Which Vaccination Strategies and Immune Responses are More Effective Against HIV Infections?

Vaccination is one of the most successful approaches for controlling various viral diseases. Novel approaches will be needed to develop highly effective vaccines to prevent infectious diseases such as HIV. There are many aspects of HIV-1 biology that make the development of an HIV vaccine difficult, including viral diversity, effective type of immune response, and suitable experimental model for preclinical trials. In spite of these challenges, recent published results showed that a vaccine regimen could reduce HIV infection rates by 31% in Thailand. This vaccine named as RV144 is composed of a recombinant canarypox vector expressing three HIV-1 proteins as a prime and two different recombinant HIV-1 gp120 envelope glycoproteins with alum adjuvant as a boost. In addition, a subunit vaccine constructed from the viral envelope protein could be efficiently developed using new techniques available through genetic engineering. The current HIV-1 vaccine development focuses on antibody-based approaches. It was shown that immunization with the viral envelope glycoprotein, gp120, should generate neutralizing antibodies that would prevent infection, thereby yielding protective immunity. However, HIV could develop many pathways to escape from antibodies that bind to the different parts of the viral envelope molecules. Thus, the generation of neutralizing antibodies is very difficult after viral infection or immunization protocols. Indeed, the viral envelope molecules (Env) possess glycosylated residues that cover surface epitopes for binding and neutralizing antibodies, even if the antibodies are produced. Furthermore, the trimeric structures of envelope molecules show rapid conformational changes due to the interaction with viral cell surface receptors, CCR5/CXCR4 and CD4; thus the transition state is very poor to be recognized by the immune system. Currently, studies focus on generating stable trimeric envelope molecules (gp120/gp41) as immunogens that can induce neutralizing antibodies that can compete for binding to the cell surface receptors. Altogether, it is clear that the design of a vaccine to elicit HIV-neutralizing antibodies is not straightforward, and it causes major challenges in structural biology and immunology, several other studies strongly suggest cytotoxic T-lymphocyte (CTL)-based immune responses against HIV infections. Indeed, CD8+ T cells play a major role in controlling viral replication during primary HIV infections and in maintaining a stable viral load during the chronic phase. In this line, live-attenuated vaccines could elicit more potent and durable pathogen-specific immune responses than inactivated or subunit vaccines. Generally, DNA vaccines are poorly immunogenic alone, and viral vector vaccines are ineffective due to vector-specific immune responses if used repeatedly; hence, the two approaches have often been tested in combination as prime-boost vaccination strategies. Indeed, the prime-boost vaccination has been considered as an efficient strategy against HIV infections. In this chapter, we will represent challenges to determine the best vaccine strategies against HIV infections

Different expression systems for production of HCV structural proteins

     Hepatitis C virus (HCV) is an important agent causing chronic liver infection, which often leads to liver cirrhosis and lethal hepatocellular carcinoma (HCC). At present, there is no effective HCV vaccine for prevention of hepatic disease and the standard treatment is neither economical nor fully effective in all the patients. However, vaccination based on structural and nonstructural proteins of HCV has attracted a special interest. Different heterologous systems have been used to generate the recombinant HCV core, E1, and E2 proteins including Escherichia coli, yeast, insects and mammalian cells. Further studies showed that the amounts of HCV recombinant proteins in E. coli are more suitable and un-expensive compared to other systems. It should be considered that this system is not efficient for generation of the glycosylated proteins. Thus, the structure of proteins is an important agent of selection for expression systems. The selection of expression systems will be critical for the use of recombinant proteins as an immunogen. In this mini-review, we briefly describe different expression systems for generation of the HCV recombinant structural proteins applied in vaccine design

Improvement of different vaccine delivery systems for cancer therapy

Cancer vaccines are the promising tools in the hands of the clinical oncologist. Many tumor-associated antigens are excellent targets for immune therapy and vaccine design. Optimally designed cancer vaccines should combine the best tumor antigens with the most effective immunotherapy agents and/or delivery strategies to achieve positive clinical results. Various vaccine delivery systems such as different routes of immunization and physical/chemical delivery methods have been used in cancer therapy with the goal to induce immunity against tumor-associated antigens. Two basic delivery approaches including physical delivery to achieve higher levels of antigen production and formulation with microparticles to target antigen-presenting cells (APCs) have demonstrated to be effective in animal models. New developments in vaccine delivery systems will improve the efficiency of clinical trials in the near future. Among them, nanoparticles (NPs) such as dendrimers, polymeric NPs, metallic NPs, magnetic NPs and quantum dots have emerged as effective vaccine adjuvants for infectious diseases and cancer therapy. Furthermore, cell-penetrating peptides (CPP) have been known as attractive carrier having applications in drug delivery, gene transfer and DNA vaccination. This review will focus on the utilization of different vaccine delivery systems for prevention or treatment of cancer. We will discuss their clinical applications and the future prospects for cancer vaccine development

Polymorphism analysis of the CTLA-4 (rs231775) gene as a marker of inhibitor development in Iranian patients with hemophilia A

Background: Development of factor VIII (FVIII) inhibitor is the main problem of replacement therapy in patients with hemophilia A. Recently, the correlation of polymorphisms of some genes involved in immune system has been determined with inhibitor development. The reports showed that cytotoxic T lymphocyte antigen-4 (CTLA-4) plays an important role in regulating T cell activation and thus, CTLA-4 gene polymorphism is related to genetic susceptibility to various autoimmune diseases. This study aimed at investigating the correlation between polymorphism of CTLA-4 gene and inhibitor development in Iranian hemophilia A patients for the first time. Materials and Methods: In this case-control study, the genomic DNA was extracted from blood samples of 55 inhibitor positive and 45 inhibitor negative hemophilia A patients. Then, the genotyping of the CTLA-4 gene was performed using the Tetra Primer ARMS PCR. Moreover, the validation of single nucleotide polymorphisms (SNPs) in the CTLA-4 gene was determined by DNA sequencing. On the other hand, the role of HCV infection was determined in inhibitor-positive and inhibitor-negative HA patients. Results: Results showed that no statistically significant difference was observed between the genotypic and allelic frequencies with the presence of inhibitors (P>0.05). Moreover, a significant correlation was observed between HCV infections and development of inhibitors (P<0.05). Conclusion: The CTLA-4 gene polymorphism does not play a role for inhibiting coagulation factor in Iranian patients with hemophilia type A

Different physical delivery systems: An important approach for delivery of biological molecules in vivo

   Delivery of exogenous materials such as nucleic acids, peptides, proteins, and drugs into cells is an important strategy in modern cellular and molecular biology. Recently, the development of gene carriers for efficient gene transfer into cells has attracted a great attention. Furthermore, lack of effective drug delivery is one of the major problems of cancer chemotherapy. Many physical methods have been studied to enhance the efficiency of gene and drug delivery. These strategies help to cross the materials from membranes including needle injection, photodynamic therapy, jet injection, gene gun, electroporation, hydrodynamic injection, laser, magnetofection, and tattooing. The physical systems improve the transfer of genes from extracellular to nucleus by creating transient membrane pores using physical forces including local or rapid systemic injection, particle impact, electric pulse, ultrasound, and laser irradiation. The recent optimization techniques of transdermal patches could improve the transdermal drug delivery through the skin. Among different physical carriers, electroporation and gene gun are the most potent methods for gene transfection and drug delivery in vivo. However, the researchers have focused on enhancing their potency with the structural modifications. Regarding to numerous barriers for biomolecules delivery in cells, this review is concentrated on description and optimization of different physical delivery systems for gene or drug transfer across membrane

Reverse staining method of polyacrylamide gels by imidazole-zinc salts for

The human papillomavirus L1 major capsid protein (HPV L1), the basis of the current vaccines, self-assembles into virus-like particles (VLPs). Herein, we describe the expression and purification of recombinant HPV16 L1 in E. coli system. The L1 protein was generated in a fused form using an inducible expression system. The recombinant GST-L1 fusion protein migrated as a 82 kDa protein in SDS-PAGE. The L1 proteins formed inclusion bodies which were purified by Zn+2 reverse staining of sodium dodecyl sulfate polyacrylamide gels (SDS-PAGE) as a sensitive detection method. In western blotting, the existence of a 82 kDa band for GST-L1 protein was confirmed by anti-HPV16 L1 monoclonal antibody Camvir 1. The purified protein fraction was concentrated by ultrafiltration and dialyzed against PBS. This study has implications for the development of L1 protein purification as well as chromatographic separation used by other studies. Indeed, we could present a simple method to purify L1 protein in E. coli