Type I interferon gene therapy protects against cytomegalovirus-induced myocarditis

Elucidation for the pharmacological effects and mechanism of Shen Bai formula in treating myocardial injury based on energy metabolism and serum metabolomic approaches

ETHNOPHARMACOLOGICAL RELEVANCE

Shen Bai formula (SBF) is a proven effective traditional Chinese medicine for treating viral myocarditis (VMC) sequelae in clinic, and myocardial injury is the pathological basis of VMC sequelae. However, the pharmacological action and mechanism of SBF have not been systematically elucidated.

AIM OF THE STUDY

In present research, the doxorubicin-induced myocardial injury rat model was used to evaluate the efficacy of SBF, and energy metabolism and metabolomics approaches were applied to elucidate the effects of SBF on myocardial injury.

MATERIALS AND METHODS

Through energy metabolism measurement system and UPLC-Q-TOF-MS/MS oriented blood metabolomics, directly reflected the therapeutic effect of SBF at a macro level, and identified biomarkers of myocardial injury in microcosmic, revealing its metabolomic mechanism.

RESULTS

Results showed that SBF significantly improved the electrocardiogram (ECG), heart rate (HR), extent of myocardial tissue lesion, and ratio of heart and spleen. In addition, the serum levels of AST, CK, LDH, α-HBDH, cTnI, BNP, and MDA decreased, whereas SOD and ATP activity and content increased. Moreover, SBF increased locomotor activity and basic daily metabolism in rats with myocardial injury, restoring their usual level of energy metabolism. A total of 45 potential metabolomic biomarkers were identified. Among them, 44 biomarkers were significantly recalled by SBF, including representative biomarkers arachidonic acid (AA), 12-HETE, prostaglandin J2 (PGJ2), 15-deoxy-Δ-12,14-PGJ2, 15-keto-PGE2, 15(S)-HPETE, 15(S)-HETE, 8,11,14-eicosatrienoic acid and 9(S)-HODE, which involved AA metabolism, biosynthesis of unsaturated fatty acids and linoleic acid metabolism.

CONCLUSION

We successfully replicated a myocardial injury rat model with the intraperitoneal injection of doxorubicin, and elucidated the mechanism of SBF in treating myocardial injury. This key mechanism may be achieved by targeting action on COX, Alox, CYP, and 15-PGDH to increase or decrease the level of myocardial injury biomarker, and then emphatically interven in AA metabolism, biosynthesis of unsaturated fatty acids and linoleic acid metabolism, and participate in regulating purine metabolism, sphingolipid metabolism, primary bile acid biosynthesis, and steroid hormone synthesis.

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.

Distinct effects of treatment with two different interferon-alpha subtypes on HIV-1-associated T-cell activation and dysfunction in humanized mice

OBJECTIVE

Interferon-alpha (IFN-α) has been associated with excessive immune activation and dysfunction during HIV-1 infection. However, evidence suggests specific IFN-α subtypes may be beneficial rather than detrimental. This study compared the effects of treatment with two different IFN-α subtypes on indicators of T-cell activation and dysfunction during HIV-1 infection.

DESIGN

Humanized mice were infected with HIV-1 for 5 weeks and then treated with two different IFN-α subtypes for an additional 3 weeks. Splenic T cells were assessed both immediately posttreatment and again 6 weeks after treatment cessation.

METHODS

HIV-1 infected triple-knockout bone marrow-liver-thymus mice received daily intraperitoneal injections of either IFN-α14 or the clinically approved subtype, IFN-α2. T cells were analysed directly ex vivo for indicators of activation and dysfunction or stimulated to determine their proliferative capacity and ability to produce functional mediators.

RESULTS

Unlike IFN-α2, IFN-α14 treatment reduced viremia and resulted in less activated CD4+ T cells and a lower naïve to effector CD8+ T-cell ratio. Despite exhibiting a reduced proliferative response, the frequency of CD8+ T cells from IFN-α14 treated mice that produced functional mediators and expressed markers of dysfunction was more similar to healthy controls than untreated and IFN-α2 treated mice. Frequencies of exhaustion marker expression remained higher in untreated and IFN-α2 treated mice 6 weeks posttreatment despite similar viral loads between groups at this timepoint.

CONCLUSIONS

Treatment with different IFN-α subtypes had distinctive effects on T cells during HIV-1 infection. IFN-α14 was associated with fewer indicators of T-cell dysfunction whereas IFN-α2 treatment had little impact.

IFNβ Is a Potent Adjuvant for Cancer Vaccination Strategies

Cancer vaccination drives the generation of anti-tumor T cell immunity and can be enhanced by the inclusion of effective immune adjuvants such as type I interferons (IFNs). Whilst type I IFNs have been shown to promote cross-priming of T cells, the role of individual subtypes remains unclear. Here we systematically compared the capacity of distinct type I IFN subtypes to enhance T cell responses to a whole-cell vaccination strategy in a pre-clinical murine model. We show that vaccination in combination with IFNβ induces significantly greater expansion of tumor-specific CD8+ T cells than the other type I IFN subtypes tested. Optimal expansion was dependent on the presence of XCR1+ dendritic cells, CD4+ T cells, and CD40/CD40L signaling. Therapeutically, vaccination with IFNβ delayed tumor progression when compared to vaccination without IFN. When vaccinated in combination with anti-PD-L1 checkpoint blockade therapy (CPB), the inclusion of IFNβ associated with more mice experiencing complete regression and a trend in increased overall survival. This work demonstrates the potent adjuvant activity of IFNβ, highlighting its potential to enhance cancer vaccination strategies alone and in combination with CPB.

Diverse Anti-Tumor Immune Potential Driven by Individual IFNα Subtypes

Immunotherapies harnessing T cell immunity have shown remarkable clinical success for the management of cancer. However, only a proportion of patients benefit from these treatments. The presence of type I interferon (IFN) within the tumor microenvironment is critical for driving effective tumor-specific T cell immunity. Individuals can produce 12 distinct subtypes of IFNα, which all signal through a common receptor. Despite reported differences in anti-viral potencies, the concept that distinct IFNα subtypes can improve anti-cancer treatments remains unclear. We tested whether expression of unique IFNα subtypes confined to the tumor microenvironment enhances tumor control. This was systematically evaluated by transplantation of B16 murine melanoma cells secreting five unique IFNα subtypes (B16_IFNα2; B16_IFNα4; B16_IFNα5; B16_IFNα6; B16_IFNα9) into a pre-clinical murine model. We show that IFNα2 and IFNα9 are the only subtypes capable of completely controlling tumor outgrowth, with this protection dependent on the presence of an adaptive immune response. We next determined whether these differences extended to other model systems and found that the adoptive transfer of tumor-specific CD8⁺ T cells engineered to secrete IFNα9 delays tumor growth significantly and improves survival, whereas no enhanced survival was observed using T cells secreting IFNα4. Overall, our data shows that the expression of distinct IFNα subtypes within the tumor microenvironment results in different anti-tumor activities, and differentially affects the efficacy of a cancer therapy targeting established disease.

SOCS and Herpesviruses, With Emphasis on Cytomegalovirus Retinitis

Suppressor of cytokine signaling (SOCS) proteins provide selective negative feedback to prevent pathogeneses caused by overstimulation of the immune system. Of the eight known SOCS proteins, SOCS1 and SOCS3 are the best studied, and systemic deletion of either gene causes early lethality in mice. Many viruses, including herpesviruses such as herpes simplex virus and cytomegalovirus, can manipulate expression of these host proteins, with overstimulation of SOCS1 and/or SOCS3 putatively facilitating viral evasion of immune surveillance, and SOCS suppression generally exacerbating immunopathogenesis. This is particularly poignant within the eye, which contains a diverse assortment of specialized cell types working together in a tightly controlled microenvironment of immune privilege. When the immune privilege of the ocular compartment fails, inflammation causing severe immunopathogenesis and permanent, sight-threatening damage may occur, as in the case of AIDS-related human cytomegalovirus (HCMV) retinitis. Herein we review how SOCS1 and SOCS3 impact the virologic, immunologic, and/or pathologic outcomes of herpesvirus infection with particular emphasis on retinitis caused by HCMV or its mouse model experimental counterpart, murine cytomegalovirus (MCMV). The accumulated data suggests that SOCS1 and/or SOCS3 can differentially affect the severity of viral diseases in a highly cell-type-specific manner, reflecting the diversity and complexity of herpesvirus infection and the ocular compartment.

Dose-Dependent Differences in HIV Inhibition by Different Interferon Alpha Subtypes While Having Overall Similar Biologic Effects

Elucidating the functional role of the IFN-α subtypes is of particular importance for the development of efficacious therapies using exogenous IFN-α. Specifically, this will help define whether IFN therapy should be based on the use of pathogen-dependent IFN subtypes or, rather, IFN mutants with optimized IFNAR binding properties.

Type I interferons (IFNs) are key players in the antiviral immune response. Interferon alpha (IFN-α) belongs to this class of IFNs and comprises 12 subtypes that differ from each other in their binding affinities for a common receptor and, thus, in their signaling potencies. Recent data suggest that IFN-α6 and -α14 are the most potent IFN-α subtypes in restricting HIV replication when applied exogenously. However, in the context of antiviral therapy, IFNs are administered at high doses, which may compensate for differences in potency seen between IFN-α subtypes. In this study, we reexamined whether IFN-α subtypes induce different biological activities, with a focus on how IFN-α treatment dose affects cellular responses to HIV in primary CD4⁺ T cells, peripheral blood mononuclear cells (PBMCs), and macrophages. We found that the subtypes’ antiviral activities were dose dependent, with >90% inhibition of HIV replication at a high dose of all IFN-αs except the weak IFN-α/β receptor (IFNAR) binder, IFN-α1. The quality of the responses engendered by IFN-α1, -α2, -α6, and -α14 was highly comparable, with essentially the same set of genes induced by all four subtypes. Hierarchal cluster analysis revealed that the individual donors were stronger determinants for the IFN-stimulated-gene (ISG) responses than the specific IFN-α subtype used for stimulation. Notably, IFN-α2-derived mutants with substantially reduced IFNAR2 binding still inhibited HIV replication efficiently, whereas mutants with increased IFNAR1 binding potentiated antiviral activity. Overall, our results support the idea that IFN-α subtypes do not induce different biological responses, given that each subtype is exogenously applied at bioequivalent doses.

IMPORTANCE Elucidating the functional role of the IFN-α subtypes is of particular importance for the development of efficacious therapies using exogenous IFN-α. Specifically, this will help define whether IFN therapy should be based on the use of pathogen-dependent IFN subtypes or, rather, IFN mutants with optimized IFNAR binding properties.

CD8+XCR1neg Dendritic Cells Express High Levels of Toll-Like Receptor 5 and a Unique Complement of Endocytic Receptors

Conventional dendritic cells (cDC) resident in the lymphoid organs of mice have been classically divided into CD8⁺ and CD8^neg subsets. It is well-established that CD8⁺ dendritic cells (DCs) and their migratory counterparts in the periphery comprise the cross-presenting cDC1 subset. In contrast, CD8^neg DCs are grouped together in the heterogeneous cDC2 subset. CD8^neg DCs are relatively poor cross-presenters and drive more prominent CD4⁺ T cell responses against exogenous antigens. The discovery of the X-C motif chemokine receptor 1 (XCR1) as a specific marker of cross-presenting DCs, has led to the identification of a divergent subset of CD8⁺ DCs that lacks the ability to cross-present. Here, we report that these poorly characterized CD8⁺XCR1^neg DCs have a gene expression profile that is consistent with both plasmacytoid DCs (pDCs) and cDC2. Our data demonstrate that CD8⁺XCR1^neg DCs possess a unique pattern of endocytic receptors and a restricted toll-like receptor (TLR) profile that is particularly enriched for TLR5, giving them a unique position within the DC immunosurveillance network.

Interferon-α Subtypes As an Adjunct Therapeutic Approach for Human Immunodeficiency Virus Functional Cure

Human immunodeficiency virus (HIV) establishes life-long latency in infected individuals. Although highly active antiretroviral therapy (HAART) has had a significant impact on the course of HIV infection leading to a better long-term outcome, the pool of latent reservoir remains substantial even under HAART. Numerous approaches have been under development with the goal of eradicating the latent HIV reservoir though with limited success. Approaches that combine immune-mediated control of HIV to activate both the innate and the adaptive immune system under suppressive therapy along with "shock and kill" drugs may lead to a better control of the reactivated virus. Interferon-α (IFN-α) is an innate cytokine that has been shown to activate intracellular defenses capable of restricting and controlling HIV. IFN-α, however, harbors numerous functional subtypes that have been reported to display different binding affinities and potency. Recent studies have suggested that certain subtypes such as IFN-α8 and IFN-α14 have potent anti-HIV activity with little or no immune activation, whereas other subtypes such as IFN-α4, IFN-α5, and IFN-α14 activate NK cells. Could these subtypes be used in combination with other strategies to reduce the latent viral reservoir? Here, we review the role of IFN-α subtypes in HIV infection and discuss the possibility that certain subtypes could be potential adjuncts to a "shock and kill" or therapeutic vaccination strategy leading to better control of the latent reservoir and subsequent functional cure.

Different antiviral effects of IFNα subtypes in a mouse model of HBV infection

Interferon alpha (IFNα) is commonly used for the treatment of chronic hepatitis B (CHB) patients. There are 13 different IFNα subtypes in humans, but only the subtype IFNα2 is used for clinical treatment. The antiviral activities of all other IFNα subtypes against HBV have not been studied. To obtain basic knowledge about the direct antiviral as well as the immunomodulatory effects of IFNα subtypes, we used the HBV hydrodynamic injection (HI) mouse model. Application of most IFNα subtype proteins inhibited HBV replication in vivo, with IFNα4 and IFNα5 being the most effective subtypes. Decreased viral loads after therapeutic application of IFNα4 and IFNα5 correlated with expanded effector cell populations of NK cells and T cells in both liver and spleen. Hydrodynamic injection of plasmids encoding for the effective IFNα subtypes (pIFNα) was even more potent against HBV than injecting IFNα proteins. The combination of pIFNα4 and pIFNα5 showed a synergistic antiviral effect on HBV replication, with a strong increase in NK cell and T cell activity. The results demonstrate distinct anti-HBV effects of different IFNα subtypes against HBV in the mouse model, which may be relevant for new therapeutic approaches.

Different antiviral effects of IFNα and IFNβ in an HBV mouse model

Interferons α and β (IFNα and IFNβ) are type I interferons produced by the host to control pathogen propagation. However, only a minority of chronic hepatitis B (CHB) patients generate a sustained response after treatment with recombinant IFNα. The anti-HBV effect of IFNβ and the underlying mechanism are not well-understood. Here, we compared the antiviral activities of IFNα and IFNβ by application of IFNα or IFNβ expression plasmids using the well-established HBV hydrodynamic injection (HI) mouse model. Injection of IFNα expression plasmid could significantly reduce HBV serum markers including HBsAg, HBeAg and HBV DNA as well as the number of HBcAg positive cells in the liver, while IFNβ showed only a weak inhibition of HBV replication. In contrast to IFNβ, IFNα resulted in elevated expression levels of IFN stimulated genes (ISGs) as well as the proinflammatory cytokine interleukin 6 (IL6) in the liver. Moreover, IFNβ treated mice showed higher expression levels of the anti-inflammatory cytokines IL10 and TGFβ in the liver compared to IFNα. Our results demonstrated that both IFNα and IFNβ exert antiviral activities against HBV in HI mouse model, but IFNα is more effective than IFNβ.

Understanding Interferon Subtype Therapy for Viral Infections: Harnessing the Power of the Innate Immune System

Type I and III interferons (IFNs) of the innate immune system belong to a polygenic family, however the individual subtype mediators of the antiviral response in viral infections have been hindered by a lack of reagents. Evaluation studies using different IFN subtypes have distinguished distinct protein properties with different efficacies towards different viruses, opening promising avenues for immunotherapy. This review largely focuses on the application of IFN-α/β and IFN-λ therapies for viral infections, influenza, herpes, HIV and hepatitis. Such IFN subtype therapies may help to cure patients with virus infections where no vaccine exists. The ability of cell types to secrete a number of IFN subtypes from a multi-gene family may be an intuitive counterattack on viruses that evade IFN subtype responses. Hence, clinical use of virus-targeted IFN subtypes may restore antiviral immunity in viral infections. Accumulating evidence suggests that individual IFN subtypes have differential efficacies in selectively activating immune cell subsets to enhance antiviral immune responses leading to production of sustained B and T cell memory. Cytokine therapy can augment innate immunity leading to clearance of acute virus infections but such treatments may have limited effects on chronic virus infections that establish lifelong latency. Therefore, exploiting individual IFN subtypes to select those with the ability to sculpt protective responses as well as reinstating those targeted by viral evasion mechanisms may inform development of improved antiviral therapy.

Persistent and compartmentalised disruption of dendritic cell subpopulations in the lung following influenza A virus infection

Immunological homeostasis in the respiratory tract is thought to require balanced interactions between networks of dendritic cell (DC) subsets in lung microenvironments in order to regulate tolerance or immunity to inhaled antigens and pathogens. Influenza A virus (IAV) poses a serious threat of long-term disruption to this balance through its potent pro-inflammatory activities. In this study, we have used a BALB/c mouse model of A/PR8/34 H1N1 Influenza Type A Virus infection to examine the effects of IAV on respiratory tissue DC subsets during the recovery phase following clearance of the virus. In adult mice, we found differences in the kinetics and activation states of DC residing in the airway mucosa (AMDC) compared to those in the parenchymal lung (PLDC) compartments. A significant depletion in the percentage of AMDC was observed at day 4 post-infection that was associated with a change in steady-state CD11b+ and CD11b- AMDC subset frequencies and significantly elevated CD40 and CD80 expression and that returned to baseline by day 14 post-infection. In contrast, percentages and total numbers of PLDC were significantly elevated at day 14 and remained so until day 21 post-infection. Accompanying this was a change in CD11b+and CD11b- PLDC subset frequencies and significant increase in CD40 and CD80 expression at these time points. Furthermore, mice infected with IAV at 4 weeks of age showed a significant increase in total numbers of PLDC, and increased CD40 expression on both AMDC and PLDC, when analysed as adults 35 days later. These data suggest that the rate of recovery of DC populations following IAV infection differs in the mucosal and parenchymal compartments of the lung and that DC populations can remain disrupted and activated for a prolonged period following viral clearance, into adulthood if infection occurred early in life.

Susceptibility of different hepatitis B virus isolates to interferon-alpha in a mouse model based on hydrodynamic injection

Interferon alpha (IFN-α) is commonly used for the treatment of chronic hepatitis B (CHB) patients. Many factors including viral genetics may determine the outcome of IFN-α therapy. In this study, we tested whether the expression of IFN-α directly in the liver inhibits HBV gene expression and replication using a HBV hydrodynamic injection (HI) mouse model. Two replication-competent clones from different HBV isolates that belonging to HBV genotype A and B based on a pAAV vector (pAAV-HBV-A and pAAV-HBV-B) were compared for their susceptibility to IFN-α. HBV clones were injected into mice either alone or in combination with a murine (m) IFN-α expression plasmid (pmIFN-α). HBsAg and HBeAg concentrations and HBV DNA levels in mice differed after injection of these two HBV clones. Co-application of pmIFN-α together with the two distinct isolates resulted in markedly different kinetics of decline of HBsAg, HBeAg, and HBV DNA levels in the mice. Immunohistochemical staining of liver sections with anti-HBc showed that mIFN-α application completely inhibited the expression of HBcAg in mice inoculated with pAAV-HBV-B, whereas the expression of HBcAg was only reduced in mice with pAAV-HBV-A. Consistently, mice injected with pAAV-HBV-B and pmIFN-α showed higher expression levels of the IFN-stimulated genes (ISGs) ISG15, OAS, PKR as well as proinflammatory cytokine IL-6 in the liver. In addition, expression levels of anti-inflammatory cytokine IL-10 was down-regulated significantly in liver of the mice injected with pAAV-HBV-B and pmIFN-α. Our data demonstrate that IFN-α exerts antiviral activity in HBV mouse model, but different HBV isolates may have diverse susceptibility to IFN-α.

Modulation of innate immune responses by influenza-specific ovine polyclonal antibodies used for prophylaxis

In the event of a novel influenza A virus pandemic, prophylaxis mediated by antibodies provides an adjunct control option to vaccines and antivirals. This strategy is particularly pertinent to unvaccinated populations at risk during the lag time to produce and distribute an effective vaccine. Therefore, development of effective prophylactic therapies is of high importance. Although previous approaches have used systemic delivery of monoclonal antibodies or convalescent sera, available supply is a serious limitation. Here, we have investigated intranasal delivery of influenza-specific ovine polyclonal IgG antibodies for their efficacy against homologous influenza virus challenge in a mouse model. Both influenza-specific IgG and F(ab')2 reduced clinical scores, body weight loss and lung viral loads in mice treated 1 hour before virus exposure. Full protection from disease was also observed when antibody was delivered up to 3 days prior to virus infection. Furthermore, effective prophylaxis was independent of a strong innate immune response. This strategy presents a further option for prophylactic intervention against influenza A virus using ruminants to generate a bulk supply that could potentially be used in a pandemic setting, to slow virus transmission and reduce morbidity associated with a high cytokine phenotype.

IFN-α subtypes: distinct biological activities in anti-viral therapy

During most viral infections, the immediate host response is characterized by an induction of type I IFN. These cytokines have various biological activities, including anti-viral, anti-proliferative and immunomodulatory effects. After induction, they bind to their IFN-α/β receptor, which leads to downstream signalling resulting in the expression of numerous different IFN-stimulated genes. These genes encode anti-viral proteins that directly inhibit viral replication as well as modulate immune function. Thus, the induction of type I IFN is a very powerful tool for the host to fight virus infections. Many viruses evade this response by various strategies like the direct suppression of IFN induction or inhibition of the IFN signalling pathway. Therefore, the therapeutic application of exogenous type I IFN or molecules that induce strong IFN responses should be of great potential for future immunotherapies against viral infections. Type I IFN is currently used as a treatment in chronic hepatitis B and C virus infection, but as yet is not widely utilized for other viral infections. One reason for this restricted clinical use is that type I IFN belongs to a multigene family that includes 13 different IFN-α subtypes and IFN-β, whose individual anti-viral and immunomodulatory properties have so far not been investigated in detail to improve IFN therapy against viral infections in humans. In this review, we summarize the recent achievements in defining the distinct biological functions of type I IFN subtypes in cell culture and in animal models of viral infection as well as their clinical usage in chronic hepatitis virus infections.

Interferons as biomarkers and effectors: lessons learned from animal models

Interferons (IFNs) comprise type I, II and III families with multiple subtypes. Via transcription of IFN-stimulated genes (ISGs), IFNs can exert multiple biological effects on the cell. In infectious and chronic inflammatory diseases, the IFNs and their ISG sets can be potentially utilized as biomarkers of disease outcome. Animal models allow investigations into disease pathogenesis and gene knockout models have proved cause and effect relationships of molecules related to the IFN response. Sets of IFN subtypes and their ISG products provide immunological signature patterns for different viral and other diseases. In this article, we give an overview of IFNs in several virus infection models and autoimmune diseases of medical relevance. Lessons learned from animal models inform us of IFN system parameters as indicators of disease outcome and whether clinical research is warranted. Moreover, validated IFN biomarkers for prognosis enhance our understanding of therapeutic and vaccine development.

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.

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.

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.

The regulatory elements of araBAD operon, contrary to lac-based expression systems, afford hypersynthesis of murine, and human interferons in Escherichia coli

The overexpression of four different interferons, i.e., murine interferon alpha1 and human interferons alpha1, alpha 8, and alpha 21 was challenged in Escherichia coli. Synthetic genes coding for these interferons were designed, assembled, and cloned into the vector pET9a (using the NdeI and BamHI sites), placing interferon expression under the control of phage T7 promoter. Despite an intensive screening for optimal culture conditions, no interferon synthesis was observed using overexpression systems based on the regulatory elements of lac operon (e.g., in E. coli BL21DE3). On the contrary, high levels of interferon expression were detected in E. coli BL21AI, which chromosome contains the gene coding for phage T7 RNA polymerase under the control of the araBAD promoter. To analyze the reasons of this striking difference, the molecular events associated with the lack of interferon expression in E. coli BL21DE3 were studied, and murine interferon alpha1 was chosen as a model system. Surprisingly, it was observed that this interferon represses the synthesis of T7 RNA polymerase in E. coli BL21DE3 and, in particular, the expression of lac operon. In fact, by determining beta-galactosidase activity in E. coli BL21AI, a significantly lower LacZ activity was observed in cells induced to interferon synthesis.

Cytomegalovirus immune evasion

Human cytomegalovirus (HCMV) has become a paradigm for viral immune evasion due to its unique multitude of immune-modulatory strategies. HCMV modulates the innate as well as adaptive immune response at every step of its life cycle. It dampens the induction of antiviral interferon-induced genes by several mechanisms. Further striking is the multitude of genes and strategies devoted to modulating and escaping the cellular immune response. Several genes are independently capable of inhibiting antigen presentation to cytolytic T cells by downregulating MHC class I. Recent data revealed an astounding variety of methods in triggering or inhibiting activatory and inhibitory receptors found on NK cells, NKT cells, T cells as well as auxiliary cells of the immune system. The multitude and complexity of these mechanisms is fascinating and continues to reveal novel insights into the host-pathogen interaction and novel cell biological and immunological concepts.

Induction and evasion of the type I interferon response by cytomegaloviruses

Cytomegaloviruses represent supreme pathogens in that they are capable of occupying healthy mammalian hosts for life in the face of constant antiviral immune reactions. The inability of the host to eliminate the virus likely results from numerous counteractive strategies employed to disrupt the immune response. The role of type I interferon in the antiviral response has been well documented although only recently have the pathways of induction of this powerful cytokine been described. Cytomegaloviruses have been shown to both induce and be sensitive to the effects of type I interferon. Yet these viruses also possess numerous and varied phenotypes capable of inhibiting not only interferon induction but also interferon signaling and interferon-induced antiviral processes. The balance between induction and evasion of type I interferon responses by cytomegaloviruses is discussed in this review.

Differential activities of alpha/beta IFN subtypes against influenza virus in vivo and enhancement of specific immune responses in DNA vaccinated mice expressing haemagglutinin and nucleoprotein

Vaccines are urgently needed to elicit immunity to different influenza virus strains. DNA vaccines can elicit partial protective immunity, however their efficacy requires improvement. We assessed the capacity of individual type I IFN multigene family members as subtype transgenes to abrogate influenza virus replication in a vaccination/challenge mouse model. Differences in antiviral efficacy were found among the subtypes with IFNA5 and IFNA6 being most effective, while IFNA1 was the least effective in reducing lung virus replication. Mice vaccinated with combinatorial HA/IFNA6 or NP/IFNA6 showed reduced lung viral titres, clinical score, body weight loss, and pulmonary tissue damage compared to IFNA6, HA, or NP viral vaccination alone. In addition, IFNA6 increased IgG2a titres with upregulation of IFN-gamma response in the respiratory tract. We conclude that IFN-alpha 6 has antiviral and immunomodulatory effects, which improve efficacy of DNA vaccines for enhanced control of influenza.

The role of type I interferons in non-viral infections

For a long time, the family of type I interferons (IFN-alpha/beta) has received little attention outside the fields of virology and tumor immunology. In recent years, IFN-alpha/beta regained the interest of immunologists, due to the phenotypic and functional characterization of IFN-alpha/beta-producing cells, the definition of novel immunomodulatory functions and signaling pathways of IFN-alpha/beta, and the observation that IFN-alpha/beta not only exerts antiviral effects but is also relevant for the pathogenesis or control of certain bacterial and protozoan infections. This review summarizes the current knowledge on the production and function of IFN-alpha/beta during non-viral infections in vitro and in vivo.

Type I IFN-beta gene therapy suppresses cardiac CD8+ T-cell infiltration during autoimmune myocarditis

Gene therapy using DNA encoding type I IFN subtypes IFNA6, IFNA9 and IFNB suppresses murine cytomegalovirus (MCMV)-myocarditis, a predominantly cell-mediated disease in BALB/c mice. CD8(+) T cells are the principal cell type within the inflamed myocardium. As such, we investigated the effects of IFN subtype treatment on this T-cell subset and other cell types in the cardiac infiltrate. In the acute phase of disease, IFNA6 and IFNA9 treatments significantly reduced the number of CD8(+) T cells within the foci of cellular infiltration in the heart. During the chronic phase, which is primarily autoimmune in nature, IFNB treatment significantly reduced CD8(+) T cells. B-cell and neutrophil numbers in the cardiac infiltrate were also reduced following IFNB immunotherapy. Although early inflammatory responses are important for resolution of virus infection, high numbers of lymphocytes persisting in the myocardium may lead to exacerbation of disease. Our data suggests that type I IFN DNA therapy regulates cardiac cellular infiltration. Thus, treatment with IFN-beta administered prophylactically to high-risk patients in acquiring CMV infection may reduce the development of chronic autoimmune myocarditis.

Protection against progressive leishmaniasis by IFN-beta

Type I IFNs (IFN-alphabeta) exert potent antiviral and immunoregulatory activities during viral infections, but their role in bacterial or protozoan infections is poorly understood. In this study, we demonstrate that the application of low, but not of high doses of IFN-beta protects 60 or 100% of BALB/c mice from progressive cutaneous and fatal visceral disease after infection with a high (10(6)) or low (10(4)) number of Leishmania major parasites, respectively. IFN-beta treatment of BALB/c mice restored the NK cell cytotoxic activity, increased the lymphocyte proliferation, and augmented the production of IFN-gamma and IL-12 in the draining lymph node. Low, but not high doses of IFN-beta caused enhanced tyrosine phosphorylation of STAT1 and STAT4, suppressed the levels of suppressor of cytokine signaling-1, and up-regulated the expression of inducible NO synthase in vivo. The IFN-beta-induced increase of IFN-gamma production was dependent on STAT4. Protection by IFN-beta strictly required the presence of inducible NO synthase. In the absence of STAT4 or IL-12, IFN-beta led to an amelioration of the cutaneous and visceral disease, but was unable to prevent its progression. These results identify IFN-beta as a novel cytokine with a strong, dose-dependent protective effect against progressive cutaneous leishmaniasis that results from IL-12- and STAT4-dependent as well as -independent events.

Interferon-beta suppresses herpes simplex virus type 1 replication in trigeminal ganglion cells through an RNase L-dependent pathway

The induction of an antiviral state by type I interferons (IFN) was evaluated in primary trigeminal ganglion cell cultures using herpes simplex virus type 1 (HSV-1). Cells treated with mouse IFN-beta consistently showed the greatest resistance to HSV-1 infection in comparison to cells treated with IFN-alpha1, IFN-alpha4, IFN-alpha5, IFN-alpha6, or IFN-alpha9. The antiviral efficacy was dose-dependent and correlated with the induction of the IFN-inducible, antiviral genes, 2'-5' oligoadenylate synthetase (OAS) and double-stranded RNA-dependent protein kinase. In trigeminal ganglion cells deficient in the downstream effector molecule of the OAS pathway, RNase L, the antiviral state induced by IFN-beta was lost.

Cytokine expression in murine cytomegalovirus-induced myocarditis: modulation with interferon-alpha therapy

Cytomegalovirus-induced myocarditis is largely immune-mediated. BALB/c mice produced higher levels of IL-4 in the heart indicative of a Th2-like response. Although IL-6, IL-10, IL-18, and TNF-alpha were produced in the heart during acute infection, BALB/c mice lacked a substantial IL-2 and IFN-gamma response. Conversely, C57BL/6 mice produced significant levels of IFN-gamma in the heart with no significant levels of IL-4 or IL-6, suggestive of a dominant Th1-like response to virus infection. IFN-alpha/beta immunotherapy is known to suppress the development of MCMV-myocarditis. Cytokine secretion in IFN-stimulated MCMV-infected BALB/c myocytes was found to be IFN subtype-dependent with elevation of IL-6 and IL-18 levels. During the chronic phase of disease, IFNA6 DNA treatment in vivo increased IL-18 production in the heart. These results suggest that IFN subtype therapy may have immunomodulating effects in reducing disease severity in BALB/c mice via regulation of cytokine production in the heart.

Type I interferon differential therapy for erythroleukemia: specificity of STAT activation

Type I interferons (IFNs), pleiotropic cytokines with antiviral, antiproliferative, apoptotic, and immunoregulatory functions, are efficacious in the treatment of malignancies, viral infections, and autoimmune diseases. Binding of these cytokines to their cognate receptor leads to activation of the Jak-signal transducers and activators of transcription (STAT) signaling pathway and altered gene expression. This signal pathway has been intensely studied using human IFN-alpha 2 and IFN-beta. However, there are over 14 human IFN-alpha subtypes and over 10 murine IFN-alpha subtypes, with a single IFN-beta subtype in both species. J2E cells are immortalized at the proerythroblast stage of development and produce a rapid and fatal erythroleukemia in vivo. These cells retain the ability to respond to erythropoietin in vitro by proliferating, differentiating, and remaining viable in the absence of serum. Here, we show that J2E cells are also functionally regulated differentially by IFN subtype treatment in vitro. A novel finding was the selective activation of STAT and mitogen-activated protein kinase (MAPK) molecules by different subtypes binding the IFN receptor. These findings indicate distinct effects for individual type I IFN subtypes, which are able to differentially activate members of the STAT and MAPK family. Finally, we investigated the efficacy of IFN naked DNA therapy in treating J2E-induced erythroleukemia in athymic nude mice. IFN subtypes differentially regulated the onset of erythroleukemia with delayed onset and increased survival, possibly via a reduction in cell viability, and enhanced antiproliferative and apoptotic effects observed for IFNA6 and IFNA9 treatment, respectively. Moreover, these data highlight the necessity to choose the best IFN subtype in disease treatment.

Optimization of Naked DNA Delivery for Interferon Subtype Immunotherapy in Cytomegalovirus Infection

Type I interferon (IFN) gene therapy modulates the immune response leading to inflammatory heart disease following cytomegalovirus (CMV) infection in a murine model of post-viral myocarditis. Efficacy of different immunisation protocols for the IFN constructs was influenced by the dose of DNA, subtype choice, combination use, pre-medication, and timing of DNA administration. Optimal efficacy was found with bupivacaine treatment prior to DNA inoculation of 200mg IFN DNA 14 days prior to virus challenge. Maximal antiviral and antimyocarditic effects were achieved with this vaccination schedule. Furthermore, inoculation of synergistic IFN subtypes demonstrated enhanced efficacy when delivered either alone or with CMV gB DNA vaccination in the CMV model. Thus naked DNA delivery of IFN provides an avenue of immunotherapy for regulating herpesvirus-induced diseases.

Coimmunisation with type I IFN genes enhances protective immunity against cytomegalovirus and myocarditis in gB DNA-vaccinated mice

Viral DNA vaccines encoding the glycoprotein B (gB) of cytomegalovirus provide partial protective immunity upon challenge with infectious virus. Although it is known that type I IFN can stimulate the adaptive immune response, their direct use in vaccines has been limited. Here we show that coimmunisation of type I IFN and gB CMV DNA constructs enhances protective immunity in mice. In vivo expression of IFN transgenes ranged from 1.2 to 2.0 x 10(4) IU/g tibialis anterior muscle. Viral titre in major target organs and the severity of acute CMV-induced myocarditis was reduced preferentially with either IFN-alpha 9 or IFN-beta, but not with IFN-alpha 6, coimmunisation. However, all IFN subtypes investigated markedly reduced chronic myocarditis in gB-vaccinated mice. The early antiviral IgG1 and IgG2a titres were enhanced with IFN-beta coimmunisation. TNF and IL-10 was increased in response to MCMV infection in mice coimmunised with IFN subtypes and viral gB DNA. Indeed T cells from IFN-inoculated mice reduced myocarditis upon in vivo transfer. These results suggest that select type I IFNs may act as a natural adjuvant for the immune response against CMV infection. Type I IFN DNA coimmunisation may provide increased efficacy for viral vaccines and subsequently modulate post-viral chronic inflammatory disorders.

Synergy of type I interferon-A6 and interferon-B naked DNA immunotherapy for cytomegalovirus infection

Delivery of type I IFN transgenes by naked DNA immunization can protect against cytomegalovirus infection and myocarditis. Here, we investigate IFN transgene expression, antiviral efficacy, and immunomodulation of myocarditis using various treatment regimes in a mouse CMV model. In vivo expression of the IFN transgene was observed in the sera for 35 days post-DNA inoculation. Prophylactic IFN-A6 and IFN-B DNA treatment for 14 days prior to murine cytomegalovirus (MCMV) infection was more efficacious in significantly reducing viral titres, than 2 days prior to or 2 days post-virus infection. Similarly, IFN-A6 DNA treatment commencing 14 days prior to virus infection was superior in suppressing both acute and chronic myocarditis. Furthermore, reduction of autoantibody titres was more pronounced when IFN was administered 14 days prior to viral infection. Combinational IFN gene therapy was assessed for synergy between IFN subtypes. Combination treatment with either IFN-A6/A9 or IFN-A6/B greatly reduced spleen viral titres while IFN-A6/B and IFN-A9/B reduced virus replication in the liver. Only IFN-A6/A9 and IFN-A9/B reduced acute viral myocarditis, whereas IFNA6/B treatment was most efficacious for autoimmune chronic myocarditis. Finally, treatment with IFN-A6 DNA 2 weeks post-MCMV infection proved effective at inhibiting the development of chronic autoimmune myocarditis. These findings suggest that immunomodulation of both antiviral and autoimmune responses by IFN DNA immunization may be an avenue for improved viral immunotherapy.

Differential effect of murine alpha/beta interferon transgenes on antagonization of herpes simplex virus type 1 replication

Alpha/beta interferons (IFN-alpha/beta) are potent, endogenous antiviral cytokines that suppress the replication of RNA and DNA viruses, including herpes simplex virus type 1 (HSV-1). The present study compared the efficacies of IFN-alpha/beta transgenes, including IFN-alpha1, -alpha4, -alpha5, -alpha6, -alpha9, and -beta, against HSV-1 infection. L929 cells transfected with the IFN-alpha/beta transgenes produced similar levels of IFN, as measured by bioassay and enzyme-linked immunosorbent assay. In addition, transfected cells were less susceptible to HSV-1 infection than were cells transfected with a plasmid vector control. The murine IFN-beta plasmid construct exhibited the greatest reduction, while the murine IFN-alpha5 transgene showed a modest inhibitory effect in viral titers recovered from the supernatants of transfected, infected L929 cultures. Consistent with this observation, the IFN-beta transgene antagonized viral transcript levels, including infected cell protein 27, thymidine kinase, and glycoprotein B, to a greater extent than did the IFN-alpha transgenes at 6 to 10 h postinfection as determined by real-time PCR. Cells transfected with the IFN-alpha4, IFN-alpha9, or IFN-beta transgenes showed the greatest reduction in viral protein expression relative to the other transfected cells, which was associated with increased STAT1 expression. The absence of the IFN-responsive protein kinase R (PKR) gene completely abrogated the antiviral induction by all IFN-alpha/beta against HSV-1. In the absence of RNase L, viral yields were increased 10-fold, but the antiviral effect of IFN was either unaffected or enhanced. These results suggest that the predominant IFN-mediated, antiviral pathway during HSV-1 infection taken by IFN-alpha/beta in L929 cells utilizes PKR.