STING agonist-containing microparticles improve seasonal influenza vaccine efficacy and durability in ferrets over standard adjuvant.

The current pandemic highlights the need for effective vaccines against respiratory viruses. An ideal vaccine should induce robust and long-lasting responses with high manufacturing scalability. We use an adjuvant comprised of a Stimulator of Interferon Genes (STING) agonist incorporated in a scalable microparticle platform to achieve durable protection against the influenza virus. This formulation overcomes the challenges presented by the cytosolic localization of STING and the hydrophilicity of its agonists. We evaluated a monoaxial formulation of polymeric acetalated dextran microparticles (MPs) to deliver the STING agonist cyclic GMP-AMP (cGAMP) which achieved >10× dose-sparing effects compared to other published work. Efficacy was evaluated in ferrets, a larger animal model of choice for influenza vaccines. cGAMP MPs with recombinant hemagglutinin reduced viral shedding and improved vaccine outcomes compared to a seasonal influenza vaccine. Importantly, sustained protection against a lethal influenza infection was detected a year after a single dose of the vaccine-adjuvant.

Influenza-Mediated Lung Infection Models.

Laboratory rodent influenza infection models have been and continue to be a critical tool for understanding virus-host interactions during infection. The incidence of seasonal influenza infections coupled with the need for novel therapeutics and universal vaccines highlights the need to uncover novel mechanisms of pathogenesis and protection. Mouse models are extremely useful for the evaluation of influenza vaccines and provide an invaluable tool to probe the immune response. This chapter describes the technique of intranasal inoculation of male C57BL/6J mice with an H1N1 strain of influenza (A/Puerto Rico/8/1934) and methods for assessing the optimum dose for infection, viral titers in lung tissue, and severity of disease.

Scavenging nucleic acid debris to combat autoimmunity and infectious disease.

Nucleic acid-containing debris released from dead and dying cells can be recognized as damage-associated molecular patterns (DAMPs) or pattern-associated molecular patterns (PAMPs) by the innate immune system. Inappropriate activation of the innate immune response can engender pathological inflammation and autoimmune disease. To combat such diseases, major efforts have been made to therapeutically target the pattern recognition receptors (PRRs) such as the Toll-like receptors (TLRs) that recognize such DAMPs and PAMPs, or the downstream effector molecules they engender, to limit inflammation. Unfortunately, such strategies can limit the ability of the immune system to combat infection. Previously, we demonstrated that nucleic acid-binding polymers can act as molecular scavengers and limit the ability of artificial nucleic acid ligands to activate PRRs. Herein, we demonstrate that nucleic acid scavengers (NASs) can limit pathological inflammation and nucleic acid-associated autoimmunity in lupus-prone mice. Moreover, we observe that such NASs do not limit an animal's ability to combat viral infection, but rather their administration improves survival when animals are challenged with lethal doses of influenza. These results indicate that molecules that scavenge extracellular nucleic acid debris represent potentially safer agents to control pathological inflammation associated with a wide range of autoimmune and infectious diseases.

Modified Vaccinia Ankara Virus Vaccination Provides Long-Term Protection against Nasal Rabbitpox Virus Challenge.

Modified vaccinia Ankara virus (MVA) is a smallpox vaccine candidate. This study was performed to determine if MVA vaccination provides long-term protection against rabbitpox virus (RPXV) challenge, an animal model of smallpox. Two doses of MVA provided 100% protection against a lethal intranasal RPXV challenge administered 9 months after vaccination.

A mastoparan-derived peptide has broad-spectrum antiviral activity against enveloped viruses.

Broad-spectrum antiviral drugs are urgently needed to treat individuals infected with new and re-emerging viruses, or with viruses that have developed resistance to antiviral therapies. Mammalian natural host defense peptides (mNHP) are short, usually cationic, peptides that have direct antimicrobial activity, and which in some instances activate cell-mediated antiviral immune responses. Although mNHP have potent activity in vitro, efficacy trials in vivo of exogenously provided mNHP have been largely disappointing, and no mNHP are currently licensed for human use. Mastoparan is an invertebrate host defense peptide that penetrates lipid bilayers, and we reasoned that a mastoparan analog might interact with the lipid component of virus membranes and thereby reduce infectivity of enveloped viruses. Our objective was to determine whether mastoparan-derived peptide MP7-NH2 could inactivate viruses of multiple types, and whether it could stimulate cell-mediated antiviral activity. We found that MP7-NH2 potently inactivated a range of enveloped viruses. Consistent with our proposed mechanism of action, MP7-NH2 was not efficacious against a non-enveloped virus. Pre-treatment of cells with MP7-NH2 did not reduce the amount of virus recovered after infection, which suggested that the primary mechanism of action in vitro was direct inactivation of virus by MP7-NH2. These results demonstrate for the first time that a mastoparan derivative has broad-spectrum antiviral activity in vitro and suggest that further investigation of the antiviral properties of mastoparan peptides in vivo is warranted.

Acute reactogenicity after intramuscular immunization with recombinant vesicular stomatitis virus is linked to production of IL-1ß.

Vaccines based on live viruses are attractive because they are immunogenic, cost-effective, and can be delivered by multiple routes. However, live virus vaccines also cause reactogenic side effects such as fever, myalgia, and injection site pain that have reduced their acceptance in the clinic. Several recent studies have linked vaccine-induced reactogenic side effects to production of the pro-inflammatory cytokine interleukin-1ß (IL-1ß) in humans. Our objective was therefore to determine whether IL-1ß contributed to pathology after immunization with recombinant vesicular stomatitis virus (rVSV) vaccine vectors, and if so, to identify strategies by which IL-1ß mediated pathology might be reduced without compromising immunogenicity. We found that an rVSV vaccine induced local and systemic production of IL-1ß in vivo, and that accumulation of IL-1ß correlated with acute pathology after rVSV immunization. rVSV-induced pathology was reduced in mice deficient in the IL-1 receptor Type I, but the IL-1R-/- mice were fully protected from lethal rechallenge with a high dose of VSV. This result demonstrated that IL-1 contributed to reactogenicity of the rVSV, but was dispensable for induction of protective immunity. The amount of IL-1ß detected in mice deficient in either caspase-1 or the inflammasome adaptor molecule ASC after rVSV immunization was not significantly different than that produced by wild type animals, and caspase-1-/- and ASC-/- mice were only partially protected from rVSV-induced pathology. Those data support the idea that some of the IL-1ß expressed in vivo in response to VSV may be activated by a caspase-1 and ASC-independent mechanism. Together these results suggest that rVSV vectors engineered to suppress the induction of IL-1ß, or signaling through the IL-1R would be less reactogenic in vivo, but would retain their immunogenicity and protective capacity. Such rVSV would be highly desirable as either vaccine vectors or oncolytic therapies, and would likely be better tolerated in human vaccinees.

Intramuscular immunization with a vesicular stomatitis virus recombinant expressing the influenza hemagglutinin provides post-exposure protection against lethal influenza challenge.

Vaccines currently licensed for the prevention of seasonal influenza induce antibodies against the influenza hemagglutinin (HA) and neuraminidase (NA) contained in the vaccine preparation but require at least 2 weeks after immunization for the development of protective immunity. These vaccines do not induce protective responses quickly enough to blunt the effects of infection when administered after exposure. We have developed a novel vaccine based on recombinant vesicular stomatitis virus which expresses the influenza hemagglutinin (rVSV HA) and protects mice from lethal influenza challenge when the vaccine is administered intramuscularly at least 24h after delivery of the influenza challenge virus. To our knowledge this is the first vaccine that effectively protects animals from lethal influenza challenge when delivered by a systemic route after influenza exposure has occurred. The induction of HA-specific immune responses by the vaccine is necessary for full protection from challenge, because animals immunized with an empty rVSV vector were not protected equally. Our results are consistent with a model in which vaccination induces an immediate antiviral cytokine response, followed by development of humoral and cellular immune responses which act to reduce pulmonary viral loads and accelerate recovery. Consistent with this model, mice vaccinated with the specific vaccine rVSV HA had high levels of IFN-alpha in the serum by 24h after challenge/vaccination, developed serum neutralizing Ab to influenza 2 days prior to control animals, and had detectable anti-HA CD8 T cells present in the peripheral blood 3 days prior to control mice.

Recombinant vesicular stomatitis virus expressing influenza nucleoprotein induces CD8 T-cell responses that enhance antibody-mediated protection after lethal challenge with influenza virus.

Live attenuated vaccine vectors based on recombinant vesicular stomatitis viruses (rVSVs) expressing foreign antigens are highly effective vaccines in animal models. In this study, we report that an rVSV expressing influenza nucleoprotein (VSV NP) from the first position of the VSV genome induces robust anti-NP CD8 T cells in immunized mice. These CD8 T cells are phenotypically similar to those induced by natural influenza infection and are cytotoxic in vivo. Animals immunized with an rVSV expressing the influenza hemagglutinin (rVSV HA) were protected but still exhibited considerable morbidity after challenge. Animals receiving a cocktail vaccine of rVSV NP and rVSV HA had reduced pulmonary viral loads, less weight loss, and reduced clinical signs of illness after influenza virus challenge, relative to those vaccinated with rVSV HA alone. Influenza NP is a highly conserved antigen, and induction of protective anti-NP responses may be a productive strategy for generating heterologous protection against divergent influenza strains.

Expression and function of lysophosphatidic acid LPA1 receptor in prostate cancer cells.

The bioactive phospholipid lysophosphatidic acid (LPA) promotes cell proliferation, survival, and migration by acting on cognate G protein-coupled receptors named LPA(1), LPA(2), and LPA(3). We profiled gene expression of LPA receptors in androgen-dependent and androgen-insensitive prostate cancer cells and found that LPA(1) gene is differentially expressed in androgen-insensitive and LPA-responsive but not androgen-dependent and LPA-resistant cells. In human prostate specimens, expression of LPA(1) gene was significantly higher in the cancer compared with the benign tissues. The androgen-dependent LNCaP cells do not express LPA(1) and do not proliferate in response to LPA stimulation, implying LPA(1) transduces cell growth signals. Accordingly, stable expression of LPA(1) in LNCaP cells rendered them responsive to LPA-induced cell proliferation and decreased their doubling time in serum. Implantation of LNCaP-LPA(1) cells resulted in increased rate of tumor growth in animals compared with those tumors that developed from the wild-type cells. Growth of LNCaP cells depends on androgen receptor activation, and we show that LPA(1) transduces Galphai-dependent signals to promote nuclear localization of androgen receptor and cell proliferation. In addition, treatment with bicalutamide inhibited LPA-induced cell cycle progression and proliferation of LNCaP-LPA(1) cells. These results suggest the possible utility of LPA(1) as a drug target to interfere with progression of prostate cancer.