Immunogenicity of bovine parainfluenza type 3 virus proteins encapsulated in nanoparticle vaccines, following intranasal administration to mice

Biodegradable nanoparticle delivery of inactivated swine influenza virus vaccine provides heterologous cell-mediated immune response in pigs

Swine influenza virus (SwIV) is one of the important zoonotic pathogens. Current flu vaccines have failed to provide cross-protection against evolving viruses in the field. Poly(lactic-co-glycolic acid) (PLGA) is a biodegradable FDA approved polymer and widely used in drug and vaccine delivery. In this study, inactivated SwIV H1N2 antigens (KAg) encapsulated in PLGA nanoparticles (PLGA-KAg) were prepared, which were spherical in shape with 200 to 300nm diameter, and induced maturation of antigen presenting cells in vitro. Pigs vaccinated twice with PLGA-KAg via intranasal route showed increased antigen specific lymphocyte proliferation and enhanced the frequency of T-helper/memory and cytotoxic T cells (CTLs) in peripheral blood mononuclear cells (PBMCs). In PLGA-KAg vaccinated and heterologous SwIV H1N1 challenged pigs, clinical flu symptoms were absent, while the control pigs had fever for four days. Grossly and microscopically, reduced lung pathology and viral antigenic mass in the lung sections with clearance of infectious challenge virus in most of the PLGA-KAg vaccinated pig lung airways were observed. Immunologically, PLGA-KAg vaccine irrespective of not significantly boosting the mucosal antibody response, it augmented the frequency of IFN-γ secreting total T cells, T-helper and CTLs against both H1N2 and H1N1 SwIV. In summary, inactivated influenza virus delivered through PLGA-NPs reduced the clinical disease and induced cross-protective cell-mediated immune response in a pig model. Our data confirmed the utility of a pig model for intranasal particulate flu vaccine delivery platform to control flu in humans.

Respiratory nanoparticle-based vaccines and challenges associated with animal models and translation

Vaccine development has had a huge impact on human health. However, there is a significant need to develop efficacious vaccines for several existing as well as emerging respiratory infectious diseases. Several challenges need to be overcome to develop efficacious vaccines with translational potential. This review focuses on two aspects to overcome some barriers — 1) the development of nanoparticle-based vaccines, and 2) the choice of suitable animal models for respiratory infectious diseases that will allow for translation. Nanoparticle-based vaccines, including subunit vaccines involving synthetic and/or natural polymeric adjuvants and carriers, as well as those based on virus-like particles offer several key advantages to help overcome the barriers to effective vaccine development. These include the ability to deliver combinations of antigens, target the vaccine formulation to specific immune cells, enable cross-protection against divergent strains, act as adjuvants or immunomodulators, allow for sustained release of antigen, enable single dose delivery, and potentially obviate the cold chain. While mouse models have provided several important insights into the mechanisms of infectious diseases, they are often a limiting step in translation of new vaccines to the clinic. An overview of different animal models involved in vaccine research for respiratory infections, with advantages and disadvantages of each model, is discussed. Taken together, advances in nanotechnology, combined with the right animal models for evaluating vaccine efficacy, has the potential to revolutionize vaccine development for respiratory infections.

Inactivated and subunit vaccines against porcine reproductive and respiratory syndrome: Current status and future direction

Within a few years of its emergence in the late 1980s, the PRRS virus had spread globally to become the foremost infectious disease concern for the pork industry. Since 1994, modified live-attenuated vaccines against porcine reproductive and respiratory syndrome virus (PRRSV-MLV) have been widely used, but have failed to provide complete protection against emerging and heterologous field strains of the virus. Moreover, like many other MLVs, PRRSV-MLVs have safety concerns including vertical and horizontal transmission of the vaccine virus and several documented incidences of reversion to virulence. Thus, the development of efficacious inactivated vaccines is warranted for the control and eradication of PRRS. Since the early 1990s, researchers have been attempting to develop inactivated PRRSV vaccines, but most of the candidates have failed to elicit protective immunity even against homologous virus challenge. Recent research findings relating to both inactivated and subunit candidate PRRSV vaccines have shown promise, but they need to be pursued further to improve their heterologous efficacy and cost-effectiveness before considering commercialization. In this comprehensive review, we provide information on attempts to develop PRRSV inactivated and subunit vaccines. These includes various virus inactivation strategies, adjuvants, nanoparticle-based vaccine delivery systems, DNA vaccines, and recombinant subunit vaccines produced using baculovirus, plant, and replication-deficient viruses as vector vaccines. Finally, future directions for the development of innovative non-infectious PRRSV vaccines are suggested. Undoubtedly there remains a need for novel PRRSV vaccine strategies targeted to deliver cross-protective, non-infectious vaccines for the control and eradication of PRRS.

Biodegradable nanoparticle-entrapped vaccine induces cross-protective immune response against a virulent heterologous respiratory viral infection in pigs

Biodegradable nanoparticle-based vaccine development research is unexplored in large animals and humans. In this study, we illustrated the efficacy of nanoparticle-entrapped UV-killed virus vaccine against an economically important respiratory viral disease of pigs called porcine reproductive and respiratory syndrome virus (PRRSV). We entrapped PLGA [poly (lactide-co-glycolides)] nanoparticles with killed PRRSV antigens (Nano-KAg) and detected its phagocytosis by pig alveolar macrophages. Single doses of Nano-KAg vaccine administered intranasally to pigs upregulated innate and PRRSV specific adaptive responses. In a virulent heterologous PRRSV challenge study, Nano-KAg vaccine significantly reduced the lung pathology and viremia, and the viral load in the lungs. Immunologically, enhanced innate and adaptive immune cell population and associated cytokines with decreased secretion of immunosuppressive mediators were observed at both mucosal sites and blood. In summary, we demonstrated the benefits of intranasal delivery of nanoparticle-based viral vaccine in eliciting cross-protective immune response in pigs, a potential large animal model.

Mucosal vaccines to prevent porcine reproductive and respiratory syndrome: a new perspective

Porcine reproductive and respiratory syndrome (PRRS) is an economically important infectious disease of swine. Constant emergence of variant strains of PRRS virus (PPRSV) and virus-mediated immune evasion followed by viral persistence result in increased incidence and recurrence of PRRS in swine herds. Current live and killed PRRSV vaccines administered by a parenteral route are ineffective in inducing complete protection. Thus, new approaches in design and delivery of PRRSV vaccines are needed to reduce the disease burden of the swine industry. Induction of an effective mucosal immunity to several respiratory pathogens by direct delivery of a vaccine to mucosal sites has proven to be effective in a mouse model. However, there are challenges in eliciting mucosal immunity to PRRS due to our limited understanding of safe and potent mucosal adjuvants, which could potentiate the mucosal immune response to PRRSV. The purpose of this review is to discuss methods for induction of protective mucosal immune responses in the respiratory tract of pigs. The manuscript also discusses how PRRSV modulates innate, adaptive and immunoregulatory responses at both mucosal and systemic sites of infected and/or vaccinated pigs. This information may help in the design of innovative mucosal vaccines to elicit superior cross-protective immunity against divergent field strains of PRRSV.

Opportunities and challenges of the pulmonary route for vaccination

INTRODUCTION

The respiratory tract is an attractive target for the delivery of vaccine antigens. Potential advantages of drug delivery by means of the pulmonary route include accessibility, non-invasiveness, ease of administration, and the possibility to reach an elaborate mucosal network of antigen-presenting cells.

AREAS COVERED

This review discusses current pulmonary vaccination strategies and their advantages and disadvantages.

EXPERT OPINION

To improve efficiency of vaccination and develop new strategies, a well-founded knowledge about composition and characterization of antigen-presenting cell populations throughout the respiratory tract is essential. In particular, respiratory tract dendritic cells, as key antigen-presenting cells in the lung, constitute an ideal target for vaccine delivery. Furthermore, particle size is a key factor when designing new inhalable vaccines, as size determines not only deposition in different respiratory tract compartments, but also how an antigen and its carrier will interact with lung tissue components and immune cells. An increased knowledge of different respiratory tract antigen-presenting cell populations and their interactions with other components of the immune system will enable new targeting strategies to improve the efficacy of pulmonary vaccination.

Nasal vaccine innovation

The current vaccine market is gaining momentum in the development of alternative administration routes namely intranasal, oral, topical, pulmonary, vaginal, and rectal; the nasal route offers the most promising opportunity for vaccine administration. It can enhance convenience, safety, elicit both local and systemic immune responses; thus potentially provide protection from pathogens at the site of entry. Nasal vaccine innovation comes with both opportunities and challenges. The innovative strategies used by industry and researchers to overcome the hurdles are discussed in this article: these include live-attenuated vaccines, adjuvants, mucoadhesives, particulate delivery systems, virus-like particles, vaccine manufacture, challenges of regulatory authorities, and the nasal vaccine impact on market potential. Critical issues for effective nasal vaccination are the antigen-retention period that enables its interaction with the lymphatic system and choice of an adjuvant that is nontoxic and induces the required immune response. Co-adjuvanting by means of a mucoadhesive technology addresses some of these issues. ChiSys(®), a natural bioadhesive with proven intranasal safety profile, has already demonstrated efficacy for several nasally delivered vaccines including norovirus. With the looming threat of a pandemic, alternatives such as intranasal vaccination will ultimately facilitate greater public compliance and rapid mass global vaccination.

Nanoparticle vaccines against respiratory viruses

Influenza virus, respiratory syncytial virus (RSV), and parainfluenza type 3 virus (PI-3V) are the major viral agents which are consistently involved in causing lower respiratory tract disease in humans and animals. The virus infection begins in the upper respiratory tract, where immune responses are initiated, and then progresses to the lower respiratory tract where destruction of cells and tissues leads to bronchitis, bronchiolitis, and pneumonia, which is occasionally fatal. Nanoparticle vaccines, incorporating antigenic components from influenza, RSV, or PI-3V have been shown to be capable of stimulating mucosal and systemic immune responses, which can prevent the spread of infection to the lower respiratory tract. The encapsulation of viral proteins within nanoparticles may also facilitate production of respiratory vaccines which are efficacious in infants, where presence of maternally derived antibodies can reduce vaccine efficacy.

PMMA particle-mediated DNA vaccine for cervical cancer

DNA vaccination is a novel immunization strategy that possesses many potential advantages over other vaccine strategies. One of the major difficulties hindering the clinical application of DNA vaccination is the relative poor immunogenicity of DNA vaccines. Poly(methyl methacrylate) (PMMA) is a synthetic polymer approved by the Food and Drug Administration for certain human clinical applications such as the bone cement. In vivo, PMMA particles are phagocytosable and have the potential to initiate strong immune responses by stimulating the production of inflammatory cytokines. In this study, we synthesized a series of PMMA particles (PMMA 1-5) with different particle sizes and surface charges to test the feasibility of implementing such polymer particles for DNA vaccination. To our knowledge, this is the first report to show that the gene gun can deliver DNA vaccine by propelling PMMA particles mixed with plasmid DNA for cervical cancer. It was found that PMMA 4 particles (particle size: 460 +/- 160 nm, surface charge: +11.5 +/- 1.8 mV) stimulated the highest level of TNF-alpha production by macrophages in vitro and yielded the best result of antitumor protection in vivo. Therefore, our results possess the potential for translation and implementation of polymer particles in gene gun delivering DNA vaccination.

Nanomedicine for respiratory diseases

Nanotechnology provides new materials in the nanometer range with many potential applications in clinical medicine and research. Due to their unique size-dependent properties nanomaterial such as nanoparticles offer the possibility to develop both new therapeutic and diagnostic tools. Thus, applied nanotechnology to medical problems--nanomedicine--can offer new concepts that are reviewed. The ability to incorporate drugs into nanosystems displays a new paradigm in pharmacotherapy that could be used for cell-targeted drug delivery. Nontargeted nanosystems such as nanocarriers that are coated with polymers or albumin and solid lipid particles have been used as transporter in vivo. However, nowadays drugs can be coupled to nanocarriers that are specific for cells and/or organs. Thus, drugs that are either trapped within the carriers or deposited in subsurface oil layers could be specifically delivered to organs, tumors and cells. These strategies can be used to concentrate drugs in selected target tissues thus minimizing systemic side effects and toxicity. In addition to these therapeutic options, nanoparticle-based "molecular" imaging displays a field in which this new technology has set the stage for an evolutionary leap in diagnostic imaging. Based on the recent progress in nanobiotechnology there is potential for nanoparticles and -systems to become useful tools as therapeutic and diagnostic tools in the near future.

Use of biodegradable PLGA microspheres as a slow release delivery system for the Boophilus microplus synthetic vaccine SBm7462

The synthetic anti-Boophilus microplus vaccine SBm7462 derived from the tick intestinal protein, Bm86, induced a protective immune response when emulsified in saponin and used in cattle. Using a mice model, and with the objective of improving the vaccine by continual peptide release, it was encapsulated in PLGA 50:50 microspheres and inoculated in BALB/c mice to assess the immunological response by detection of anti-peptide IgGs. Comparative studies were made with the peptide emulsified in saponin and with another synthetic vaccine, and the microsphere/peptide was characterized for efficiency of encapsulation, in vitro release profile, morphology, size, peptide integrity after encapsulation and stability in different pHs. The findings showed that saponin enhances a better immune response from SBm7462 and that the PLGA 50:50 microspheres are suitable for use with this peptide.