Search

Vibrio natriegens strain PWH3a, isolated from the Texas Gulf Coast, is used as a model organism in marine microbiology. Here, we report the complete genome sequence of strain PWH3a, which has two circular chromosomes, 4,650 coding sequences, 34 rRNA, 4 noncoding RNA (ncRNA), 131 tRNA genes, and one Mu-like prophage sequence.

Neurolymphomatosis (NL) is a rare condition caused by the lymphomatous or leukemic infiltration of nerves and manifests as neuropathy. Most often, NL is associated with B-lineage non-Hodgkin lymphoma (NHL) and only infrequently occurs in conjunction with T- or NK-lineage NHL. Extranodal NK/T-cell lymphoma (ENKTL)-associated NL is exceedingly unusual, with only 9 cases described in the English language literature, in addition to our case. Diagnosis of NL is challenging, as the entity can mimic neuropathies of more common etiologies, and an adequate biopsy may be difficult to obtain. Timely diagnosis demands a high index of suspicion, especially for patients without a history of hematologic malignancy. We expand upon a unique case of NL exclusively involving cranial nerves and cauda equina nerve roots, as the initial manifestation of ENKTL, and contextualize our findings within the framework of previously reported NK/T-lineage NL cases.

Temperate coastal marine waters are often thermally stratified from spring through fall but can be dynamic and disrupted by tidal currents and wind-driven upwelling. These mixing events introduce deeper, cooler water with a higher partial pressure of CO2 (pCO2), and its associated microbial communities to the surface. Anecdotally, these events impact shellfish hatcheries and farms, warranting improved understanding of changes in composition and activity of marine microbial communities in relation to environmental processes. To characterize both compositional and functional changes associated with abiotic factors, here we generate a reference metatranscriptome from the Strait of Georgia over representative seasons and analyze metatranscriptomic profiles of the microorganisms present within intake water containing different pCO2 levels at a shellfish hatchery in British Columbia from June through October. Abiotic factors studied include pH, temperature, alkalinity, aragonite, calcite and pCO2. Community composition changes were observed to occur at broad taxonomic levels, and most notably to vary with temperature and pCO2. Functional gene expression profiles indicated a strong difference between early (June-July) and late summer (August-October) associated with viral activity. The taxonomic data suggests this could be due to the termination of cyanobacteria and phytoplankton blooms by viral lysis in the late season. Functional analysis indicated fewer differentially expressed transcripts associated with abiotic variables (e.g., pCO2) than with the temporal effect. Microbial composition and activity in these waters varies with both short-term effects observed alongside abiotic variation as well as long-term effects observed across seasons. The analysis of both taxonomy and functional gene expression simultaneously in the same samples by environmental RNA (eRNA metatranscriptomics) provided a more comprehensive view for monitoring water bodies than either would in isolation.

Key Points Myoclonic jerks and inattentiveness may be rare neurologic complications of ATO toxicity. Clinicians must be aware of this rare toxicity given that the ATO and ATRA combination is now standard-of-care treatment of low-risk APL.

Microbes are by far the dominant biomass in the world’s oceans and drive biogeochemical cycles that are critical to life on Earth. The composition of marine microbial communities is highly dynamic spatially and temporally, with consequent effects on their functional roles. In part, these changes in composition result from viral lysis, which is taxon-specific and estimated to account for about half of marine microbial mortality. Here we determined taxon-specific cell lysis of prokaryotes in coastal seawater by sequencing extracellular and cellular ribosomal RNA (rRNA). We detected lysis in about 15% of the 16946 prokaryotic amplicon sequence variants (ASVs) identified, and lysis of up to 34% of the ASVs within a water sample. High lysis was most commonly associated with rare but typically highly productive bacteria, while relatively low lysis was more common in taxa that are often abundant, consistent with the proposed model of “kill the winner”, and the idea that less abundant taxa generally experience higher relative lysis than dominant taxa. These results provide an explanation to the long-standing conundrum of why highly productive bacteria that are readily isolated from seawater are often in very low abundance.One Sentence SummaryExtracellular rRNA shows wide variation in cell lysis among prokaryotic taxa.

Given its rare incidence, there are few epidemiological case series on paraneoplastic neurologic syndromes (PNS). We present a 10-year series compiled in the Section of Neuro-Oncology, Yale Cancer Center between 2002 and 2012. Twenty-five cases met the PNS Euro-network criteria for definitive PNS. Most (64%; 16/25) had no known neoplasm. Cerebrospinal fluid pleocytosis declined logarithmically over time. Neuroimaging abnormalities were seen in 88% of cases (15/17), but with delayed onset. Therapeutic benefit correlated strongly to pre-treatment modified Rankin Scale (mRS) (p

Prasinophytes are widespread marine algae for which responses to nutrient limitation and viral infection are not well understood. We studied the picoprasinophyte, Micromonas pusilla, grown under phosphate-replete (0.65 ± 0.07 d-1 ) and 10-fold lower (low)-phosphate (0.11 ± 0.04 d-1 ) conditions, and infected by the phycodnavirus MpV-SP1. Expression of 17% of Micromonas genes in uninfected cells differed by >1.5-fold (q < 0.01) between nutrient conditions, with genes for P-metabolism and the uniquely-enriched Sel1-like repeat (SLR) family having higher relative transcript abundances, while phospholipid-synthesis genes were lower in low-P than P-replete. Approximately 70% (P-replete) and 30% (low-P) of cells were lysed 24 h post-infection, and expression of ≤5.8% of host genes changed relative to uninfected treatments. Host genes for CAZymes and glycolysis were activated by infection, supporting importance in viral production, which was significantly lower in slower growing (low-P) hosts. All MpV-SP1 genes were expressed, and our analyses suggest responses to differing host-phosphate backgrounds involve few viral genes, while the temporal program of infection involves many more, and is largely independent of host-phosphate background. Our study (i) identifies genes previously unassociated with nutrient acclimation or viral infection, (ii) provides insights into the temporal program of prasinovirus gene expression by hosts and (iii) establishes cell biological aspects of an ecologically important host-prasinovirus system that differ from other marine algal-virus systems.

Pacific oysterCrassostrea gigas, endemic to coastal Asia, has been translocated globally throughout the past century, resulting in self-sustaining introduced populations (naturalized). Oyster aquaculture industries in many parts of the world depend on commercially available seed (hatchery-farmed) or naturalized/wild oysters to move onto a farm (naturalized-farmed). It is therefore important to understand genetic variation among populations and farm types. Here we genotype naturalized/wild populations from France, Japan, China, and most extensively in coastal British Columbia, Canada. We also genotype cultured populations from throughout the Northern Hemisphere to compare with naturalized populations. In total, 16,942 markers were identified using double-digest RAD-sequencing in 182 naturalized, 112 hatchery-farmed, and 72 naturalized-farmed oysters (n = 366). Consistent with previous studies, very low genetic differentiation was observed around Vancouver Island (mean FST= 0.0019), and low differentiation between countries in the Japan-Canada-France historical translocation lineage (France-Canada FST= 0.0024; Japan-Canada FST= 0.0060). Chinese populations were more differentiated (China-Japan FST= 0.0241). Hatchery-propagated populations had higher inter-individual relatedness suggesting family structure. Within-population inbreeding was not detected on farms, but nucleotide diversity and polymorphism rate was lower in one farm population. Moving oysters from nature onto farms did not result in strong within-generation selection. Private alleles at substantial frequency were identified in several hatchery populations grown in BC, suggesting non-local origins. Tests of selection identified outlier loci consistent with selective differences associated with domestication, in some cases consistently identified in multiple farms. Top outlier candidates were nearby genes involved in calcium signaling and calmodulin activity. Implications of potential introgression from hatchery-farmed oysters depends on whether naturalized populations are valued as a locally-adapted resource or as an introduced, invasive species. Given the value of the industry in BC and the challenges the industry faces (e.g., climate change, crop losses, biotic stressors), this remains an important question.

The beluga whale is a cetacean that inhabits arctic and subarctic regions, and is the only living member of the genus Delphinapterus. The genome of the beluga whale was determined using DNA sequencing approaches that employed both microfluidic partitioning library and non-partitioned library construction. The former allowed for the construction of a highly contiguous assembly with a scaffold N50 length of over 19 Mbp and total reconstruction of 2.32 Gbp. To aid our understanding of the functional elements, transcriptome data was also derived from brain, duodenum, heart, lung, spleen, and liver tissue. Assembled sequence and all of the underlying sequence data are available at the National Center for Biotechnology Information (NCBI) under the Bioproject accession number PRJNA360851A.

Given its rare incidence, there are few epidemiological case series on paraneoplastic neurologic syndromes (PNS).We present a 10-year series compiled in the Section of Neuro-Oncology, Yale Cancer Center between 2002 and 2012.Twenty-five cases met the PNS Euro-network criteria for definitive PNS. Most (64%; 16/25) had no known neoplasm. Cerebrospinal fluid pleocytosis declined logarithmically over time. Neuroimaging abnormalities were seen in 88% of cases (15/17), but with delayed onset. Therapeutic benefit correlated strongly to pre-treatment modified Rankin Scale (mRS) (p 0.01), but not with time elapsed between syndrome onset to treatment (p = 0.8), first immunotherapy modality (corticosteroids: n = 10; IVIG: n = 10; PLEX: n = 3; p = 0.37), or number of immunotherapy modalities provided (p = 0.17). PNS-related mortality was high (24%; 6/25). Nonetheless, 16% (3/18; 7 living patients censored) survived over 6 times the anticipated median expected by tumor type and stage.PNS are rare, at an estimated incidence of 3.1 cases per million-person-years. Detection of CSF pleocytosis and MRI abnormalities depend on time of analysis. While PNS-related mortality was high, immunotherapy benefit correlated strongly with pre-treatment mRS and long-term survival is possible.

Purpose To report the incidence and outcomes of intraoperative Descemet membrane (DM) perforations during deep anterior lamellar keratoplasty (DALK). Design Retrospective, consecutive, interventional case series. Methods A retrospective audit of all DALK cases performed from 2004 to 2015 in a tertiary center, with and without intraoperative DM perforations. We excluded cases with preexisting corneal perforations before surgery. Results There were a total of 540 eyes, of which 101 (18.7%) had intraoperative DM perforations. These included 79 eyes (78.2%) with microperforations and 15 eyes (14.9%) with macroperforation. The most common steps at which DM perforation occurred intraoperatively were during deep lamellar dissection (32 cases; 31.7%), air injection (27 cases; 26.7%), and suturing (21 cases; 20.8%). Management of the DM perforations included a combination of intracameral air tamponade (49 cases; 48.5%), stromal patching (10 cases; 9.9%), fibrin glue (8 cases; 7.9%), and suturing of the defect (1 case; 1.1%). There were 2 eyes (2/540; 0.37%) that were converted to penetrating keratoplasty (PK). There were no significant differences in the postoperative unaided or best-corrected visual acuity, or in the numbers of patients with postoperative graft failure, graft rejection, or subsequent surgery at postoperative years 1 and 3. Conclusions DALK cases with DM perforations intraoperatively are often able to be managed without conversion to PK. Cases with DM perforations intraoperatively have equivalent visual acuity outcomes compared to those without DM perforations, and did not have any increased risk of graft failure, rejection, or subsequent surgery at postoperative years 1 and 3.

The leptomeninges, spinal fluid and peripheral nerves can serve as sanctuary sites for leukemia. Neurologic complications arise from direct leukemic infiltration of the central and peripheral nervous system, indirect leukemic effects (e.g., cerebral leukostasis, cerebrovascular accidents, paraneoplastic syndromes), effect from treatments or stem cell transplant (e.g., graft versus host disease, immune reconstitution inflammatory syndrome) or immune compromise. This review discusses the clinical manifestations of neurologic complications in leukemia patients and reviews the recent advances in their diagnosis and management.

The following protocol describes the isolation and purification of viruses infecting cyanobacteria using a liquid bioassay approach. Viruses infecting cyanobacteria are also known as cyanophages. This protocol was written specifically for the isolation of cyanophages infecting freshwater cyanobacteria particularly, cyanobacteria that cannot be cultured on solid media. The use of a clonal cyanobacterial culture is recommended for the isolation of viruses. Growth conditions (i.e., media, light cycle and temperature) should be modified based on the host of interest.

Glioblastoma multiforme (GBM) is an aggressive tumour that can lead to lymphopaenia. Its standard treatment involves temozolomide (TMZ) chemotherapy with radiation, often with addition of corticosteroids for symptomatic management. Although TMZ is also immunosuppressive, patients receiving TMZ rarely develop disseminated opportunistic infections. Here, we report the case of a patient with GBM receiving TMZ, radiotherapy and corticosteroids, who develops an incidental new brain lesion that is found to be disseminated Aspergillus within a new GBM tumour site. The patient received successful early treatment of her central nervous system aspergillosis. This case illustrates the profound immunosuppressive potential of GBM in conjunction with TMZ and corticosteroids, which can lead to high-morbidity opportunistic infections concurrently with tumour progression. Future research is needed to elucidate GBM, TMZ and corticosteroids’ compound immune effects and guide management that strikes a balance between treating high-morbidity infections and continuing with immunosuppressive chemotherapy.

International audience; In experiments designed primarily to investigate viral lysis, we found that the presence of viruses had a positive effect on the growth of Synechococcus. A Landry-Hassett-type stepwise dilution experiment conducted during a Synechococcus bloom in the Gulf of Mexico used both (i) 0.2-mu m filtered seawater in which the abundance of bacteria and grazers were reduced but the majority of viruses were retained, and (ii) ultrafiltered (30 000 MW cutoff) virus-free seawater in which the abundance of viruses, bacteria and grazers were reduced. High growth rates and frequency of dividing cells (FDCs) were recorded in 0.2-mm filtered treatments while growth was inhibited in incubations with a high proportion of virus-free ultrafiltered water. In two subsequent experiments using Mediterranean Sea populations, a two-point dilution approach in which viral abundance was reduced by 80-90% yielded similar results, and showed that Synechococcus only grew well in the presence of viruses, bacteria and grazers. In four further Mediterranean experiments viruses removed via ultrafiltration were added back, either untreated, or inactivated by a heat treatment. Growth rates and FDCs were higher in the presence of untreated viruses than with viruses inactivated by heat, suggesting that it was not organic matter in the virus-size fraction but rather the presence of infectious viruses which sustained growth. While Synechococcus was also infected by viruses during these experiments, our data imply that growth of Synechococcus may depend upon viral lysis of heterotrophic bacteria. This finding is consistent with the view that nutrient cycling by viral lysis of heterotrophic bacteria may control phytoplankton growth and ecosystem scale carbon production.

Modern microbialites are complex microbial communities that interface with abiotic factors to form carbonate-rich organosedimentary structures whose ancestors provide the earliest evidence of life. Past studies primarily on marine microbialites have inventoried diverse taxa and metabolic pathways, but it is unclear which of these are members of the microbialite community and which are introduced from adjacent environments. Here we control for these factors by sampling the surrounding water and nearby sediment, in addition to the microbialites and use a metagenomics approach to interrogate the microbial community. Our findings suggest that the Pavilion Lake microbialite community profile, metabolic potential and pathway distributions are distinct from those in the neighboring sediments and water. Based on RefSeq classification, members of the Proteobacteria (e.g alpha and delta classes) were the dominant taxa in the microbialites, and possessed novel functional guilds associated with the metabolism of heavy metals, antibiotic resistance, primary alcohol biosynthesis and urea metabolism; the latter may help drive biomineralization. Urea metabolism within Pavilion Lake microbialites is a feature not previously associated in other microbialites. The microbialite communities were also significantly enriched for cyanobacteria and acidobacteria, which likely play an important role in biomineralization. Additional findings suggest that Pavilion Lake microbialites are under viral selection as genes associated with viral infection (e.g CRISPR-Cas, phage shock and phage excision) are abundant within the microbialite metagenomes. The morphology of Pavilion Lake microbialites changes dramatically with depth; yet, metagenomic data did not vary significantly by morphology or depth, indicating that microbialite morphology is altered by other factors, perhaps transcriptional differences or abiotic conditions. This work provides a comprehensive metagenomic perspective of the interactions and differences between microbialites and their surrounding environment, and reveals the distinct nature of these complex communities.

Modern microbialites are complex microbial communities that interface with abiotic factors to form carbonate-rich organosedimentary structures whose ancestors provide the earliest evidence of life. Past studies primarily on marine microbialites have inventoried diverse taxa and metabolic pathways, but it is unclear which of these are members of the microbialite community and which are introduced from adjacent environments. Here we control for these factors by sampling the surrounding water and nearby sediment, in addition to the microbialites and use a metagenomics approach to interrogate the microbial community. Our findings suggest that the Pavilion Lake microbialite community profile, metabolic potential and pathway distributions are distinct from those in the neighboring sediments and water. Based on RefSeq classification, members of the Proteobacteria (e.g., alpha and delta classes) were the dominant taxa in the microbialites, and possessed novel functional guilds associated with the metabolism of heavy metals, antibiotic resistance, primary alcohol biosynthesis and urea metabolism; the latter may help drive biomineralization. Urea metabolism within Pavilion Lake microbialites is a feature not previously associated in other microbialites. The microbialite communities were also significantly enriched for cyanobacteria and acidobacteria, which likely play an important role in biomineralization. Additional findings suggest that Pavilion Lake microbialites are under viral selection as genes associated with viral infection (e.g CRISPR-Cas, phage shock and phage excision) are abundant within the microbialite metagenomes. The morphology of Pavilion Lake microbialites changes dramatically with depth; yet, metagenomic data did not vary significantly by morphology or depth, indicating that microbialite morphology is altered by other factors, perhaps transcriptional differences or abiotic conditions. This work provides a comprehensive metagenomic perspective of the interactions and differences between microbialites and their surrounding environment, and reveals the distinct nature of these complex communities.

This collection presents some of the most widely used methodological approaches for isolation and purification of bacteriophages and cyanophages, the first step in detailed studies of virus–host interactions and viral genetic composition, and discusses the applications and limitations of different isolation procedures. Most work on phage isolation has been carried out with aerobic heterotrophic bacteria and cyanobacteria, culturable both on agar plates and in enriched liquid cultures. The procedures presented here are limited to lytic viruses infecting such hosts. In addition to the isolation procedures, methods for life cycle characterization (one-step growth experiments) of bacteriophages and cyanophages are described.

For use in "One-step growth experiments (cyanophages)"

Several methods have been presented by Adams (1959) to determine adsorption kinetics of bacteriophages. One way to measure the adsorption efficiency of cyanophages is to assay for free unadsorbed phages (Suttle and Chan 1993). The principle of this assay is to add a known quantity of viruses to host cells (e.g., at an MOI = 0.01 to 0.1). Over a period of 1 to 2 h, small subsamples of the virus:host solution are removed ca. every 15 min and diluted 100-fold to stop further adsorption. The host is then separated from free viruses by centrifugation, and the number of free viruses remaining in the supernatant determined by plaque or end-point dilution assays. A plot of the abundance of free viruses remaining in solution as a function of time should produce a straight line. The slope of this line is then used to calculate the adsorption rate. This procedure can be adapted for other host–virus systems. The example given is for host BBC1 and cyanophage BBC1-P1 (Suttle and Chan 1993).

For use in "Isolation of cyanophages by liquid enrichment assay"

For use in "Obtaining pure cyanophage stock: plaque purification"

For use in "Obtaining pure cyanophage stock: plaque purification"

For use in "Isolation of cyanophages by plaque assyays"

For use in "Obtaining pure cyanophage stocks (liquid assay)"

For use in "Obtaining pure cyanophage stocks (liquid assay)"

For use in "Isolation of cyanophages by plaque assays"

More than 40 years ago, Safferman and Morris (1963) used the plaque assay method to isolate the first cyanophage that infects a freshwater filamentous cyanobacterium, Plectonema boryanum. Since then, this approach has been used successfully to detect and isolate a number of different phages infecting marine Synechoccocus and Prochlorococcus (e.g., Suttle and Chan 1993; Waterbury and Valois 1993; Wilson et al. 1993; Sullivan et al. 2003). The advantages of this method are that results are easily interpreted as plaques formed on pigmented lawns can be easily identified. Since a plaque is the result of a single infection event, the virus can be easily purified and cloned.The first part of the procedures described as follows: (1) preparation of base plates and (2) preparation of top agar/agarose are applicable also for bacteriophage plaque assays.

For use in "Isolation of cyanophages by liquid bioassays"

Multiwell plates are convenient for isolating cyanophages from environmental samples using the liquid bioassay approach (Table 1). This protocol describesa typical procedure (96-well assay) used to detect and isolate cyanophages from marine samples that lyses Synechococcus sp. strain DC2 (also known as CCMP1334 or WH7803). Using this method, greater than 105 lytic phages per milliliter of seawater have been detected in the Gulf of Mexico (Suttle and Chan 1994) that lyses this permissive target host.

For use in "Isolation of cyanophages by plaque assays"

Another convenient way to screen larger sample volumes is to perform liquid enrichment cultures (Suttle 1993). By this approach, larger volumes of water samples can be screened for cyanophages, thus enabling detection of “rare” viruses. Similar to the use of enrichment cultures for bacteriophages, the disadvantages include the fact that lysis of the host cells are not always obvious, especially if the initial titer is low or if the host culture is not clonal or unialgal.

Phage lysis of host bacteria can be visualized by plaque formation on lawns of host cells in soft agar overlayed on agar plates (Adams, 1959; Sambrook et al. 1989). This principle can be used for the detection and subsequent isolation of specific lytic phages in environmental samples (e.g., Carlson 2005). Spotting environmental samples on lawns of a target host cell would thus reveal the presence of a lytic phage for that particular host cell in the given sample.

Clearing zones on lawns of host bacteria potentially contain all lytic phages against the given host that were present in the original water sample. Little is still known about the occurrence and diversity of phages infecting specific hosts, but generally isolation procedures as those described above may reveal multiple phages against specific target bacteria (e.g., Comeau et al. 2006; Holmfeldt et al. 2007; Stenholm et al. 2008). It is therefore necessary to further isolate the phages to obtain specific stocks of single phages.

A generally more efficient way of isolating lytic phages from marine environments is by the use of enrichment cultures. In this approach, the prefiltered water sample that is to be screened for phages against a given target bacterium, is enriched with a bacterial growth medium and amended with that target bacteria (Eisenstark 1967; Carlson 2005). This allows any lytic phages present in the sample to infect the target bacteria and propagate in the cultures, and subsequently, be isolated and purified. The two main advantages of the enrichment approach are 1) that it allows for screening for phages in a much larger volume of sample (typically 25–50 mL, rather than 5–10 µL), thus increasing the probability of isolating rare phages, and 2) that it allows the combination of different target hosts (e.g., different strains of a specific bacteria of interest) in the same incubation, again increasing the possibility of phage isolation.

The distribution and chemical form of iron in marine environments is of particular interest to oceanographers because of its effect on primary productivity. The high abundance of viruses in the ocean and their small size suggest that they might serve as nucleation centers for iron adsorption and precipitation in the ocean. Hence, we performed laboratory experiments to quantify the adsorption and precipitation of iron by a marine bacteriophage (PWH3a-P1). Acid–base titrations and zeta potential measurements were performed to determine if the virus interacted with protons, and if so, to determine the type, concentration, and reactivity of functional groups present on the viruses. Iron precipitation experiments were conducted to investigate interactions between iron and the viruses. The titrations and zeta potential measurements were well described by a model considering two types of reactive sites on the viruses, with log K values of � 4.44 and � 8.18, and a total site concentration of 3.64� 10 � 18 mol per virus. High-magnification observations of the viruses in the presence of iron by whole-mount transmission electron microscopy showed evidence of both adsorption and mineral nucleation. The experimental results clearly demonstrate the potential of marine bacteriophage to serve as nuclei for iron adsorption and precipitation, and the models developed from the data suggest that viruses might represent a significant reservoir of iron in seawater. However, these experiments utilized greatly simplified chemistry and a limited range of iron-to-virus concentration ratios relative to natural seawater, and so the results of this study do not prove that viruses affect the marine iron cycle, but rather serve to justify continued research into iron–virus interactions, in the laboratory and in the field. D 2004 Elsevier B.V. All rights reserved.

HaRNAV, a novel virus that infects the toxic bloomforming alga Heterosigma akashiwo (Hada) Hada ex Hada et Chihara, was characterized based on morphology, pathology, nucleic acid type, structural proteins, and the range of host strains that it infects. HaRNAV is a 25-nm single-stranded RNA (ssRNA) virus with a genome size of approximately 9100 nucleotides. This is the first report of an ssRNA virus that causes lysis of a phytoplankton species. The virus particle is sensitive to chloroform and contains at least five structural proteins ranging in apparent size from 24 to 34 kDa. HaRNAV infection causes swelling of the endoplasmic reticulum and progeny virus particles assemble in the cytoplasm of the host, frequently in crystalline arrays. The infectivity of HaRNAV was tested against 15 strains of H. akashiwo isolated from Japanese waters, the Northeast Pacific, and the Northwest Atlantic. HaRNAV caused lysis of three strains from the Northeast Pacific and two strains from Japan but none from the Northwest Atlantic. The characterization of HaRNAV demonstrates that HaRNAV is a novel type of phytoplankton virus but has some similarities with plant viruses belonging to the Sequiviridae and to other known ssRNA viruses. Further genomic analysis, however, is necessary to determine any phylogenetic relationships. The discovery of HaRNAV emphasizes the diversity of H. akashiwo viral pathogens and, more importantly, algal‐virus pathogens and the complexity of virus‐host interactions in the environment.