The family Kitaviridae comprises plant-infecting viruses with segmented, positive-sense (+), ssRNA genomes, most of which are polyadenylated at the 3'-end. Members are classified into different genera based on their genome organization. Virions are short bacilliform, ellipsoidal or quasi-spherical and, in some species, enveloped. Transmission occurs via Brevipalpus mites (for members of the genera Cilevirus and Higrevirus) or eriophyid mites (for some members of the genus Blunervirus). Infections are typically localized due to the lack of or inefficient systemic viral movement. Kitavirids cause economically important plant diseases, including citrus leprosis. Phylogenetically, kitavirids are closely related to unclassified arthropod-infecting viruses. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the family Kitaviridae, which is available at ictv.global/report/kitaviridae.

The genus Ovobates (Oribatida, Oribatulidae) comprises two species distributed in the Oriental region. A new species-Ovobates ochrocarpicussp. nov.-is described, based on adult and nymphal instars, collected from branches of the ochrocarp tree in southern Vietnam. The adult of the new species is characterized by the presence of the five pairs of notogastral porose areas and the epimeral formula 3-1-3-3. The nymphs of the new species are characterized by presence of clavate bothridial seta; setiform interlamellar seta; short, setiform, thin gastronotic setae c1, c2, da, la; medium-sized to long, setiform, gastronotic setae dm c3, lm, p2, and p3; medium-sized, bacilliform gastronotic setae dp, h1, and h3; long, subflagellate, gastronotic setae lp, h2, and p1; epimeral formula 3-1-2-2 in tritonymph; and seven setae on the leg tarsus IV in protonymph. The generic diagnosis and a morphological comparison of adults and juvenile instars of the known species of Ovobates are presented.

The family Rhabdoviridae comprises viruses with unsegmented, bi-segmented or tri-segmented negative-sense (-) RNA genomes of 10-16 kb. Virions are typically enveloped, with bullet-shaped or bacilliform morphology, but can also be non-enveloped filaments. Rhabdoviruses infect plants or animals, including vertebrates or invertebrates such as arthropods, which can serve as single hosts or act as biological vectors for transmission to animals or plants. Rhabdoviruses include important pathogens of humans, livestock, fish or agricultural crops. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the family Rhabdoviridae, which is available at ictv.global/report/rhabdoviridae.

Influenza A viruses (IAV) are clinically important pathogens that cause seasonal epidemics and pandemics in humans. IAV produce pleomorphic, enveloped virions, which can range from a spherical or bacilliform morphology, the predominant form in the most commonly studied laboratory strains, to long filamentous virions which are characteristic of clinical and veterinary isolates. Understanding the structure and function of filamentous virions is crucial for clarifying their role in viral persistence and immune evasion, and for informing the development of therapeutics that target their entry and/or egress pathways. Structural characterisation of influenza virions is challenging however owing to their fragility, heterogeneity and compared to most virus particles, unusually large size. Here, we combined structural and compositional approaches with integrative modelling to define the complete molecular architecture of influenza virions. In doing so we provide the first description of distinctive structural features of IAV filaments, including the selective incorporation of lipids, specific enrichment of viral and host proteins, and a viral cytoskeleton including a secondary helical layer within the viral capsid and extended fibrils of cofilactin. Collectively our findings suggest an important regulatory role for cofilactin in driving filament morphogenesis and provide important insights into the organisation and composition of IAV filamentous virions.

Viruses are the most pervasive biological entities on Earth and they profoundly shape host ecology and evolution. However, for many microbial lineages, knowledge of their viromes remains limited, especially for those inhabiting remote environments, including deep-sea ecosystems. Here, we leverage one of the most extensively cultivated and genomically characterized archaeal lineages, the Thermococcales, to identify novel viral genomes. By utilizing CRISPR spacers from isolates and spacer arrays reconstructed from metagenomes, we mined mobile genetic elements (MGEs) in 1,172 publicly available and newly sequenced hydrothermal vent metagenomic datasets. Comparative genomics and identification of viral hallmark proteins revealed 620 viral genomes across 19 taxonomic families, most of which were previously undescribed. Structural modeling of major capsid proteins (MCPs) revealed diverse virion morphotypes, including viruses with spindle-shaped, head-tailed, icosahedral, filamentous, ovoid and bacilliform virions, greatly expanding the previously limited Thermococcales virome. Family-level comparisons uncovered extensive flux of virus-encoded replication proteins that are evolutionarily and structurally distinct from host homologs, as well as dramatic variation in glycan-binding lectins suggestive of diverse infection strategies. Together, our results substantially broaden the Thermococcales virosphere and demonstrate the power of combining cultivated isolates with culture-independent, CRISPR-guided metagenomics to interrogate archaeal virus diversity and evolution.

Yam (Dioscorea spp.) is a major staple food, contributing significantly to food security and income generation for millions of people worldwide. In 2019, surveys were conducted across the seven agro-ecological zones (AEZs) of Côte d'Ivoire, the third highest producer of yam globally, to ascertain the current status of viral diseases. In the 324 fields surveyed, a total of 1242 yam leaf samples were collected and tested for the presence of Potyvirus yamtesselati (yam mosaic virus, YMV), Potyvirus yamplacidum (yam mild mosaic virus, YMMV), Cucumovirus CMV (cucumber mosaic virus, CMV), and the badnaviruses using PCR, RT-PCR, and RCA followed by Sanger or MinION sequencing. The incidence of yam viral disease varied across the AEZs, with the lowest mean incidence observed in yam farms within the AEZ VII (71.95%) and the highest in AEZ V (88.15%). Viral disease symptom severity was moderate across the country, with more severe symptoms identified in AEZs II and VI. The virus screening revealed a potyvirus detection rate of 35.83% in all the AEZs. YMMV infection (25.12%) is the most prevalent in the samples, followed by YMV infection (15.61%). RCA-MinION sequencing revealed the presence of badnaviruses belonging to the T15 episomal groups K8, K9, and K5. Also, the use of this technique enabled the amplification and sequencing of four full-length episomal badnaviruses, namely Dioscorea bacilliform AL virus in group K8 and Dioscorea bacilliform RT virus in group K5. CMV was not detected in all the samples. It is noteworthy that 22.13% of mixed infections were detected in asymptomatic samples. This study revealed the first occurrence of YMMV in all the AEZs of Côte d'Ivoire. Of the yam species, Dioscorea alata was more widespread (78.03%) than Dioscorea cayenensis-rotundata (21.92%) in the visited fields. Also, D. alata had a highest incidence of YMMV (23.67%) infection than Dioscorea cayenensis-rotundata, while D. cayenensis-rotundata registered the highest incidence of YMV (15.84%) infection compared to D. alata. Phylogenetic analysis of representative of the various viruses detected in the country revealed that the sequences have high diversity for each virus species. This study revealed that viruses infecting yam are widespread and occur in mixed infection, which poses a real threat to yam production in Côte d'Ivoire.

The family Caulimoviridae comprises plant-infecting pararetroviruses that replicate by reverse transcription and encapsidate a circular double-stranded DNA genome. They can occur as episomal (encapsidated and replicative forms) and endogenous forms integrated into the host genome. Some endogenous sequences can give rise to episomal forms. In this study, we report and characterize a new badnavirus infecting Pelargonium × hortorum. We propose the name Pelargonium vein banding virus (PVBV). The episomal genome is 7,586 bp in length. Endogenous PVBV (ePVBV) DNA was identified in healthy plants and characterized. Southern blotting and PCR suggest that in many cultivars, the ePVBV consists of a tandem array of the complete PVBV genome. The ePVBV tandem array was not detected in 'Maverick White'. The major parents of P. × hortorum hybrids are P. zonale and P. inquinans. P. zonale contained ePVBV, but P. inquinans did not. The sequence of ePVBV recovered from the cultivar 'BullsEye Salmon' was >99% identical to the episomal sequence. Agroinoculation experiments demonstrated that ePVBV is infectious. Bacilliform-shaped virions with a modal particle length of 144 nm and 33 nm in diameter were recovered from leaves of agroinfected Maverick White exhibiting mosaic symptoms and chlorosis surrounding the veins. P. zonale and P. × hortorum varieties with full ePVBV genomes were not infected. Interestingly, P. inquinans, which does not contain ePVBV, was also not infected.

Nucleorhabdoviruses, classified into four distinct genera within the family Rhabdoviridae (subfamily Betarhabdovirinae), are plant-infecting viruses, characterized by nucleus-associated, enveloped, bacilliform virions. Nucleorhabdoviruses possess an unsegmented, single-stranded, negative-sense RNA genome (ca. 12-15.2 kb) that encodes six to eight proteins. Here, by exploring large publicly available metatranscriptomics datasets, we report the identification and genomic characterization of 47 novel viruses with genetic and evolutionary hallmarks of nucleorhabdoviruses. These viruses are associated with 45 distinct host plant species and were previously hidden in public database. Our findings significantly broaden the known host range of nucleorhabdoviruses, including the first nucleorhabdovirus associated with ferns and the first gammanucleorhabdoviruses linked to dicot hosts. Genetic divergence and evolutionary analyses suggest that all these novel viruses likely represent members of novel species. Phylogenetic reconstruction indicates that ten novel viruses are related to alphanucleorhabdoviruses, 25 to betanucleorhabdoviruses, eight to deltanucleorhabdoviruses and four to gammanucleorhabdoviruses. This study constitutes the final chapter in a trilogy chronicling a data mining expedition into the cryptic diversity of plant-associated rhabdoviruses, a journey that began with varicosaviruses and continued with cytorhabdoviruses. These new findings yield the most comprehensive phylogeny of nucleorhabdoviruses to date, significantly expanding our genomic understanding and illuminating the phylogenetic relationships and evolutionary dynamics of this virus group. Further, this work underscores the value of large-scale sequence data mining in advancing our understanding of the hidden world of plant rhabdoviruses.

SUMMARYPleomorphism in influenza viruses, characterized by diverse morphological forms ranging from spherical virions to elongated filaments, has been suggested to present significant implications for pathogenesis. This review examines the role of pleomorphism on the influenza virus life cycle, encompassing viral attachment and entry, replication, assembly, and budding, as well as transmission dynamics. It explores the determinants' underlying morphological variability in virions and their impact on viral fitness and host interactions. Insights into how pleomorphic forms of the virus influence disease severity and the efficacy of antivirals are discussed. Understanding the implications of pleomorphism in influenza virus pathogenesis is crucial for the development of effective disease prevention, control, and treatment strategies.

Bromoviridae is a family of plant viruses with tripartite, positive-sense RNA genomes of about 8 kb in total. Genomic RNAs are packaged in separate virions that may also contain sub-genomic, defective or satellite RNAs. Virions are variable in morphology (spherical or bacilliform) and may be transmitted between hosts mechanically, via pollen, or non-persistently by insect vectors. Members of the family are responsible for major disease epidemics in fruit, vegetable and fodder crops such as tomatoes, cucurbits, bananas, fruit trees, common beans and alfalfa. Since the adoption of metagenomic high-throughput sequencing methodologies, there has been a notable increase in the number of species in the genus Ilarvirus. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the family Bromoviridae, which is available at ictv.global/report/bromoviridae.

Nanomedicines have been widely used in colorectal cancer treatment, but their suboptimal targeting and deficient penetration capabilities remain obstacles in the delivery of therapeutics. In this study, inspired by the natural tumor tropism and intestinal invasion of Salmonella, we engineered highly biomimetic nanoparticles (SM-AuNRs) utilizing a Salmonella membrane to coat bacilliform Au nanorods. The engineered SM-AuNRs were able to mimic the germ's morphology and biological surface. SM-AuNRs containing the specific proteins inherited from the Salmonella membrane facilitated specific targeting and internalization into tumor cells. Meanwhile, SM-AuNRs with the rod-shaped morphology effectively traversed mucus barriers and tumor stroma. Due to the superior biological barrier penetrating and tumor targeting capabilities, doxorubicin-loaded SM-AuNRs with near-infrared laser irradiation displayed remarkable photothermal-chemotherapeutic antitumor effects in mouse orthotopic colorectal cancer models. Our findings pave the way for the design of bacteria-mimicking nanoparticles, presenting a promising avenue for the targeting and efficient treatment of colorectal cancer.

The confused gene expressions and molecular mechanisms for mitochondrial dysfunction of traditional nanoenzymes is a challenge for tumor therapy. Herein, a nano-bacilliform-enzyme obtains the ability to inhibit p52-ZER6 signal pathway, regulate the genes related to mitochondrial metabolism, and possess the GOx/CAT/POD-like property. NBE acquires catalytic activity from the electronic energy transition. The tannin of NBE as a mitochondrial (Mito)-targeting guide overloads MitoROS, and then metabolic disorder and lipid peroxidation of Mito membrane occurs, thus leading to a novel death pathway called PAFerroptosis (pyroptosis, apoptosis, and Ferroptosis). Simultaneously, in order to refrain from mitophagy, hydroxychloroquine is mixed with NBE to form a combo with strength pyroptosis. As a result, NBE/combo improves the PAFerroptosis obviously by activation of CD8+T cells and inactivation of MDSC cells, up-regulating expression of caspase-3 signal pathway, intercepting DHODH pathway to arrive excellent antitumor effect (93%). Therefore, this study establishes a rational nanoenzyme for mitochondrial dysfunction without mitophagy for effective antitumor therapy.

Promoters are one of the most important components for many gene-based research as they can fine-tune precise gene expression. Many unique plant promoters have been characterized, but strong promoters with dual expression in both monocot and dicot systems are still lacking. In this study, we attempted to make such a promoter by combining specific domains from monocot-infecting pararetroviral-based promoters sugarcane bacilliform virus (SCBV) and banana streak virus (BSV) to a strong dicot-infecting pararetroviral-based promoter mirabilis mosaic virus (MMV). The generated chimeric promoters, MS, SM, MB, and BM, were tested in monocot and dicot systems and further validated in transgenic tobacco plants. We found that the developed chimeric promoters were species-specific (monocot or dicot), which depended on their respective core promoter (CP) region. Furthermore, with this knowledge, deletion-hybrid promoters were developed and evaluated, which led to the development of a unique dual-expressing promoter, MSD3, with high gene expression efficiency (GUS and GFP reporter genes) in rice, pearl millet, and tobacco plants. We conclude that the MSD3 promoter can be an important genetic tool and will be valuable in plant biology research and application.

The genome of a new member of the Nimaviridae family has been sequenced. The Chionoecetes bairdi bacilliform virus (CbBV) causes Milky Hemolymph Syndrome (MHS) in Chionoecetes bairdi populations of the Pacific coast of Kamchatka. The CbBV genome is represented by double-stranded DNA with a length of 245,567 nucleotides containing 120 ORFs. Of these, 85 proteins had significant matches in the NCBI database, and 57 genes encoded capsid, envelope, tegument and nonstructural proteins. Comparative analysis of the genomes of CbBV and a number of representatives of the class nuclear arthropod large DNA viruses (NALDVs) made it possible to isolate 49 evolutionarily conserved orthologue core genes. Among them, 5 were multicopy genes, and 44 were single-copy genes. There were ancestral genes characteristic of all Naldaviricetes - per os infectivity complex genes, one DNA polymerase gene and one thymidylate synthase gene. Phylogenetic analysis of representatives of the Nimaviridae family revealed that the CbBV and Chionoecetes opilio bacilliform virus (CoBV) form an independent clade within the family separate from the clade containing WSSV strains. This is supported by data on the order and arrangement of genes in the genomes of nimaviruses that were identical within each clade but differed between them. In addition, a high identity of the genomes and proteomes of CbBV and CoBV (approximately 99%) was shown, and their identity with WSSV strains was no more than 33%. The data on the structure of the genome of the new virus that causes MHS in C. bairdi indicate that it belongs to the family Nimaviridae, genus Whispovirus. Thus, the CbBV infecting the commercially important species of Tanner crab in populations of the Pacific coast of Kamchatka is the second "wild" representative of replicating nimaviruses whose genome has been characterized after the CoBV that causes MHS in C. opilio in populations of the Sea of Japan. The discovery of a new member of the family that infects decapods indicates the prevalence of nimaviruses in marine ecosystems. The information obtained is important for understanding the evolution of representatives of the class of nuclear arthropod large DNA viruses. The discovery of a new nimavirus that causes MHS in Chionoecetes crabs, in contrast to the white spot syndrome (WSS) caused by WSSV strains, makes it relevant to identify two variants and possibly species within the family, namely, WSSV and Milky Hemolymph Syndrome virus (MHSV).

Phloem-specific promoter efficiently triggers graft-transmissible RNA interference (gtRNAi). We leveraged a phloem-specific promoter derived from the Rice tungro bacilliform virus, optimizing the RNAi mechanism's efficiency and specificity. Here, we detail the construction of phloem-specific promoter-based gtRNAi system and its application through grafting experiments, demonstrating its effectiveness in inducing tomato yellow leaf curl Thailand virus (TYLCHTV) resistance in non-transgenic scions. This strategy presents a practical application for protecting crops against viruses without genetically modifying the entire plant.