Differential effects of the type I interferons alpha4, beta, and epsilon on antiviral activity and vaccine efficacy

Interferon-ε as potential inhibitor of Chlamydia trachomatis infection

Chlamydia trachomatis, the main cause of bacterial sexually transmitted diseases, is responsible for severe reproductive sequelae. Amongst all the cytokines involved in host immunity towards this pathogen, IFN-ε has recently acquired importance for its potential contribution to the female reproductive tract innate defenses. Herein, our study aimed to explore, for the first time, the activity of IFN-ε toward C. trachomatis in an in vitro infection model, by testing its effects on the different phases of chlamydial developmental cycle, as well as on the ultrastructural characteristics of chlamydial inclusions, via transmission electron microscopy. Main result is the capability of IFN-ε to alter C. trachomatis growth, as suggested by reduced infectious progenies, as well as a patchy distribution of bacteria and altered morphology of reticulate bodies within inclusions. In conclusion, our results suggest that IFN-ε could play a role in the innate and adaptive immune defenses against C. trachomatis; in the future, it will be needed to investigate its activity on an infection model more closely resembling the physiological environment of the female genital tract.

Interferon ɛ restricts Zika virus infection in the female reproductive tract

Interferon ɛ (IFNɛ) is a unique type I IFN that has been implicated in host defense against sexually transmitted infections. Zika virus (ZIKV), an emerging pathogen, can infect the female reproductive tract (FRT) and cause devastating diseases, particularly in pregnant women. How IFNɛ contributes to protection against ZIKV infection in vivo is unknown. In this study, we show that IFNɛ plays a critical role in host protection against vaginal ZIKV infection in mice. We found that IFNɛ was expressed not only by epithelial cells in the FRT but also by immune and stromal cells at baseline or after exposure to viruses or specific Toll-like receptor (TLR) agonists. IFNɛ-deficient mice exhibited abnormalities in the epithelial border and underlying tissue in the cervicovaginal tract, and these defects were associated with increased susceptibility to vaginal but not subcutaneous ZIKV infection. IFNɛ deficiency resulted in an increase in magnitude, duration, and depth of ZIKV infection in the FRT. Critically, intravaginal administration of recombinant IFNɛ protected Ifnɛ-/- mice and highly susceptible Ifnar1-/- mice against vaginal ZIKV infection, indicating that IFNɛ was sufficient to provide protection even in the absence of signals from other type I IFNs and in an IFNAR1-independent manner. Our findings reveal a potentially critical role for IFNɛ in mediating protection against the transmission of ZIKV in the context of sexual contact.

Epithelially Restricted Interferon Epsilon Protects Against Colitis

BACKGROUND & AIMS

Type I interferon (T1IFN) signalling is crucial for maintaining intestinal homeostasis. We previously found that the novel T1IFN, IFNε, is highly expressed by epithelial cells of the female reproductive tract, where it protects against pathogens. Its function has not been studied in the intestine. We hypothesize that IFNε is important in maintaining intestinal homeostasis.

METHODS

We characterized IFNε expression in mouse and human intestine by immunostaining and studied its function in the dextran sulfate sodium (DSS) colitis model using both genetic knockouts and neutralizing antibody.

RESULTS

We demonstrate that IFNε is expressed in human and mouse intestinal epithelium, and expression is lost in inflammation. Furthermore, we show that IFNε limits intestinal inflammation in mouse models. Regulatory T cell (Treg) frequencies were paradoxically decreased in DSS-treated IFNε-/- mice, suggesting a role for IFNε in maintaining the intestinal Treg compartment. Colitis was ameliorated by transfer of wild-type Tregs into IFNε-/- mice. This demonstrates that IFNε supports intestinal Treg function.

CONCLUSIONS

Overall, we have shown IFNε expression in intestinal epithelium and its critical role in gut homeostasis. Given its known role in the female reproductive tract, we now show IFNε has a protective role across multiple mucosal surfaces.

Interferon ε restricts Zika virus infection in the female reproductive tract

Interferon ε (IFNε) is a unique type I IFN that has been implicated in host defense against sexually transmitted infections (STIs). Zika virus (ZIKV), an emerging pathogen, can infect the female reproductive tract (FRT) and cause devastating diseases, particularly in pregnant women. How IFNε contributes to protection against ZIKV infection in vivo is unknown. Here, we show that IFNε plays a critical role in host protection against vaginal ZIKV infection in mice. We found that IFNε was expressed not only by epithelial cells in the FRT, but also by certain immune and other cells at baseline or after exposure to viruses or specific TLR agonists. IFNε-deficient mice exhibited abnormalities in the epithelial border and underlying tissue in the cervicovaginal tract, and these defects were associated with increased susceptibility to vaginal, but not subcutaneous ZIKV infection. IFNε-deficiency resulted in an increase in magnitude, duration, and depth of ZIKV infection in the FRT. Critically, intravaginal administration of recombinant IFNε protected Ifnε-/- mice and highly susceptible Ifnar1-/- mice against vaginal ZIKV infection, indicating that IFNε was sufficient to provide protection even in the absence of signals from other type I IFNs and in an IFNAR1-independent manner. Our findings reveal a potentially critical role for IFNε in mediating protection against transmission of ZIKV in the context of sexual contact.

The regulation of antiviral activity of interferon epsilon

Interferon epsilon (IFN-ε) is a type I IFN. Some biological properties has been identified in many species, such as antiproliferative, anti-tumor, and antiviral effects, of IFN-ε, which are much weaker than those of IFN-α, have also been revealed. It has been shown to play a role in mucosal immunity and bacterial infection and in the prevention of certain sexually transmitted diseases, such as human immunodeficiency virus (HIV). This paper reviews the known activity of IFN-ε, particularly in some viruses. In general, this review provides a better understanding of effective IFN-ε treatment in the future.

Interferon Epsilon Signaling Confers Attenuated Zika Replication in Human Vaginal Epithelial Cells

Zika virus (ZIKV) is an emerging flavivirus that causes congenital birth defects and neurological compilations in the human host. Although ZIKV is primarily transmitted through infected mosquitos, recent studies reveal sexual contact as a potential transmission route. In vagina-bearing individuals, the vaginal epithelium constitutes the first line of defense against viruses. However, it is unclear how ZIKV interacts with the vaginal epithelium to initiate ZIKV transmission. In this study, we demonstrate that exposing ZIKV to human vaginal epithelial cells (hVECs) resulted in de novo viral RNA replication, increased envelope viral protein production, and a steady, extracellular release of infectious viral particles. Interestingly, our data show that, despite an increase in viral load, the hVECs did not exhibit significant cytopathology in culture as other cell types typically do. Furthermore, our data reveal that the innate antiviral state of hVECs plays a crucial role in preventing viral cytopathology. For the first time, our data show that interferon epsilon inhibits ZIKV replication. Collectively, our results in this study provide a novel perspective on the viral susceptibility and replication dynamics during ZIKV infection in the human vaginal epithelium. These findings will be instrumental towards developing therapeutic agents aimed at eliminating the pathology caused by the virus.

The Analyses of Cetacean Virus-Responsive Genes Reveal Evolutionary Marks in Mucosal Immunity-Associated Genes

Viruses are the most common and abundant organisms in the marine environment. To better understand how cetaceans have adapted to this virus-rich environment, we compared cetacean virus-responsive genes to those from terrestrial mammals. We identified virus-responsive gene sequences in seven species of cetaceans, which we compared with orthologous sequences in seven terrestrial mammals. As a result of evolution analysis using the branch model and the branch-site model, 21 genes were selected using at least one model. IFN-ε, an antiviral cytokine expressed at mucous membranes, and its receptor IFNAR1 contain cetacean-specific amino acid substitutions that might change the interaction between the two proteins and lead to regulation of the immune system against viruses. Cetacean-specific amino acid substitutions in IL-6, IL-27, and the signal transducer and activator of transcription (STAT)1 are also predicted to alter the mucosal immune response of cetaceans. Since mucosal membranes are the first line of defense against the external environment and are involved in immune tolerance, our analysis of cetacean virus-responsive genes suggests that genes with cetacean-specific mutations in mucosal immunity-related genes play an important role in the protection and/or regulation of immune responses against viruses.

Revelations About Aging and Disease from Unconventional Vertebrate Model Organisms

Aging is a major risk factor for multiple diseases. Understanding the underlying mechanisms of aging would help to delay and prevent age-associated diseases. Short-lived model organisms have been extensively used to study the mechanisms of aging. However, these short-lived species may be missing the longevity mechanisms that are needed to extend the lifespan of an already long-lived species such as humans. Unconventional long-lived animal species are an excellent resource to uncover novel mechanisms of longevity and disease resistance. Here, we review mechanisms that evolved in nonmodel vertebrate species to counteract age-associated diseases. Some antiaging mechanisms are conserved across species; however, various nonmodel species also evolved unique mechanisms to delay aging and prevent disease. This variety of antiaging mechanisms has evolved due to the remarkably diverse habitats and behaviors of these species. We propose that exploring a wider range of unconventional vertebrates will provide important resources to study antiaging mechanisms that are potentially applicable to humans.

Immunoregulation by type I interferons in the peritoneal cavity

The peritoneal cavity, a fluid-containing potential space surrounding the abdominal and pelvic organs, is home to a rich network of immune cells that maintain tissue homeostasis and provide protection against infection. However, under pathological conditions such as peritonitis, endometriosis, and peritoneal carcinomatosis, the peritoneal immune system can become dysregulated, resulting in nonresolving inflammation and disease progression. An enhanced understanding of the factors that regulate peritoneal immune cells under both homeostatic conditions and in disease contexts is therefore required to identify new treatment strategies for these often life-limiting peritoneal pathologies. Type I interferons (T1IFNs) are a family of cytokines with broad immunoregulatory functions, which provide defense against viruses, bacteria, and cancer. There have been numerous reports of immunoregulation by T1IFNs within the peritoneal cavity, which can contribute to both the resolution or propagation of peritoneal disease states, depending on the specifics of the disease setting and local environment. In this review, we provide an overview of the major immune cell populations that reside in the peritoneal cavity (or infiltrate it under inflammatory conditions) and highlight their contribution to the initiation, progression, or resolution of peritoneal diseases. Additionally, we will discuss the role of T1IFNs in the regulation of peritoneal immune cells, and summarize the results of laboratory studies and clinical trials which have investigated T1IFNs in peritonitis/sepsis, endometriosis, and peritoneal carcinomatosis.

Viral infection of the ovaries compromises pregnancy and reveals innate immune mechanisms protecting fertility

Viral infections during pregnancy are a considerable cause of adverse outcomes and birth defects, and the underlying mechanisms are poorly understood. Among those, cytomegalovirus (CMV) infection stands out as the most common intrauterine infection in humans, putatively causing early pregnancy loss. We employed murine CMV as a model to study the consequences of viral infection on pregnancy outcome and fertility maintenance. Even though pregnant mice successfully controlled CMV infection, we observed highly selective, strong infection of corpus luteum (CL) cells in their ovaries. High infection densities indicated complete failure of immune control in CL cells, resulting in progesterone insufficiency and pregnancy loss. An abundance of gap junctions, absence of vasculature, strong type I interferon (IFN) responses, and interaction of innate immune cells fully protected the ovarian follicles from viral infection. Our work provides fundamental insights into the effect of CMV infection on pregnancy loss and mechanisms protecting fertility.

Vaccine Considerations for Multiple Sclerosis in the COVID-19 Era

People with multiple sclerosis (MS) are at risk for infections that can result in amplification of baseline symptoms and possibly trigger clinical relapses. Vaccination can prevent infection through the activation of humoral and cellular immune responses. This is particularly pertinent in the era of emerging novel vaccines against severe acute respiratory syndrome coronavirus 2, the virus that causes coronavirus disease 2019 (COVID-19). MS disease-modifying therapies (DMTs), which affect the immune system, may impact immune responses to COVID-19 vaccines in people with MS. The objective of this article is to provide information on immune system responses to vaccinations and review previous studies of vaccine responses in people with MS to support the safety and importance of receiving currently available and emerging COVID-19 vaccines. Immunological studies have shown that coordinated interactions between T and B lymphocytes of the adaptive immune system are key to successful generation of immunological memory and production of neutralizing antibodies following recognition of vaccine antigens by innate immune cells. CD4+ T cells are essential to facilitate CD8+ T cell and B cell activation, while B cells drive and sustain T cell memory. Data suggest that some classes of DMT, including type 1 interferons and glatiramer acetate, may not significantly impair the response to vaccination. DMTs-such as sphingosine-1-phosphate receptor modulators, which sequester lymphocytes from circulation; alemtuzumab; and anti-CD20 therapies, which rely on depleting populations of immune cells-have been shown to attenuate responses to conventional vaccines. Currently, three COVID-19 vaccines have been granted emergency use authorization in the USA on the basis of promising interim findings of ongoing trials. Because analyses of these vaccines in people with MS are not available, decisions regarding COVID-19 vaccination and DMT choice should be informed by data and expert consensus, and personalized with considerations for disease burden, risk of infection, and other factors.

Innate Viral Sensor MDA5 and Coxsackievirus Interplay in Type 1 Diabetes Development

Type 1 diabetes (T1D) is a polygenic autoimmune disease characterized by immune-mediated destruction of insulin-producing β-cells. The concordance rate for T1D in monozygotic twins is ≈30-50%, indicating that environmental factors also play a role in T1D development. Previous studies have demonstrated that enterovirus infections such as coxsackievirus type B (CVB) are associated with triggering T1D. Prior to autoantibody development in T1D, viral RNA and antibodies against CVB can be detected within the blood, stool, and pancreata. An innate pathogen recognition receptor, melanoma differentiation-associated protein 5 (MDA5), which is encoded by the IFIH1 gene, has been associated with T1D onset. It is unclear how single nucleotide polymorphisms in IFIH1 alter the structure and function of MDA5 that may lead to exacerbated antiviral responses contributing to increased T1D-susceptibility. Binding of viral dsRNA via MDA5 induces synthesis of antiviral proteins such as interferon-alpha and -beta (IFN-α/β). Viral infection and subsequent IFN-α/β synthesis can lead to ER stress within insulin-producing β-cells causing neo-epitope generation, activation of β-cell-specific autoreactive T cells, and β-cell destruction. Therefore, an interplay between genetics, enteroviral infections, and antiviral responses may be critical for T1D development.

Should Patients with MS Discontinue Their Medications During the COVID-19 Pandemic?

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In vitro model for the assessment of human immune responses to subunit RSV vaccines

Respiratory syncytial virus (RSV) is the single most important cause of serious lower respiratory tract disease in infants and young children worldwide and a high priority for vaccine development. Despite over 50 years of research, however, no vaccine is yet available. One block to vaccine development is an incomplete understanding of the aberrant memory response to the formalin-inactivated RSV vaccine (FI-RSV) given to children in the 1960s. This vaccine caused enhanced respiratory disease (ERD) with later natural RSV infection. Concern that any non-live virus vaccine may also cause ERD has blocked development of subunit vaccines for young children. A number of animal FI-RSV studies suggest various immune mechanisms behind ERD. However, other than limited data from the original FI-RSV trial, there is no information on the human ERD-associated responses. An in vitro model with human blood specimens may shed light on the immune memory responses likely responsible for ERD. Memory T cell responses to an antigen are guided by the innate responses, particularly dendritic cells that present an antigen in conjunction with co-stimulatory molecules and cytokine signaling. Our in vitro model involves human monocyte derived dendritic cells (moDC) and allogenic T cell cultures to assess innate responses that direct T cell responses. Using this model, we evaluated human responses to live RSV, FI-RSV, and subunit RSV G vaccines (G-containing virus-like particles, G-VLP). Similar to findings in animal studies, FI-RSV induced prominent Th2/Th17-biased responses with deficient type-1 responses compared to live virus. Responses to G-VLPs were similar to live virus, i.e. biased towards a Th1 and not a Th2/Th17. Also mutating CX3C motif in G gave a more pronounced moDC responses associated with type-1 T cell responses. This in vitro model identifies human immune responses likely associated with ERD and provides another pre-clinical tool to assess the safety of RSV vaccines.

PROPERTIES AND FUNCTIONS OF THE NOVEL TYPE I INTERFERON EPSILON

Interferon epsilon (IFNε) is a type I IFN with unusual patterns of expression and therefore, function. It is constitutively expressed by reproductive tract epithelium and regulated by hormones during estrus cycle, reproduction, and menopause and by exogenous hormones. The IFNe protein is encoded by a gene in the type I IFN locus, binds to IFNAR1 and 2 which are required for signaling via the JAK STAT pathway. Its affinity for binding receptors and transducing signals is less potent than IFNα or β subtypes in vitro. Nevertheless, in vivo experiments indicate its efficacy in regulating mucosal immune responses and protecting from bacterial and viral infections. These studies demonstrate a different mechanism of action to type I IFNs. In this organ system with dynamic fluxes in cellularity, requirement to tolerate an implanted fetus, and be protected from disease, there is co-option of a special IFN from a family of effective immunoregulators, with unique controls and modified potency to make it a safe and effective constitutive reproductive tract cytokine.

The Arabian camel, Camelus dromedarius interferon epsilon: Functional expression, in vitro refolding, purification and cytotoxicity on breast cancer cell lines

The current study highlights, for the first time, cloning, overexpression and purification of the novel interferon epsilon (IFNƐ), from the Arabian camel Camelus dromedaries. The study then assesses the cytotoxicity of IFNε against two human breast cancer cell lines MDA-MB-231 and MCF-7. Full-length cDNA encoding interferon epsilon (IFNε) was isolated and cloned from the liver of the Arabian camel, C. dromedarius using reverse transcription-polymerase chain reaction. The sequence analysis of the camel IFNε cDNA showed a 582-bp open reading frame encoding a protein of 193 amino acids with an estimated molecular weight of 21.230 kDa. A BLAST search analysis revealed that the C. dromedarius IFNε shared high sequence identity with the IFN genes of other species, such as Camelus ferus, Vicugna pacos, and Homo sapiens. Expression of the camel IFNε cDNA in Escherichia coli gave a fusion protein band of 24.97 kDa after induction with either isopropyl β-D-1-thiogalactopyranoside or lactose for 5 h. Recombinant IFNε protein was overexpressed in the form of inclusion bodies that were easily solubilized and refolded using SDS and KCl. The solubilized inclusion bodies were purified to apparent homogeneity using nickel affinity chromatography. We examined the effect of IFNε on two breast cancer cell lines MDA-MB-231 and MCF-7. In both cell lines, IFNε inhibited cell survival in a dose dependent manner as observed by MTT assay, morphological changes and apoptosis assay. Caspase-3 expression level was found to be increased in MDA-MB-231 treated cells as compared to untreated cells.

Differential regulation of IFNα, IFNβ and IFNε gene expression in human cervical epithelial cells

Interferonε (IFNε) is a unique type I IFN that has distinct functions from IFNα/β. IFNε is constitutively expressed at mucosal tissues, including the female genital mucosa, and is reported to be modulated by estrogen and seminal plasma. However, its regulation by cytokines, including TNFα, IL-1β, IL-6, IL-8, IL-17, IL-22 and IFNα, which are commonly present in the female genital mucosa, is not well documented in freshly isolated primary cervical cells from tissues. We determined the effect of these cytokines on gene expression of type I IFNs in an immortalized endocervical epithelial cell line (A2EN) and in primary cervical epithelial cells. Several pro-inflammatory cytokines were found to induce IFNε, and TNFα induced the strongest response in both cell types. Pretreatment of cells with the IκB inhibitor, which blocks the NF-κB pathway, suppressed TNFα-mediated IFNε gene induction and promoter activation. Expression of IFNα, IFNβ, and IFNε was differentially regulated in response to various cytokines. Taken together, our results show that regulation of these IFNs depends on cell type, cytokine concentration, and incubation time, highlighting the complexity of the cytokine network in the cervical epithelium.

IFN- protects primary macrophages against HIV infection

IFN-ε is a unique type I IFN that is not induced by pattern recognition response elements. IFN-ε is constitutively expressed in mucosal tissues, including the female genital mucosa. Although the direct antiviral activity of IFN-ε was thought to be weak compared with IFN-α, IFN-ε controls Chlamydia muridarum and herpes simplex virus 2 in mice, possibly through modulation of immune response. We show here that IFN-ε induces an antiviral state in human macrophages that blocks HIV-1 replication. IFN-ε had little or no protective effect in activated CD4⁺ T cells or transformed cell lines unless activated CD4⁺ T cells were infected with replication-competent HIV-1 at a low MOI. The block to HIV infection of macrophages was maximal after 24 hours of treatment and was reversible. IFN-ε acted on early stages of the HIV life cycle, including viral entry, reverse transcription, and nuclear import. The protection did not appear to operate through known type I IFN-induced HIV host restriction factors, such as APOBEC3A and SAMHD1. IFN-ε-stimulated immune mediators and pathways had the signature of type I IFNs but were distinct from IFN-α in macrophages. IFN-ε induced significant phagocytosis and ROS, which contributed to the block to HIV replication. These findings indicate that IFN-ε induces an antiviral state in macrophages that is mediated by different factors than those induced by IFN-α. Understanding the mechanism of IFN-ε-mediated HIV inhibition through immune modulation has implications for prevention.

Pangolin genomes and the evolution of mammalian scales and immunity

Pangolins, unique mammals with scales over most of their body, no teeth, poor vision, and an acute olfactory system, comprise the only placental order (Pholidota) without a whole-genome map. To investigate pangolin biology and evolution, we developed genome assemblies of the Malayan (Manis javanica) and Chinese (M. pentadactyla) pangolins. Strikingly, we found that interferon epsilon (IFNE), exclusively expressed in epithelial cells and important in skin and mucosal immunity, is pseudogenized in all African and Asian pangolin species that we examined, perhaps impacting resistance to infection. We propose that scale development was an innovation that provided protection against injuries or stress and reduced pangolin vulnerability to infection. Further evidence of specialized adaptations was evident from positively selected genes involving immunity-related pathways, inflammation, energy storage and metabolism, muscular and nervous systems, and scale/hair development. Olfactory receptor gene families are significantly expanded in pangolins, reflecting their well-developed olfaction system. This study provides insights into mammalian adaptation and functional diversification, new research tools and questions, and perhaps a new natural IFNE-deficient animal model for studying mammalian immunity.

New Interferons

New interferons (IFNs) include members of the type I IFN family, such as IFN epsilon (IFNε), IFN tau, IFN omega, and IFN kappa, as well as the type III IFN family, also known as the IFN lambdas. By comparison the classical or ‘old’ IFNs comprise the 14 subtypes of IFN alpha and IFN beta, which are all members of the type I IFN family, as well as type II IFN gamma. In this article, we examine the new IFNs and specifically discuss their discovery, comparative structures, functions in physiology and disease, the signaling pathways they initiate, and their regulatory controls. We highlight IFNε that was discovered in our laboratory and characterized for its role in protecting the female reproductive tract from infections.

Interferon Beta and Interferon Alpha 2a Differentially Protect Head and Neck Cancer Cells from Vesicular Stomatitis Virus-Induced Oncolysis

Oncolytic viruses (OV) preferentially kill cancer cells due in part to defects in their antiviral responses upon exposure to type I interferons (IFNs). However, IFN responsiveness of some tumor cells confers resistance to OV treatment. The human type I IFNs include one IFN-β and multiple IFN-α subtypes that share the same receptor but are capable of differentially inducing biological responses. The role of individual IFN subtypes in promoting tumor cell resistance to OV is addressed here. Two human IFNs which have been produced for clinical use, IFN-α2a and IFN-β, were compared for activity in protecting human head and neck squamous cell carcinoma (HNSCC) lines from oncolysis by vesicular stomatitis virus (VSV). Susceptibility of HNSCC lines to killing by VSV varied. VSV infection induced increased production of IFN-β in resistant HNSCC cells. When added exogenously, IFN-β was significantly more effective at protecting HNSCC cells from VSV oncolysis than was IFN-α2a. In contrast, normal keratinocytes and endothelial cells were protected equivalently by both IFN subtypes. Differential responsiveness of tumor cells to IFN-α and -β was further supported by the finding that autocrine IFN-β but not IFN-α promoted survival of HNSCC cells during persistent VSV infection. Therefore, IFN-α and -β differentially affect VSV oncolysis, justifying the evaluation and comparison of IFN subtypes for use in combination with VSV therapy. Pairing VSV with IFN-α2a may enhance selectivity of oncolytic VSV therapy for HNSCC by inhibiting VSV replication in normal cells without a corresponding inhibition in cancer cells.

IMPORTANCE

There has been a great deal of progress in the development of oncolytic viruses. However, a major problem is that individual cancers vary in their sensitivity to oncolytic viruses. In many cases this is due to differences in their production and response to interferons (IFNs). The experiments described here compared the responses of head and neck squamous cell carcinoma cell lines to two IFN subtypes, IFN-α2a and IFN-β, in protection from oncolytic vesicular stomatitis virus. We found that IFN-α2a was significantly less protective for cancer cells than was IFN-β, whereas normal cells were equivalently protected by both IFNs. These results suggest that from a therapeutic standpoint, selectivity for cancer versus normal cells may be enhanced by pairing VSV with IFN-α2a.

Natural interferon-beta treatment for patients with chronic hepatitis C in Japan

Chronic hepatitis C virus (HCV) infection can cause liver cirrhosis and hepatocellular carcinoma (HCC). Several studies have demonstrated that the eradication of HCV reduces the occurrence of HCC. In Japan, as many people live to an advanced age, HCV-infected patients are also getting older, and the age at HCC diagnosis has also increased. Although older HCV-infected patients have a risk of developing HCC, the treatment response to peginterferon-alpha plus ribavirin therapy is relatively poor in these patients because of drop-out or discontinuation of this treatment due to adverse events. It is established that the mechanism of action between interferon-alpha and interferon-beta is slightly different. Short-term natural interferon-beta monotherapy is effective for patients with acute hepatitis C and patients infected with HCV genotype 2 and low viral loads. Natural interferon-beta plus ribavirin for 48 wk or for 24 wk are also effective for some patients with HCV genotype 1 or HCV genotype 2. Natural interferon-beta plus ribavirin has been used for certain “difficult-to-treat” HCV-infected patients. In the era of direct-acting anti-virals, natural interferon-beta plus ribavirin may be one of the therapeutic options for special groups of HCV-infected patients. In the near future, signal transduction pathways of interferon-beta will inform further directions.

The mucosal expression pattern of interferon-ε in rhesus macaques

Type I IFNs play an important role in innate and adaptive immunity against viral infections. A novel type I IFN, namely IFN-ε, which can protect against vaginal transmission of HSV2 and Chlamydia muridarum bacterial infection, has been described in mice and humans. Nevertheless, the principle cell type and the expression pattern of IFN-ε in tissues remain uncertain. In addition, the expression of IFN-ε in Indian rhesus macaques (Macaca mulatta) has not been reported. Here, we analyzed IFN-ε expression in multiple mucosal sites of uninfected or SIV-infected Indian rhesus macaques using IHCS. We report for the first time the detection of IFN-ε expression in situ in the lung, foreskin, vaginal, cervical, and small and large intestinal mucosae of rhesus macaques. We found that the expression of IFN-ε was exclusive to the epithelial cells in all of the aforementioned mucosal tissues. Furthermore, the macaque IFN-ε sequence in this study revealed that macaque IFN-ε is highly conserved among human and other nonhuman primates. Lastly, SIV rectal infection did not significantly alter the expression of IFN-ε in rectal mucosae. Together, these findings indicate that IFN-ε may function as the first line of defense against the invasion of mucosal pathogens. Further studies should be conducted to examine IFN-ε protection against gastrointestinal as well as respiratory infections.

Unraveling the convoluted biological roles of type I interferons in infection and immunity: a way forward for therapeutics and vaccine design

It has been well-established that type I interferons (IFN-Is) have pleiotropic effects and play an early central role in the control of many acute viral infections. However, their pleiotropic effects are not always beneficial to the host and in fact several reports suggest that the induction of IFN-Is exacerbate disease outcomes against some bacterial and chronic viral infections. In this brief review, we probe into this mystery and try to develop answers based on past and recent studies evaluating the roles of IFN-Is in infection and immunity as this is vital for developing effective IFN-Is based therapeutics and vaccines. We also discuss the biological roles of an emerging IFN-I, namely IFN-ε, and discuss its potential use as a mucosal therapeutic and/or vaccine adjuvant. Overall, we anticipate the discussions generated in this review will provide new insights for better exploiting the biological functions of IFN-Is in developing efficacious therapeutics and vaccines in the future.

Internal ribosome entry site-based attenuation of a flavivirus candidate vaccine and evaluation of the effect of beta interferon coexpression on vaccine properties

Infectious clone technologies allow the rational design of live attenuated viral vaccines with the possibility of vaccine-driven coexpression of immunomodulatory molecules for additional vaccine safety and efficacy. The latter could lead to novel strategies for vaccine protection against infectious diseases where traditional approaches have failed. Here we show for the flavivirus Murray Valley encephalitis virus (MVEV) that incorporation of the internal ribosome entry site (IRES) of Encephalomyocarditis virus between the capsid and prM genes strongly attenuated virulence and that the resulting bicistronic virus was both genetically stable and potently immunogenic. Furthermore, the novel bicistronic genome organization facilitated the generation of a recombinant virus carrying an beta interferon (IFN-β) gene. Given the importance of IFNs in limiting virus dissemination and in efficient induction of memory B and T cell antiviral immunity, we hypothesized that coexpression of the cytokine with the live vaccine might further increase virulence attenuation without loss of immunogenicity. We found that bicistronic mouse IFN-β coexpressing MVEV yielded high virus and IFN titers in cultured cells that do not respond to the coexpressed IFN. However, in IFN response-sufficient cell cultures and mice, the virus produced a self-limiting infection. Nevertheless, the attenuated virus triggered robust innate and adaptive immune responses evidenced by the induced expression of Mx proteins (used as a sensitive biomarker for measuring the type I IFN response) and the generation of neutralizing antibodies, respectively. IMPORTANCE The family Flaviviridae includes a number of important human pathogens, such as Dengue virus, Yellow fever virus, Japanese encephalitis virus, West Nile virus, and Hepatitis C virus. Flaviviruses infect large numbers of individuals on all continents. For example, as many as 100 million people are infected annually with Dengue virus, and 150 million people suffer a chronic infection with Hepatitis C virus. However, protective vaccines against dengue and hepatitis C are still missing, and improved vaccines against other flaviviral diseases are needed. The present study investigated the effects of a redesigned flaviviral genome and the coexpression of an antiviral protein (interferon) on virus replication, pathogenicity, and immunogenicity. Our findings may aid in the rational design of a new class of well-tolerated and safe vaccines.

Unique IL-13Rα2-based HIV-1 vaccine strategy to enhance mucosal immunity, CD8(+) T-cell avidity and protective immunity

We have established that mucosal immunization can generate high-avidity human immunodeficiency virus (HIV)-specific CD8(+) T cells compared with systemic immunization, and interleukin (IL)-13 is detrimental to the functional avidity of these T cells. We have now constructed two unique recombinant HIV-1 vaccines that co-express soluble or membrane-bound forms of the IL-13 receptor α2 (IL-13Rα2), which can "transiently" block IL-13 activity at the vaccination site causing wild-type animals to behave similar to an IL-13 KO animal. Following intranasal/intramuscular prime-boost immunization, these IL-13Rα2-adjuvanted vaccines have shown to induce (i) enhanced HIV-specific CD8(+) T cells with higher functional avidity, with broader cytokine/chemokine profiles and greater protective immunity using a surrogate mucosal HIV-1 challenge, and also (ii) excellent multifunctional mucosal CD8(+) T-cell responses, in the lung, genito-rectal nodes (GN), and Peyer's patch (PP). Data revealed that intranasal delivery of these IL-13Rα2-adjuvanted HIV vaccines recruited large numbers of unique antigen-presenting cell subsets to the lung mucosae, ultimately promoting the induction of high-avidity CD8(+) T cells. We believe our novel IL-13R cytokine trap vaccine strategy offers great promise for not only HIV-1, but also as a platform technology against range of chronic infections that require strong sustained high-avidity mucosal/systemic immunity for protection.

IFN-ε is constitutively expressed by cells of the reproductive tract and is inefficiently secreted by fibroblasts and cell lines

Type-I interferons (IFNs) form a large family of cytokines that primarily act to control the early development of viral infections. Typical type-I IFN genes, such as those encoding IFN-α or IFN-β are upregulated by viral infection in many cell types. In contrast, the gene encoding IFN-ε was reported to be constitutively expressed by cells of the female reproductive tract and to contribute to the protection against vaginal infections with herpes simplex virus 2 and Chlamydia muridarum. Our data confirm the lack of induction of IFN-ε expression after viral infection and the constitutive expression of IFN-ε by cells of the female but also of the male reproductive organs. Interestingly, when expressed from transfected expression plasmids in 293T, HeLa or Neuro2A cells, the mouse and human IFN-ε precursors were inefficiently processed and secretion of IFN-ε was minimal. Analysis of chimeric constructs produced between IFN-ε and limitin (IFN-ζ) showed that both the signal peptide and the mature moiety of IFN-ε contribute to poor processing of the precursor. Immunofluorescent detection of FLAG-tagged IFN-ε in transfected cells suggested that IFN-ε and chimeric proteins were defective for progression through the secretory pathway. IFN-ε did not, however, act intracellularly and impart an antiviral state to producing cells. Given the constitutive expression of IFN-ε in specialized cells and the poor processing of IFN-ε precursor in fibroblasts and cell lines, we hypothesize that IFN-ε secretion may require a co-factor specifically expressed in cells of the reproductive organs, that might secure the system against aberrant release of this IFN.

Novel role for molecular transporter importin 9 in posttranscriptional regulation of IFN-ε expression

IFN-ε is a unique type I IFN whose constitutive expression in lung, brain, small intestine, and reproductive tissues is only partially understood. Our previous observation that posttranscriptional events participate in the regulation of IFN-ε mRNA expression led us to investigate whether the 5' and/or 3' untranslated regions (UTR) have regulatory functions. Surprisingly, we found that full-length IFN-ε 5'UTR markedly suppressed mRNA expression under basal conditions. Analysis of the secondary structure of this region predicted formation of two stable stem-loop structures, loops 1 and 2. Studies using luciferase constructs harboring various stretches of IFN-ε 5'UTR and mutant constructs in which the conformation of loop structures was disrupted showed that loop 1 is essential for regulation of mRNA expression. Incubation of HeLa cell extracts with agarose-bound RNAs harboring IFN-ε loop structures identified importin 9 (IPO9), a molecular transporter and chaperone, as a candidate that associates with these regions of the 5'UTR. IPO9 overexpression decreased, and IPO9 silencing increased basal IFN-ε expression. Our studies uncover a previously undescribed function for IPO9 as a specific, and negative, posttranscriptional regulator of IFN-ε expression, and they identify key roles for IFN-ε stem-loop structure 1 in this process. IPO9-mediated effects on 5'UTRs appear to extend to additional mRNAs, including hypoxia-inducible factor-1α, that can form specific loop structures.

Role of novel type I interferon epsilon in viral infection and mucosal immunity

Intranasal infection with vaccinia virus co-expressing interferon epsilon (VV-HIV-IFN-ε) was used to evaluate the role of IFN-ε in mucosal immunity. VV-HIV- IFN-ε infection induced a rapid VV clearance in lung that correlated with (i) an elevated lung VV-specific CD8(+)CD107a(+)IFN-γ(+) population expressing activation markers CD69/CD103, (ii) enhanced lymphocyte recruitment to lung alveoli with reduced inflammation, and (iii) an heightened functional/cytotoxic CD8(+)CD4(+) T-cell subset (CD3(hi)CCR7(hi)CD62L(lo)) in lung lymph nodes. These responses were different to that observed with intranasal VV-HA-IFN-α(4) or VV-HA-IFN-β infections. When IFN-ε was used in an intranasal/intramuscular heterologous HIV prime-boost immunization, elevated HIV-specific effector, but not memory CD8(+)T cells responses, were observed in spleen, genito-rectal nodes, and Peyer's patch. Homing marker α4β7 and CCR9 analysis indicated that unlike other type I IFNs, IFN-ε could promote migration of antigen-specific CD8(+)T cells to the gut. Our results indicate that IFN-ε has a unique role in the mucosae and most likely can be used to control local lung and/or gut infections (i.e., microbicide) such as tuberculosis, HIV-1, or sexually transmitted diseases.

Innate immune recognition of poxviral vaccine vectors

The study of poxviruses pioneered the field of vaccinology after Jenner's remarkable discovery that 'vaccination' with the phylogenetically related cowpox virus conferred immunity to the devastating disease of smallpox. The study of poxviruses continues to enrich the field of virology because the global eradication of smallpox provides a unique example of the potency of effective immunization. Other poxviruses have since been developed as vaccine vectors for clinical and veterinary applications and include modified vaccinia virus strains such as modified vaccinia Ankara and NYVAC as well as the avipox viruses, fowlpox virus and canarypox virus. Despite the empirical development of poxvirus-based vectored vaccines, it is only now becoming apparent that we need to better understand how the innate arm of the immune system drives adaptive immunity to poxviruses, and how this information is relevant to vaccine design strategies, which are the topics addressed in this article.

Replication-competent recombinant porcine reproductive and respiratory syndrome (PRRS) viruses expressing indicator proteins and antiviral cytokines

Porcine reproductive and respiratory syndrome virus (PRRSV) can subvert early innate immunity, which leads to ineffective antimicrobial responses. Overcoming immune subversion is critical for developing vaccines and other measures to control this devastating swine virus. The overall goal of this work was to enhance innate and adaptive immunity following vaccination through the expression of interferon (IFN) genes by the PRRSV genome. We have constructed a series of recombinant PRRS viruses using an infectious PRRSV cDNA clone (pCMV-P129). Coding regions of exogenous genes, which included Renilla luciferase (Rluc), green and red fluorescent proteins (GFP and DsRed, respectively) and several interferons (IFNs), were constructed and expressed through a unique subgenomic mRNA placed between ORF1b and ORF2 of the PRRSV infectious clone. The constructs, which expressed Rluc, GFP, DsRed, efficiently produced progeny viruses and mimicked the parental virus in both MARC-145 cells and porcine macrophages. In contrast, replication of IFN-expressing viruses was attenuated, similar to the level of replication observed after the addition of exogenous IFN. Furthermore, the IFN expressing viruses inhibited the replication of a second PRRS virus co-transfected or co-infected. Inhibition by the different IFN subtypes corresponded to their anti-PRRSV activity, i.e., IFNω5 ° IFNα1 > IFN-β > IFNδ3. In summary, the indicator-expressing viruses provided an efficient means for real-time monitoring of viral replication thus allowing high‑throughput elucidation of the role of host factors in PRRSV infection. This was shown when they were used to clearly demonstrate the involvement of tumor susceptibility gene 101 (TSG101) in the early stage of PRRSV infection. In addition, replication‑competent IFN-expressing viruses may be good candidates for development of modified live virus (MLV) vaccines, which are capable of reversing subverted innate immune responses and may induce more effective adaptive immunity against PRRSV infection.

In vitro inhibition of monkeypox virus production and spread by Interferon-β

Background

The Orthopoxvirus genus contains numerous virus species that are capable of causing disease in humans, including variola virus (the etiological agent of smallpox), monkeypox virus, cowpox virus, and vaccinia virus (the prototypical member of the genus). Monkeypox is a zoonotic disease that is endemic in the Democratic Republic of the Congo and is characterized by systemic lesion development and prominent lymphadenopathy. Like variola virus, monkeypox virus is a high priority pathogen for therapeutic development due to its potential to cause serious disease with significant health impacts after zoonotic, accidental, or deliberate introduction into a naïve population.

Results

The purpose of this study was to investigate the prophylactic and therapeutic potential of interferon-β (IFN-β) for use against monkeypox virus. We found that treatment with human IFN-β results in a significant decrease in monkeypox virus production and spread in vitro. IFN-β substantially inhibited monkeypox virus when introduced 6-8 h post infection, revealing its potential for use as a therapeutic. IFN-β induced the expression of the antiviral protein MxA in infected cells, and constitutive expression of MxA was shown to inhibit monkeypox virus infection.

Conclusions

Our results demonstrate the successful inhibition of monkeypox virus using human IFN-β and suggest that IFN-β could potentially serve as a novel safe therapeutic for human monkeypox disease.

Improved vaccine protection against retrovirus infection after co-administration of adenoviral vectors encoding viral antigens and type I interferon subtypes

BACKGROUND

Type I interferons (IFNs) exhibit direct antiviral effects, but also distinct immunomodulatory properties. In this study, we analyzed type I IFN subtypes for their effect on prophylactic adenovirus-based anti-retroviral vaccination of mice against Friend retrovirus (FV) or HIV.

RESULTS

Mice were vaccinated with adenoviral vectors encoding FV Env and Gag proteins alone or in combination with vectors encoding IFNα1, IFNα2, IFNα4, IFNα5, IFNα6, IFNα9 or IFNβ. Only the co-administration of adenoviral vectors encoding IFNα2, IFNα4, IFNα6 and IFNα9 resulted in strongly improved immune protection of vaccinated mice from subsequent FV challenge infection with high control over FV-induced splenomegaly and reduced viral loads. The level of protection correlated with augmented virus-specific CD4(+) T cell responses and enhanced antibody titers. Similar results were obtained when mice were vaccinated against HIV with adenoviral vectors encoding HIV Env and Gag-Pol in combination with various type I IFN encoding vectors. Here mainly CD4(+) T cell responses were enhanced by IFNα subtypes.

CONCLUSIONS

Our results indicate that certain IFNα subtypes have the potential to improve the protective effect of adenovirus-based vaccines against retroviruses. This correlated with augmented virus-specific CD4(+) T cell and antibody responses. Thus, co-expression of select type I IFNs may be a valuable tool for the development of anti-retroviral vaccines.

Interferons as potential adjuvants in prophylactic vaccines

IMPORTANCE OF THE FIELD

Vaccines are still one of the best approaches to manage infectious diseases. Despite the advances in drug therapies, prophylactic medicine is still more cost efficient and minimizes the burden in the heath system. Despite all the research in vaccine development, many infectious diseases are still without an effective vaccine. The use of adjuvants in vaccines has been one successful strategy to increase efficacy. IFNs are widely expressed cytokines that have potent antiviral effects. These cytokines are the first line of defense against viral infections and have important roles in immuno surveillance for malignant cells. One of the most promising uses of IFNs is as adjuvants that are co-applied with antigen in vaccines.

AREAS COVERED IN THIS REVIEW

In this review, a cumulative analysis of many of the studies that have used IFN-α, -β, -γ and -λ as adjuvants between 1987 and the present suggests that many do possess the capacity to serve as potent immunoadjuvants for vaccination.

WHAT THE READER WILL GAIN

This review provides a very large collection of studies involving all types of IFNs used as adjuvants in vaccines using different vaccination strategies and various animal models.

TAKE HOME MESSAGE

It is clear that the use of IFNs not only improved the efficacy and safety of most vaccines, but also had important immunomodulatory effect directing T(H)1 immune responses.

Evaluating vaccinia virus cytokine co-expression in TLR GKO mice

Using Toll-like receptor (TLR) and MyD88 gene knock-out (GKO) mice the effect of TLRs and MyD88 on virus replication, interferon (IFN)-β production, natural killer (NK) cell and CD8T cell responses were assessed following ectromelia virus (ECTV) and recombinant vaccinia virus (rVV) infection. The capacity for rVVs encoding cytokines to restore immune function in MyD88(-/-) mice was clearly demonstrated. Results showed that TLR2(-/-), TLR4(-/-)and TLR7(-/-) mice survived ECTV infection whereas MyD88(-/-) and TLR9(-/-)mice, in contrast, were highly susceptible. Next, following infection with rVV, MyD88(-/-) mice elicited reduced serum IFN-β, NK cell and CD8T cell responses compared with wild-type mice, whereas TLR9(-/-) mice showed elevated CD8T cell responses. When MyD88(-/-)mice were infected with rVV co-expressing IFN-β these mice were able to restore IFN-β levels and CD8T cell responses but not NK cell activation. Interestingly, even though rVV co-expressing interleukin (IL)-2 enhanced NK cell activation in MyD88(-/-) mice, this was not associated with an antiviral effect, as observed in normal mice. Surprisingly, co-infection with rVV IL-2/rVV IL-12, but not rVV IL-2/rVV IFN-β, restored the attenuated phenotype of rVV IL-2 in MyD88(-/-) mice indicating that the IL-2/IL-12 combination promotes antiviral responses. Our results clearly show that the CD8T cell defect observed in MyD88(-/-) mice to vaccinia virus infection can be restored by rVV-encoding IFN-β demonstrating the critical role of this cytokine in T cell mediated immunity and illustrates that the model can provide an effective platform for the elucidation of cytokine immunobiology.

Human immunodeficiency virus-1 vaccine design: where do we go now?

Numerous human immunodeficiency virus (HIV)-1 vaccines have been developed over the last three decades, but to date an effective HIV-1 vaccine that can be used for prophylactic or therapeutic purposes in humans has not been identified. The failures and limited successes of HIV-1 vaccines have highlighted the gaps in our knowledge with regard to fundamental immunity against HIV-1 and have provided insights for vaccine strategies that may be implemented for designing more effective HIV-1 vaccines in the future. Recent studies have shown that robust mucosal immunity, high avidity and polyfunctional T cells, and broadly neutralizing antibodies are important factors governing the induction of protective immunity against HIV-1. Furthermore, optimization of vaccine delivery methods for DNA or live viral vector-based vaccines, elucidating the immune responses of individuals who remain resistant to HIV-1 infections and also understanding the core immune responses mediating protection against simian immunodeficiency viruses (SIV) and HIV-1 in animal models following vaccination, are key aspects to be regarded for designing more effective HIV-1 vaccines in the future.

Vaccinia virus vaccines: past, present and future

Vaccinia virus (VACV) has been used more extensively for human immunization than any other vaccine. For almost two centuries, VACV was employed to provide cross-protection against variola virus, the causative agent of smallpox, until the disease was eradicated in the late 1970s. Since that time, continued research on VACV has produced a number of modified vaccines with improved safety profiles. Attenuation has been achieved through several strategies, including sequential passage in an alternative host, deletion of specific genes or genetic engineering of viral genes encoding immunomodulatory proteins. Some highly attenuated third- and fourth-generation VACV vaccines are now being considered for stockpiling against a possible re-introduction of smallpox through bioterrorism. Researchers have also taken advantage of the ability of the VACV genome to accommodate additional genetic material to produce novel vaccines against a wide variety of infectious agents, including a recombinant VACV encoding the rabies virus glycoprotein that is administered orally to wild animals. This review provides an in-depth examination of these successive generations of VACV vaccines, focusing on how the understanding of poxviral replication and viral gene function permits the deliberate modification of VACV immunogenicity and virulence.

Inborn errors of interferon (IFN)-mediated immunity in humans: insights into the respective roles of IFN-alpha/beta, IFN-gamma, and IFN-lambda in host defense

Interferon (IFN) was originally identified as a substance 'interfering' with viral replication in vitro. The first IFNs to be identified were classified as type I IFNs (IFN-alpha/beta and related molecules), two other types have since been identified: type II IFN (IFN-gamma) and type III IFNs (IFN-lambda). Each IFN binds to one of three type-specific receptors. In the mouse model of experimental infections in vivo, IFN-alpha/beta are essential for immunity to most viruses tested, whereas IFN-gamma is important for immunity to a smaller number of viruses, together with bacteria, fungi, and parasites, consistent with IFN-gamma acting as the 'macrophage activating factor.' The precise role of IFN-lambda remains unclear. In recent years, inborn errors affecting the production of, or the response to, IFNs have been reported in human patients, shedding light onto the function of IFNs in natura. Disorders of IFN-gamma production, caused by IL12B, IL12RB1, and specific NEMO mutations, or of IFN-gamma responses, caused by IFNGR1, IFNGR2, and dominant STAT1 mutations, confer predisposition to mycobacterial disease in patients resistant to most viruses. By contrast, disorders of IFN-alpha/beta and IFN-lambda production, caused by UNC93B1 and TLR3 mutations, confer predisposition to herpes simplex encephalitis (HSE) in otherwise healthy patients. Consistently, patients with impaired responses to IFN-alpha/beta, IFN-gamma, and presumably IFN-lambda (carrying recessive mutations in STAT1), or with impaired responses to IFN-alpha/beta and impaired IFN-gamma production (carrying mutations in TYK2), or with impaired production of IFN-alpha/beta, IFN-gamma, and IFN-lambda (carrying specific mutations in NEMO), are vulnerable to mycobacterial and viral infections, including HSE. These experiments of nature suggest that the three types of IFNs play at least two different roles in host defense. IFN-gamma is essential for anti-mycobacterial immunity, whereas IFN-alpha/beta and IFN-lambda are essential for anti-viral immunity. Future studies in humans aim to define the specific roles of IFN-alpha/beta and IFN-lambda types and individual molecules in host defense in natura.