Mismatched dsRNA (ampligen) induces protection against genomic variants of the human immunodeficiency virus type 1 (HIV-1) in a multiplicity of target cells

Effects of Adjuvants on HIV-1 Envelope Glycoprotein SOSIP Trimers In Vitro

Native-like, soluble, recombinant SOSIP trimers of various designs and based on several env genes of human immunodeficiency virus type 1 (HIV-1) are being tested as immunogens in different animal models. These experiments almost always involve coformulating the trimers with an adjuvant to boost the magnitude of the immune responses. One factor relevant to the choice of an adjuvant is that it should not physically damage the immunogen or impede its ability to present relevant epitopes. As examples, an adjuvant formulation that includes harsh detergents could disrupt the structural integrity of a trimer, and any charged compounds in the formulation could bind to countercharged regions of the trimer and physically occlude nearby epitopes. While a few adjuvants have been tested for their potential effects on SOSIP trimers in vitro, there has been no systematic study. Here, we have assessed how nine different adjuvants of various compositions affect SOSIP trimers of the BG505 and B41 genotypes. We used negative-stain electron microscopy, thermal denaturation, and gel electrophoresis to evaluate effects on trimer integrity and immunoassays to measure effects on the presentation of various epitopes. We conclude that most of the tested adjuvants are benign from these perspectives, but some raise grounds for concern. An acidified alum formulation is highly disruptive to trimer integrity, and a DNA-based polyanionic CpG oligodeoxynucleotide adjuvant binds to trimers and occludes the trimer apex epitope for the PGT145 neutralizing antibody. The methods described here should be generalizable to protein subunit vaccines targeting various pathogens.

IMPORTANCE Adjuvant formulations increase the magnitude of immune responses to vaccine antigens. They are critically important for formulation of HIV-1 envelope glycoprotein (Env) vaccines intended to induce antibody production, as Env proteins are otherwise only very weakly immunogenic. The HIV-1 vaccine field now uses the well-defined structures of trimeric Env glycoproteins, like SOSIPs, to present multiple known epitopes for broad and potent neutralizing human antibodies in a native-like conformation. Successful adjuvant formulations must not disrupt how the trimers are folded, as that could adversely affect their performance as immunogens. We studied whether the various adjuvants most commonly used in animal experiments affect the integrity of two different SOSIP trimers in vitro. Most adjuvant classes are not problematic, but an aluminum sulfate formulation is highly damaging, as it exposes trimers to acidic pH and a nucleic acid-based adjuvant can bind to the trimer and block access to a key neutralizing epitope.

Vaccine adjuvant uses of poly-IC and derivatives

Pathogen-associated molecular patterns (PAMPs) are stand-alone immunomodulators or 'danger signals,' that are increasingly recognized as critical components of many modern vaccines. Polyinosinic-polycytidylic acid (poly-IC) is a synthetic dsRNA that can activate multiple elements of the host defense in a pattern that parallels that of a viral infection. When properly combined with an antigen, it can be utilized as a PAMP-adjuvant, resulting in modulation and optimization of the antigen-specific immune response. We briefly review the preclinical and clinical uses of poly-IC and two poly-IC derivatives, poly-IC12U (Ampligen) and poly-ICLC (Hiltonol), as vaccine adjuvants.

Protective role of Toll-like Receptor 3-induced type I interferon in murine coronavirus infection of macrophages

Toll-like Receptors (TLRs) sense viral infections and induce production of type I interferons (IFNs), other cytokines, and chemokines. Viral recognition by TLRs and other pattern recognition receptors (PRRs) has been proven to be cell-type specific. Triggering of TLRs with selected ligands can be beneficial against some viral infections. Macrophages are antigen-presenting cells that express TLRs and have a key role in the innate and adaptive immunity against viruses. Coronaviruses (CoVs) are single-stranded, positive-sense RNA viruses that cause acute and chronic infections and can productively infect macrophages. Investigation of the interplay between CoVs and PRRs is in its infancy. We assessed the effect of triggering TLR2, TLR3, TLR4, and TLR7 with selected ligands on the susceptibility of the J774A.1 macrophage cell line to infection with murine coronavirus (mouse hepatitis virus, [MHV]). Stimulation of TLR2, TLR4, or TLR7 did not affect MHV production. In contrast, pre-stimulation of TLR3 with polyinosinic-polycytidylic acid (poly I:C) hindered MHV infection through induction of IFN-β in macrophages. We demonstrate that activation of TLR3 with the synthetic ligand poly I:C mediates antiviral immunity that diminishes (MHV-A59) or suppresses (MHV-JHM, MHV-3) virus production in macrophages.

Assays for the assessment of neutralizing antibody activities against Severe Acute Respiratory Syndrome (SARS) associated coronavirus (SCV)

Accurate assessment of neutralizing antibody activities is important either for patients infected with Severe Acute Respiratory Syndrome (SARS) or for animals and volunteers immunized with the experimental vaccines against the SARS associated coronavirus (SCV). However, the current assay based on the cytopathic effect (CPE) which has been frequently cited in literature has several limitations. The CPE assay relies on the visual observation on the damage of SCV infected target cells under a microscope. It is subjected to observer variations and it is difficult to generate a quantitative determination of neutralizing activities based on the level of CPE. In the current study, we established the utility of two additional assays to measure the neutralizing activities against SCV: the plaque reduction (PR) and the neutral red staining (NRS) assays. The PR assay described in this study was modified from the traditional viral plaque reduction assay by using an improved crystal staining method to achieve better plague formation in SCV infected Vero E6 cells. The NRS neutralization assay was adopted from a similar system used for detecting neutralizing antibody responses against human immunodeficiency virus type 1 (HIV-1). In this assay, the protective effect of neutralizing antibodies was determined by the cell viability which is measured by the uptake of neutral red dye at A₅₄₀. The neutralizing antibody titers can be easily determined with either of the two new assays. In this report, we described the utility of these two new neutralization assays in measuring the neutralizing activities against SCV infection from rabbit sera immunized with various forms of spike protein of SCV.

Mismatched double-stranded RNA (polyI-polyC(12)U) is synergistic with multiple anti-HIV drugs and is active against drug-sensitive and drug-resistant HIV-1 in vitro

Although highly active anti-retroviral therapy (HAART) is successful in the treatment of HIV infection, problems with toxicity, drug-resistant variants, and therapeutic failures have compromised the long-term utility of existing combination regimens. Mismatched double-stranded RNA (polyI-polyC(12)U) is an immune modulator with inherent anti-HIV activity. Cell toxicities and anti-HIV activities of fourteen anti-HIV agents were determined alone and in combination with polyI-polyC(12)U. Combination analyses for anti-HIV activity were performed at three drug ratios. Using Mixed Dose Effect analyses and the CalcuSyn for Windows software package, combination indeces were determined for all drug combinations. In general, polyI-polyC(12)U was synergistic in combination with abacavir, zidovudine, zalcitabine, didanosine, stavudine, efavirenz, indinavir, ritonavir, nelfinavir, and amprenavir. It was synergistic to antagonistic with lamivudine, delavirdine, nevirapine, and saquinavir. Thus, polyI-polyC(12)U is synergistic with most anti-HIV agents at most drug ratios and across most effective concentrations in vitro, although, certain members of each class were exceptions. PolyI-polyC(12)U alone was equally active against wild-type HIV and HIV resistant to nevirapine, protease inhibitors, or nucleoside analogue reverse transcriptase inhibitors. These results suggest that polyI-polyC(12)U should be re-evaluated as a potential adjunct therapy in patients who have failed current anti-retroviral therapeutic regimens.

Anti-human immunodeficiency virus effects of zidovudine in combination with double-stranded RNA poly I poly C in T cells and monocytes-macrophages

A comparison of the activity against human immunodeficiency virus 1 of zidovudine (AZT) and poly I poly C double-stranded RNA both alone and in combination in MT4 cells and primary monocyte/macrophage (M/M) cultures was made. The inhibition of the HIV-induced cytopathic effect or reverse transcriptase production by AZT in MT4 cells was not modified by the combination of the two agents. In contrast, AZT inhibition of reverse transcriptase production in the supernatant of M/M cultures was enhanced by the addition of poly I poly C. The inhibitory effect of the drug combination was more marked in M/M than in MT4 cells, indicating that the evaluation of compounds involving the induction of an antiviral state should be tested not only CD4+ T cells but also in monocyte-macrophages.

Mismatched double-stranded RNA, Ampligen (poly(I): poly(C12U), demonstrates antiviral and immunostimulatory activities in HIV disease

Mismatched double-stranded RNA (Ampligen) has broad spectrum antiviral and immunomodulatory activities. These activities generate stabilization or improvement in three important surrogate markers of HIV disease progression. Patients with HIV disease treated with Ampligen do not become positive for p24 antigen, in contrast to patients treated with AZT or placebo. Viral burden can also be decreased in patients receiving Ampligen/AZT therapy. In vitro studies indicate that both AZT sensitive and AZT resistant viruses can be inhibited by Ampligen alone and are synergistically inhibited by Ampligen in combination with AZT. The immunomodulatory effects of Ampligen are manifested as a stabilization of CD4 counts. When Ampligen is combined with AZT, an increase in CD4 count is seen. Furthermore, a return or increase in delayed type hypersensitivity to mumps, Candida, and trichophyton was seen in approximately 70% of patients treated with Ampligen. The activity of Ampligen in HIV disease is due to its multifunctional activity as an antiviral and immune stimulating agent. The antiviral effect directly inhibits HIV-infection and other viruses which have been implicated in HIV disease acceleration and progression. The immunomodulatory activity can stabilize, increase, or restore immune function. This enhanced immune function can also lead to the further inhibition of additional infections associated with disease progression. Thus, Ampligen has multiple mechanisms of action against HIV disease.

Phosphorothioate and cordycepin analogues of 2',5'-oligoadenylate: inhibition of human immunodeficiency virus type 1 reverse transcriptase and infection in vitro

Natural antiviral activity can be mediated by the interferon-induced synthesis of 2',5'-oligoadenylates (2-5As) and subsequent RNase L activation by these molecules. Analogues of 2-5A that are biologically active and metabolically stable were synthesized and analyzed for antiviral activity against the human immunodeficiency virus type 1 (HIV-1). Replacement of the 3' hydroxyl group of the adenosine moieties of 2-5A with hydrogen atoms (i.e., cordycepin analogues of 2-5A) converted authentic 2-5A trimer into anti-HIV-1 agents in vitro. These cordycepin analogues of 2-5A also inhibited partially purified HIV-1 reverse transcriptase. Introduction of chirality into the 2',5'-phosphodiester internucleotide linkages or 5'-phosphate moieties of the 2-5A molecule (i.e., phosphorothioate analogues of 2-5A) converted authentic 2-5A into more potent inhibitors of HIV-1 reverse transcriptase. However, these phosphorothioate 2-5As demonstrated little or no anti-HIV-1 activity in vitro. Thus, some analogues of 2-5A may form a class of anti-HIV-1 drugs with possible pleiotropic activities that include activation of latent RNase L and inhibition of reverse transcription.

Inhibition of HIV-1 proviral DNA synthesis and RNA accumulation by mismatched dsRNA

The antiviral activity of mismatched dsRNA of the form poly(I):poly(C12-U)n (Ampligen) against the human immunodeficiency virus type 1 (HIV-1) was investigated by RNA-RNA and RNA-DNA hybridizations. Mismatched dsRNA delayed the appearance of newly transcribed HIV-1 RNA as detected by liquid dot-blot hybridization in cultures of H9 T-lymphoblastoid cells following virus challenge. The appearance of proviral DNA as detected by Southern hybridization following virus challenge in H9 cells was also delayed. Mismatched dsRNA had no effect in syncytium inhibition assays performed by fusing MT-2 cells with H9/HTLV-IIIB cells. These results suggest that the in vitro anti-HIV-1 activity of mismatched dsRNA occurs, at least in part, at an early stage in the viral replication cycle following initial gp120-CD4 binding.