Evolution of the interferon alpha gene family in eutherian mammals

Comparative genomics provides insights into chromosomal evolution and immunological adaptation in horseshoe bats

Horseshoe bats are natural hosts of zoonotic viruses, yet the genetic basis of their antiviral immunity is poorly understood. Here we generated two new chromosomal-level genome assemblies for horseshoe bat species (Rhinolophus) and three close relatives, and show that, during their diversification, horseshoe bats underwent extensive chromosomal rearrangements and gene expansions linked to segmental duplications. These expansions have generated new adaptive variations in type I interferons and the interferon-stimulated gene ANXA2R, which potentially enhance antiviral states, as suggested by our functional assays. Genome-wide selection screens, including of candidate introgressed regions, uncover numerous putative molecular adaptations linked to immunity, including in viral receptors. By expanding taxon coverage to ten horseshoe bat species, we identify new variants of the SARS-CoV-2 receptor ACE2, and report convergent functionally important residues that could explain wider patterns of susceptibility across mammals. We conclude that horseshoe bats have numerous signatures of adaptation, including some potentially related to immune response to viruses, in genomic regions with diverse and multiscale mutational changes.

Asian elephant interferons alpha and beta and their anti-herpes viral activity

The type I interferons (IFNs) are a group of key cytokines of the vertebrate innate immune system that induce an antiviral state in uninfected cells. Experimental in-vitro and in-vivo data have proven the fundamental role these cytokines possess in the protective response to a wide variety of pathogens, including herpesviruses. In a clinical setting, IFNs have been an important treatment in humans for several decades and increasing evidence demonstrates their potential in controlling viral haemorrhagic fevers when administered early in disease. In juvenile Asian elephants, elephant endotheliotropic herpesvirus haemorrhagic disease (EEHV-HD) often proves fatal when an effective adaptive immune response cannot be mounted in time, suggesting that an enhancement of the innate immune response could provide protection. This study sequenced six members of the Asian elephant type I IFNs, most closely related to sequences from the African elephant and Florida manatee. Subsequently, recombinant Asian elephant IFNα and IFNβ proteins were expressed and assessed for bioactivity in-vitro, relative to recombinant human IFNs, using a novel infection model incorporating primary Asian elephant fibroblasts and bovine alphaherpesvirus 1 (BoHV-1) as a surrogate for EEHV. In a dose-dependent manner, both Asian elephant IFNs and human IFNα2a protected cells from BoHV-1 infection in this proof-of-concept study, even if applied up to 24 hours post-infection in-vitro.

Innate and adaptive immune responses that control lymph-borne viruses in the draining lymph node

The interstitial fluids in tissues are constantly drained into the lymph nodes (LNs) as lymph through afferent lymphatic vessels and from LNs into the blood through efferent lymphatics. LNs are strategically positioned and have the appropriate cellular composition to serve as sites of adaptive immune initiation against invading pathogens. However, for lymph-borne viruses, which disseminate from the entry site to other tissues through the lymphatic system, immune cells in the draining LN (dLN) also play critical roles in curbing systemic viral dissemination during primary and secondary infections. Lymph-borne viruses in tissues can be transported to dLNs as free virions in the lymph or within infected cells. Regardless of the entry mechanism, infected myeloid antigen-presenting cells, including various subtypes of dendritic cells, inflammatory monocytes, and macrophages, play a critical role in initiating the innate immune response within the dLN. This innate immune response involves cellular crosstalk between infected and bystander innate immune cells that ultimately produce type I interferons (IFN-Is) and other cytokines and recruit inflammatory monocytes and natural killer (NK) cells. IFN-I and NK cell cytotoxicity can restrict systemic viral spread during primary infections and prevent serious disease. Additionally, the memory CD8+ T-cells that reside or rapidly migrate to the dLN can contribute to disease prevention during secondary viral infections. This review explores the intricate innate immune responses orchestrated within dLNs that contain primary viral infections and the role of memory CD8+ T-cells following secondary infection or CD8+ T-cell vaccination.

Standing on Shoulders: Interferon Research From Viral Interference to Lupus Pathogenesis and Treatment

The discovery of interferon in the 1950s represents much more than the identification of the first cytokine and the key mediator of antiviral host defense. Defining the molecular nature and complexity of the type I interferon family, as well as its inducers and molecular mechanisms of action, was the work of investigators working at the highest level and producing insights of great consequence. Current knowledge of receptor-ligand interactions, cell signaling, and transcriptional regulation derives from studies of type I interferon. It is on the shoulders of the giants who produced that knowledge that others stand and have revealed critical mechanisms of the pathogenesis of systemic lupus erythematosus and other autoimmune diseases. The design of novel therapeutics is informed by the advances in investigation of type I interferon, with the potential for important impact on patient management.

IFNα Subtypes in HIV Infection and Immunity

Type I interferons (IFN), immediately triggered following most viral infections, play a pivotal role in direct antiviral immunity and act as a bridge between innate and adaptive immune responses. However, numerous viruses have evolved evasion strategies against IFN responses, prompting the exploration of therapeutic alternatives for viral infections. Within the type I IFN family, 12 IFNα subtypes exist, all binding to the same receptor but displaying significant variations in their biological activities. Currently, clinical treatments for chronic virus infections predominantly rely on a single IFNα subtype (IFNα2a/b). However, the efficacy of this therapeutic treatment is relatively limited, particularly in the context of Human Immunodeficiency Virus (HIV) infection. Recent investigations have delved into alternative IFNα subtypes, identifying certain subtypes as highly potent, and their antiviral and immunomodulatory properties have been extensively characterized. This review consolidates recent findings on the roles of individual IFNα subtypes during HIV and Simian Immunodeficiency Virus (SIV) infections. It encompasses their induction in the context of HIV/SIV infection, their antiretroviral activity, and the diverse regulation of the immune response against HIV by distinct IFNα subtypes. These insights may pave the way for innovative strategies in HIV cure or functional cure studies.

Efficient repair of human genetic defect by CRISPR/Cas9-mediated interlocus gene conversion

DNA double-strand breaks (DSBs) induced by gene-editing tools are primarily repaired through non-homologous end joining (NHEJ) or homology-directed repair (HDR) using synthetic DNA templates. However, error-prone NHEJ may result in unexpected indels at the targeted site. For most genetic disorders, precise HDR correction using exogenous homologous sequence is ideal. But, the therapeutic application of HDR might be especially challenging given the requirement for the codelivery of exogenous DNA templates with toxicity into cells, and the low efficiency of HDR could also limit its clinical application. In this study, we efficiently repair pathogenic mutations in HBB coding regions of hematopoietic stem cells (HSCs) using CRISPR/Cas9-mediated gene conversion (CRISPR/GC) using the paralog gene HBD as the internal template. After transplantation, these edited HSCs successfully repopulate the hematopoietic system and generate erythroid cells with significantly reduced thalassemia propensity. Moreover, a range of pathogenic gene mutations causing β-thalassemia in HBB coding regions were effectively converted to normal wild-type sequences without exogenous DNA templates using CRISPR/GC. This highlights the promising potential of CRISPR/GC, independent of synthetic DNA templates, for genetic disease gene therapy.

Delayed engagement of host defenses enables SARS-CoV-2 viremia and productive infection of distal organs in the hamster model of COVID-19

Clinical presentations that develop in response to infection result from interactions between the pathogen and host defenses. SARS-CoV-2, the etiologic agent of COVID-19, directly antagonizes these defenses, leading to delayed immune engagement in the lungs that materializes only as cells succumb to infection and are phagocytosed. Leveraging the golden hamster model of COVID-19, we sought to understand the dynamics between SARS-CoV-2 infection in the airways and the systemic host response that ensues. We found that early SARS-CoV-2 replication was largely confined to the respiratory tract and olfactory system and, to a lesser extent, the heart and gastrointestinal tract but generated a host antiviral response in every organ as a result of circulating type I and III interferons. Moreover, we showed that diminishing the response in the airways by immunosuppression or administration of SARS-CoV-2 intravenously resulted in decreased immune priming, viremia, and increased viral tropism, including productive infection of the liver, kidney, spleen, and brain. Last, we showed that productive infection of the airways was required for mounting an effective and system-wide antiviral response. Together, these data illustrate how COVID-19 can result in diverse clinical presentations in which disease outcomes can be a by-product of the speed and strength of immune engagement. These studies provide additional evidence for the mechanistic basis of the diverse clinical presentations of COVID-19 and highlight the ability of the respiratory tract to generate a systemic immune defense after pathogen recognition.

Shared and Unique Features of Human Interferon-Beta and Interferon-Alpha Subtypes

Type I interferons (IFN-I) were first discovered as an antiviral factor by Isaacs and Lindenmann in 1957, but they are now known to also modulate innate and adaptive immunity and suppress proliferation of cancer cells. While much has been revealed about IFN-I, it remains a mystery as to why there are 16 different IFN-I gene products, including IFNβ, IFNω, and 12 subtypes of IFNα. Here, we discuss shared and unique aspects of these IFN-I in the context of their evolution, expression patterns, and signaling through their shared heterodimeric receptor. We propose that rather than investigating responses to individual IFN-I, these contexts can serve as an alternative approach toward investigating roles for IFNα subtypes. Finally, we review uses of IFNα and IFNβ as therapeutic agents to suppress chronic viral infections or to treat multiple sclerosis.

Context Is Key: Delineating the Unique Functions of IFNα and IFNβ in Disease

Type I interferons (IFNs) are critical effector cytokines of the immune system and were originally known for their important role in protecting against viral infections; however, they have more recently been shown to play protective or detrimental roles in many disease states. Type I IFNs consist of IFNα, IFNβ, IFNϵ, IFNκ, IFNω, and a few others, and they all signal through a shared receptor to exert a wide range of biological activities, including antiviral, antiproliferative, proapoptotic, and immunomodulatory effects. Though the individual type I IFN subtypes possess overlapping functions, there is growing appreciation that they also have unique properties. In this review, we summarize some of the mechanisms underlying differential expression of and signaling by type I IFNs, and we discuss examples of differential functions of IFNα and IFNβ in models of infectious disease, cancer, and autoimmunity.

Autoantibodies against type I IFNs in patients with life-threatening COVID-19

Interindividual clinical variability in the course of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is vast. We report that at least 101 of 987 patients with life-threatening coronavirus disease 2019 (COVID-19) pneumonia had neutralizing immunoglobulin G (IgG) autoantibodies (auto-Abs) against interferon-ω (IFN-ω) (13 patients), against the 13 types of IFN-α (36), or against both (52) at the onset of critical disease; a few also had auto-Abs against the other three type I IFNs. The auto-Abs neutralize the ability of the corresponding type I IFNs to block SARS-CoV-2 infection in vitro. These auto-Abs were not found in 663 individuals with asymptomatic or mild SARS-CoV-2 infection and were present in only 4 of 1227 healthy individuals. Patients with auto-Abs were aged 25 to 87 years and 95 of the 101 were men. A B cell autoimmune phenocopy of inborn errors of type I IFN immunity accounts for life-threatening COVID-19 pneumonia in at least 2.6% of women and 12.5% of men.

Evolutionary Pattern of Interferon Alpha Genes in Bovidae and Genetic Diversity of IFNAA in the Bovine Genome

Interferons are secretory proteins induced in response to specific extracellular stimuli which stimulate intra- and intercellular networks for regulating innate and acquired immunity, resistance to viral infections, and normal and tumor cell survival and death. Type 1 interferons plays a major role in the CD8 T-cell response to viral infection. The genomic analysis carried out here for type I interferons within Bovidae family shows that cattle, bison, water buffalo, goat, and sheep (all Bovidae), have different number of genes of the different subtypes, with a large increase in the numbers, compared to human and mouse genomes. A phylogenetic analysis of the interferon alpha (IFNA) proteins in this group shows that the genes do not follow the evolutionary pattern of the species, but rather a cycle of duplications and deletions in the different species. In this study we also studied the genetic diversity of the bovine interferon alpha A (IFNAA), as an example of the IFNA genes in cattle, sequencing a fragment of the coding sequence in 18 breeds of cattle from Pakistan, Nigeria and USA. Similarity analysis allowed the allocation of sequences into 22 haplotypes. Bhagnari, Brangus, Sokoto Gudali, and White Fulani, had the highest number of haplotypes, while Angus, Hereford and Nari Master had the least. However, when analyzed by the average haplotype count, Angus, Bhagnari, Hereford, Holstein, Muturu showed the highest values, while Cholistani, Lohani, and Nari Master showed the lowest values. Haplotype 4 was found in the highest number of individuals (74), and in 15 breeds. Sequences for yak, bison, and water buffalo, were included within the bovine haplotypes. Medium Joining network showed that the sequences could be divided into 4 groups: one with highly similar haplotypes containing mostly Asian and African breeds, one with almost all of the Bos taurus American breeds, one mid-diverse group with mostly Asian and African sequences, and one group with highly divergent haplotypes with five N'Dama sequences and one from each of White Fulani, Dhanni, Tharparkar, and Bhagnari. The large genetic diversity found in IFNAA could be a very good indication of the genetic variation among the different genes of IFNA and could be an adaptation for these species in response to viral challenges they face.

Gene conversion generates evolutionary novelty that fuels genetic conflicts

Genetic conflicts arise when the evolutionary interests of two genetic elements are not aligned. Conflicts between genomes (e.g. pathogen versus host) or within the same genome (e.g. internal parasitic DNA sequences versus the rest of the host genome) can both foster 'molecular arms races', in which genes on both sides of the conflict rapidly evolve due to bouts of adaptation and counter-adaptation. Importantly, a source of genetic novelty is needed to fuel these arms races. In this review, we highlight gene conversion as a major force in generating the novel alleles on which selection can act. Using examples from both intergenomic and intragenomic conflicts, we feature the mechanisms by which gene conversion facilitates the rapid evolution of genes in conflict.

Discovery of All Three Types in Cartilaginous Fishes Enables Phylogenetic Resolution of the Origins and Evolution of Interferons

Interferons orchestrate host antiviral responses in jawed vertebrates. They are categorized into three classes; IFN1 and IFN3 are the primary antiviral cytokine lineages, while IFN2 responds to a broader variety of pathogens. The evolutionary relationships within and between these three classes have proven difficult to resolve. Here, we reassess interferon evolution, considering key phylogenetic pitfalls including taxon sampling, alignment quality, model adequacy, and outgroup choice. We reveal that cartilaginous fishes, and hence the jawed vertebrate ancestor, possess(ed) orthologs of all three interferon classes. We show that IFN3 groups sister to IFN1, resolve the origins of the human IFN3 lineages, and find that intronless IFN3s emerged at least three times. IFN2 genes are highly conserved, except for IFN-γ-rel, which we confirm resulted from a teleost-specific duplication. Our analyses show that IFN1 phylogeny is highly sensitive to phylogenetic error. By accounting for this, we describe a new backbone IFN1 phylogeny that implies several IFN1 genes existed in the jawed vertebrate ancestor. One of these is represented by the intronless IFN1s of tetrapods, including mammalian-like repertoires of reptile IFN1s and a subset of amphibian IFN1s, in addition to newly-identified intron-containing shark IFN1 genes. IFN-f, previously only found in teleosts, likely represents another ancestral jawed vertebrate IFN1 family member, suggesting the current classification of fish IFN1s into two groups based on the number of cysteines may need revision. The providence of the remaining fish IFN1s and the coelacanth IFN1s proved difficult to resolve, but they may also be ancestral jawed vertebrate IFN1 lineages. Finally, a large group of amphibian-specific IFN1s falls sister to all other IFN1s and was likely also present in the jawed vertebrate ancestor. Our results verify that intronless IFN1s have evolved multiple times in amphibians and indicate that no one-to-one orthology exists between mammal and reptile IFN1s. Our data also imply that diversification of the multiple IFN1s present in the jawed vertebrate ancestor has occurred through a rapid birth-death process, consistent with functional maintenance over a 450-million-year host-pathogen arms race. In summary, this study reveals a new model of interferon evolution important to our understanding of jawed vertebrate antiviral immunity.

Identification of four type I IFNs from Japanese eel with differential expression properties and Mx promoter inducibility

Type I IFNs are a family of cytokines with antiviral, anti-proliferative and immune-modulatory functions. In this study, four type I IFNs (termed AjIFN1-4) have been cloned from the Japanese eel, Anguilla japonica. The open reading frames of AjIFN1-4 are 552, 534, 546 and 561 bp in length, encoding 183, 177, 181, and 186 amino acids (aa), respectively. Sequence comparison and phylogenetic analysis results revealed that AjIFN1 and AjIFN2 belong to group one (2C-containing) IFNs, while AjIFN3 and AjIFN4 belong to group two (4C-containing) IFNs. Syntenic comparison showed that chromosome block duplication and rearrangement events might have occurred at IFN loci in different teleost lineages. Expression analysis revealed the rapid induction of AjIFNl and AjIFN2 in response to poly I:C stimulation, while AjIFN3 and AjIFN4 were predominantly expressed at later time points. Two Mx promoter reporter assays were conducted to assess the Mx-inducing capability of AjIFN1-4. It is shown that the overexpression of AjIFN1-4 all promoted the luciferase activity of MxB reporter, but the activity of MxC reporter increased only in cells transfected with AjIFN1. Collectively, it is suggested that teleost IFNs were evolved independently in different lineages of fish and may function differently in teleost antiviral immunity.

Evolutional conservation of molecular structure and antiviral function of a type I interferon, IFN-kappa, in poultry

IFN-kappa (IFN-κ) is a type I IFN expressed by keratinocytes, monocytes and dendritic cells with important roles during the innate immune response period. This research was conducted to elaborate the evolution and characteristics of IFN-κ in poultry. Chicken IFN-κ is located on the sex-determining Z chromosome, which is greatly different from mammals. Poultry IFN-κ cluster together in a species-specific manner through positive selection pressure and share only 19-33% homology with mammalian IFN-κ and poultry other type I IFN. Both chicken and duck IFN-κ was constitutively expressed in spleen, skin, lung, and peripheral blood mononuclear cells (PBMC), as well as being significantly induced after treatment with virus in PBMC. Biologically, poultry IFN-κ has antiviral activity against VSV in chicken embryonic fibroblasts and duck embryonic fibroblasts (CEF and DEF) cells, and induces the expression of IFN stimulated genes (ISGs). After treatment with JAK1 inhibitor, the ISGs expression can be down-regulated. Overall, our research on poultry IFN-κ not only enriches the knowledge about IFN-κ but also facilitates further research on the role of type I IFNs in antiviral defense responses in poultry.

Type I Interferons in Autoimmune Disease

Type I interferons, which make up the first cytokine family to be described and are the essential mediators of antivirus host defense, have emerged as central elements in the immunopathology of systemic autoimmune diseases, with systemic lupus erythematosus as the prototype. Lessons from investigation of interferon regulation following virus infection can be applied to lupus, with the conclusion that sustained production of type I interferon shifts nearly all components of the immune system toward pathologic functions that result in tissue damage and disease. We review recent data, mainly from studies of patients with systemic lupus erythematosus, that provide new insights into the mechanisms of induction and the immunologic consequences of chronic activation of the type I interferon pathway. Current concepts implicate endogenous nucleic acids, driving both cytosolic sensors and endosomal Toll-like receptors, in interferon pathway activation and suggest targets for development of novel therapeutics that may restore the immune system to health.

Nearly neutral evolution in IFNL3 gene retains the immune function to detect and clear the viral infection in HCV

IFNL3 gene plays a crucial role in immune defense against viruses. It induces the interferon stimulated genes (ISGs) with antiviral properties by activating the JAK-STAT pathway. In this study, we investigated the evolutionary force involved in shaping the IFNL3 gene to perform its downstream function as a regulatory gene in HCV clearance. We have selected 25 IFNL3 coding sequences with human gene as a reference sequence and constructed a phylogeny. Furthermore, rate of variation, substitution saturation test, phylogenetic informativeness and differential selection were also analysed. The codon evolution result suggests that nearly neutral mutation is the key pattern in shaping the IFNL3 evolution. The results were validated by subjecting the human IFNL3 protein variants to that of the native through a molecular dynamics simulation study. The molecular dynamics simulation clearly depicts the negative impact on the reported variants in human IFNL3 protein. However, these detrimental mutations (R157Q and R157W) were shown to be negatively selected in the evolutionary study of the mammals. Hence, the variation revealed a mild impact on the IFNL3 function and may be removed from the population through negative selection due to its high functional constraints. In a nutshell, our study may contribute the overall evidence in phylotyping and structural transformation that takes place in the non-synonymous substitutions of IFNL3 protein. Substantially, our obtained theoretical knowledge will lay the path to extend the experimental validation in HCV clearance.

Interferon α subtypes in HIV infection

Type I interferons (IFN), which are immediately induced after most virus infections, are central for direct antiviral immunity and link innate and adaptive immune responses. However, several viruses have evolved strategies to evade the IFN response by preventing IFN induction or blocking IFN signaling pathways. Thus, therapeutic application of exogenous type I IFN or agonists inducing type I IFN responses are a considerable option for future immunotherapies against chronic viral infections. An important part of the type I IFN family are 12 IFNα subtypes, which all bind the same receptor, but significantly differ in their biological activities. Up to date only one IFNα subtype (IFNα2) is being used in clinical treatment against chronic virus infections, however its therapeutic success rate is rather limited, especially during Human Immunodeficiency Virus (HIV) infection. Recent studies addressed the important question if other IFNα subtypes would be more potent against retroviral infections in in vitro and in vivo experiments. Indeed, very potent IFNα subtypes were defined and their antiviral and immunomodulatory properties were characterized. In this review we summarize the recent findings on the role of individual IFNα subtypes during HIV and Simian Immunodeficiency Virus infection. This includes their induction during HIV/SIV infection, their antiretroviral activity and the regulation of immune response against HIV by different IFNα subtypes. The findings might facilitate novel strategies for HIV cure or functional cure studies.

A Biomolecular Network Driven Proteinic Interaction in HCV Clearance

Hepatitis C virus infection causes chronic liver disease that leads to cancer-related mortality. Presently around 30% of the HCV (infected) affected population get rid of the infection through spontaneous disease clearance. This phenomenon is conducted by a set of reported immune candidate genes. Hence, this study focuses only on these immune-response related genes with aid of network approach, where the idea is to disseminate the network for better understanding of key functional genes and their transcription control activity. Based on the network analysis the IFNG, TNF, IFNB1, STAT1, NFKB1, STAT3, SOCS1, and MYD88 genes are prioritized as hub genes along with their common transcription factors (TFs), IRF9, NFKB1, and STAT1. The dinucleotide frequency of TF binding elements indicated GG-rich motifs in these regulatory elements. On the other hand, gene enrichment report suggests the regulation of response to interferon gamma signaling pathway, which plays central role in the spontaneous HCV clearance. Therefore, our study tends to prioritize the genes, TFs, and their regulatory pathway towards HCV clearance. Even so, the resultant hub genes and their TFs and TF binding elements could be crucial in underscoring the clearance activity in specific populations.

Type I interferons in the pathogenesis and treatment of canine diseases

Type I interferons (IFNs) such as IFN-α, IFN-β, IFN-ε, IFN-κ, and IFN-ω represent cytokines, which are deeply involved in the regulation and activation of innate and adaptive immune responses. They possess strong antiviral, antiproliferative, and immunomodulatory activities allowing their use in the therapy of different viral diseases, neoplasms, and immune-mediated disorders, respectively. Initially, treatment strategies were based on nonspecific inducers of type I IFNs, which were soon replaced by different recombinant proteins. Drugs with type I IFNs as active agents are currently used in the treatment of hepatitis B and C virus infection, lymphoma, myeloid leukemia, renal carcinoma, malignant melanoma, and multiple sclerosis in humans. In addition, recombinant feline IFN-ω has been approved for the treatment of canine parvovirus, feline leukemia virus, and feline immunodeficiency virus infections. However, the role of type I IFNs in the pathogenesis of canine diseases remains largely undetermined so far, even though some share pathogenic mechanisms and clinical features with their human counterparts. This review summarizes the present knowledge of type I IFNs and down-stream targets such as Mx and 2',5'-oligoadenylate synthetase proteins in the pathogenesis of infectious and immune-mediated canine diseases. Moreover, studies investigating the potential use of type I IFNs in the treatment of canine lymphomas, melanomas, sarcomas, and carcinomas, canine distemper virus, parvovirus, and papillomavirus infections as well as immune-mediated keratoconjunctivitis sicca and atopic dermatitis are presented. A separate chapter is dedicated to the therapeutic potential of IFN-λ, a type III IFN, in canine diseases. However, further future studies are still needed to unravel the exact functions of the different subtypes of type I IFNs and their target genes in healthy and diseased dogs and the full potential action of type I IFNs as treatment strategy.

Characterization of genome-wide segmental duplications reveals a common genomic feature of association with immunity among domestic animals

BACKGROUND

Segmental duplications (SDs) commonly exist in plant and animal genomes, playing crucial roles in genomic rearrangement, gene innovation and the formation of copy number variants. However, they have received little attention in most livestock species.

RESULTS

Aiming at characterizing SDs across the genomes of diverse livestock species, we mapped genome-wide SDs of horse, rabbit, goat, sheep and chicken, and also enhanced the existing SD maps of cattle and pig genomes based on the most updated genome assemblies. We adopted two different detection strategies, whole genome analysis comparison and whole genome shotgun sequence detection, to pursue more convincing findings. Accordingly we identified SDs for each species with the length of from 21.7 Mb to 164.1 Mb, and 807 to 4,560 genes were harboured within the SD regions across different species. More interestingly, many of these SD-related genes were involved in the process of immunity and response to external stimuli. We also found the existence of 59 common genes within SD regions in all studied species except goat. These common genes mainly consisted of both UDP glucuronosyltransferase and Interferon alpha families, implying the connection between SDs and the evolution of these gene families.

CONCLUSIONS

Our findings provide insights into livestock genome evolution and offer rich genomic sources for livestock genomic research.

Evolution-guided functional analyses reveal diverse antiviral specificities encoded by IFIT1 genes in mammals

IFIT (interferon-induced with tetratricopeptide repeats) proteins are critical mediators of mammalian innate antiviral immunity. Mouse IFIT1 selectively inhibits viruses that lack 2'O-methylation of their mRNA 5' caps. Surprisingly, human IFIT1 does not share this antiviral specificity. Here, we resolve this discrepancy by demonstrating that human and mouse IFIT1 have evolved distinct functions using a combination of evolutionary, genetic and virological analyses. First, we show that human IFIT1 and mouse IFIT1 (renamed IFIT1B) are not orthologs, but are paralogs that diverged >100 mya. Second, using a yeast genetic assay, we show that IFIT1 and IFIT1B proteins differ in their ability to be suppressed by a cap 2'O-methyltransferase. Finally, we demonstrate that IFIT1 and IFIT1B have divergent antiviral specificities, including the discovery that only IFIT1 proteins inhibit a virus encoding a cap 2'O-methyltransferase. These functional data, combined with widespread turnover of mammalian IFIT genes, reveal dramatic species-specific differences in IFIT-mediated antiviral repertoires.

Conservation and Innovation of APOBEC3A Restriction Functions during Primate Evolution

LINE-1 (long interspersed element-1) retroelements are the only active autonomous endogenous retroelements in human genomes. Their retrotransposition activity has created close to 50% of the current human genome. Due to the apparent costs of this proliferation, host genomes have evolved multiple mechanisms to curb LINE-1 retrotransposition. Here, we investigate the evolution and function of the LINE-1 restriction factor APOBEC3A, a member of the APOBEC3 cytidine deaminase gene family. We find that APOBEC3A genes have evolved rapidly under diversifying selection in primates, suggesting changes in APOBEC3A have been recurrently selected in a host-pathogen "arms race." Nonetheless, in contrast to previous reports, we find that the LINE-1 restriction activity of APOBEC3A proteins has been strictly conserved throughout simian primate evolution in spite of its pervasive diversifying selection. Based on these results, we conclude that LINE-1s have not driven the rapid evolution of APOBEC3A in primates. In contrast to this conserved LINE-1 restriction, we find that a subset of primate APOBEC3A genes have enhanced antiviral restriction. We trace this gain of antiviral restriction in APOBEC3A to the common ancestor of a subset of Old World monkeys. Thus, APOBEC3A has not only maintained its LINE-1 restriction ability, but also evolved a gain of antiviral specificity against other pathogens. Our findings suggest that while APOBEC3A has evolved to restrict additional pathogens, only those adaptive amino acid changes that leave LINE-1 restriction unperturbed have been tolerated.

The type I interferons: Basic concepts and clinical relevance in immune-mediated inflammatory diseases

There is increasing scientific and clinical interest in elucidating the biology of type I Interferons, which began approximately 60 years ago with the concept of "viral interference", a property that reduces the ability of a virus to infect cells. Although our understanding of the multiple cellular and molecular functions of interferons has advanced significantly, much remains to be learned and type I Interferons remain an active and fascinating area of inquiry. In this review, we cover some general aspects of type I interferon genes, with emphasis on interferon-alpha, and various aspects of molecular mechanisms triggered by type I interferons and toll-like receptor signaling by the Janus activated kinase/signal transducer activation of transcription (JAK-STAT) pathway and interferon regulatory factor pathway. We will also describe the role of type I interferons in autoimmune and inflammatory diseases, and its potential use as therapeutic agent.

IFNA2: The prototypic human alpha interferon

The human interferon α2 (IFNα2) was the first highly active IFN subtype to be cloned in the early eighties. It was also the first IFN and the first cytokine to be produced and commercialized by the pharmaceutical industry. Ipso facto it became the favorite IFNα subtype for academic researchers. For this fortunate reason IFNα2 has been at the origin of most discoveries related to the mechanism of action of type I interferons.

Cut, copy, move, delete: The study of human interferon genes reveal multiple mechanisms underlying their evolution in amniotes

Interferons (IFNs) are rapidly evolving cytokines released when viral infections are detected in cells. Previous research suggests that genes encoding IFNs and their receptors duplicated extensively throughout vertebrate evolution. We present molecular genetic evidence that supports the use of nonallelic homologous recombination (NAHR) to expand select IFN genes during amniote evolution. The duplication of long regions of genome (encompassing at least one functional IFN gene) followed by the insertion of this genome fragment near its parent's location, is commonly observed in many amniote genomes. Duplicates inserted away from duplication hotspots are not as frequently perturbed with new duplicates, and tend to survive long periods of evolution, sometimes becoming new IFN subtypes. Although most duplicates are inserted parallel to and near the original sequence, the insertion of the Kelch-like 9 gene within the Type I IFN locus of placental mammals promoted antiparallel insertion of gene duplicates between the Kelch-like 9 and IFN-ε loci. Genetic exchange between highly similar Type I gene duplicates as well as between Type III IFN gene duplicates homogenized their diversification. Oddly, Type III IFN genes migrated long distances throughout the genome more frequently than did Type I IFN genes. The inter-chromosomal movement of Type I IFN genes in amniotes correlated with complete intron loss in their gene structure, and repeatedly occurred with occasional Type III IFN genes.

Interferons and Their Receptors in Birds: A Comparison of Gene Structure, Phylogenetic Analysis, and Cross Modulation

Interferon may be thought of as a key, with the interferon receptor as the signal lock: Crosstalk between them maintains their balance during viral infection. In this review, the protein structure of avian interferon and the interferon receptor are discussed, indicating remarkable similarity between different species. However, the structures of the interferon receptors are more sophisticated than those of the interferons, suggesting that the interferon receptor is a more complicated signal lock system and has considerable diversity in subtypes or structures. Preliminary evolutionary analysis showed that the subunits of the interferon receptor formed a distinct clade, and the orthologs may be derived from the same ancestor. Furthermore, the development of interferons and interferon receptors in birds may be related to an animal’s age and the maintenance of a balanced state. In addition, the equilibrium between interferon and its receptor during pathological and physiological states revealed that the virus and the host influence this equilibrium. Birds could represent an important model for studies on interferon’s antiviral activities and may provide the basis for new antiviral strategies.

Cloning, expression and antiviral bioactivity of red-crowned crane interferon-α

Interferon-α (IFN-α) genes have been cloned from a variety of animals, but information regarding crane IFN-α has not been reported to date. In this study, we cloned a full-length Red-crowned Crane interferon-α (crIFN-α) gene sequence consisting of a 486bp partial 5' UTR, 741bp complete ORF and 559bp partial 3' UTR. This gene encodes a protein of 246 amino acids and shares 60 to 80% identity with avian IFN-α and less than 45% identity with mammalian IFN-α. The expression of crIFN-α with an N-terminal His-tag was investigated in Escherichia coli, and the protein was purified on a nickel column. To obtain activated proteins, crIFN-α inclusion bodies were renatured by dialysis. In vitro cytopathic inhibition assays indicated that the recombinant crIFN-α could inhibit the replication of vesicular stomatitis virus in chicken fibroblasts. These antiviral activities were abrogated by rabbit anti-crIFN-α antibodies in vitro. In addition, an immunofluorescence assay indicated that crIFN-α could be expressed in chicken fibroblasts and was primarily located in the cytoplasm. Taken together, our results suggest that the crIFN-α gene may play an important role in inhibiting the replication of viruses.

Lineage-specific expansion of IFIT gene family: an insight into coevolution with IFN gene family

In mammals, IFIT (Interferon [IFN]-induced proteins with Tetratricopeptide Repeat [TPR] motifs) family genes are involved in many cellular and viral processes, which are tightly related to mammalian IFN response. However, little is known about non-mammalian IFIT genes. In the present study, IFIT genes are identified in the genome databases from the jawed vertebrates including the cartilaginous elephant shark but not from non-vertebrates such as lancelet, sea squirt and acorn worm, suggesting that IFIT gene family originates from a vertebrate ancestor about 450 million years ago. IFIT family genes show conserved gene structure and gene arrangements. Phylogenetic analyses reveal that this gene family has expanded through lineage-specific and species-specific gene duplication. Interestingly, IFN gene family seem to share a common ancestor and a similar evolutionary mechanism; the function link of IFIT genes to IFN response is present early since the origin of both gene families, as evidenced by the finding that zebrafish IFIT genes are upregulated by fish IFNs, poly(I:C) and two transcription factors IRF3/IRF7, likely via the IFN-stimulated response elements (ISRE) within the promoters of vertebrate IFIT family genes. These coevolution features creates functional association of both family genes to fulfill a common biological process, which is likely selected by viral infection during evolution of vertebrates. Our results are helpful for understanding of evolution of vertebrate IFN system.

Genomic analysis and mRNA expression of equine type I interferon genes

This study aimed at identifying all of the type I interferon (IFN) genes of the horse and at monitoring their expression in equine cells on in vitro induction. We identified 32 putative type I IFN loci on horse chromosome 23 and an unplaced genomic scaffold. A phylogentic analysis characterized these into 8 different type I IFN classes, that is, putative functional genes for 6 IFN-α, 4 IFN-β, 8 IFN-ω (plus 4 pseudogenes), 3 IFN-δ (plus 1 pseudogene), 1 IFN-κ and 1 IFN-ε, plus 1 IFN-ν pseudogene, and 3 loci belonging to what has previously been called IFN-αω. Our analyses indicate that the IFN-αω genes are quite distinct from both IFN-α and IFN-ω, and we refer to this type I IFN as IFN-μ. Results from cell cultures showed that leukocytes readily expressed IFN-α, IFN-β, IFN-δ, IFN-μ, and IFN-ω mRNA on induction with, for example, live virus; while fibroblasts only expressed IFN-β mRNA on stimulation. IFN-κ or IFN-ε expression was not consistently induced in these cell cultures. Thus, the equine type I IFN family comprised 8 classes, 7 of which had putative functional genes, and mRNA expression of 5 was induced in vitro. Moreover, a relatively low number of IFN-α subtypes was found in the horse compared with other eutherian mammals.

Distinct evolution process among type I interferon in mammals

Interferon (IFN) is thought to play an important role in the vertebrate immune system, but systemic knowledge of IFN evolution has yet to be elucidated. To evaluate the phylogenic distribution and evolutionary history of type I IFNs, 13genomes were searched using BLASTn program, and a phylogenetic tree of vertebrate type I IFNs was constructed. In the present study, an IFNδ-like gene in the human genome was identified, refuting the concept that humans have no IFNδ genes, and other mammalian IFN genes were also identified. In the phylogenetic tree, the mammalian IFNβ, IFNɛ, and IFNκ formed a clade separate from the other mammalian type I IFNs, while piscine and avian IFNs formed distinct clades. Based on this phylogenetic analysis and the various characteristics of type I IFNs, the evolutionary history of type I IFNs was further evaluated. Our data indicate that an ancestral IFNα-like gene forms a core from which new IFNs divided during vertebrate evolution. In addition, the data suggest how the other type I IFNs evolved from IFNα and shaped the complex type I IFN system. The promoters of type I IFNs were conserved among different mammals, as well as their genic regions. However, the intergenic regions of type I IFN clusters were not conserved among different mammals, demonstrating a high selection pressure upon type I IFNs during their evolution.

HIV downregulates interferon-stimulated genes in primary macrophages

HIV is able to outpace the innate immune response, including that mediated by interferon (IFN), to establish a productive infection. Primary macrophages, however, may be protected from HIV infection by treatment with type I IFN before virus exposure. The ability of HIV to modulate the type I IFN-mediated innate immune response when it encounters a cell that has already been exposed to IFN remains poorly defined. The optimal pretreatment time (12 h) and the most potent HIV-inhibitors (e.g., IFN-α2 and -ω) were identified to investigate the ability of HIV to modulate an established type I IFN response. Gene expression at the level of the entire transcriptome was then compared between primary macrophages treated with type I IFNs, as opposed to treated with IFNs and then infected with HIV. Although HIV was not able to establish a robust infection, the virus was able to downregulate a number of IFN-stimulated genes (ISGs) with a fold change greater than 1.5 (i.e., AXL, IFI27, IFI44, IFI44L, ISG15, OAS1, OAS3, and XAF1). The downregulation of OAS1 by the presence of HIV was confirmed by real-time quantitative polymerase chain reaction. In conclusion, even though HIV replication is significantly inhibited by IFN pretreatment, the virus is able to downregulate the transcription of known antiviral ISGs (e.g., IFI44, ISG15, and OAS1).

Expression profiles of human interferon-alpha and interferon-lambda subtypes are ligand- and cell-dependent

Recent genome-wide association studies suggest distinct roles for 12 human interferon-alpha (IFN-α) and 3 IFN-λ subtypes that may be elucidated by defining the expression patterns of these sets of genes. To overcome the impediment of high homology among each of the sets, we designed a quantitative real-time PCR assay that incorporates the use of molecular beacon and locked nucleic acid (LNA) probes, and in some instances, LNA oligonucleotide inhibitors. We then measured IFN subtype expression by human peripheral blood mononuclear cells and by purified monocytes, myeloid dendritic cells (mDC), plasmacytoid dendritic cells (pDC), and monocyte-derived macrophages (MDM), and -dendritic cells (MDDC) in response to poly I:C, lipopolysaccharide (LPS), imiquimod and CpG oligonucleotides. We found that in response to poly I:C and LPS, monocytes, MDM and MDDC express a subtype pattern restricted primarily to IFN-β and IFN-λ1. In addition, while CpG elicited expression of all type I IFN subtypes by pDC, imiquimod did not. Furthermore, MDM and mDC highly express IFN-λ, and the subtypes of IFN-λ are expressed hierarchically in the order IFN-λ1 followed by IFN-λ2, and then IFN-λ3. These data support a model of coordinated cell- and ligand-specific expression of types I and III IFN. Defining IFN subtype expression profiles in a variety of contexts may elucidate specific roles for IFN subtypes as protective, therapeutic or pathogenic mediators.

High-throughput quantitative real-time polymerase chain reaction array for absolute and relative quantification of rhesus macaque types I, II, and III interferon and their subtypes

Rhesus macaques provide a valuable research and preclinical model for cancer and infectious diseases, as nonhuman primates share immune pathways with humans. Interferons (IFNs) are key cytokines in both innate and adaptive immunity, so a detailed analysis of gene expression in peripheral blood and tissues may shed insight into immune responses. Macaques have 18 IFN genes, of which 14 encode for 13 distinct IFN-α subtypes, and one for IFN-β. Here, we developed a high-throughput array to evaluate each of the IFN-α subtypes, as well as IFN-β, IFN-γ and 2 subtypes of IFN-λ. With this array, expression of each IFN species may be quantified as relative to a reference (housekeeping) gene (ΔCq) or fitted to its own 4-point standard curve for absolute quantification (copy number per mass unit RNA). After validating the assay with IFN complementary DNA, we determined the IFN expression profile of peripheral blood mononuclear cells from 3 rhesus macaques in response to TLR agonists, and demonstrated that the profiles are consistent among animals. Furthermore, because the IFN expression profiles differ depending on the TLR stimuli, they suggest different biological functions for many of the IFN species measured, including individual subtypes of IFN-α.

Recruitment of histone deacetylase 3 to the interferon-A gene promoters attenuates interferon expression

BACKGROUND

Induction of Type I Interferon (IFN) genes constitutes an essential step leading to innate immune responses during virus infection. Sendai virus (SeV) infection of B lymphoid Namalwa cells transiently induces the transcriptional expression of multiple IFN-A genes. Although transcriptional activation of IFN-A genes has been extensively studied, the mechanism responsible for the attenuation of their expression remains to be determined.

PRINCIPAL FINDINGS

In this study, we demonstrate that virus infection of Namalwa cells induces transient recruitment of HDAC3 (histone deacetylase 3) to IFN-A promoters. Analysis of chromatin-protein association by Chip-QPCR demonstrated that recruitment of interferon regulatory factor (IRF)3 and IRF7, as well as TBP correlated with enhanced histone H3K9 and H3K14 acetylation, whereas recruitment of HDAC3 correlated with inhibition of histone H3K9/K14 acetylation, removal of IRF7 and TATA-binding protein (TBP) from IFN-A promoters and inhibition of virus-induced IFN-A gene transcription. Additionally, HDAC3 overexpression reduced, and HDAC3 depletion by siRNA enhanced IFN-A gene expression. Furthermore, activation of IRF7 enhanced histone H3K9/K14 acetylation and IFN-A gene expression, whereas activation of both IRF7 and IRF3 led to recruitment of HDAC3 to the IFN-A gene promoters, resulting in impaired histone H3K9 acetylation and attenuation of IFN-A gene transcription.

CONCLUSION

Altogether these data indicate that reversal of histone H3K9/K14 acetylation by HDAC3 is required for attenuation of IFN-A gene transcription during viral infection.

Revealing mammalian evolutionary relationships by comparative analysis of gene clusters

Many software tools for comparative analysis of genomic sequence data have been released in recent decades. Despite this, it remains challenging to determine evolutionary relationships in gene clusters due to their complex histories involving duplications, deletions, inversions, and conversions. One concept describing these relationships is orthology. Orthologs derive from a common ancestor by speciation, in contrast to paralogs, which derive from duplication. Discriminating orthologs from paralogs is a necessary step in most multispecies sequence analyses, but doing so accurately is impeded by the occurrence of gene conversion events. We propose a refined method of orthology assignment based on two paradigms for interpreting its definition: by genomic context or by sequence content. X-orthology (based on context) traces orthology resulting from speciation and duplication only, while N-orthology (based on content) includes the influence of conversion events. We developed a computational method for automatically mapping both types of orthology on a per-nucleotide basis in gene cluster regions studied by comparative sequencing, and we make this mapping accessible by visualizing the output. All of these steps are incorporated into our newly extended CHAP 2 package. We evaluate our method using both simulated data and real gene clusters (including the well-characterized α-globin and β-globin clusters). We also illustrate use of CHAP 2 by analyzing four more loci: CCL (chemokine ligand), IFN (interferon), CYP2abf (part of cytochrome P450 family 2), and KIR (killer cell immunoglobulin-like receptors). These new methods facilitate and extend our understanding of evolution at these and other loci by adding automated accurate evolutionary inference to the biologist's toolkit. The CHAP 2 package is freely available from http://www.bx.psu.edu/miller_lab.

Evolutionary genetic dissection of human interferons

As revealed by population genetic analyses, different human interferon genes evolved under distinct selective constraints and signatures of positive selection vary according to geographic region, suggesting that some sequence changes may have conferred an advantage by increasing resistance to viral infection.

Interferons (IFNs) are cytokines that play a key role in innate and adaptive immune responses. Despite the large number of immunological studies of these molecules, the relative contributions of the numerous IFNs to human survival remain largely unknown. Here, we evaluated the extent to which natural selection has targeted the human IFNs and their receptors, to provide insight into the mechanisms that govern host defense in the natural setting. We found that some IFN-α subtypes, such as IFN-α6, IFN-α8, IFN-α13, and IFN-α14, as well as the type II IFN-γ, have evolved under strong purifying selection, attesting to their essential and nonredundant function in immunity to infection. Conversely, selective constraints have been relaxed for other type I IFNs, particularly for IFN-α10 and IFN-ε, which have accumulated missense or nonsense mutations at high frequencies within the population, suggesting redundancy in host defense. Finally, type III IFNs display geographically restricted signatures of positive selection in European and Asian populations, indicating that genetic variation at these genes has conferred a selective advantage to the host, most likely by increasing resistance to viral infection. Our population genetic analyses show that IFNs differ widely in their biological relevance, and highlight evolutionarily important determinants of host immune responsiveness.

The early interferon alpha subtype response in infant macaques infected orally with SIV

Type I interferons play an important role in the early defense against viral and other pathogens. These innate responses are also critically important in shaping the subsequent adaptive response. Thus, a more thorough knowledge of innate response types and mechanisms will improve our understanding of pathogenesis and guide the development of new therapeutics. Interferon alpha (IFN-alpha) is used clinically in the treatment of HIV and hepatitis C infections. The majority of IFA-alpha therapy is based on a single IFN-alpha subtype, IFN-alpha2. However, IFN-alpha comprises a family of multiple subtypes. The biologic functions of the distinct subtypes and how they relate to disease are poorly understood. The current study developed the tools to distinguish and measure multiple IFN-alpha subtypes on the mRNA level in rhesus macaques that are used widely as an important animal model for human diseases. We were able to identify and measure nine distinct rhesus IFN-alpha subtypes. Furthermore, we could demonstrate that in response to oral pathogenic SIV infection, several IFN-alpha subtypes are rapidly induced in lymphoid but not at oral and gastrointestinal mucosal surfaces. Although each IFN-alpha subtype was induced at distinct levels, their relative expression patterns were identical in all lymphoid tissues examined.

Type I interferon in organ-targeted autoimmune and inflammatory diseases

A significant role for IFNα in the pathogenesis of systemic lupus erythematosus is well supported, and clinical trials of anti-IFNα monoclonal antibodies are in progress in this disease. In other autoimmune diseases characterized by substantial inflammation and tissue destruction, the role of type I interferons is less clear. Gene expression analysis of peripheral blood cells from patients with rheumatoid arthritis and multiple sclerosis demonstrate an interferon signature similar to but less intense than that seen in patients with lupus. In both of those diseases, presence of the interferon signature has been associated with more significant clinical manifestations. At the same time, evidence supports an anti-inflammatory and beneficial role of IFNβ locally in the joints of patients with rheumatoid arthritis and in murine arthritis models, and many patients with multiple sclerosis show a clinical response to recombinant IFNβ. As can also be proposed for type I diabetes mellitus, type I interferon appears to contribute to the development of autoimmunity and disease progression in multiple autoimmune diseases, while maintaining some capacity to control established disease - particularly at local sites of inflammation. Recent studies in both rheumatoid arthritis and multiple sclerosis suggest that quantification of type I interferon activity or target gene expression might be informative in predicting responses to distinct classes of therapeutic agents.

Chiropteran types I and II interferon genes inferred from genome sequencing traces by a statistical gene-family assembler

Background

The rate of emergence of human pathogens is steadily increasing; most of these novel agents originate in wildlife. Bats, remarkably, are the natural reservoirs of many of the most pathogenic viruses in humans. There are two bat genome projects currently underway, a circumstance that promises to speed the discovery host factors important in the coevolution of bats with their viruses. These genomes, however, are not yet assembled and one of them will provide only low coverage, making the inference of most genes of immunological interest error-prone. Many more wildlife genome projects are underway and intend to provide only shallow coverage.

Results

We have developed a statistical method for the assembly of gene families from partial genomes. The method takes full advantage of the quality scores generated by base-calling software, incorporating them into a complete probabilistic error model, to overcome the limitation inherent in the inference of gene family members from partial sequence information. We validated the method by inferring the human IFNA genes from the genome trace archives, and used it to infer 61 type-I interferon genes, and single type-II interferon genes in the bats Pteropus vampyrus and Myotis lucifugus. We confirmed our inferences by direct cloning and sequencing of IFNA, IFNB, IFND, and IFNK in P. vampyrus, and by demonstrating transcription of some of the inferred genes by known interferon-inducing stimuli.

Conclusion

The statistical trace assembler described here provides a reliable method for extracting information from the many available and forthcoming partial or shallow genome sequencing projects, thereby facilitating the study of a wider variety of organisms with ecological and biomedical significance to humans than would otherwise be possible.

Positive selection of the bat interferon alpha gene family

Type I interferons (IFNs) are produced by leukocytes in reaction to pathogenic infection and function as positive mediators in antiviral pathways. Among IFNs, IFN alpha (IFNA) has the largest number of family members and plays an important role against the invasion of pathogens. Bats are putative and proven vectors for numerous viruses; however, the evolution of the IFNA family in bats has not been addressed. Here, we construct a phylogeny of IFNA families, including one fruit bat (Dobsonia viridis), with other vertebrates as references. Site-model estimation reveals that positive selection has shaped bat IFNA genes, showing that positive selection drives the evolution of bat IFNA genes.

Genomic organization and molecular phylogenies of the beta (beta) keratin multigene family in the chicken (Gallus gallus) and zebra finch (Taeniopygia guttata): implications for feather evolution

BACKGROUND

The epidermal appendages of reptiles and birds are constructed of beta (beta) keratins. The molecular phylogeny of these keratins is important to understanding the evolutionary origin of these appendages, especially feathers. Knowing that the crocodilian beta-keratin genes are closely related to those of birds, the published genomes of the chicken and zebra finch provide an opportunity not only to compare the genomic organization of their beta-keratins, but to study their molecular evolution in archosaurians.

RESULTS

The subfamilies (claw, feather, feather-like, and scale) of beta-keratin genes are clustered in the same 5' to 3' order on microchromosome 25 in chicken and zebra finch, although the number of claw and feather genes differs between the species. Molecular phylogenies show that the monophyletic scale genes are the basal group within birds and that the monophyletic avian claw genes form the basal group to all feather and feather-like genes. Both species have a number of feather clades on microchromosome 27 that form monophyletic groups. An additional monophyletic cluster of feather genes exist on macrochromosome 2 for each species. Expression sequence tag analysis for the chicken demonstrates that all feather beta-keratin clades are expressed.

CONCLUSIONS

Similarity in the overall genomic organization of beta-keratins in Galliformes and Passeriformes suggests similar organization in all Neognathae birds, and perhaps in the ancestral lineages leading to modern birds, such as the paravian Anchiornis huxleyi. Phylogenetic analyses demonstrate that evolution of archosaurian epidermal appendages in the lineage leading to birds was accompanied by duplication and divergence of an ancestral beta-keratin gene cluster. As morphological diversification of epidermal appendages occurred and the beta-keratin multigene family expanded, novel beta-keratin genes were selected for novel functions within appendages such as feathers.

Interferon-alpha: a therapeutic target in systemic lupus erythematosus

The long history of elevated interferon (IFN)-alpha in association with disease activity in patients who have systemic lupus erythematosus (SLE) has assumed high significance in the past decade, with accumulating data strongly supporting broad activation of the type I IFN pathway in cells of patients who have lupus, and association of IFN pathway activation with significant clinical manifestations of SLE and increased disease activity based on validated measures. In addition, a convincing association of IFN pathway activation with the presence of autoantibodies specific for RNA-binding proteins has contributed to delineation of an important role for Toll-like receptor activation by RNA-containing immune complexes in amplifying innate immune system activation and IFN pathway activation. Although the primary triggers of SLE and the IFN pathway remain undefined, rapid progress in lupus genetics is helping define lupus-associated genetic variants with a functional relationship to IFN production or response in patients. Together, the explosion of data and understanding related to the IFN pathway in SLE have readied the lupus community for translation of those insights to improved patient care. Patience will be needed to allow collection of clinical data and biologic specimens across multiple clinical centers required to support testing of IFN activity, IFN-inducible gene expression and chemokine gene products as candidate biomarkers. Meanwhile, promising clinical trials are moving forward to test the safety and efficacy of monoclonal antibody inhibitors of IFN-alpha. Other therapeutic approaches to target the IFN pathway may follow close behind.

Analysis of recent segmental duplications in the bovine genome

BACKGROUND

Duplicated sequences are an important source of gene innovation and structural variation within mammalian genomes. We performed the first systematic and genome-wide analysis of segmental duplications in the modern domesticated cattle (Bos taurus). Using two distinct computational analyses, we estimated that 3.1% (94.4 Mb) of the bovine genome consists of recently duplicated sequences (>or= 1 kb in length, >or= 90% sequence identity). Similar to other mammalian draft assemblies, almost half (47% of 94.4 Mb) of these sequences have not been assigned to cattle chromosomes.

RESULTS

In this study, we provide the first experimental validation large duplications and briefly compared their distribution on two independent bovine genome assemblies using fluorescent in situ hybridization (FISH). Our analyses suggest that the (75-90%) of segmental duplications are organized into local tandem duplication clusters. Along with rodents and carnivores, these results now confidently establish tandem duplications as the most likely mammalian archetypical organization, in contrast to humans and great ape species which show a preponderance of interspersed duplications. A cross-species survey of duplicated genes and gene families indicated that duplication, positive selection and gene conversion have shaped primates, rodents, carnivores and ruminants to different degrees for their speciation and adaptation. We identified that bovine segmental duplications corresponding to genes are significantly enriched for specific biological functions such as immunity, digestion, lactation and reproduction.

CONCLUSION

Our results suggest that in most mammalian lineages segmental duplications are organized in a tandem configuration. Segmental duplications remain problematic for genome and assembly and we highlight genic regions that require higher quality sequence characterization. This study provides insights into mammalian genome evolution and generates a valuable resource for cattle genomics research.

IFN-alpha expression and antiviral effects are subtype and cell type specific in the cardiac response to viral infection

The interferon-beta (IFN-beta) response is critical for protection against viral myocarditis in several mouse models, and IFN-alpha or -beta treatment is beneficial against human viral myocarditis. The IFN-beta response in cardiac myocytes and cardiac fibroblasts forms an integrated network for organ protection; however, the different IFN-alpha subtypes have not been studied in cardiac cells. We developed a quantitative RT-PCR assay that distinguishes between 13 highly conserved IFN-alpha subtypes and found that reovirus T3D induces five IFN-alpha subtypes in primary cardiac myocyte and fibroblast cultures: IFN-alpha1, -alpha2, -alpha4, -alpha5, and -alpha8/6. Murine IFN-alpha1, -alpha2, -alpha4, or -alpha5 treatment induced IRF7 and ISG56 and inhibited reovirus T3D replication in both cell types. This first investigation of IFN-alpha subtypes in cardiac cells for any virus demonstrates that IFN-alpha is induced in cardiac cells, that it is both subtype and cell type specific, and that it is likely important in the antiviral cardiac response.