The research, led by Xuan Dong of the Yellow Sea Fisheries Research Institute at the Chinese Academy of Fishery Sciences together with Weifeng Shi of Shanghai Jiao Tong University School of Medicine and a large international team, drew on an unusually rich collection of 403 samples gathered over six years, from 2019 through 2024. Sampling spanned a remarkable geographic range: the seas near the Antarctic Peninsula and the South Shetland Islands, the South Orkney Islands, and South Georgia Island in Western Antarctica, along with the Cosmonauts Sea in Eastern Antarctica. Specimens were collected with the assistance of the crews of the research icebreakers Xuelong and Xuelong 2 and scientific observers working with the Chinese krill fishery, an arrangement that allowed the team to reach remote waters across multiple seasons.

Technically, the study relied on metatranscriptomic sequencing, an approach that captures the total RNA present in a sample rather than targeting a single gene or organism. Because RNA viruses must replicate through RNA intermediates, sequencing the transcriptomes of host tissues and associated microbes simultaneously surfaces viral genomes that would be missed by DNA-based methods. The team screened the resulting data using RdRp-scan, a pipeline built around hidden Markov model profiles that detect the RNA-dependent RNA polymerase, the hallmark enzyme conserved across RNA virus lineages. Candidates passing initial screening were then subjected to increasingly conservative validation criteria, including DIAMOND-based similarity searches, to distinguish genuine viral polymerases from cellular genes or sequencing artifacts. This two-tier strategy, combining a sensitive discovery scan with a stringent confirmation analysis, allowed the researchers to characterize both complete viral genomes and highly fragmented sequences that hint at even more diversity lurking in the data.

The viral inventory that emerged was dominated by positive-sense single-stranded RNA viruses, with 37 representatives, a group that includes many of the most familiar virus families infecting animals and plants. Sixteen double-stranded RNA viruses and five negative-sense single-stranded RNA viruses rounded out the collection. Among the named discoveries were Lawrence virus and Vespucci virus, along with a member of the Picornaviridae, a family that includes poliovirus and foot-and-mouth disease virus among its terrestrial relatives. The sheer proportion of novel agents underscores how little is known about viral life in polar ecosystems, where cold, ice-covered waters and isolated food webs may have fostered long, independent evolutionary histories for their microbial inhabitants.

To understand how these viral communities are organized, the researchers applied alpha and beta diversity analyses, standard ecological tools for measuring within-sample richness and between-sample compositional differences. The alpha diversity comparisons, whether based on RdRp-scan results or the more stringent dataset, showed no statistically significant differences in viral richness or Shannon diversity across host species or sampling locations, with one-way ANOVA yielding p-values above 0.05 in every comparison. In other words, no single host or site carried a categorically richer virome than another. Beta diversity told a different story: the composition of viral communities differed significantly among host species, indicating that host identity, not geography, is the dominant force structuring which viruses live where. The authors note that the influence of geographic location on virome composition warrants further study, particularly given the wide and seasonally variable sampling range.

The most consequential finding, however, came from comparing viral sequences across the Antarctic food web. The team detected near-identical strains of Lawrence virus, sharing 99.35 percent identity in the RNA-dependent RNA polymerase gene, in both Antarctic krill and their predators. Vespucci virus strains found in krill and fish shared 97.70 to 99.08 percent RdRp identity with sequences from the same predators, and a picornavirus showed a similar pattern. The predators in question were the chinstrap penguin, Pygoscelis antarcticus, and the Antarctic fur seal, Arctocephalus gazella, two species that feed heavily on krill and fish in the Southern Ocean. Such high sequence identity between viruses found in prey and their consumers is suggestive of cross-species transmission moving up the food chain, although the authors are careful to frame this as a potential route rather than a proven one.

Antarctic krill, Euphausia superba, sit at the center of this transmission story for good reason. The shrimp-like crustacean is among the most abundant animals on the planet by biomass and forms the dietary backbone for penguins, seals, whales, and countless fish species. Any virus capable of persisting in krill populations has, in principle, a ready-made vehicle for reaching a wide range of vertebrate hosts through predation. The near-identical viral sequences in krill, fish, penguins, and fur seals provide the first genomic evidence that this trophic pathway may carry RNA viruses between distantly related animals in the Southern Ocean, a dynamic that has been hypothesized for other ecosystems but rarely documented in polar waters.

Beyond its ecological implications, the study carries practical weight for biosecurity. Warming temperatures and expanding human activity, from tourism to fisheries to scientific operations, are increasing the movement of people, equipment, and potentially pathogens into and out of the Antarctic. At the same time, shifting sea ice and changing prey distributions may alter contact patterns among wildlife species, creating new opportunities for viral exchange. The authors position their dataset as an essential baseline for assessing these risks, arguing that understanding which viruses currently circulate in Antarctic aquatic animals is a prerequisite for detecting any future incursions or range expansions. The evolutionary adaptability of RNA viruses, whose high mutation rates allow rapid adjustment to new hosts and conditions, makes this baseline all the more urgent to establish.

The work also demonstrates how modern genomic surveillance can be extended to environments where traditional virology has struggled to gain a foothold. Cold-chain logistics, remote fieldwork, and the difficulty of culturing polar pathogens have long limited virus discovery in Antarctica, but metatranscriptomics sidesteps many of these barriers by reading viral genetic material directly from field samples. The detection of 160 distinct RNA-dependent RNA polymerase groups in the broader screening analysis, many of them recurring across multiple libraries, suggests that the 58 fully characterized viruses represent only a portion of the diversity present. As sequencing costs continue to fall and reference databases expand, similar surveys in other polar and deep-sea ecosystems are likely to reveal comparable hidden reservoirs.

For now, the study stands as a reminder that even the planet’s most isolated continent is not virologically empty. Its waters host a diverse and largely novel array of RNA viruses, shaped primarily by the hosts they infect and connected to top predators through the food they eat. Whether any of these agents pose risks to wildlife health, fisheries, or human activity remains an open question, but the answer will depend on the kind of systematic, multi-year surveillance this research exemplifies. With the Southern Ocean changing faster than almost any marine environment on Earth, cataloging its viral inhabitants before the ecosystem shifts further may prove to be one of the most time-sensitive tasks in polar science.

Subject of Research: Diversity and food-web transmission of RNA viruses in Antarctic aquatic animals

Article Title: Underexplored diversity and transmission of RNA viruses in Antarctic aquatic animals

Article References: Dong, X., Zhou, Q., Luo, J., Su, Q., Wang, X., Zhu, J., Fan, G., Zhang, J., Ying, Y., Zhao, Y., Liu, L., Xu, Q., Liu, S., Wang, X., Li, J., Li, C., Yan, Y., Meng, F., Li, X., … Shi, W. (2026). Underexplored diversity and transmission of RNA viruses in Antarctic aquatic animals. Microbiome. https://doi.org/10.1186/s40168-026-02544-0

Image Credits: AI Generated

DOI: 10.1186/s40168-026-02544-0

Keywords: Antarctica, RNA viruses, virome, metatranscriptomics, Antarctic krill, chinstrap penguin, Antarctic fur seal, viral transmission, virus discovery, Southern Ocean, biodiversity, biosecurity

The new assay, described in Plant Cell Reports, relies on LwaCas13a, a type VI CRISPR effector protein originally harnessed for human pathogen detection in the SHERLOCK platform. Unlike Cas9 or Cas12, Cas13 targets RNA rather than DNA and does not require a protospacer adjacent motif, which simplifies guide design considerably. Once the protein’s CRISPR RNA guide finds a complementary viral sequence, the enzyme undergoes a conformational change that unleashes indiscriminate collateral cleavage of nearby single-stranded RNA. The researchers exploit this behavior with a fluorescent reporter oligonucleotide carrying a FAM fluorophore on one end and a quencher on the other; cleavage separates the two molecules, producing a measurable rise in fluorescence that signals a positive detection.

To build the test, the team obtained sequence data for all three viruses from the USDA-APHIS Plant Germplasm Quarantine Program in Maryland and aligned the genomes using the MUSCLE algorithm in Geneious Prime software. They designed five candidate 28-nucleotide crRNA target sites for each virus and screened every candidate against the NCBI BLAST database to rule out off-target matches to related viruses, host plant genetic material, or other organisms associated with sugarcane production. The reverse complements of the selected sites were appended to the LwaCas13a direct repeat sequence to generate functional guide RNAs, which were then synthesized commercially.

Because working with quarantine pathogens requires specialized containment, the team first validated the assay using synthetic pseudo-virus targets. They embedded the five 28-nucleotide target sequences for each virus into 700-base-pair synthetic DNA constructs separated by scrambled sequences, placed under a T7 promoter, and produced single-stranded RNA by in vitro transcription. Serial log dilutions of these RNA targets established the limit of detection, which varied among target sites but reached approximately 1.5 picomolar at its best. The top-performing guides were site 5 on ScMV, site 3 on ScSMV, and site 1 on ScYLV. The authors note that this sensitivity represents roughly a tenfold improvement over a recent report of amplification-free Cas13 detection of plant viruses, although they caution that the intrinsic enzyme kinetics of Cas13 still limit how low the detection floor can go without pre-amplification.

A key feature of the platform is its multiplexing capacity. In a cross-reactivity matrix, the researchers combined every pseudo-virus target with every crRNA and found that fluorescence rose only when a viral target matched its corresponding guide, with matched wells producing relative fluorescence units between roughly 39,000 and 60,000 compared with 4,500 to 8,100 for mismatched combinations. Strikingly, after just 15 to 20 minutes the fluorescent signal was strong enough to be visible with a standard gel documentation reader, an instrument not designed for such measurements. This strict specificity means a single microplate can screen a sample for any of the three viruses in one multiplexed well while simultaneously running simplex wells for each virus individually, yielding both detection and genotyping in one run.

The decisive test came with real plant material. Working inside the USDA-APHIS quarantine facility, the team extracted bulk RNA from infected sugarcane and sorghum plants—sorghum serving as an alternative host for ScMV—using the same commercial kit employed by the agency’s own diagnosticians. They first benchmarked the samples with five conventional RT-PCR protocols, including genus-level potyvirus assays and two separate primer sets for ScYLV that exist because of that virus’s considerable genetic diversity. The CRISPR assay then processed the same extracts directly, with no dilution and no cDNA synthesis step, reading fluorescence over a two-hour run at 37 degrees Celsius.

The two methods broadly agreed, but the discrepancies proved illuminating. A sorghum sample called Rio tested positive in the generic Potyvirus RT-PCR protocols, but only the CRISPR assay—and a follow-up sequencing step—could pin the infection specifically on ScMV, since the conventional protocols detect the genus rather than the species. Another sorghum sample, Z1536, produced signals above threshold for all three viruses in the CRISPR assay while remaining negative or ambiguous by RT-PCR, and sugarcane sample Z1502, which showed no RT-PCR bands at all, yielded a clear CRISPR positive for ScYLV. The authors attribute such gaps to several factors: low or seasonally fluctuating viral titers, mutations at primer binding sites that can silence PCR amplification, the added variability of the two-step cDNA-plus-amplification workflow, and possible weak cross-reactivity of the Poty2 primer set with ScSMV observed in sample Z1501.

Beyond speed, the platform offers practical advantages for diagnostic laboratories. The conventional workflow requires five separate RT-PCR protocols, each with cDNA preparation and post-amplification gel electrophoresis, and a skilled technician might need a day or two to fully characterize even one sample. The CRISPR assay completes detection and virus identification in four hours or less for high-titer infections, on a single plate, with fewer handling steps and correspondingly fewer opportunities for contamination. The fluorescence-based readout also provides a semi-quantitative measure of viral load, whereas conventional RT-PCR as performed here is essentially a presence-or-absence test. To guard against false positives from natural degradation of the RNA reporter during the long incubation, the team set a conservative threshold of three standard deviations above the mean of background-subtracted negative control values.

The researchers are candid about the method’s limits. At roughly 1.5 picomolar, the sensitivity may not suffice for very early or light infections, where RT-PCR or an added pre-amplification step would still be needed, and the study was constrained by a limited number of infected samples, leaving more rigorous statistical benchmarking on larger field collections as the obvious next step. Still, because the assay needs only a single conserved target region per virus—rather than the paired primer sites PCR demands—and Cas13 requires no PAM, redesigning guides as viruses evolve is straightforward. The team envisions extending the approach with kinetic barcoding for richer multiplexing, engineered guides for greater specificity, and enhanced collateral cleavage activity, ultimately expanding the panel to many more pathogens and molecular markers.

For an industry in which viruses can account for more than half of yield reduction and global commerce in planting material keeps introducing quarantine pathogens to new regions, a rapid, amplification-free test that names its target within hours could materially change surveillance practice. The authors suggest that, equipped with cold storage and a suitable plate reader, the workflow could even be adapted into field-deployable diagnostics, offering a way to catch outbreaks early enough to contain them before the damage reaches the mill—or the next season’s seed cane.

Subject of Research: Amplification-free CRISPR-Cas13 detection of quarantine-significant sugarcane RNA viruses

Article Title: CRISPR-Cas13-based amplification-free detection of three quarantine-significant sugarcane viruses

Article References: Lagner, J., Paulson, A., Schulden, T., Adhikari, B., Koob, J., Vakulskas, C., & Qi, Y. (2026). CRISPR-Cas13-based amplification-free detection of three quarantine-significant sugarcane viruses. Plant Cell Reports, 45(10), Article 307. https://doi.org/10.1007/s00299-026-03994-4

Image Credits: AI Generated

DOI: 10.1007/s00299-026-03994-4

Keywords: CRISPR-Cas13, LwaCas13a, sugarcane viruses, Sugarcane mosaic virus, Sugarcane streak mosaic virus, Sugarcane yellow leaf virus, plant pathology, molecular diagnostics, amplification-free detection, multiplexed assay, RNA viruses, agricultural biotechnology

The central logic of the host-targeting approach rests on a fundamental constraint of virology. Viruses are genomic minimalists. They carry only a handful of their own proteins and rely extensively on host-cell factors for nearly every step of replication, from translation of viral messages to genome replication, packaging, and assembly. RNA viruses in particular, which include many of the most medically important pathogens such as influenza, SARS-CoV-2, Ebola, dengue, and enteroviruses, depend heavily on the host cell’s RNA-processing infrastructure. Host RNA-binding proteins, which normally regulate messenger RNA splicing, stability, localization, and translation, are among the most frequently co-opted factors. When a virus enters a cell, these proteins are recruited to viral RNA genomes and transcripts, where they perform functions essential to the invader.

This dependence creates what antiviral researchers call a genetic vulnerability. Because the virus cannot easily replace a missing host function with one of its own, a drug that blocks a critical host RNA-binding protein interaction can place the virus in an evolutionary bind. Resistance mutations that arise against direct-acting antivirals, which typically alter the viral target protein so the drug no longer binds, are far harder to evolve against host targets. The host protein remains unchanged, and any viral mutation that restores dependence on the blocked pathway would itself carry a fitness cost. The result, according to the review, is a higher barrier to drug resistance, one of the persistent weaknesses of conventional antiviral development.

The broad-spectrum potential of this strategy is equally significant. Traditional antivirals are narrow: a drug designed to inhibit the influenza neuraminidase does nothing against coronaviruses, and a protease inhibitor for hepatitis C has no effect on Ebola. This narrowness has repeatedly left clinicians without options when new pathogens emerge, as the early months of the COVID-19 pandemic made painfully clear. Host-targeted antivirals, by contrast, could in principle cover many viruses at once. If diverse RNA viruses all require, for example, host proteins involved in RNA cap formation, translation initiation, or RNA granule dynamics, then a single molecule that modulates that shared host pathway could suppress multiple unrelated infections. Such agents could be stockpiled in advance of outbreaks and deployed rapidly against known and unknown threats, a concept increasingly discussed under the umbrella of pandemic preparedness.

The technical challenge, the article acknowledges, is selectivity. Human RNA-binding proteins are not optional accessories; they are central to the biology of every cell. An inhibitor that shut down a host RNA-binding protein globally would be toxic. The most promising targets, therefore, are those for which viral dependence is unusually high or for which the host can tolerate partial inhibition. Some RNA-binding proteins, such as certain members of the heterogeneous nuclear ribonucleoprotein family and the La autoantigen, have known viral interaction surfaces that are structurally distinct from the regions used for normal cellular functions. Drugs that bind to these viral-specific interfaces, or that disrupt the protein-protein contacts between host factors and viral polymerases or nucleocapsids, could in theory block the virus while sparing the host pathway. Structure-based drug design, enabled by high-resolution cryo-electron microscopy and computational modeling, is making such precision interference increasingly feasible.

Recent advances in the RNA biology toolkit have accelerated the identification of candidate targets. Enhanced crosslinking and immunoprecipitation methods now allow researchers to map, at single-nucleotide resolution, which host proteins bind which viral RNAs inside infected cells. Proteomics approaches quantify how the composition of RNA-bound protein complexes shifts during infection. Together, these techniques have generated dense interaction maps that reveal which host RNA-binding contacts are recurrent across viral families and therefore represent the most broadly useful drug targets. The review synthesizes this growing literature to highlight proteins whose perturbation has been shown, in cell culture and in some cases animal models, to impair multiple viruses simultaneously while remaining tolerable to the host cell.

Several concrete examples illustrate the concept’s maturity. Host proteins involved in mRNA capping and methylation are recruited by viruses ranging from coronaviruses to flaviviruses, which either steal or mimic cap structures to ensure their RNAs are translated. Interfering with these host cofactors can block a step the virus cannot perform independently. Similarly, stress granule components and other RNA granule proteins have emerged as double-edged factors: viruses must either suppress or exploit granule formation, and pharmacological modulation of granule dynamics has been shown in multiple studies to restrict infection. RNA-binding proteins that regulate innate immune sensing, such as those controlling the accessibility of viral RNA to pattern-recognition receptors, offer another angle, since modulating them can amplify the cell’s own antiviral response rather than directly inhibiting the virus.

Translation of these findings into approved medicines remains a work in progress, and the review is candid about the obstacles. Host-targeted drugs must clear a higher toxicity bar than direct-acting antivirals, because their targets are present in healthy tissue. Delivery, dose scheduling, and patient selection all require careful optimization. Combination regimens, pairing a host-targeted agent with a traditional direct-acting antiviral, may offer the best of both worlds: the broad coverage and high resistance barrier of host targeting combined with the potency and safety profile of virus-specific inhibition. Such combinations could also be effective against chronic infections, where resistance development during long-term therapy is a persistent clinical problem. The authors point to the success of host-targeted drugs in other fields, including certain oncology therapies, as evidence that drugging host factors is a realistic goal when the biology is well understood.

The strategic case for investing in this area is framed against the backdrop of recurring epidemic threats. RNA viruses continue to spill over from animal reservoirs, and the review argues that a portfolio of broad-spectrum host-targeted antivirals would function as a form of pharmaceutical insurance, providing immediately deployable countermeasures during the critical window before pathogen-specific drugs and vaccines can be developed. The COVID-19 pandemic demonstrated both the speed with which a novel virus can circle the globe and the difficulty of repurposing narrow antivirals against it. Building a validated pipeline of host RNA-binding protein targets, supported by structural biology, chemical biology, and rigorous animal models, is presented as a research priority that could materially change the outcome of the next outbreak.

Subject of Research: Host RNA-binding proteins as broad-spectrum antiviral drug targets

Article Title: Host RNA-binding proteins as broad-spectrum targets for antiviral therapy

Article References: Biswas, S. (2026). Host RNA-binding proteins as broad-spectrum targets for antiviral therapy. npj Viruses. https://doi.org/10.1038/s44298-026-00234-0

Image Credits: AI Generated

DOI: 10.1038/s44298-026-00234-0

Keywords: antiviral therapy, RNA-binding proteins, host-directed antivirals, RNA viruses, broad-spectrum antivirals, drug resistance, virus-host interactions, pandemic preparedness, viral replication, innate immunity, SARS-CoV-2, influenza