Global screening for human viral pathogens

The Discovery of Phages in the Substantia Nigra and Its Implication for Parkinson's Disease

Background: A century ago, a mystery between a virus and Parkinson's disease (PD) was described. Owing to the limitation of human brain biopsy and the challenge of electron microscopy in observing virions in human brain tissue, it has been difficult to study the viral etiology of PD. Recent discovery of virobiota reveals that viruses coexist with humans as symbionts. Newly developed transcriptomic sequencing and novel bioinformatic approaches for mining the encrypted virome in human transcriptome make it possible to study the relationship between symbiotic viruses and PD. Nevertheless, whether viruses exist in the human substantia nigra (SN) and whether symbiotic viruses underlie PD pathogenesis remain unknown. Methods: We collected current worldwide human SN transcriptomic datasets from the United States, the United Kingdom, the Netherlands, and Switzerland. We used bioinformatic approaches including viruSITE and the Viral-Track to identify the existence of viruses in the SN of patients. The comprehensive RNA sequencing-based virome analysis pipeline was used to characterize the virobiota in the SN. The Pearson's correlation analysis was used to examine the association between the viral RNA fragment counts (VRFCs) and PD-related human gene sequencing reads in the SN. The differentially expressed genes (DEGs) in the SN between PD patients and non-PD individuals were used to examine the molecular signatures of PD and also evaluate the impact of symbiotic viruses on the SN. Findings: We observed the existence of viruses in the human SN. A dysbiosis of virobiota was found in the SN of PD patients. A marked correlation between VRFC and PD-related human gene expression was detected in the SN of PD patients. These PD-related human genes correlated to VRFC were named as the virus-correlated PD-related genes (VPGs). We identified 3 bacteriophages (phages), including the Proteus phage VB_PmiS-Isfahan, the Escherichia phage phiX174, and the Lactobacillus phage Sha1, that might impair the gene expression of neural cells in the SN of PD patients. The Proteus phage VB_PmiS-Isfahan was a common virus in the SN of patients from the United Kingdom, the Netherlands, and Switzerland. VPGs and DEGs together highlighted that the phages might dampen dopamine biosynthesis and weaken the cGAS-STING function. Interpretation: This is the first study to discover the involvement of phages in PD pathogenesis. A lifelong low symbiotic viral load in the SN may be a contributor to PD pathogenesis. Our findings unlocked the black box between brain virobiota and PD, providing a novel insight into PD etiology from the perspective of phage-human symbiosis.

Can Water-Only DNA Extraction Reduce the Logistical Footprint of Biosurveillance and Planetary Health Diagnostics? Toward a New Method

The coronavirus disease-2019 (COVID-19) pandemic has raised the stakes for planetary health diagnostics. Because pandemics pose enormous burdens on biosurveillance and diagnostics, reduction of the logistical burdens of pandemics and ecological crises is essential. Moreover, the disruptive effects of catastrophic bioevents impact the supply chains in both highly populated urban centers and rural communities. One "upstream" focus of methodological innovation in biosurveillance is the footprint of Nucleic Acid Amplification Test (NAAT)-based assays. We report in this study a water-only DNA extraction, as an initial step in developing future protocols that may require few expendables, and with low environmental footprints, in terms of wet and solid laboratory waste. In the present work, boiling-hot distilled water was used as the main cell lysis agent for direct polymerase chain reactions (PCRs) on crude extracts. After evaluation (1) in blood and mouth swabs for human biomarker genotyping, and (2) in mouth swabs and plant tissue for generic bacterial or fungal detection, and using different combinations of extraction volume, mechanical assistance, and extract dilution, we found the method to be applicable in low-complexity samples, but not in high-complexity ones such as blood and plant tissue. In conclusion, this study examined the doability of a lean approach for template extraction in the case of NAAT-based diagnostics. Testing our approach with different biosamples, PCR settings, and instruments, including portable ones for COVID-19 or dispersed applications, warrant further research. Minimal resources analysis is a concept and practice, vital and timely for biosurveillance, integrative biology, and planetary health in the 21st century.

Abundance and Diversity of Phages, Microbial Taxa, and Antibiotic Resistance Genes in the Sediments of the River Ganges Through Metagenomic Approach

In this study, we have analyzed the metagenomic DNA from the pooled sediment sample of the river Ganges to explore the abundance and diversity of phages, microbial community, and antibiotic resistance genes (ARGs). Utilizing data from Illumina platform, 4,174 (∼0.0013%) reads were classified for the 285 different DNA viruses largely dominated by the group of 260 distinctive phages (3,602 reads, ∼86.3%). Among all, Microcystis (782 hits), Haemophilus (403), Synechococcus (386), Pseudomonas (279), Enterococcus (232), Bacillus (196), Rhodococcus (166), Caulobacter (163), Salmonella (146), Enterobacteria (143), Mycobacterium and (128) phages show the highest abundance and account for ∼90% of the total identified phages. In addition, we have also identified corresponding host pertaining to these phages. Mainly, Proteobacteria (∼69.3%) dominates the microbial population structure. Primarily, orders such as Caulobacterales (∼28%), Burkholderiales (∼13.9%), Actinomycetales (∼13.7%), and Pseudomonadales (∼7.5%) signify the core section. Furthermore, 21,869 (∼0.00695%) reads were classified in 20 ARG types (classes) and 240 ARGs (subtypes), among which 4 ARG types, namely multidrug resistance (12,041 reads, ∼55%), bacitracin (3,202 reads, ∼15%), macrolide-lincosamide-streptogramin (1,744 reads, ∼7.98%), and fosmidomycin (990 reads, ∼4.53%), have the highest abundance. Simultaneously, six resistance mechanisms were also recognized with the dominance of antibiotic efflux (72.8%, 15,919 reads). The results unveil the distribution of (pro)-phages; microbial community; and various ARGs in the Ganges river sediments.

Pathogen genomic surveillance elucidates the origins, transmission and evolution of emerging viral agents in China

In the past twenty years, numerous novel zoonotic viral agents with pandemic potential have emerged in China, such as the severe acute respiratory syndrome (SARS) coronavirus and, more recently, the avian-origin influenza A/H7N9 virus, which have caused outbreaks among humans with high morbidity and mortality. In addition, several emerging and re-emerging viral pathogens have also been imported into China from travelers, e.g. the Middle East respiratory syndrome (MERS) coronavirus and Zika virus (ZIKV). Herein, we review these emerging viral pathogens in China and focus on how surveillance by pathogen genomics has been employed to discover and annotate novel pathogenic agents, identify natural reservoirs, monitor the transmission events and delineate their evolution and adaption to the human host. We also highlight the application of genomic sequencing in the recent Ebola epidemics in Western Africa. In summary, genomic sequencing has become a standard research tool in the field of emerging infectious diseases which has been proven invaluable in containing these viral infections and reducing burden of disease in humans and animals. Genomic surveillance of pathogenic agents will serve as a key epidemiological and research tool in the modern era of precision infectious diseases and in the future studies of virosphere.

An Ecological Framework of the Human Virome Provides Classification of Current Knowledge and Identifies Areas of Forthcoming Discovery

Recent advances in sequencing technologies have opened the door for the classification of the human virome. While taxonomic classification can be applied to the viruses identified in such studies, this gives no information as to the type of interaction the virus has with the host. As follow-up studies are performed to address these questions, the description of these virus-host interactions would be greatly enriched by applying a standard set of definitions that typify them. This paper describes a framework with which all members of the human virome can be classified based on principles of ecology. The scaffold not only enables categorization of the human virome, but can also inform research aimed at identifying novel virus-host interactions.

High sensitive and direct fluorescence detection of single viral DNA sequences by integration of double strand probes onto microgels particles

A novel class of probes for fluorescence detection was developed and combined to microgel particles for a high sensitive fluorescence detection of nucleic acids.

[Splitting into two lines: The historical development of the analytical and the gas ultracentrifuge]

In a historical perspective the ultracentrifuge is often taken as perfect example of a research technology according to Shinn and Joerges (Shinn and Joerges 2000, 2002). Research technologies are defined by a generic device, its own metrology and the interstitiality of the historical actors connected with the device. In our paper we give a detailed analysis of the development of the ultracentrifuge and thereby reveal two different lines of development: analytical ultracentrifuges and gas ultra centrifuges used for isotope separation. Surprisingly, we could not find any interstitial and transversal connections for these two lines. The lines end up with two different devices based on two different technical concepts. Moreover, the great majority of the actors stick to one line. These results are in accordance withother authors, who developed the concept of research technologies further and tried to sharpen their definition.

Viruses in a 14th-century coprolite

Coprolites are fossilized fecal material that can reveal information about ancient intestinal and environmental microbiota. Viral metagenomics has allowed systematic characterization of viral diversity in environmental and human-associated specimens, but little is known about the viral diversity in fossil remains. Here, we analyzed the viral community of a 14th-century coprolite from a closed barrel in a Middle Ages site in Belgium using electron microscopy and metagenomics. Viruses that infect eukaryotes, bacteria, and archaea were detected, and we confirmed the presence of some of them by ad hoc suicide PCR. The coprolite DNA viral metagenome was dominated by sequences showing homologies to phages commonly found in modern stools and soil. Although their phylogenetic compositions differed, the metabolic functions of the viral communities have remained conserved across centuries. Antibiotic resistance was one of the reconstructed metabolic functions detected.

Preparation of metagenomic libraries from naturally occurring marine viruses

Microbes are now well recognized as major drivers of the biogeochemical cycling that fuels the Earth, and their viruses (phages) are known to be abundant and important in microbial mortality, horizontal gene transfer, and modulating microbial metabolic output. Investigation of environmental phages has been frustrated by an inability to culture the vast majority of naturally occurring diversity coupled with the lack of robust, quantitative, culture-independent methods for studying this uncultured majority. However, for double-stranded DNA phages, a quantitative viral metagenomic sample-to-sequence workflow now exists. Here, we review these advances with special emphasis on the technical details of preparing DNA sequencing libraries for metagenomic sequencing from environmentally relevant low-input DNA samples. Library preparation steps broadly involve manipulating the sample DNA by fragmentation, end repair and adaptor ligation, size fractionation, and amplification. One critical area of future research and development is parallel advances for alternate nucleic acid types such as single-stranded DNA and RNA viruses that are also abundant in nature. Combinations of recent advances in fragmentation (e.g., acoustic shearing and tagmentation), ligation reactions (adaptor-to-template ratio reference table availability), size fractionation (non-gel-sizing), and amplification (linear amplification for deep sequencing and linker amplification protocols) enhance our ability to generate quantitatively representative metagenomic datasets from low-input DNA samples. Such datasets are already providing new insights into the role of viruses in marine systems and will continue to do so as new environments are explored and synergies and paradigms emerge from large-scale comparative analyses.

Computational tools for viral metagenomics and their application in clinical research

There are 100 times more virions than eukaryotic cells in a healthy human body. The characterization of human-associated viral communities in a non-pathological state and the detection of viral pathogens in cases of infection are essential for medical care and epidemic surveillance. Viral metagenomics, the sequenced-based analysis of the complete collection of viral genomes directly isolated from an organism or an ecosystem, bypasses the “single-organism-level” point of view of clinical diagnostics and thus the need to isolate and culture the targeted organism. The first part of this review is dedicated to a presentation of past research in viral metagenomics with an emphasis on human-associated viral communities (eukaryotic viruses and bacteriophages). In the second part, we review more precisely the computational challenges posed by the analysis of viral metagenomes, and we illustrate the problem of sequences that do not have homologs in public databases and the possible approaches to characterize them.

Translational research in infectious disease: current paradigms and challenges ahead

In recent years, the biomedical community has witnessed a rapid scientific and technologic evolution after the development and refinement of high-throughput methodologies. Concurrently and consequentially, the scientific perspective has changed from the reductionist approach of meticulously analyzing the fine details of a single component of biology to the "holistic" approach of broadmindedly examining the globally interacting elements of biological systems. The emergence of this new way of thinking has brought about a scientific revolution in which genomics, proteomics, metabolomics, and other "omics" have become the predominant tools by which large amounts of data are amassed, analyzed, and applied to complex questions of biology that were previously unsolvable. This enormous transformation of basic science research and the ensuing plethora of promising data, especially in the realm of human health and disease, have unfortunately not been followed by a parallel increase in the clinical application of this information. On the contrary, the number of new potential drugs in development has been decreasing steadily, suggesting the existence of roadblocks that prevent the translation of promising research into medically relevant therapeutic or diagnostic application. In this article, we will review, in a noninclusive fashion, several recent scientific advancements in the field of translational research, with a specific focus on how they relate to infectious disease. We will also present a current picture of the limitations and challenges that exist for translational research, as well as ways that have been proposed by the National Institutes of Health to improve the state of this field.

Viral Genomics: Implications for the Understanding and Control of Emerging Viral Diseases

In recent decades, many infectious diseases have significantly increased in incidence and/or geographic range, in some cases impacting heavily on human, animal or plant populations. Some of these ‘emerging infectious diseases’ are associated with pathogens that have appeared in populations for the first time as a result of cross-species transmission (e.g. human immunodeficiency virus—acquired immunodeficiency syndrome (HIV-AIDS), severe acute respiratory syndrome (SARS)), while others were previously known but are rapidly increasing in incidence or geographic range as a result of underlying epidemiological changes (e.g. multi-drug resistant Staphylococcus aureus (MRSA) infection, dengue, West Nile encephalitis, foot and mouth disease, cassava mosaic disease). The latter include prominent diseases as tuberculosis, malaria and yellow fever that were once on the decline but are now ‘re-emerging diseases’.

Rapid detection of avian influenza virus in chicken fecal samples by immunomagnetic capture reverse transcriptase-polymerase chain reaction assay

Avian influenza virus (AIV) causes great economic losses for the poultry industry worldwide and threatens the human population with a pandemic. The conventional detection method for AIV involves sample preparation of viral RNA extraction and purification from raw sample such as bird droppings. In this study, magnetic beads were applied for immunoseparation and purification of AIV from spiked chicken fecal sample. The beads were conjugated with monoclonal antibodies against the AIV nucleoprotein, which is conserved in all the AIV. The bead-captured virus was detected by reverse transcriptase-polymerase chain reaction (RT-PCR) without RNA extraction because of effective removal of RT-PCR inhibitors. The developed bead-based assay showed a similar detection limit comparable to the RNA extraction and the classic virus isolation method. Using ready-to-use antibody-conjugated bead, the method requires less than 5 h. Furthermore, the method has potential to integrate into a Lab-on-a-chip system for rapid detection and identification of AIV.

Genome-virome interactions: examining the role of common viral infections in complex disease

New technologies have widened our view of 'complex diseases': those with both genetic and environmental risk factors. In this Review, we explore recent genetic and virological evidence implicating host-virus interactions in three diseases: type 1 diabetes, inflammatory bowel disease and asthma. The viruses implicated in these diseases cause mucosal infections that affect most of the population but are asymptomatic or mild in many hosts. These findings place a new emphasis on common viral infections as important environmental factors in the pathogenesis of complex diseases, and they compel the field to pursue a better understanding of host interactions with the human virome.

Metagenomic analysis of the viromes of three North American bat species: viral diversity among different bat species that share a common habitat

Effective prediction of future viral zoonoses requires an in-depth understanding of the heterologous viral population in key animal species that will likely serve as reservoir hosts or intermediates during the next viral epidemic. The importance of bats as natural hosts for several important viral zoonoses, including Ebola, Marburg, Nipah, Hendra, and rabies viruses and severe acute respiratory syndrome-coronavirus (SARS-CoV), has been established; however, the large viral population diversity (virome) of bats has been partially determined for only a few of the ∼1,200 bat species. To assess the virome of North American bats, we collected fecal, oral, urine, and tissue samples from individual bats captured at an abandoned railroad tunnel in Maryland that is cohabitated by 7 to 10 different bat species. Here, we present preliminary characterization of the virome of three common North American bat species, including big brown bats (Eptesicus fuscus), tricolored bats (Perimyotis subflavus), and little brown myotis (Myotis lucifugus). In samples derived from these bats, we identified viral sequences that were similar to at least three novel group 1 CoVs, large numbers of insect and plant virus sequences, and nearly full-length genomic sequences of two novel bacteriophages. These observations suggest that bats encounter and disseminate a large assortment of viruses capable of infecting many different animals, insects, and plants in nature.

Metagenomics for the discovery of novel human viruses

Modern laboratory techniques for the detection of novel human viruses are greatly needed as physicians and epidemiologists increasingly deal with infectious diseases caused by new or previously unrecognized pathogens. There are many clinical syndromes in which viruses are suspected to play a role, but for which traditional microbiology techniques routinely fail in uncovering the etiologic agent. In addition, new viruses continue to challenge the human population owing to the encroachment of human settlements into animal and livestock habitats, globalization, climate change, growing numbers of immunocompromised people and bioterrorism. Metagenomics-based tools, such as microarrays and high-throughput sequencing are ideal for responding to these challenges. Pan-viral microarrays, containing representative sequences from all known viruses, have been used to detect novel and distantly-related variants of known viruses. Sequencing-based methods have also been successfully employed to detect novel viruses and have the potential to detect the full spectrum of viruses, including those present in low numbers.

Advancing full length genome sequencing for human RNA viral pathogens

In the face of numerous emerging and re-emerging viral threats, large-scale genome sequencing efforts are underway to monitor viral evolution in real-time. To fully appreciate the mechanisms of viral adaptation and evolution, and to also develop reagents and resources for a better molecular diagnosis of emerging and re-emerging viral infections, there has been an increasing effort toward producing full length viral genome sequences. To date, high-throughput platforms have been developed using traditional Sanger-based sequencing and there are currently prospects to apply next generation sequencing methods to develop an ultra high-throughput strategy for viral genome sequencing and analysis.

Viral metagenomics

Characterisation of new viruses is often hindered by difficulties in amplifying them in cell culture, limited antigenic/serological cross-reactivity or the lack of nucleic acid hybridisation to known viral sequences. Numerous molecular methods have been used to genetically characterise new viruses without prior in vitro replication or the use of virus-specific reagents. In the recent metagenomic studies viral particles from uncultured environmental and clinical samples have been purified and their nucleic acids randomly amplified prior to subcloning and sequencing. Already known and novel viruses were then identified by comparing their translated sequence to those of viral proteins in public sequence databases. Metagenomic approaches to viral characterisation have been applied to seawater, near shore sediments, faeces, serum, plasma and respiratory secretions and have broadened the range of known viral diversity. Selection of samples with high viral loads, purification of viral particles, removal of cellular nucleic acids, efficient sequence-independent amplification of viral RNA and DNA, recognisable sequence similarities to known viral sequences and deep sampling of the nucleic acid populations through large scale sequencing can all improve the yield of new viruses. This review lists some of the animal viruses recently identified using sequence-independent methods, current laboratory and bioinformatics methods, together with their limitations and potential improvements. Viral metagenomic approaches provide novel opportunities to generate an unbiased characterisation of the viral populations in various organisms and environments.

Rarity gives a charm: evaluation of trace proteins in plasma and serum

Since plasma potentially contacts every cell as it circulates through the body, it may carry clues both to diagnosis and treatment of disease. It is commonly expected that the growing ability to detect and characterize trace proteins will result in discovery of novel therapeutics and biomarkers; however, the familiar, super-abundant plasma proteins remain a fundamental stumbling block. Furthermore, robust validation of proteomic data is a sometimes overlooked but always necessary component for the eventual development of clinical reagents. This review surveys some of the uses of typical and atypical low-abundance proteins, current analytical methods, existing impediments to discovery, and some innovations that are overcoming the challenges to evaluation of trace proteins in plasma and serum.

Detection and monitoring of virus infections by real-time PCR

The employment of polymerase chain reaction (PCR) techniques for virus detection and quantification offers the advantages of high sensitivity and reproducibility, combined with an extremely broad dynamic range. A number of qualitative and quantitative PCR virus assays have been described, but commercial PCR kits are available for quantitative analysis of a limited number of clinically important viruses only. In addition to permitting the assessment of viral load at a given time point, quantitative PCR tests offer the possibility of determining the dynamics of virus proliferation, monitoring of the response to treatment and, in viruses displaying persistence in defined cell types, distinction between latent and active infection. Moreover, from a technical point of view, the employment of sequential quantitative PCR assays in virus monitoring helps identifying false positive results caused by inadvertent contamination of samples with traces of viral nucleic acids or PCR products. In this review, we provide a survey of the current state-of-the-art in the application of the real-time PCR technology to virus analysis. Advantages and limitations of the RQ-PCR methodology, and quality control issues related to standardization and validation of diagnostic assays are discussed.

Detection and monitoring of virus infections by real-time PCR

The employment of polymerase chain reaction (PCR) techniques for virus detection and quantification offers the advantages of high sensitivity and reproducibility, combined with an extremely broad dynamic range. A number of qualitative and quantitative PCR virus assays have been described, but commercial PCR kits are available for quantitative analysis of a limited number of clinically important viruses only. In addition to permitting the assessment of viral load at a given time point, quantitative PCR tests offer the possibility of determining the dynamics of virus proliferation, monitoring of the response to treatment and, in viruses displaying persistence in defined cell types, distinction between latent and active infection. Moreover, from a technical point of view, the employment of sequential quantitative PCR assays in virus monitoring helps identifying false positive results caused by inadvertent contamination of samples with traces of viral nucleic acids or PCR products. In this review, we provide a survey of the current state-of-the-art in the application of the real-time PCR technology to virus analysis. Advantages and limitations of the RQ-PCR methodology, and quality control issues related to standardization and validation of diagnostic assays are discussed.

Germline and somatic diversification of immune recognition elements in Metazoa

The histories of the immune systems of Metazoa during evolution are envisaged like as many adaptations to the continuous diversification of immune receptors and effectors genes under the pressure of changing environments. A basic diversity of potential immune receptor genes existed in primitive Metazoa. Their subsequent recruitment into immunity, their diversification revolving around the conservation of signaling cascades was paralleled by cell specialization and the introduction of regulatory networks. Polymorphism, duplication and somatic mechanisms of diversification affected independently and still affect different gene families in many phyla, creating a greater variety of immune system exhibiting sometimes little homology but much analogy to one another. Diversity and multiplicity of receptors was generated by duplication and creation of multigene families. Independently in several phyla further diversity is created somatically by alternate splicing, somatic mutation, gene conversion and gene rearrangement. In several instances combinatorial usage of polypeptide chains or genes segments increases the repertoire of the recognition structures. Metazoa had to adapt to the conditions generated by this diversity: the control of expression of multiple genes and the risk of autoimmunity.

Meeting the Demand for Innate and Adaptive Immunities During Evolution

An ideal immune system should provide each individual with rapid and efficient responses, a diverse repertoire of recognition and effector molecules and a certain flexibility to match the changing internal and external environment. It should be economic in cells and genes. Specific memory would be useful. It should not be autoreactive. These requirements, a mixture of innate and adaptive immunity features, are modulated in function of the dominant mode of selection for each species of metazoa during evolution (K or r). From sponges to man, a great diversity of receptors and effector mechanisms, some of them shared with plants, are articulated around conserved signalling cascades. Multiple attempts at combining innate and adaptive immunity somatic features can be observed as new somatic mechanisms provide individualized repertoires of receptors throughout metazoa, in agnathans, prochordates, echinoderms and mollusks. The adaptive immunity of vertebrates with lymphocytes and their specific receptors of the immunoglobulin superfamily, the major histocompatibility complex, developed from innate immunity evolutionary lines that can be traced back in earlier deuterostomes.

Potential of DNA microarrays for developing parallel detection tools (PDTs) for microorganisms relevant to biodefense and related research needs

Development of parallel detection tools using microarrays is critically reviewed in view of the need for screening multiple microorganisms in a single test. Potential research needs with respect to probe design and specificity, validation, sample concentration, selective target enrichment and amplification, and data analysis are discussed. Data illustrating selected probe design issues for detecting multiple targets in mixed microbial systems is presented. Challenges with respect to cost, time, and ease of use compared to other methods are also summarized.

Emerging infections in transfusion medicine

The risk of transfusion-transmitted infectious diseases (TTIDs) has declined dramatically in high-income nations over the past 2 decades, primarily because of extraordinary success in preventing HIV and other established transfusion-transmitted viruses from entering the blood supply. Despite this achievement, TTIDs remain a public health concern, and attention is refocusing on new and emerging pathogens, such as West Nile virus, infectious proteins (the presumed cause of variant Creutzfeldt-Jakob disease), and other transmissible organisms such as bacteria and parasites. In this article the authors concentrate on this heterogeneous group of infectious agents, describe individual pathogens and the risks they pose to transfusion recipients, and comment on existing and evolving procedures that are designed to protect the blood supply from this threat.

Secreted Immunomodulatory Viral Proteins as Novel Biotherapeutics

Many viruses have learned to evade or subvert the host antiviral immune responses by encoding and expressing immunomodulatory proteins that protect the virus from attack by elements of the innate and acquired immune systems. Some of these viral anti-immune regulators are expressed as secreted proteins that engage specific host immune targets in the extracellular environment, where they exhibit potent anti-immune properties. We review here viral immunomodulatory proteins that have been tested as anti-inflammatory reagents in animal models of disease caused by excessive inflammation or hyperactivated immune pathways. The potential for such viral molecules for the development of novel drugs to treat immune-based or inflammatory disorders is discussed.