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

Canine Transmissible Venereal Tumor: An Infectious Neoplasia in Dogs

Canine transmissible venereal tumor is the oldest cancer in dogs and is transplanted via viable cancer cells. This cancer has a specific host, easy transmission, noticeable gross lesions, a predictable growth pattern, an immunologic relative host response, unique molecular characteristics, and is responsive to chemotherapeutic treatment. These points make researchers and practitioners interested in this cancer. Genital cases are noticeable and therefore easier to diagnose and treat than extragenital cases. By contrasting the anatomical features of the two types of cases, we highlight the uniqueness of canine transmissible venereal tumors and discuss the diagnosis, treatment, and prevention of this ancient cancer.

SARS-CoV-2 Spike Protein Suppresses ACE2 and Type I Interferon Expression in Primary Cells From Macaque Lung Bronchoalveolar Lavage

SARS-CoV-2 virus causes upper and lower respiratory diseases including pneumonia, and in some cases, leads to lethal pulmonary failure. Angiotensin converting enzyme-2 (ACE2), the receptor for cellular entry of SARS-CoV-2 virus, has been shown to protect against severe acute lung failure. Here, we provide evidence that SARS-CoV-2 spike protein S1 reduced the mRNA expression of ACE2 and type I interferons in primary cells of lung bronchoalveolar lavage (BAL) from naïve rhesus macaques. The expression levels of ACE2 and type I interferons were also found to be correlated with each other, consistent with the recent finding that ACE2 is an interferon-inducible gene. Furthermore, induction of ACE2 and type I interferons by poly I:C, an interferon inducer, was suppressed by S1 protein in primary cells of BAL. These observations suggest that the downregulation of ACE2 and type I interferons induced by S1 protein may directly contribute to SARS-CoV-2-associated lung diseases.

Heightened resistance to host type 1 interferons characterizes HIV-1 at transmission and after antiretroviral therapy interruption

Type 1 interferons (IFN-I) are potent innate antiviral effectors that constrain HIV-1 transmission. However, harnessing these cytokines for HIV-1 cure strategies has been hampered by an incomplete understanding of their antiviral activities at later stages of infection. Here, we characterized the IFN-I sensitivity of 500 clonally derived HIV-1 isolates from the plasma and CD4+ T cells of 26 individuals sampled longitudinally after transmission or after antiretroviral therapy (ART) and analytical treatment interruption. We determined the concentration of IFNα2 and IFNβ that reduced viral replication in vitro by 50% (IC50) and found consistent changes in the sensitivity of HIV-1 to IFN-I inhibition both across individuals and over time. Resistance of HIV-1 isolates to IFN-I was uniformly high during acute infection, decreased in all individuals in the first year after infection, was reacquired concomitant with CD4+ T cell loss, and remained elevated in individuals with accelerated disease. HIV-1 isolates obtained by viral outgrowth during suppressive ART were relatively IFN-I sensitive, resembling viruses circulating just before ART initiation. However, viruses that rebounded after treatment interruption displayed the highest degree of IFNα2 and IFNβ resistance observed at any time during the infection course. These findings indicate a dynamic interplay between host innate responses and the evolving HIV-1 quasispecies, with the relative contribution of IFN-I to HIV-1 control affected by both ART and analytical treatment interruption. Although elevated at transmission, host innate pressures are the highest during viral rebound, limiting the viruses that successfully become reactivated from latency to those that are IFN-I resistant.

In vitro Effect of Recombinant Feline Interferon-Ω (rFeIFN-Ω) on the Primary CanineTransmissible Venereal Tumor Culture

Background: Interferons (IFNs), signaling proteins produced by host cells, are secreted in response to pathogen activity as well as to tumor cells, and display antiviral, antiproliferative, and immunomodulatory effects. Recombinant feline interferon omega (rFeIFN-ω) has in vitro growth inhibition activities on various canine and feline tumor cell lines. Canine transmissible venereal tumor (CTVT) is used as an animal model for immunotherapy due to its specific growth phase. Previous studies have usually focused on the interaction between tumor infiltrating lymphocytes (TILs) and CTVT cells. However, the specific effects of rFeIFN-ω on CTVT cells remains poorly defined.

Aims: The aims of this study, therefore, were to evaluate the in vitro effect of rFeIFN-ω on primary CTVT cells and to study the mRNA expression of apoptotic genes and drug resistance genes.

Materials and Methods: Purified CTVT cells were treated with various concentrations of rFeIFN-ω and the viability of the cultured cells was ascertained at 24, 48, and 72 h post treatment (hpt) and a dose-response curve plotted. The mRNA expression of apoptotic (BAX and BCL-2) and drug resistance (ABCB1 and ABCG2) genes was performed by reverse transcription quantitative real-time PCR at 72 hpt.

Results: rFeIFN-ω displayed an effect against CTVT cell viability, which decreasing viability in a dose-dependent manner within 72 hpt. The relative mRNA expression of BCL-2 was upregulated only at a rFeIFN-ω concentration of 10⁴ IU/100 μl. However, higher concentrations of rFeIFN-ω gave a higher level of relative mRNA expression of ABCB1 transporter gene.

Conclusion: This study provided the information of in vitro effect of rFeIFN-ω on CTVT cell viability in a dose dependent manner, as well as, the alteration of BCL-2 and ABCB1 gene expression after treatment. These results encourage future in vivo studies to evaluate the potential efficacy of this treatment in CTVT cases.

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.

Antivirals for Virus Induced Exacerbations of Asthma and COPD Treatment

Viral respiratory infections in patients with asthma or chronic obstructive pulmonary disease (COPD) can cause severe exacerbations, increasing the risk of secondary bacterial infections and having a significant impact on disease-related morbidity and mortality. Several antivirals such as oseltamivir and zanamivir evaluated in influenza and other virus-induced respiratory infections are discussed in this review as a starting point of their potential use in improving the outcome of asthma and COPD exacerbations. However, the efficacy of antiviral therapy for asthma/COPD exacerbations needs a further evaluation.

The role of respiratory epithelium in host defence against influenza virus infection

The respiratory epithelium is the major interface between the environment and the host. Sophisticated barrier, sensing, anti-microbial and immune regulatory mechanisms have evolved to help maintain homeostasis and to defend the lung against foreign substances and pathogens. During influenza virus infection, these specialised structural cells and populations of resident immune cells come together to mount the first response to the virus, one which would play a significant role in the immediate and long term outcome of the infection. In this review, we focus on the immune defence machinery of the respiratory epithelium and briefly explore how it repairs and regenerates after infection.

Antibody immunoprophylaxis and immunotherapy for influenza virus infection: Utilization of monoclonal or polyclonal antibodies?

Control programs for emerging influenza are in urgent need of novel therapeutic strategies to mitigate potentially devastating threats from pathogenic strains with pandemic potential. Current vaccines and antivirals have inherent limitations in efficacy, especially with rapid evolutionary changes of influenza viruses. Antibody-based antiviral protection harnesses the natural power of the immune system. Antibodies present prophylactic and therapeutic intervention options for prevention and control of influenza, especially for at-risk populations. Specific monoclonal antibodies are well defined in purity and initial efficacy but polyclonal antibodies are easier to scale-up and cost-effective with long-term efficacy, using batches with broadly neutralizing properties against influenza variants. This review presents the pros and cons of monoclonal versus polyclonal antibody therapy for influenza.

hrHPV E5 oncoprotein: immune evasion and related immunotherapies

The immune response is a key factor in the fight against HPV infection and related cancers, and thus, HPV is able to promote immune evasion through the expression of oncogenes. In particular, the E5 oncogene is responsible for modulation of several immune mechanisms, including antigen presentation and inflammatory pathways. Moreover, E5 was suggested as a promising therapeutic target, since there is still no effective medical therapy for the treatment of HPV-related pre-neoplasia and cancer. Indeed, several studies have shown good prospective for E5 immunotherapy, suggesting that it could be applied for the treatment of pre-cancerous lesions. Thus, insofar as the majority of cervical, oropharyngeal and anal cancers are caused by high-risk HPV (hrHPV), mainly by HPV16, the aim of this review is to discuss the immune pathways interfered by E5 oncoprotein of hrHPV highlighting the various aspects of the potential immunotherapeutic approaches.

The Role of IFN-β during the Course of Sepsis Progression and Its Therapeutic Potential

Sepsis is a complex biphasic syndrome characterized by both pro- and anti-inflammatory immune states. Whereas early sepsis mortality is caused by an acute, deleterious pro-inflammatory response, the second sepsis phase is governed by acute immunosuppression, which predisposes patients to long-term risk for life-threatening secondary infections. Despite extensive basic research and clinical trials, there is to date no specific therapy for sepsis, and mortality rates are on the rise. Although IFN-β is one of the most-studied cytokines, its diverse effects are not fully understood. Depending on the disease or type of infection, it can have beneficial or detrimental effects. As IFN-β has been used successfully to treat diverse diseases, emphasis has been placed on understanding the role of IFN-β in sepsis. Analyses of mouse models of septic shock attribute a pro-inflammatory role to IFN-β in sepsis development. As anti-inflammatory treatments in humans with antibodies to TNF-α or IL1-β resulted disappointing, cytokine modulation approaches were discouraged and neutralization of IFN-β has not been pursued for sepsis treatment. In the case of patients with delayed sepsis and immunosuppression, there is a debate as to whether the use of specific cytokines would restore the deactivated immune response. Recent reports show an association of low IFN-β levels with the hyporesponsive state of monocytes from sepsis patients and after endotoxin tolerance induction. These data, discussed here, project a role for IFN-β in restoring monocyte function and reversing immunosuppression, and suggest IFN-β-based additive immunomodulatory therapy. The dichotomy in putative therapeutic approaches, involving reduction or an increase in IFN-β levels, mirrors the contrasting nature of the early hyperinflammatory state and the delayed immunosuppression phase.