Vaccine delivery system for tuberculosis based on nano-sized hepatitis B virus core protein particles

A Glance on Nanovaccine: A Potential Approach for Disease Prevention

There are several vaccines available for preventing various bacterial and viral infections, but still, there are many challenges that require the development of noninvasive, more efficient, and active vaccines. The advancement in biotechnological tools has provided safer antigens, such as nucleic acids, proteins etc., but due to their lower immunogenic property, adjuvants of stronger immune response are required. Nanovaccines are effective vaccines when compared with conventional vaccines as they can induce both Humoral and cell-mediated immune responses and also provide longer immunogenic memory. The nanocarriers used in vaccines act as adjuvant. They provide site-specific delivery of antigens and can be used in conjugation with immunostimulatory molecules for enhancing adjuvant therapy. The nanovaccines avoid degrading cell pathways and provide effective absorption into blood vessels. The higher potential of nanovaccines to treat various diseases, such as acquired immuno deficiency syndrome, cancer, tuberculosis, malaria and many others, along with their immunological mechanisms and different types, have been discussed in the review.

Recent advance in the development of tuberculosis vaccines in clinical trials and virus-like particle-based vaccine candidates

Tuberculosis (TB) remains a serious public health threat around the world. An effective vaccine is urgently required for cost-effective, long-term control of TB. However, the only licensed vaccine Bacillus Calmette-Guerin (BCG) is limited to prevent TB for its highly variable efficacy. Substantial progress has been made in research and development (R&D) of TB vaccines in the past decades, and a dozen vaccine candidates, including live attenuated mycobacterial vaccines, killed mycobacterial vaccines, adjuvanted subunit vaccines, viral vector vaccines, and messenger RNA (mRNA) vaccines were developed in clinical trials to date. Nevertheless, many challenges to the successful authorization for the use and deployment of an effective tuberculosis vaccine remain. Therefore, it is still necessary and urgent to continue exploring new vaccine construction approaches. Virus-like particles (VLPs) present excellent prospects in the field of vaccine development because of their helpful immunological features such as being safe templates without containing viral nucleic acid, repetitive surface geometry, conformational epitopes similar to natural viruses, and enhancing both innate and adaptive immune responses. The marketization process of VLP vaccines has never stopped despite VLP vaccines face several shortcomings such as their complex and slow development process and high production cost, and several VLP-based vaccines, including vaccines against Human papillomavirus (HPV), Hepatitis B Virus (HBV) and malaria, are successfully licensed for use at the market. In this review, we provide an update on the current progress regarding the development of TB vaccines in clinical trials and seek to give an overview of VLP-based TB vaccine candidates.

The Influence of Nanoparticle on Vaccine Responses against Bacterial Infection

Nowadays, nanovaccine is considered as an evolving method in the field of vaccination to induce immunity in the human body against various diseases, including bacterial or viral diseases as well as virulent tumors. Nanovaccines are more efficient than traditional vaccines since they could potentially induce both humoral and cellular immune reactions. Various studies have shown that nanoparticles with multiple compounds have been designed as delivery systems or as adjuvants for vaccines. Nanoparticles could function as a drug delivery tool, as an adjuvant to promote antigen processing, and as an immune modulator to induce immune responses. These nanoparticles generate immune responses through activating immune cells as well as through the production of antibody responses. Design engineering of nanoparticles (NPs) used to produce nanovaccines to induce immunity in the human body needs comprehensive information about the ways they interact with the component of immune system. Challenges remain due to the lack of sufficient and comprehensive information about the nanoparticles' mode of action. Several studies have described the interactions between various classes of nanoparticles and the immune system in the field of prevention of bacterial infections. The results of some studies conducted in recent years on the interaction between nanoparticles and biosystems have considerably affected the methods used to design nanoparticles for medical applications. In this review, NPs’ characteristics influencing their interplay with the immune system were discussed in vivo. The information obtained could lead to the development of strategies for rationalizing the design of nanovaccines in order to achieve optimum induction of immune response.

Virus-Like particles as a Novel Targeted Drug Delivery Platform for Biomedical Applications

Virus-Like Particles (VLP) mimics virions immunologically which induces high titers of neutralizing antibodies to conformational epitopes due to the high-density display of epitopes, present multiple proteins which are optimal for uptake by dendritic cells and are assembled in vivo. VLP triggers the immune response of the body against the diseases and is broadly two types like non enveloped VLP’s and Enveloped VLP’s. The present review discusses the production, analysis, and mechanism of action of virus-like particles. Various applications, the Indian Scenario of VLP, Limitations, and future scopes are briefly reviewed and discussed. VLPs imitate authentic viruses in antigenic morphology and offer a stable alternative to attenuated and inactivated viruses in the production of vaccines. It can effectively deliver foreign nucleic acids, proteins, or conjugated compounds to the system, or even to particular types of cells, due to their transducing properties. It retains the ability to infiltrate and render cells useful for a wide range of applications. Used as a tool to increase the immunogenicity of poorly immunogenic antigens, VLP therapeutics can be developed and manufactured in a way that would be sufficiently cheap to be seen globally in many countries. The ability to mass-produce them cost-effectively improves their possibility of being introduced to undeveloped countries.

Advancements in prophylactic and therapeutic nanovaccines

Vaccines activate suitable immune responses to fight against diseases but can possess limitations such as compromised efficacy and immunogenic responses, poor stability, and requirement of adherence to multiple doses. ‘Nanovaccines’ have been explored to elicit a strong immune response with the advantages of nano-sized range, high antigen loading, enhanced immunogenicity, controlled antigen presentation, more retention in lymph nodes and promote patient compliance by a lower frequency of dosing. Various types of nanoparticles with diverse pathogenic or foreign antigens can help to overcome immunotolerance and alleviate the need of booster doses as required with conventional vaccines. Nanovaccines have the potential to induce both cell-mediated and antibody-mediated immunity and can render long-lasting immunogenic memory. With such properties, nanovaccines have shown high potential for the prevention of infectious diseases such as acquired immunodeficiency syndrome (AIDS), malaria, tuberculosis, influenza, and cancer. Their therapeutic potential has also been explored in the treatment of cancer. The various kinds of nanomaterials used for vaccine development and their effects on immune system activation have been discussed with special relevance to their implications in various pathological conditions.

Statement of Significance

Interaction of nanoparticles with the immune system has opened multiple avenues to combat a variety of infectious and non-infectious pathological conditions. Limitations of conventional vaccines have paved the path for nanomedicine associated benefits with a hope of producing effective nanovaccines. This review highlights the role of different types of nanovaccines and the role of nanoparticles in modulating the immune response of vaccines. The applications of nanovaccines in infectious and non-infectious diseases like malaria, tuberculosis, AIDS, influenza, and cancers have been discussed. It will help the readers develop an understanding of mechanisms of immune activation by nanovaccines and design appropriate strategies for novel nanovaccines.

Recent Advances in Nanovaccines Using Biomimetic Immunomodulatory Materials

The development of vaccines plays a vital role in the effective control of several fatal diseases. However, effective prophylactic and therapeutic vaccines have yet to be developed for completely curing deadly diseases, such as cancer, malaria, HIV, and serious microbial infections. Thus, suitable vaccine candidates need to be designed to elicit appropriate immune responses. Nanotechnology has been found to play a unique role in the design of vaccines, providing them with enhanced specificity and potency. Nano-scaled materials, such as virus-like particles, liposomes, polymeric nanoparticles (NPs), and protein NPs, have received considerable attention over the past decade as potential carriers for the delivery of vaccine antigens and adjuvants, due to their beneficial advantages, like improved antigen stability, targeted delivery, and long-time release, for which antigens/adjuvants are either encapsulated within, or decorated on, the NP surface. Flexibility in the design of nanomedicine allows for the programming of immune responses, thereby addressing the many challenges encountered in vaccine development. Biomimetic NPs have emerged as innovative natural mimicking biosystems that can be used for a wide range of biomedical applications. In this review, we discuss the recent advances in biomimetic nanovaccines, and their use in anti-bacterial therapy, anti-HIV therapy, anti-malarial therapy, anti-melittin therapy, and anti-tumor immunity.

Synthetic biology for bioengineering virus-like particle vaccines

Vaccination is the most effective method of disease prevention and control. Many viruses and bacteria that once caused catastrophic pandemics (e.g., smallpox, poliomyelitis, measles, and diphtheria) are either eradicated or effectively controlled through routine vaccination programs. Nonetheless, vaccine manufacturing remains incredibly challenging. Viruses exhibiting high antigenic diversity and high mutation rates cannot be fairly contested using traditional vaccine production methods and complexities surrounding the manufacturing processes, which impose significant limitations. Virus-like particles (VLPs) are recombinantly produced viral structures that exhibit immunoprotective traits of native viruses but are noninfectious. Several VLPs that compositionally match a given natural virus have been developed and licensed as vaccines. Expansively, a plethora of studies now confirms that VLPs can be designed to safely present heterologous antigens from a variety of pathogens unrelated to the chosen carrier VLPs. Owing to this design versatility, VLPs offer technological opportunities to modernize vaccine supply and disease response through rational bioengineering. These opportunities are greatly enhanced with the application of synthetic biology, the redesign and construction of novel biological entities. This review outlines how synthetic biology is currently applied to engineer VLP functions and manufacturing process. Current and developing technologies for the identification of novel target-specific antigens and their usefulness for rational engineering of VLP functions (e.g., presentation of structurally diverse antigens, enhanced antigen immunogenicity, and improved vaccine stability) are described. When applied to manufacturing processes, synthetic biology approaches can also overcome specific challenges in VLP vaccine production. Finally, we address several challenges and benefits associated with the translation of VLP vaccine development into the industry.

Evaluation of a temperature-restricted, mucosal tuberculosis vaccine in guinea pigs

Tuberculosis (TB) is currently the leading cause of death in humans by a single infectious agent, Mycobacterium tuberculosis. The Bacillus Calmette-Guérin (BCG) vaccine prevents pulmonary TB with variable efficacy, but can cause life-threatening systemic infection in HIV-infected infants. In this study, TBvac85, a derivative of Mycobacterium shottsii expressing M. tuberculosis Antigen 85B, was examined as a safer alternative to BCG. Intranasal vaccination of guinea pigs with TBvac85, a naturally temperature-restricted species, resulted in serum Ag85B-specific IgG antibodies. Delivery of the vaccine by this route also induced protection equivalent to intradermal BCG based on organ bacterial burdens and lung pathology six weeks after aerosol challenge with M. tuberculosis strain Erdman. These results support the potential of TBvac85 as the basis of an effective TB vaccine. Next-generation derivatives expressing multiple M. tuberculosis immunogens are in development.

Nanoparticle Vaccines Against Infectious Diseases

Due to emergence of new variants of pathogenic micro-organisms the treatment and immunization of infectious diseases have become a great challenge in the past few years. In the context of vaccine development remarkable efforts have been made to develop new vaccines and also to improve the efficacy of existing vaccines against specific diseases. To date, some vaccines are developed from protein subunits or killed pathogens, whilst several vaccines are based on live-attenuated organisms, which carry the risk of regaining their pathogenicity under certain immunocompromised conditions. To avoid this, the development of risk-free effective vaccines in conjunction with adequate delivery systems are considered as an imperative need to obtain desired humoral and cell-mediated immunity against infectious diseases. In the last several years, the use of nanoparticle-based vaccines has received a great attention to improve vaccine efficacy, immunization strategies, and targeted delivery to achieve desired immune responses at the cellular level. To improve vaccine efficacy, these nanocarriers should protect the antigens from premature proteolytic degradation, facilitate antigen uptake and processing by antigen presenting cells, control release, and should be safe for human use. Nanocarriers composed of lipids, proteins, metals or polymers have already been used to attain some of these attributes. In this context, several physico-chemical properties of nanoparticles play an important role in the determination of vaccine efficacy. This review article focuses on the applications of nanocarrier-based vaccine formulations and the strategies used for the functionalization of nanoparticles to accomplish efficient delivery of vaccines in order to induce desired host immunity against infectious diseases.

Platform technologies for modern vaccine manufacturing

Improved understanding of antigenic components and their interaction with the immune system, as supported by computational tools, permits a sophisticated approach to modern vaccine design. Vaccine platforms provide an effective tool by which strategically designed peptide and protein antigens are modularized to enhance their immunogenicity. These modular vaccine platforms can overcome issues faced by traditional vaccine manufacturing and have the potential to generate safe vaccines, rapidly and at a low cost. This review introduces two promising platforms based on virus-like particle and liposome, and discusses the methodologies and challenges.

Subunit Protein Vaccine Delivery System for Tuberculosis Based on Hepatitis B Virus Core VLP (HBc-VLP) Particles

Despite the development of modern medicine, tuberculosis (TB), caused by the pathogenic bacterium, Mycobacterium tuberculosis (Mtb), remains one of the deadliest diseases. This bacterium can lay dormant in individuals and get activated when immunity goes down and has also shown considerable prowess in mutating into drug resistant forms. The global emergence of such drug resistant Mtb and the lack of efficacy of Bacille Calmette Guérin (BCG), the only vaccine available so far, have resulted in a situation which cries out for a safe and effective tuberculosis vaccine.Number of different strategies has been used for developing new anti-TB vaccines and several protective antigens have been identified so far. One strategy, the use of protein subunits, has the potential to develop into a powerful tuberculosis vaccine, not only because of its efficacy and safety, but also because they are economical. The proper delivery of protein subunit vaccines with adjuvants or novel delivery systems is necessary for inducing protective immune responses. The available adjuvants or delivery systems are inadequate for generating such a response. In the present method, we have constructed a vaccine delivery system for tuberculosis based on Virus-Like Particles (VLPs). Hepatitis B Virus core antigen gene was recombinantly modified using Overlap Extension PCR (OEPCR). The final construct was designed to express HBc-VLP carrying external antigen (fusion VLP). Mycobacterium tuberculosis antigen CFP-10 was used for the construction of fusion VLP. The recombinant gene for the construct was cloned into a pET expression system and transformed into E. coli BL21(DE3) and induced with IPTG to express the protein. The fusion protein was purified using the Histidine tag and allowed to form VLPs. The preformed VLPs were purified by sucrose density gradient centrifugation. The VLPs were characterized using Transmission Electron Microscopy (TEM).

A Modular Vaccine Development Platform Based on Sortase-Mediated Site-Specific Tagging of Antigens onto Virus-Like Particles

Virus-like particles (VLPs) can be used as powerful nanoscale weapons to fight against virus infection. In addition to direct use as vaccines, VLPs have been extensively exploited as platforms on which to display foreign antigens for prophylactic vaccination and immunotherapeutic treatment. Unfortunately, fabrication of new chimeric VLP vaccines in a versatile, site-specific and highly efficient manner is beyond the capability of traditional VLP vaccine design approaches, genetic insertion and chemical conjugation. In this study, we described a greatly improved VLP display strategy by chemoenzymatic site-specific tailoring antigens on VLPs surface with high efficiency. Through the transpeptidation mediated by sortase A, one protein and two epitopes containing N-terminal oligoglycine were conjugated to the LPET motif on the surface of hepatitis B virus core protein (HBc) VLPs with high density. All of the new chimeric VLPs induced strong specific IgG responses. Furthermore, the chimeric VLPs with sortase A tagged enterovirus 71 (EV71) SP70 epitope could elicit effective antibodies against EV71 lethal challenging as well as the genetic insertion chimeric VLPs. The sortase A mediated chemoenzymatic site-specific tailoring of the HBc VLP approach shows great potential in new VLP vaccine design for its simplicity, site specificity, high efficiency, and versatility.

Subviral particle as vaccine and vaccine platform

Recombinant subvirual particles retain similar antigenic features of their authentic viral capsids and thus have been applied as nonreplicating subunit vaccines against viral infection and illness. Additionally, the self-assembled, polyvalent subviral particles are excellent platforms to display foreign antigens for immune enhancement for vaccine development. These subviral particle-based vaccines are noninfectious and thus safer than the conventional live attenuated and inactivated vaccines. While several VLP vaccines are available in the markets, numerous others, including dual vaccines against more than one pathogen, are under clinical or preclinical development. This article provides an update of these efforts.