Scavengers as Prospective Sentinels of Viral Diversity: the Snowy Sheathbill Virome as a Potential Tool for Monitoring Virus Circulation, Lessons from Two Antarctic Expeditions.

Antarctica is a unique environment due to its extreme meteorological and geological conditions. In addition to this, its relative isolation from human influences has kept it undisturbed. This renders our limited understanding of its fauna and its associated microbial and viral communities a relevant knowledge gap to fill. This includes members of the order Charadriiformes such as snowy sheathbills. They are opportunistic predator/scavenger birds distributed on Antarctic and sub-Antarctic islands that are in frequent contact with other bird and mammal species. This makes them an interesting species for surveillance studies due to their high potential for the acquisition and transport of viruses. In this study, we performed whole-virome and targeted viral surveillance for coronaviruses, paramyxoviruses, and influenza viruses in snowy sheathbills from two locations, the Antarctic Peninsula and South Shetland. Our results suggest the potential role of this species as a sentinel for this region. We highlight the discovery of two human viruses, a member of the genus Sapovirus GII and a gammaherpesvirus, and a virus previously described in marine mammals. Here, we provide insight into a complex ecological picture. These data highlight the surveillance opportunities provided by Antarctic scavenger birds. IMPORTANCE This article describes whole-virome and targeted viral surveillance for coronaviruses, paramyxoviruses, and influenza viruses in snowy sheathbills from the Antarctic Peninsula and South Shetland. Our results suggest an important role of this species as a sentinel for this region. This species' RNA virome showcased a diversity of viruses likely tied to its interactions with assorted Antarctic fauna. We highlight the discovery of two viruses of likely human origin, one with an intestinal impact and another with oncogenic potential. Analysis of this data set detected a variety of viruses tied to various sources (from crustaceans to nonhuman mammals), depicting a complex viral landscape for this scavenger species.

Contact-number-driven virus evolution: A multi-level modeling framework for the evolution of acute or persistent RNA virus infection.

Viruses evolve in infected host populations, and host population dynamics affect viral evolution. RNA viruses with a short duration of infection and a high peak viral load, such as SARS-CoV-2, are maintained in human populations. By contrast, RNA viruses characterized by a long infection duration and a low peak viral load (e.g., borna disease virus) can be maintained in nonhuman populations, and the process of the evolution of persistent viruses has rarely been explored. Here, using a multi-level modeling approach including both individual-level virus infection dynamics and population-scale transmission, we consider virus evolution based on the host environment, specifically, the effect of the contact history of infected hosts. We found that, with a highly dense contact history, viruses with a high virus production rate but low accuracy are likely to be optimal, resulting in a short infectious period with a high peak viral load. In contrast, with a low-density contact history, viral evolution is toward low virus production but high accuracy, resulting in long infection durations with low peak viral load. Our study sheds light on the origin of persistent viruses and why acute viral infections but not persistent virus infection tends to prevail in human society.

Epidemiological inference for emerging viruses using segregating sites.

Epidemiological models are commonly fit to case and pathogen sequence data to estimate parameters and to infer unobserved disease dynamics. Here, we present an inference approach based on sequence data that is well suited for model fitting early on during the expansion of a viral lineage. Our approach relies on a trajectory of segregating sites to infer epidemiological parameters within a Sequential Monte Carlo framework. Using simulated data, we first show that our approach accurately recovers key epidemiological quantities under a single-introduction scenario. We then apply our approach to SARS-CoV-2 sequence data from France, estimating a basic reproduction number of approximately 2.3-2.7 under an epidemiological model that allows for multiple introductions. Our approach presented here indicates that inference approaches that rely on simple population genetic summary statistics can be informative of epidemiological parameters and can be used for reconstructing infectious disease dynamics during the early expansion of a viral lineage.

Biochemistry-informed design selects potent siRNAs against SARS-CoV-2.

RNA interference (RNAi) offers an efficient way to repress genes of interest, and it is widely used in research settings. Clinical applications emerged more recently, with 5 approved siRNAs (the RNA guides of the RNAi effector complex) against human diseases. The development of siRNAs against the SARS-CoV-2 virus could therefore provide the basis of novel COVID-19 treatments, while being easily adaptable to future variants or to other, unrelated viruses. Because the biochemistry of RNAi is very precisely described, it is now possible to design siRNAs with high predicted activity and specificity using only computational tools. While previous siRNA design algorithms tended to rely on simplistic strategies (raising fully complementary siRNAs against targets of interest), our approach uses the most up-to-date mechanistic description of RNAi to allow mismatches at tolerable positions and to force them at beneficial positions, while optimizing siRNA duplex asymmetry. Our pipeline proposes 8 siRNAs against SARS-CoV-2, and ex vivo assessment confirms the high antiviral activity of 6 out of 8 siRNAs, also achieving excellent variant coverage (with several 3-siRNA combinations recognizing each correctly-sequenced variant as of September2022). Our approach is easily generalizable to other viruses as long as avariant genome database is available. With siRNA delivery procedures being currently improved, RNAi could therefore become an efficient and versatile antiviral therapeutic strategy.

Metagenomics characterization of respiratory viral RNA pathogens in children under five years with severe acute respiratory infection in the Free State, South Africa.

Prompt detection of viral respiratory pathogens is crucial in managing respiratory infection including severe acute respiratory infection (SARI). Metagenomics next-generation sequencing (mNGS) and bioinformatics analyses remain reliable strategies for diagnostic and surveillance purposes. This study evaluated the diagnostic utility of mNGS using multiple analysis tools compared with multiplex real-time PCR for the detection of viral respiratory pathogens in children under 5 years with SARI. Nasopharyngeal swabs collected in viral transport media from 84 children admitted with SARI as per the World Health Organization definition between December 2020 and August 2021 in the Free State Province, South Africa, were used in this study. The obtained specimens were subjected to mNGS using the Illumina MiSeq system, and bioinformatics analysis was performed using three web-based analysis tools; Genome Detective, One Codex and Twist Respiratory Viral Research Panel. With average reads of 211323, mNGS detected viral pathogens in 82 (97.6%) of the 84 patients. Viral aetiologies were established in nine previously undetected/missed cases with an additional bacterial aetiology (Neisseria meningitidis) detected in one patient. Furthermore, mNGS enabled the much needed viral genotypic and subtype differentiation and provided significant information on bacterial co-infection despite enrichment for RNA viruses. Sequences of nonhuman viruses, bacteriophages, and endogenous retrovirus K113 (constituting the respiratory virome) were also uncovered. Notably, mNGS had lower detectability rate for severe acute respiratory syndrome coronavirus 2 (missing 18/32 cases). This study suggests that mNGS, combined with multiple/improved bioinformatics tools, is practically feasible for increased viral and bacterial pathogen detection in SARI, especially in cases where no aetiological agent could be identified by available traditional methods.

Metagenomics of gut microbiome for migratory seagulls in Kunming city revealed the potential public risk to human health.

BACKGROUND: Seagull as a migratory wild bird has become most popular species in southwest China since 1980s. Previously, we analyzed the gut microbiota and intestinal pathogenic bacteria configuration for this species by using 16S rRNA sequencing and culture methods. To continue in-depth research on the gut microbiome of migratory seagulls, the metagenomics, DNA virome and RNA virome were both investigated for their gut microbial communities of abundance and diversity in this study. RESULTS: The metagenomics results showed 99.72% of total species was bacteria, followed by viruses, fungi, archaea and eukaryota. In particular, Shigella sonnei, Escherichia albertii, Klebsiella pneumonia, Salmonella enterica and Shigella flexneri were the top distributed taxa at species level. PCoA, NMDS, and statistics indicated some drug resistant genes, such as adeL, evgS, tetA, PmrF, and evgA accumulated as time went by from November to January of the next year, and most of these genes were antibiotic efflux. DNA virome composition demonstrated that Caudovirales was the most abundance virus, followed by Cirlivirales, Geplafuvirales, Petitvirales and Piccovirales. Most of these phages corresponded to Enterobacteriaceae and Campylobacteriaceae bacterial hosts respectively. Caliciviridae, Coronaviridae and Picornaviridae were the top distributed RNA virome at family level of this migratory animal. Phylogenetic analysis indicated the sequences of contigs of Gammacoronavirus and Deltacoronavirus had highly similarity with some coronavirus references. CONCLUSIONS: In general, the characteristics of gut microbiome of migratory seagulls were closely related to human activities, and multiomics still revealed the potential public risk to human health.

Differentially-regulated miRNAs in COVID-19: A systematic review.

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is responsible for coronavirus disease of 2019 (COVID-19) that infected more than 760 million people worldwide with over 6.8 million deaths to date. COVID-19 is one of the most challenging diseases of our times due to the nature of its spread, its effect on multiple organs, and an inability to predict disease prognosis, ranging from being completely asymptomatic to death. Upon infection, SARS-CoV-2 alters the host immune response by changing host-transcriptional machinery. MicroRNAs (miRNAs) are regarded as post-transcriptional regulators of gene expression that can be perturbed by invading viruses. Several in vitro and in vivo studies have reported such dysregulation of host miRNA expression upon SARS-CoV-2 infection. Some of this could occur as an anti-viral response of the host to the viral infection. Viruses themselves can counteract that response by mounting their own pro-viral response that facilitates virus infection, an aspect which may cause pathogenesis. Thus, miRNAs could serve as possible disease biomarkers in infected people. In the current review, we have summarised and analysed the existing data about miRNA dysregulation in patients infected with SARS-CoV-2 to determine their concordance between studies, and identified those that could serve as potential biomarkers during infection, disease progression, and death, even in people with other co-morbidities. Having such biomarkers can be vital in not only predicting COVID-19 prognosis, but also the development of novel miRNA-based anti-virals and therapeutics which can become invaluable in case of the emergence of new viral variants with pandemic potential in the future.

PepGM: a probabilistic graphical model for taxonomic inference of viral proteome samples with associated confidence scores.

MOTIVATION: Inferring taxonomy in mass spectrometry-based shotgun proteomics is a complex task. In multi-species or viral samples of unknown taxonomic origin, the presence of proteins and corresponding taxa must be inferred from a list of identified peptides, which is often complicated by protein homology: many proteins do not only share peptides within a taxon but also between taxa. However, the correct taxonomic inference is crucial when identifying different viral strains with high-sequence homology-considering, e.g., the different epidemiological characteristics of the various strains of severe acute respiratory syndrome-related coronavirus-2. Additionally, many viruses mutate frequently, further complicating the correct identification of viral proteomic samples. RESULTS: We present PepGM, a probabilistic graphical model for the taxonomic assignment of virus proteomic samples with strain-level resolution and associated confidence scores. PepGM combines the results of a standard proteomic database search algorithm with belief propagation to calculate the marginal distributions, and thus confidence scores, for potential taxonomic assignments. We demonstrate the performance of PepGM using several publicly available virus proteomic datasets, showing its strain-level resolution performance. In two out of eight cases, the taxonomic assignments were only correct on the species level, which PepGM clearly indicates by lower confidence scores. AVAILABILITY AND IMPLEMENTATION: PepGM is written in Python and embedded into a Snakemake workflow. It is available at https://github.com/BAMeScience/PepGM.

Mapping human pathogens in wastewater using a metatranscriptomic approach.

The monitoring of cities' wastewaters for the detection of potentially pathogenic viruses and bacteria has been considered a priority during the COVID-19 pandemic to monitor public health in urban environments. The methodological approaches frequently used for this purpose include deoxyribonucleic acid (DNA)/Ribonucleic acid (RNA) isolation followed by quantitative polymerase chain reaction (qPCR) and reverse transcription (RT)‒qPCR targeting pathogenic genes. More recently, the application of metatranscriptomic has opened opportunities to develop broad pathogenic monitoring workflows covering the entire pathogenic community within the sample. Nevertheless, the high amount of data generated in the process requires an appropriate analysis to detect the pathogenic community from the entire dataset. Here, an implementation of a bioinformatic workflow was developed to produce a map of the detected pathogenic bacteria and viruses in wastewater samples by analysing metatranscriptomic data. The main objectives of this work was the development of a computational methodology that can accurately detect both human pathogenic virus and bacteria in wastewater samples. This workflow can be easily reproducible with open-source software and uses efficient computational resources. The results showed that the used algorithms can predict potential human pathogens presence in the tested samples and that active forms of both bacteria and virus can be identified. By comparing the computational method implemented in this study to other state-of-the-art workflows, the implementation analysis was faster, while providing higher accuracy and sensitivity. Considering these results, the processes and methods to monitor wastewater for potential human pathogens can become faster and more accurate. The proposed workflow is available at https://github.com/waterpt/watermonitor and can be implemented in currently wastewater monitoring programs to ascertain the presence of potential human pathogenic species.

Rapid multiplex PCR for respiratory viruses reduces time to result and improves clinical care: Results of a systematic review and meta-analysis.

OBJECTIVES: The clinical impact of rapid sample-to-answer "syndromic" multiplex polymerase chain reaction (PCR) testing for respiratory viruses is not clearly established. We performed a systematic literature review and meta-analysis to evaluate this impact for patients with possible acute respiratory tract infection in the hospital setting. METHODS: We searched EMBASE, MEDLINE, and Cochrane databases from 2012 to present and conference proceedings from 2021 for studies comparing clinical impact outcomes between multiplex PCR testing and standard testing. RESULTS: Twenty-seven studies with 17,321 patient encounters were included in this review. Rapid multiplex PCR testing was associated with a reduction of - 24.22 h (95% CI -28.70 to -19.74 h) in the time to results. Hospital length of stay was decreased by -0.82 days (95% CI -1.52 to -0.11 days). Among influenza positive patients, antivirals were more likely to be given (RR 1.25, 95% CI 1.06-1.48) and appropriate infection control facility use was more common with rapid multiplex PCR testing (RR 1.55, 95% CI 1.16-2.07). CONCLUSIONS: Our systematic review and meta-analysis demonstrates a reduction in time to results and length of stay for patients overall along with improvements in appropriate antiviral and infection control management among influenza-positive patients. This evidence supports the routine use of rapid sample-to-answer multiplex PCR testing for respiratory viruses in the hospital setting.

DRAVP: A Comprehensive Database of Antiviral Peptides and Proteins.

Viruses with rapid replication and easy mutation can become resistant to antiviral drug treatment. With novel viral infections emerging, such as the recent COVID-19 pandemic, novel antiviral therapies are urgently needed. Antiviral proteins, such as interferon, have been used for treating chronic hepatitis C infections for decades. Natural-origin antimicrobial peptides, such as defensins, have also been identified as possessing antiviral activities, including direct antiviral effects and the ability to induce indirect immune responses to viruses. To promote the development of antiviral drugs, we constructed a data repository of antiviral peptides and proteins (DRAVP). The database provides general information, antiviral activity, structure information, physicochemical information, and literature information for peptides and proteins. Because most of the proteins and peptides lack experimentally determined structures, AlphaFold was used to predict each antiviral peptide's structure. A free website for users (http://dravp.cpu-bioinfor.org/, accessed on 30 August 2022) was constructed to facilitate data retrieval and sequence analysis. Additionally, all the data can be accessed from the web interface. The DRAVP database aims to be a useful resource for developing antiviral drugs.

Aid or Antagonize: Nuclear Long Noncoding RNAs Regulate Host Responses and Outcomes of Viral Infections.

Long noncoding RNAs (lncRNAs) are transcripts measuring >200 bp in length and devoid of protein-coding potential. LncRNAs exceed the number of protein-coding mRNAs and regulate cellular, developmental, and immune pathways through diverse molecular mechanisms. In recent years, lncRNAs have emerged as epigenetic regulators with prominent roles in health and disease. Many lncRNAs, either host or virus-encoded, have been implicated in critical cellular defense processes, such as cytokine and antiviral gene expression, the regulation of cell signaling pathways, and the activation of transcription factors. In addition, cellular and viral lncRNAs regulate virus gene expression. Viral infections and associated immune responses alter the expression of host lncRNAs regulating immune responses, host metabolism, and viral replication. The influence of lncRNAs on the pathogenesis and outcomes of viral infections is being widely explored because virus-induced lncRNAs can serve as diagnostic and therapeutic targets. Future studies should focus on thoroughly characterizing lncRNA expressions in virus-infected primary cells, investigating their role in disease prognosis, and developing biologically relevant animal or organoid models to determine their suitability for specific therapeutic targeting. Many cellular and viral lncRNAs localize in the nucleus and epigenetically modulate viral transcription, latency, and host responses to infection. In this review, we provide an overview of the role of nuclear lncRNAs in the pathogenesis and outcomes of viral infections, such as the Influenza A virus, Sendai Virus, Respiratory Syncytial Virus, Hepatitis C virus, Human Immunodeficiency Virus, and Herpes Simplex Virus. We also address significant advances and barriers in characterizing lncRNA function and explore the potential of lncRNAs as therapeutic targets.

ICTV Virus Taxonomy Profile: Coronaviridae 2023.

The family Coronaviridae includes viruses with positive-sense RNA genomes of 22-36 kb that are expressed through a nested set of 3' co-terminal subgenomic mRNAs. Members of the subfamily Orthocoronavirinae are characterized by 80-160 nm diameter, enveloped virions with spike projections. The orthocoronaviruses, severe acute respiratory syndrome coronavirus and Middle East respiratory syndrome-related coronavirus are extremely pathogenic for humans and in the last two decades have been responsible for the SARS and MERS epidemics. Another orthocoronavirus, severe acute respiratory syndrome coronavirus 2, was responsible for the recent global COVID-19 pandemic. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the family Coronaviridae which is available at www.ictv.global/report/coronaviridae.

Genotype Diversity of Enteric Viruses in Wastewater Amid the COVID-19 Pandemic.

Viruses remain the leading cause of acute gastroenteritis (AGE) worldwide. Recently, we reported the abundance of AGE viruses in raw sewage water (SW) during the COVID-19 pandemic, when viral AGE patients decreased dramatically in clinics. Since clinical samples were not reflecting the actual state, it remained important to determine the circulating strains in the SW for preparedness against impending outbreaks. Raw SW was collected from a sewage treatment plant in Japan from August 2018 to March 2022, concentrated by polyethylene-glycol-precipitation method, and investigated for major gastroenteritis viruses by RT-PCR. Genotypes and evolutionary relationships were evaluated through sequence-based analyses. Major AGE viruses like rotavirus A (RVA), norovirus (NoV) GI and GII, and astrovirus (AstV) increased sharply (10-20%) in SW during the COVID-19 pandemic, though some AGE viruses like sapovirus (SV), adenovirus (AdV), and enterovirus (EV) decreased slightly (3-10%). The prevalence remained top in the winter. Importantly, several strains, including G1 and G3 of RVA, GI.1 and GII.2 of NoV, GI.1 of SV, MLB1 of AstV, and F41 of AdV, either emerged or increased amid the pandemic, suggesting that the normal phenomenon of genotype changing remained active over this time. This study crucially presents the molecular characteristics of circulating AGE viruses, explaining the importance of SW investigation during the pandemic when a clinical investigation may not produce the complete scenario.

The Clinical Performance of the BioCode Respiratory Pathogen Panel for the Detection of Viruses and Bacteria from Nasopharyngeal Swabs.

Early detection of microbial pathogens causing respiratory tract infection plays a crucial role in clinical management. The BioCode Respiratory Pathogen Panel (BioCode RPP) utilizes reverse transcriptase PCR (RT-PCR) in combination with barcoded magnetic beads to amplify, detect, and identify respiratory pathogens. This panel qualitatively detects and identifies 14 viruses, including influenza virus A with H1 pdm09, H1, and H3 subtyping; influenza B; respiratory syncytial virus (RSV); human metapneumovirus; parainfluenza virus 1; parainfluenza virus 2; parainfluenza virus 3; parainfluenza virus 4; coronavirus (229E, NL63, OC43, and HKU1); adenovirus; and human rhinovirus/enterovirus, and 3 bacteria, including Chlamydia pneumoniae, Mycoplasma pneumoniae, and Bordetella pertussis. Reproducibility, which was assessed with contrived specimens containing 12 targets at 3 clinical sites, with 2 operators at each site for 5 days, was 99.4% for Flu A H3 and Flu B, 98.9% for RSV, and 100% for the remaining 9 targets assayed. A multicenter clinical trial evaluated the performance of the BioCode RPP with 2,647 nasopharyngeal swab specimens from 5 geographically distinct sites and revealed comparable performance between the BioCode RPP and FilmArray Respiratory Panel (FA-RP). Specifically, the positive percent agreements (PPAs) for various pathogens ranged between 80.8% and 100% compared with the FA-RP (1.7 and 2.0). Negative percent agreement ranged from 98.4% to 100% for BioCode RPP. The BioCode RPP also offers scalable automated testing capability of up to 96 specimens in a single run with total sample-to-result time under 5 h. The invalid rate of the BioCode RPP on initial testing was 1.0% (26/2,649). IMPORTANCE Early detection of microbial pathogens causing respiratory tract infection plays a crucial role in clinical management. The BioCode Respiratory Pathogen Panel (BioCode RPP) is a high-throughput test that utilizes RT-PCR in combination with barcoded magnetic beads to amplify, detect, and identify 17 respiratory pathogens, including 14 viruses and 3 bacteria. This study summarizes data generated from a multicenter clinical trial evaluating the performance of the BioCode RPP on 2,647 nasopharyngeal swab specimens from five geographically distinct sites.

Host-mediated RNA editing in viruses.

Viruses rely on hosts for life and reproduction, cause a variety of symptoms from common cold to AIDS to COVID-19 and provoke public health threats claiming millions of lives around the globe. RNA editing, as a crucial co-/post-transcriptional modification inducing nucleotide alterations on both endogenous and exogenous RNA sequences, exerts significant influences on virus replication, protein synthesis, infectivity and toxicity. Hitherto, a number of host-mediated RNA editing sites have been identified in diverse viruses, yet lacking a full picture of RNA editing-associated mechanisms and effects in different classes of viruses. Here we synthesize the current knowledge of host-mediated RNA editing in a variety of viruses by considering two enzyme families, viz., ADARs and APOBECs, thereby presenting a landscape of diverse editing mechanisms and effects between viruses and hosts. In the ongoing pandemic, our study promises to provide potentially valuable insights for better understanding host-mediated RNA editing on ever-reported and newly-emerging viruses.

U.S. scientists brace for greater scrutiny of risky research.

Expert panel recommends broader reviews of research involving pathogens or toxins that could have "dual use".

Development of a validated molecular analytical method to determine the viral safety of F(AB´)2 products: A novel application for a well-known technique.

The immunotherapy agents derived from horses are biological products that allow the neutralization of clinically relevant immunogens, such as the SARS-CoV-2 virus that causes COVID-19, or the neutralization of toxins present in the venoms of snakes, spiders, and other poisonous animals. Due to their importance, detecting adventitious viruses in equine hyperimmune serum (raw material in industrial processes) is a critical step to support the safety of products for human use, and, in consequence, it is a requirement for commercialization and distribution. The safety of the finished product is based on three complementary approaches: (i) testing of the source material (horse serum) donations, (ii) release of the starting material (i.e., pool of horse serum) based on non-reactivity for a range of human infectious or pathogenic viruses, and (iii) validate (selected) steps of the manufacturing process for their capacity to inactivate and/or remove a wide range of viruses potentially present in the starting material. Orthogonal approaches to reduce viral contamination risk include implementing a reliable and validated system for detecting adventitious viruses. Thus, it is necessary to establish trustworthy and sufficiently sensitive analytical methods to evidence the lack of viruses to assure the safety of the therapeutic product. Therefore, in this research, an analytical method based on end-point Reverse Transcription Polymerase Chain Reaction (RT-PCR) was developed, implemented, and validated in hyperimmune equine serum samples to detect Venezuelan equine encephalitis virus, West Nile virus, and Rabies virus.

In viral games, refs go to the replay.

After more than 2 years of intensive investigation, the direct ancestors of the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remain unidentified. Molecular epidemiology strongly supports a timeline marked by multiple, independent zoonoses in late 2019 (Pekar et al, 2022) solidifying the consensus hypothesis that close relatives of SARS-CoV-2 with high zoonotic potential were naturally circulating prior to the start of the pandemic (Andersen et al, 2020). Understanding where and when these ancestors acquired the genomic features that resulted in a virus with epidemic potential could enable the identification and mitigation of future pandemic viruses, even before the first human infection.

Prophylactic intranasal administration of lipid nanoparticle formulated siRNAs reduce SARS-CoV-2 and RSV lung infection.

RNA interference (RNAi) is an emerging and promising therapy for a wide range of respiratory viral infections. This highly specific suppression can be achieved by the introduction of short-interfering RNA (siRNA) into mammalian systems, resulting in the effective reduction of viral load. Unfortunately, this has been hindered by the lack of a good delivery system, especially via the intranasal (IN) route. Here, we have developed an IN siRNA encapsulated lipid nanoparticle (LNP) in vivo delivery system that is highly efficient at targeting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and respiratory syncytial virus (RSV) lung infection in vivo. Importantly, IN siRNA delivery without the aid of LNPs abolishes anti-SARS-CoV-2 activity in vivo. Our approach using LNPs as the delivery vehicle overcomes the significant barriers seen with IN delivery of siRNA therapeutics and is a significant advancement in our ability to delivery siRNAs. The study presented here demonstrates an attractive alternate delivery strategy for the prophylactic treatment of both future and emerging respiratory viral diseases.