divergent species of the family Geminiviridae and have been tentatively named Opuntia virus 1 (OpV1). A total of 79 apparently complete OpV1 genomes were recovered from 31 different cactus plants (belonging to 20 different cactus species from both the Cactoideae and Opuntioideae clades) and from nine cactus-feeding cochineal insects (Dactylopius sp.) sampled in the USA and Mexico. These 79 OpV1 genomes all share > 78.4% nucleotide identity with one another and < 64.9% identity with previously characterized geminiviruses. Collectively, the OpV1 genomes display evidence of frequent recombination, with some genomes displaying up to five recombinant regions. In one case, recombinant regions span ~40% of the genome. We demonstrate that an infectious clone of an OpV1 genome can replicate in Nicotiana benthamiana and Opuntia microdasys. In addition to expanding the inventory of viruses that are known to infect cacti, the OpV1 group is so distantly related to other known geminiviruses that it likely represents a new geminivirus genus. It remains to be determined whether, like its cactus hosts, its geographical distribution spans the globe.

Symptom evolution following the emergence of maize streak virus

For pathogens infecting single host species evolutionary trade-offs have previously been demonstrated between pathogen-induced mortality rates and transmission rates. It remains unclear, however, how such trade-offs impact sub-lethal pathogen-inflicted damage, and whether these trade-offs even occur in broad host-range pathogens. Here, we examine changes over the past 110 years in symptoms induced in maize by the broad host-range pathogen, maize streak virus (MSV). Specifically, we use the quantified symptom intensities of cloned MSV isolates in differentially resistant maize genotypes to phylogenetically infer ancestral symptom intensities and check for phylogenetic signal associated with these symptom intensities. We show that whereas symptoms reflecting harm to the host have remained constant or decreased, there has been an increase in how extensively MSV colonizes the cells upon which transmission vectors feed. This demonstrates an evolutionary trade-off between amounts of pathogen-inflicted harm and how effectively viruses position themselves within plants to enable onward transmission.

Emergence of Southern Rice Black-Streaked Dwarf Virus in the Centuries-Old Chinese Yuanyang Agrosystem of Rice Landraces

Southern rice black-streaked dwarf virus (SRBSDV), which causes severe disease symptoms in rice (Oriza sativa L.) has been emerging in the last decade throughout northern Vietnam, southern Japan and southern, central and eastern China. Here we attempt to quantify the prevalence of SRBSDV in the Honghe Hani rice terraces system (HHRTS)-a Chinese 1300-year-old traditional rice production system. We first confirm that genetically diverse rice varieties are still being cultivated in the HHRTS and categorize these varieties into three main genetic clusters, including the modern hybrid varieties group (MH), the Hongyang improved modern variety group (HY) and the traditional indica landraces group (TIL). We also show over a 2-year period that SRBSDV remains prevalent in the HHRTS (20.1% prevalence) and that both the TIL (17.9% prevalence) and the MH varieties (5.1% prevalence) were less affected by SRBSDV than were the HY varieties (30.2% prevalence). Collectively we suggest that SRBSDV isolates are freely moving within the HHRTS and that TIL, HY and MH rice genetic clusters are not being preferentially infected by particular SRBSDV lineages. Given that SRBSDV can cause 30-50% rice yield losses, our study emphasizes both the need to better monitor the disease in the HHRTS, and the need to start considering ways to reduce its burden on rice production.

Combined spinal/caudal catheter anesthesia: extending the boundaries of regional anesthesia for complex pediatric urological surgery

BACKGROUND

Spinal anesthesia (SA) is an established anesthetic technique for short outpatient pediatric urological cases. To avoid general anesthesia (GA) and expand regional anesthetics to longer and more complex pediatric surgeries, the authors began a program using a combined spinal/caudal catheter (SCC) technique.

STUDY DESIGN

The authors retrospectively reviewed the charts of all patients scheduled for surgery under SCC between December 2016 and April 2018 and recorded age, gender, diagnosis, procedure, conversion to GA/airway intervention, operative time, neuraxial and intravenous medications administered, complications, and outcomes. The SCC technique typically involved an initial intrathecal injection of 0.5% isobaric bupivacaine followed by placement of a caudal epidural catheter. At the discretion of the anesthesiologist, patients received 0.5 mg per kilogram of oral midazolam approximately 30 min prior to entering the operating room. One hour after the intrathecal injection, 3% chloroprocaine was administered via the caudal catheter to prolong the duration of surgical block. Intra-operative management included either continuous infusion or bolus dosing of dexmedetomidine, as needed, for patient comfort and to optimize surgical conditions. Prior to removal of caudal catheter in the post-anesthesia care unit, a supplemental bolus dose of local anesthesia was given through the catheter to provide prolonged post-operative analgesia.

RESULTS

Overall, 23 children underwent attempted SCC. SA was unsuccessful in three patients, and surgery was performed under GA. The remaining 20 children all had successful SCC placement. There were 11 girls and nine boys, with a mean age of 16.5 months (3.3-43.8). Surgeries performed under SCC included seven ureteral reimplantations, two ureterocele excisions/reimplantations, two megaureter repairs, four first-stage hypospadias repairs, one distal hypospadias repair, one second-stage hypospadias repair, two feminizing genitoplasties, and one open pyeloplasty. Average length of surgery was 109 min (range 63-172 min). Pre-operative midazolam was given in 13/20 (65%). All SCC patients were spontaneously breathing room air during the operation, and there were no airway interventions. Only one SCC patient received opioids intra-operatively. There were no intra-operative or perioperative complications.

DISCUSSION

This pilot study shows that the technique of SCC allows one to do more complex urologic surgery under regional anesthesia than what would be possible under pure SA alone. The main limitations of the study include the relatively small number of patients and the small median length of the operative procedures. As a proof of concept, however, this does show that complex genital surgery bladder level procedures such as ureteral reimplantation can be performed under regional anesthesia.

CONCLUSION

SCC allows for more complex surgeries to be performed exclusively under regional anesthesia, thus obviating the need for airway intervention, minimizing or eliminating the use of opioids, and thus avoiding known and potential risks associated with GA. The latter is of particular importance given current concerns regarding hypothetical neurocognitive effects of GA on children aged below 3 years.

Exploring the diversity of Poaceae-infecting mastreviruses on Reunion Island using a viral metagenomics-based approach

Mostly found in Africa and its surrounding islands, African streak viruses (AfSV) represent the largest group of known mastreviruses. Of the thirteen AfSV species that are known to infect either cultivated or wild Poaceae plant species, six have been identified on Reunion Island. To better characterize AfSV diversity on this island, we undertook a survey of a small agroecosystem using a new metagenomics-based approach involving rolling circle amplification with random PCR amplification tagging (RCA-RA-PCR), high-throughput sequencing (Illumina HiSeq) and the mastrevirus reads classification using phylogenetic placement. Mastreviruses that likely belong to three new species were discovered and full genome sequences of these were determined by Sanger sequencing. The geminivirus-focused metagenomics approach we applied in this study was useful in both the detection of known and novel mastreviruses. The results confirm that Reunion Island is indeed a hotspot of AfSV diversity and that many of the mastrevirus species have likely been introduced multiple times. Applying a similar approach in other natural and agricultural environments should yield sufficient detail on the composition and diversity of geminivirus communities to precipitate major advances in our understanding of the ecology and the evolutionary history of this important group of viruses.

Evolution and ecology of plant viruses

The discovery of the first non-cellular infectious agent, later determined to be tobacco mosaic virus, paved the way for the field of virology. In the ensuing decades, research focused on discovering and eliminating viral threats to plant and animal health. However, recent conceptual and methodological revolutions have made it clear that viruses are not merely agents of destruction but essential components of global ecosystems. As plants make up over 80% of the biomass on Earth, plant viruses likely have a larger impact on ecosystem stability and function than viruses of other kingdoms. Besides preventing overgrowth of genetically homogeneous plant populations such as crop plants, some plant viruses might also promote the adaptation of their hosts to changing environments. However, estimates of the extent and frequencies of such mutualistic interactions remain controversial. In this Review, we focus on the origins of plant viruses and the evolution of interactions between these viruses and both their hosts and transmission vectors. We also identify currently unknown aspects of plant virus ecology and evolution that are of practical importance and that should be resolvable in the near future through viral metagenomics.

Need for additional anesthesia after single injection spinal analgesia for labor: a retrospective cohort study

BACKGROUND

There is little information about the use and efficacy of single injection spinal blocks for labor analgesia; specifically, how frequently subsequent analgesia or anesthesia is needed. This study determined how frequently an additional anesthetic intervention was needed in women who received single injection spinal analgesia.

METHODS

This retrospective study examined electronic medical records to find all single injection spinal analgesic blocks for labor analgesia over a 14-year (2003-2016) period. Patient and block characteristics and patient outcomes were recorded. The primary outcome was need for an additional anesthetic intervention following single injection spinal for labor analgesia.

RESULTS

Four-hundred-and-twenty-eight patients received single injection spinal blocks for labor and 60 (14.0%) needed an additional anesthetic either for labor analgesia (n=49) or an unexpected procedure (n=11). Two of these (0.5%) required general anesthesia. Parity of zero (nulliparous), a low cervical dilation at the time of the spinal injection, and induction of labor status, were associated with an increased risk of needing an additional anesthetic intervention.

CONCLUSIONS

This retrospective review provides evidence that single injection spinal anesthesia may be used for multiparous women with spontaneous labor and more advanced cervical dilation.

Evolutionary dynamics of ten novel Gamma-PVs: insights from phylogenetic incongruence, recombination and phylodynamic analyses

Background

Human papillomaviruses (HPVs) are genetically diverse, belonging to five distinct genera: Alpha, Beta, Gamma, Mu and Nu. All papillomaviruses have double stranded DNA genomes that are thought to evolve slowly because they co-opt high-fidelity host cellular DNA polymerases for their replication. Despite extensive efforts to catalogue all the HPV species that infect humans, it is likely that many still remain undiscovered. Here we use the sequences of ten novel Gammapapillomaviruses (Gamma-PVs) characterized in previous studies and related HPVs to analyse the evolutionary dynamics of these viruses at the whole genome and individual gene scales.

Results

We found statistically significant incongruences between the phylogenetic trees of different genes which imply gene-to-gene variation in the evolutionary processes underlying the diversification of Gamma-PVs. We were, however, only able to detect convincing evidence of a single recombination event which, on its own, cannot explain the observed incongruences between gene phylogenies. The divergence times of the last common ancestor (LCA) of the Alpha, Beta, Mu, Nu and Gamma genera was predicted to have existed between 49.7–58.5 million years ago, before splitting into the five main lineages. The LCA of the Gamma-PVs at this time was predicted to have existed between 45.3 and 67.5 million years ago: approximately at the time when the simian and tarsier lineages of the primates diverged.

Conclusion

Consequently, we report here phylogenetic tree incongruence without strong evidence of recombination.

Nanopore-based detection and characterization of yam viruses

We here assessed the capability of the MinION sequencing approach to detect and characterize viruses infecting a water yam plant. This sequencing platform consistently revealed the presence of several plant virus species, including Dioscorea bacilliform virus, Yam mild mosaic virus and Yam chlorotic necrosis virus. A potentially novel ampelovirus was also detected by a complimentary Illumina sequencing approach. The full-length genome sequence of yam chlorotic necrosis virus was determined using Sanger sequencing, which enabled determination of the coverage and sequencing accuracy of the MinION technology. Whereas the total mean sequencing error rate of yam chlorotic necrosis virus-related MinION reads was 11.25%, we show that the consensus sequence obtained either by de novo assembly or after mapping the MinION reads on the virus genomic sequence was >99.8% identical with the Sanger-derived reference sequence. From the perspective of potential plant disease diagnostic applications of MinION sequencing, these degrees of sequencing accuracy demonstrate that the MinION approach can be used to both reliably detect and accurately sequence nearly full-length positive-sense single-strand polyadenylated RNA plant virus genomes.

New Isolates of Sweet potato feathery mottle virus and Sweet potato virus C: Biological and Molecular Properties, and Recombination Analysis Based on Complete Genomes

Sweet potato feathery mottle virus (SPFMV) and Sweet potato virus C (SPVC) isolates were obtained from sweetpotato shoot or tuberous root samples from three widely separated locations in Australia's tropical north (Cairns, Darwin, and Kununurra). The samples were planted in the glasshouse and scions obtained from the plants were graft inoculated to Ipomoea setosa plants. Virus symptoms were recorded in the field in Kununurra and in glasshouse-grown sweetpotato and I. setosa plants. RNA extracts from I. setosa leaf samples were subjected to high-throughput sequencing. New complete SPFMV (n = 17) and SPVC (n = 6) genomic sequences were obtained and compared with 47 sequences from GenBank. Phylogenetic analysis revealed that the 17 new SPFMV genomes all fitted within either major phylogroup A, minor phylogroup II, formerly O; or major phylogroup B, formerly RC. Major phylogroup A's minor phylogroup I, formerly EA, only appeared when recombinants were included. Numbers of SPVC genomes were insufficient to subdivide it into phylogroups. Within phylogroup A's minor phylogroup II, the closest genetic match between an Australian and a Southeast Asian SPFMV sequence was the 97.4% nucleotide identity with an East Timorese sequence. Recombination analysis of the 43 SPFMV and 27 SPVC sequences revealed evidence of 44 recombination events, 16 of which involved interspecies sequence transfers between SPFMV and SPVC and 28 intraspecies transfers, 17 in SPFMV and 11 in SPVC. Within SPFMV, 11 intraspecies recombination events were between different major phylogroups and 6 were between members of the same major phylogroup. Phylogenetic analysis accounting for the detected recombination events within SPFMV sequences yielded evidence of minor phylogroup II and phylogroup B but the five sequences from minor phylogroup I were distributed in two separate groups among the sequences of minor phylogroup II. For the SPVC sequences, phylogenetic analysis accounting for the detected recombination events revealed three major phylogroups (A, B, and C), with major phylogroup A being further subdivided into two minor phylogroups. Within the recombinant genomes of both viruses, their PI, NIa-Pro, NIb, and CP genes contained the highest numbers of recombination breakpoints. The high frequency of interspecies and interphylogroup recombination events reflects the widespread occurrence of mixed SPVC and SPFMV infections within sweetpotato plants. The prevalence of infection in northern Australian sweetpotato samples reinforces the need for improved virus testing in healthy sweetpotato stock programs. Furthermore, evidence of genetic connectivity between Australian and East Timorese SPFMV genomes emphasizes the need for improved biosecurity measures to protect against potentially damaging international virus movements.

World Management of Geminiviruses

Management of geminiviruses is a worldwide challenge because of the widespread distribution of economically important diseases caused by these viruses. Regardless of the type of agriculture, management is most effective with an integrated pest management (IPM) approach that involves measures before, during, and after the growing season. This includes starting with resistant cultivars and virus- and vector-free transplants and propagative plants. For high value vegetables, protected culture (e.g., greenhouses and screenhouses) allows for effective management but is limited owing to high cost. Protection of young plants in open fields is provided by row covers, but other measures are typically required. Measures that are used for crops in open fields include roguing infected plants and insect vector management. Application of insecticide to manage vectors (whiteflies and leafhoppers) is the most widely used measure but can cause undesirable environmental and human health issues. For annual crops, these measures can be more effective when combined with host-free periods of two to three months. Finally, given the great diversity of the viruses, their insect vectors, and the crops affected, IPM approaches need to be based on the biology and ecology of the virus and vector and the crop production system. Here, we present the general measures that can be used in an IPM program for geminivirus diseases, specific case studies, and future challenges.