Enhanced immunogenicity of HPV16E7 accompanied by Gp96 as an adjuvant in two vaccination strategies

HIV-1 Accessory Proteins: Which one is Potentially Effective in Diagnosis and Vaccine Development?

BACKGROUND

The combination antiretroviral therapy (cART) could increase the number of circulating naive CD4 T lymphocytes, but was not able to eradicate human immunodeficiency virus-1 (HIV-1) infection.

OBJECTIVE

Thus, induction of strong immune responses is important for control of HIV-1 infection. Furthermore, a simple and perfect serological method is required to detect virus in untreated-, treated- and drug resistant- HIV-1 infected individuals.

METHODS

This study was conducted to assess and compare immunogenic properties of Nef, Vif, Vpr and Vpu accessory proteins as an antigen candidate in mice and their diagnostic importance in human as a biomarker.

RESULTS

Our data showed that in mice, all heterologous prime/ boost regimens were more potent than homologous prime/ boost regimens in eliciting Th1 response and Granzyme B secretion as CTL activity. Moreover, the Nef, Vpu and Vif proteins could significantly increase Th1 immune response. In contrast, the Vpr protein could considerably induce Th2 immune response. On the other hand, among four accessory proteins, HIV-1 Vpu could significantly detect treated group from untreated group as a possible biomarker in human.

CONCLUSION

Generally, among accessory proteins, Nef, Vpu and Vif antigens were potentially more suitable vaccine antigen candidates than Vpr antigen. Human antibodies against all these proteins were higher in HIV-1 different groups than healthy group. Among them, Vpu was known as a potent antigen in diagnosis of treated from untreated individuals. The potency of accessory proteins as an antigen candidate in an animal model and a human cohort study are underway.

Evaluation of HIV-1 Regulatory and Structural Proteins as Antigen Candidate in Mice and Humans

BACKGROUND

The diagnosis of HIV infection is important among different groups. Moreover, combination antiretroviral therapy is used to treat HIV-1, but it cannot eradicate the infection. Thus, the development of therapeutic vaccines, along with antiretroviral therapy, is recommended. This study evaluates the values of four HIV proteins as antigen candidates in therapeutic vaccine design as well as a possible diagnostic marker for HIV infection in humans.

METHODS

In this study, the HIV-1 Tat and Rev regulatory proteins and structural Gp120 and p24 proteins were generated in E. coli expression system. Their immunogenicity was evaluated in BALB/ c mice using homologous and heterologous prime/boost strategies. Moreover, the detection of anti- HIV IgG antibodies against these recombinant proteins was assessed in untreated (Naïve/ HIV-infected), treated, and drug-resistant patients compared to the healthy (control) group as a possible diagnostic marker for HIV infection.

RESULTS

In humans, our results showed that among HIV-1 proteins, anti-Gp120 antibody was not detected in treated individuals compared to the healthy (control) group. The levels of anti-Gp120 antibody were significantly different between the treated group and Naïve as well as drug-resistant subjects. Moreover, the level of anti-p24 antibody was significantly lower in the treated group than the Naive group. In mice, the results of immunization indicated that the Rev antigen could significantly induce IgG2a, IgG2b, and IFN-γ secretion aimed at Th1 response as well as Granzyme B generation as CTL activity in comparison with other antigens. Furthermore, the heterologous DNA prime/ protein boost regimen was more potent than the homologous regimen for stimulation of cellular immunity.

CONCLUSION

Briefly, the levels of both anti-Gp120 and anti-p24 antibodies can be considered for the diagnosis of the HIV-infected individuals in different groups compared to the healthy group. Moreover, among four recombinant proteins, Rev elicited Th1 cellular immunity and CTL activity in mice as an antigen candidate in therapeutic vaccine development.

HCV Core/NS3 Protein Immunization with "N-Terminal Heat Shock gp96 Protein (rNT (gp96))" Induced Strong and Sustained Th1-Type Cytokines in Immunized Mice

Feeble cellular responses induced by T cell-based vaccines are a major challenge for the development of an effective vaccine against Hepatitis C virus (HCV) infection. To address this challenge, the potential of N-terminal fragment of gp96 heat shock protein (rNT (gp96) as an adjuvant was evaluated and compared to that of the CpG (as a recognized Th1-type adjuvant) in the formulation of HCV core/NS3 antigens in three immunization strategies of protein/protein, DNA/DNA, and DNA/protein. Immunized mice were evaluated for elicited immune responses in week 3 (W3) and 11 post-immunizations. Our results demonstrated that the protein (subunit) vaccine formulated with rNT (gp96) in protein/protein strategy (core/NS3 + gp96) was significantly more efficient than CpG oligodeoxynucleotides (CpG ODN) formulation and all other immunization strategies in the induction of Th1-type cytokines. This group of mice (core/NS3 + gp96) also elicited a high level of anti-Core-NS3 total immunoglobulin G (IgG) with dominant IgG2a isotype at W3. Thus, the co-administration of recombinant NT (gp96) protein with rHCV proteins might be a promising approach in the formulation of HCV subunit vaccine candidates for induction of high levels of Th1 cytokines and humoral responses.

Heat Shock Proteins 90 kDa: Immunomodulators and Adjuvants in Vaccine Design Against Infectious Diseases

Heat shock proteins 90 kDa (Hsp90s) were originally identified as stress-responsive proteins and described to participate in several homeostatic processes. Additionally, extracellular Hsp90s have the ability to bind to surface receptors and activate cellular functions related to immune response (cytokine secretion, cell maturation, and antigen presentation), making them very attractive to be studied as immunomodulators. In this context, Hsp90s are proposed as new adjuvants in the design of novel vaccine formulations that require the induction of a cell-mediated immune response to prevent infectious diseases. In this review, we summarized the adjuvant properties of Hsp90s when they are either alone, complexed, or fused to a peptide to add light to the knowledge of Hsp90s as carriers and adjuvants in the design of vaccines against infectious diseases. Besides, we also discuss the mechanisms by which Hsp90s activate and modulate professional antigen-presenting cells.

In vivo delivery of a multiepitope peptide and Nef protein using novel cell-penetrating peptides for development of HIV-1 vaccine candidate

OBJECTIVES

A potent HIV vaccine should overcome some limitations such as polymorphism of human HLA, the diversity of HIV-1 virus, and the lack of an effective delivery system. In this study, a DNA construct encoding Nef_60-84, Nef_126-144, Vpr_34-47, Vpr_60-75, Gp160_30-53, Gp160_308-323, and P24_8-151 epitopes was designed using bioinformatics tools. The pcDNA3.1-nef-vpr-gp160-p24 and pcDNA3.1-nef constructs were prepared in large scale as endotoxin-free form. Moreover, the recombinant Nef-Vpr-Gp160-p24 polypeptide and Nef protein were generated inE. coli. These constructs were delivered using cell penetrating peptides (CPPs) in vivo, and immune responses were assessed for different modalities in BALB/c mice.

RESULTS

The recombinant DNA constructs were confirmed as the ~ 867 bp and ~ 648 bp bands related tonef-vpr-gp160-p24 andnef genes on agarose gel. Moreover, the purified Nef-Vpr-Gp160-p24 polypeptide and Nef protein showed the ~ 32 kDa and ~ 30 kDa bands on SDS-PAGE, respectively. The results of immune responses indicated that the heterologous prime/boost regimens using both Nef-Vpr-Gp160-P24 and Nef antigens induced significantly the secretion of IgG2a, IgG2b, IFN-γ and Granzyme B compared to other groups. The levels of Granzyme B in mice immunized with Nef antigen were higher than those immunized with Nef-Vpr-Gp160-P24 antigen. The CPPs showed the same potency with Montanide adjuvant for eliciting immune responses.

CONCLUSIONS

The heterologous prime/boost regimens for both antigens could significantly direct immune responses toward Th1 and CTL activity compared to other regimens. Comparing the efficiency of Nef-Vpr-Gp160-P24 and Nef constructs, the Nef-Vpr-Gp160-P24 constructs delivered by CPPs showed promising results as an HIV vaccine candidate.

Anti-viral Effects of Superpositively Charged Mutant of Green Fluorescent Protein

BACKGROUND

Supercharged GFP proteins were known as effective carriers for delivery of macromolecules into eukaryotic cells as well as fluorescent fusion tags for in vitro and in vivo detection.

OBJECTIVE

Herein, anti-viral effects of +36 GFP and its anti-tumor effects were studied in vitro and in vivo, respectively.

METHODS

We evaluated anti-HIV, anti-HSV, and anti-HCV effects of +36 GFP in vitro using ELISA, and real time PCR as common techniques for their detection, respectively. Moreover, we assessed the role of +36 GFP for eliciting HPV-related anti-tumor effects in mice due to the lack of HPV replication in vitro.

RESULTS

Our data showed that +36 GFP efficiently enter the cells and augment the transfection rate of HPV16E7 antigen, as well. Furthermore, +36 GFP significantly reduced HCV, HIV and HSV replication up to 75%, 49% and 43% in HCV-infected Huh7.5 cells, HIV-infected Hela cells and HSV-infected Vero cells, respectively. On the other hand, mice immunization with +36 GFP complexed with HPV16 E7 antigen (+36GFP + E7) or fused to HPV16 E7 antigen (+36GFP-E7) elicited a higher Th1 cellular immune response with the predominant IgG2a, IgG2b, IFN-γ and Granzyme B levels than those induced by other groups. These regimens protected mice against TC- 1 tumor challenge (~ 67%) compared to E7 protein alone (~ 33%). These data suggested that +36 GFP can act as an anti-viral agent at certain dose due to its high efficiency in cell penetration in vitro and in vivo.

CONCLUSION

Generally, +36 GFP targets viral replication in vitro as well as helps to suppress the growth of HPV-related tumors in vivo.

Heat-shock proteins in diagnosis and treatment: an overview of different biochemical and immunological functions

Heat-shock proteins (HSPs) have been involved in different functions including chaperone activity, protein folding, apoptosis, autophagy and immunity. The HSP families have powerful effects on the stimulation of innate immune responses through Toll-like receptors and scavenger receptors. Moreover, HSP-mediated phagocytosis directly enhances the processing and presentation of internalized antigens via the endocytic pathway in adaptive immune system. These properties of HSPs have been used for development of prophylactic and therapeutic vaccines against infectious and noninfectious diseases. Several studies also demonstrated the relationship between HSPs and drug resistance as well as their use as a novel biomarker for detecting tumors in patients. The present review describes different roles of HSPs in biology and medicine especially biochemical and immunological aspects.

Current strategies against persistent human papillomavirus infection (Review)

Human papillomavirus (HPV) is the most common sexually transmitted infection, exhibiting a tropism for the epidermis and mucosae. The link between persistent HPV infection and malignancies involving the anogenital tract as well as the head and neck has been well‑established, and it is estimated that HPV‑related cancers involving various anatomical sites account for 4.5% of all human cancers. Current prophylactic vaccines against HPV have enabled the prevention of associated malignancies. However, the sizeable population base of current infection in whom prophylactic vaccines are not applicable, certain high‑risk HPV types not included in vaccines, and the vast susceptible population in developing countries who do not have access to the costly prophylactic vaccines, put forward an imperative need for effective therapies targeting persistent infection. In this article, the life cycle of HPV, the mechanisms facilitating HPV evasion of recognition and clearance by the host immune system, and the promising therapeutic strategies currently under investigation, particularly antiviral drugs and therapeutic vaccines, are reviewed.

Modified DCs and MSCs with HPV E7 antigen and small Hsps: Which one is the most potent strategy for eradication of tumors?

Immunotherapy with DCs as antigen-presenting vehicles have already improved patients' outcome against a variety of tumors. Moreover, MSCs were recently used to develop anti-cancer therapeutic or anti-microbial prophylactic vaccines. The current study evaluated immune responses and anti-tumor effects generated by DCs and MSCs derived from mouse bone marrow which were modified with small heat shock proteins 27 and 20 (sHsp27 and sHsp20) and also E7 oncoprotein in tumor mouse model. Two vaccination strategies were utilized including homologous DC or MSC prime/ DC or MSC boost, and heterologous MSC or DC prime/ protein boost vaccinations. Our data revealed that DCs pulsed with E7+Hsp27 and/or E7+Hsp20 in homologous and heterologous prime/ boost vaccinations could stimulate high levels of IgG2a, IgG2b, IFN-γ and IL-10 directed toward Th1 responses. Moreover, these regimens induced an increased level of Granzyme B, and displayed complete protection more than 60 days after treatment. On the other hand, MSCs transfected with E7+Hsp27 DNA in homologous and heterologous prime/ boost vaccinations could significantly enhance the E7-specific T-cell responses and suppress tumor growth in mice. However, MSCs transfected with E7+Hsp20 DNA did not induce a complete protection against TC-1 tumor compared to DCs pulsed with E7+Hsp20 protein complexes. These results indicated that DC- and MSC-based vaccinations with specific modalities will be a useful approach for immunotherapy and protection against HPV-associated cancers.

Comparison of six cell penetrating peptides with different properties for in vitro and in vivo delivery of HPV16 E7 antigen in therapeutic vaccines

The high risk human papillomavirus (HPV) types 16 and 18 are globally linked to >50% and 20% of all cervical cancers, respectively. The HPV E7 oncoprotein was determined as a therapeutic vaccine target due to its constitutive expression by HPV-infected cells. The findings demonstrated the efficiency of therapeutic HPV DNA- and protein-based vaccines in preclinical and clinical trials. However, there are limitations for penetration of DNA and protein constructs into the cells without a suitable delivery system. Recently, several cell penetrating peptides (CPPs) have been suggested for delivery of nucleic acids and proteins into cells through covalent or non-covalent fashion. In this study, we determined highly efficient CPPs for the controlled delivery of HPV16 E7 antigen, in vitro and in vivo. Our data indicated the effective delivery of E7 protein by Pep-1, Cady-2, P28 and hPP10, and E7 DNA by MPG and +36 GFP CPPs in HEK-293T cell line at certain ratios. Moreover, immunization with the heterologous MPG + E7 DNA prime/P28 + rE7 protein boost elicited a higher Th1 cellular immune response with a predominant IFN-γ profile and strong Granzyme B secretion than those induced by other groups in a murine tumor model. Indeed, the groups vaccinated with rE7+ P28/rE7+ P28, MPG+ E7 DNA/P28+ rE7, and E7 DNA+ MPG/E7 DNA+ MPG nanovaccines displayed complete protection and remained tumor-free >60 days after treatment. These data suggest P28 and MPG as promising protein and gene delivery systems for development of HPV therapeutic vaccines.

Delivery of molecular cargoes in normal and cancer cell lines using non-viral delivery systems

OBJECTIVE

In this study, transfection efficiency of human papillomavirus (HPV) E7 DNA and protein constructs into HEK-293T normal cell line, and A549 and TC-1 tumor cell lines was evaluated by four delivery systems including supercharge GFP, hPP10 cell penetrating peptide, TurboFect and Lipofectamine using fluorescence microscopy and flow cytometry.

RESULTS

The results indicated that Lipofectamine 2000 and TurboFect produced more effective transfection for GFP and E7-GFP DNA constructs in HEK-293T cells compared to in A549 and TC-1 cells (p < 0.05). In contrast, the supercharge GFP was efficient for E7 DNA and E7 protein delivery in both normal cell (~ 83.94 and ~ 77.01% for HEK-293T), and cancer cells (~ 71.69 and ~ 67.19% for TC-1, and ~ 73.86 and ~ 67.49% for A549), respectively. Indeed, in these cell lines, transfection efficiency by +36 GFP reached ~ 60-80%. Moreover, the hPP10 produced the best transfection result for E7-GFP protein in HEK-293T cells (~ 63.66%) compared to TurboFect (~ 32.95%); however, the efficiency level of hPP10 was only ~ 17.51 and ~ 16.36% in TC-1 and A549 cells.

CONCLUSIONS

Our data suggested that the supercharge GFP is the most suitable transfection vehicle for DNA and protein delivery into TC-1 and A549 tumor cell lines compared to other carriers.

Supercharged green fluorescent protein delivers HPV16E7 DNA and protein into mammalian cells in vitro and in vivo

Macromolecules including DNA and proteins serve as important human therapeutics but are limited by their general inability to cross cell membranes. Supercharged proteins have been known as potent tools for delivery of macromolecules into mammalian cells. Thus, the use of these delivery systems is important to reduce the human papillomavirus (HPV)-associated malignancies through improvement of vaccine modalities. In this study, we used a supercharged green fluorescent protein (+36 GFP) for delivery of the full-length HPV16 E7 DNA and protein into mammalian cells and evaluated immune responses, and protective/therapeutic effects of different formulations in C57BL/6 tumor mice model. Our results showed that the complexes of E7 DNA/+36 GFP and also E7 protein/+36 GFP form stable nanoparticles through non-covalent binding with an average size of ∼ 200-300 nm. The efficient delivery of E7 DNA or protein by +36 GFP was detected in HEK-293T cell line for 4 h and 24 h post-transfection. Mice immunization with E7 protein/+36 GFP nanoparticles elicited a higher Th1 cellular immune response with the predominant IgG2a and IFN-γ levels than those induced by E7 protein, E7 DNA, E7 DNA/+36 GFP and control groups (p < .05). Moreover, the E7 DNA/+36 GFP and E7 protein/+36 GFP nanoparticles similarly protected mice against TC-1 tumor challenge (∼67%) as compared to E7 DNA and E7 protein (∼33%), respectively. These data suggest that +36 GFP may provide a promising platform to improve protein and DNA delivery in vitro and in vivo.

Human Neutrophil Peptide 1 as immunotherapeutic agent against Leishmania infected BALB/c mice

Human Neutrophil Peptide 1 (HNP1) produced by neutrophils, is a well-known antimicrobial peptide which plays a role both in innate as well as in adaptive immunity and is under intensive investigation as a potential therapeutic agent. Previous in vitro experiments have indicated the leishmaniacidal effect of recombinant HNP1 on Leishmania major (L. major) promastigotes and amastigotes. In the current study, we further extended the idea to explore the remedial effect of HNP1 in the two modalities of peptide therapy (folded HNP1) and gene therapy in L. major infected BALB/c mice. To this end, mice in five different groups received synthetic folded HNP1 (G1), pcDNA-HNP1-EGFP (G2), pcDNA-EGFP (G3), Amphotericin B (G4) and PBS (G5), which was started three weeks after infection for three consecutive weeks. Footpad swelling was monitored weekly and a day after the therapy ended, IFN-γ, IL-4, IL-10, IL-6 and nitric oxide produced by splenocytes were analyzed together with the parasite load in draining lymph nodes. Arginase activity and dermal histopathological changes were also analyzed in the infected footpads. We demonstrated that both therapeutic approaches effectively induced Th1 polarization and restricted parasite burden. It can control disease progression in contrast to non-treated groups. However, pcDNA-HNP1-EGFP is more promising in respect to parasite control than folded HNP1, but less effective than AmB treatment. We concluded with the call for a future approach, that is, a DNA-based expression of HNP1 combined with AmB as it can improve the leishmaniacidal efficacy.

The outbreak level of cutaneous leishmaniasis is approximated between one and 1.5 million individuals per year. Owning to several disadvantages of current therapies, special attention to expand novel and efficient therapies has been demanded. Among Anti-Microbial Peptides (AMPs), Human Neutrophil Peptide 1 (HNP1) is one of the most potential defensins. Our promising in vitro experiments have shown the leishmaniacidal effect of recombinant HNP1. Here, we displayed the remedial effect of HNP1 in two approaches including peptide therapy and gene therapy in susceptible mice infected with L. major. Our investigation showed that although both approaches could decrease the parasite load and induce Th1 immune response compared to the control group, pcDNA-HNP1-EGFP has a better effect compared to the folded HNP1. Hence, immunotherapy by HNP1 can help elicit proper immunity despite the direct effect on promastigotes and amastigotes forms of parasite.

LncRNA and mRNA profiling during activation of tilapia macrophages by HSP70 and Streptococcus agalactiae antigen

Objectives

To investigate the lncRNA profiling during tilapia peritoneal macrophages (TPMs) activation and discuss the relationship between lncRNA and mRNA.

Materials and Methods

RNA sequencing was used to investigate the lncRNA and mRNA profiles of TPMs activation following stimulation with Streptococcus agalactiae (Sa) antigen, heat shock protein 70 (HSP70) and HSP70+Sa. The expressions of lncRNA and mRNA were confirmed by qPCR. 356 lncRNA, 10173 mRNA and 1782 transcripts of uncertain coding potential (TUCP) were differentially expressed by pairwise comparison. These lncRNAs were shorter in length, fewer in exon number and higher in expression levels as compared with mRNAs. 683 lncRNAs and 4320 mRNAs were co-located, while 316 lncRNAs and 9997 mRNAs were in co-expression networks. Seven mRNAs (ANKRD34A, FMODA, GJA3, CNTN5, BMP10, BAI2 and HS3ST6) were involved in both networks of LNC_00035 and LNC_000466. Differentially expressed genes were involved in signaling pathways, such as "phosphorylation", "cytokine-cytokine receptor interaction", "endocytosis" and "MHC protein complex". LNC_000792, LNC_000215, LNC_000035 and LNC_000310, with cis and/or trans relationships with mRNAs, were also involved in ceRNA network.

Conclusions

These results might represent the first identified expression profile of lncRNAs and mRNAs in tilapia macrophages activated by HSP70 and Sa.

Small heat shock protein 27: An effective adjuvant for enhancement of HIV-1 Nef antigen-specific immunity

Novel vaccine modalities have been designed to improve the efficiency of vaccines against HIV infections. In this way, the HIV-1 Nef protein has been known as an attractive antigenic candidate in therapeutic vaccine development. Moreover, the endogenous adjuvants such as heat shock proteins (HSPs) and high mobility group box 1 protein (HMGB1) have been suggested effectively to induce antigen-specific humoral and cellular immune responses. In this study, different Nef DNA and protein constructs were produced in eukaryotic and prokaryotic expression systems, and their immunostimulatory properties were evaluated using small heat shock protein 27 (Hsp27) and the HMGB1-derived peptide (Hp91) in a mouse model. Generally, our results indicated that the Hsp27-Nef fusion DNA or protein could significantly elicit higher humoral and cellular immune responses than Nef DNA or protein, respectively. Analysis of the immune responses demonstrated that the Hsp27-Nef fusion protein, and also the mixture of Nef and Hp91 significantly enhanced the Nef-specific T cell responses. Indeed, these regimens induced high levels of IgG2a and IFN-γ directed toward Th1 responses and also Granzyme B secretion as compared to other immunization strategies. The immunostimulatory properties of Freund's adjuvant were significantly less than Hsp27 and Hp91 peptide in various immunization strategies. These findings showed that the use of Hsp27 and Hp91 in protein strategy could improve HIV-1 Nef-specific B- and T-cell immune responses, and also represent a promising HIV-1 vaccine candidate in future.

Immune response to recombinant Leishmania infantum lipophosphoglycan 3 plus CpG oligodeoxynucleotides in BALB/c mice

Development of a protective antileishmanial vaccine is an urgent priority for successful control of different forms of leishmaniasis. The potential of a recombinant lipophosphoglycan 3 (rLPG3) expressed by Leishmania tarentolae was evaluated in combination with CpG oligodeoxynucleotides (CpG-ODN) as a Th1-promoting adjuvant against Leishmania infantum infection in BALB/c mice. First, mice were immunized subcutaneously with rLPG3 either alone or in combination with CpG-ODN. Next, the immunogenic and protective efficacies of this vaccine were analysed in immunized mice. It was observed that coadministration of rLPG3 with CpG-ODN led to enhance in a Th1 response to rLPG3 induced by itself as the IFN-γ production was promoted in association with the predominant presence of IgG2a antibodies in the sera. However, immunization with rLPG3 plus CpG-ODN induced partial protection against infectious challenge in BALB/c mice. Taken together, further studies are required to improve the protective efficacy using either more potent immune enhancers or vaccination strategies.

Hp91 immunoadjuvant: An HMGB1-derived peptide for development of therapeutic HPV vaccines

BACKGROUND

High percentage of human cervical malignancy is related to human papillomavirus (HPV) infections. Thus, it is important to find novel non-invasive treatment strategies among various therapeutic HPV vaccines. In current study, we investigated the protective and therapeutic effects of DNA- and protein-based vaccines using HPV16 E7 as a model antigen in tumor mice model. In this line, the full length of high-mobility group box 1 (HMGB1) protein as well as an HMGB1-derived short peptide (Hp91) was used as an adjuvant for stimulating adaptive immunity and developing the potency of these vaccines.

METHODS

DNA vaccination of HPV16 E7 with HMGB1 was performed as the complexed and conjugated forms. The immunostimulatory properties of Hp91 peptide along with Hp121 control peptide were compared to Montanide 720 in protein vaccination.

RESULTS

Our data showed that co-immunization of HPV16 E7 protein with Hp91 peptide or Hp91+Hp121 peptides significantly increased the secretion of IFN-γ, IgG2a antibody response, and protected 100% of mice against a TC-1 tumor challenge. Furthermore, the linkage of HMGB1 with E7 antigen led to enhance the immunogenicity of DNA vaccine especially in combination with Hp91 and Hp121 peptides.

CONCLUSIONS

These findings suggest that Hp91 peptide, and the full length of HMGB1 gene could be an efficient adjuvant for improvement of therapeutic HPV protein- and DNA-based vaccines, respectively.

Physicochemical properties of polymers: An important system to overcome the cell barriers in gene transfection

Delivery of the macromolecules including DNA, miRNA, and antisense oligonucleotides is typically mediated by carriers due to the large size and negative charge. Different physical (e.g., gene gun or electroporation), and chemical (e.g., cationic polymer or lipid) vectors have been already used to improve the efficiency of gene transfer. Polymer-based DNA delivery systems have attracted special interest, in particular via intravenous injection with many intra- and extracellular barriers. The recent progress has shown that stimuli-responsive polymers entitled as multifunctional nucleic acid vehicles can act to target specific cells. These nonviral carriers are classified by the type of stimulus including reduction potential, pH, and temperature. Generally, the physicochemical characterization of DNA-polymer complexes is critical to enhance the transfection potency via protection of DNA from nuclease digestion, endosomal escape, and nuclear localization. The successful clinical applications will depend on an exact insight of barriers in gene delivery and development of carriers overcoming these barriers. Consequently, improvement of novel cationic polymers with low toxicity and effective for biomedical use has attracted a great attention in gene therapy. This article summarizes the main physicochemical and biological properties of polyplexes describing their gene transfection behavior, in vitro and in vivo. In this line, the relative efficiencies of various cationic polymers are compared.

Antitumor Effect of IP-10 by Using Two Different Approaches: Live Delivery System and Gene Therapy

Purpose

Immunotherapy is one of the treatment strategies for breast cancer, the most common cancer in women worldwide. In this approach, the patient's immune system is stimulated to attack microscopic tumors and control metastasis. Here, we used interferon γ-induced protein 10 (IP-10), which induces and strengthens antitumor immunity, as an immunotherapeutic agent. We employed Leishmania tarentolae, a nonpathogenic lizard parasite that lacks the ability to persist in mammalian macrophages, was used as a live delivery system for carrying the immunotherapeutic agent. It has been already shown that arginase activity, and consequently, polyamine production, are associated with tumor progression.

Methods

A live delivery system was constructed by stable transfection of pLEXSY plasmid containing the IP-10-enhanced green fluorescent protein (IP-10-egfp) fusion gene into L. tarentolae. Then, the presence of the IP-10-egfp gene and the accurate integration location into the parasite genome were confirmed. The therapeutic efficacy of IP-10 delivered via L. tarentolae and recombinant pcDNA-(IP-10-egfp) plasmid was compared by determining the arginase activity in a mouse 4T1 breast cancer model.

Results

The pcDNA-(IP-10-egfp) group showed a significant reduction in tumor weight and growth. Histological evaluation also revealed that only this group demonstrated inhibition of metastasis to the lung tissue. The arginase activity in the tissue of the pcDNA-(IP-10-egfp) mice significantly decreased in comparison with that in normal mice. No significant difference was observed in arginase activity in the sera of mice receiving other therapeutic strategies.

Conclusion

Our data indicates that IP-10 immunotherapy is a promising strategy for breast cancer treatment, as shown in the 4T1-implanted BALB/c mouse model. However, the L. tarentolae-(IP-10-EGFP) live delivery system requires dose modifications to achieve efficacy in the applied regimen (six injections in 3 weeks). Our results indicate that the arginase assay could be a good biomarker to differentiate tumoral tissues from the normal ones.

The structural HCV genes delivered by MPG cell penetrating peptide are directed to enhance immune responses in mice model

One of the significant problems in vaccination projects is the lack of an effective vaccine against hepatitis C virus (HCV). The goal of the current study is to evaluate and compare two DNA constructs encoding HCV core and coreE1E2 genes alone or complexed with MPG peptide as a delivery system for stimulation of antibody responses and IFN-γ secretion in Balb/c mice model. Indeed, MPG cell penetrating peptide was used to improve DNA immunization in mice. Our results demonstrated that MPG forms stable non-covalent nanoparticles with pcDNA-core and pcDNA-coreE1E2 at an N/P ratio of 10:1. The in vitro transfection efficiency of core or coreE1E2 DNA using MPG and TurboFect delivery systems was confirmed by western blot analysis. The results indicated the expression of the full-length core (∼21 kDa), and coreE1E2 (∼83 kDa) proteins using an anti-His monoclonal antibody. In addition, the expression of HCV core and coreE1E2 proteins was performed in bacteria and the purified recombinant proteins were injected to mice with Montanide 720 adjuvant. Our data showed that the immunized mice with HCV core and coreE1E2 proteins generated the mixture of sera IgG1 and IgG2a isotypes considerably higher than other groups. Furthermore, DNA constructs encoding core and coreE1E2 complexed with MPG could significantly induce IFN-γ secretion in lower concentrations than the naked core and coreE1E2 DNAs. Taken together, the DNA formulations as well as protein regimens used in this study triggered high-level IFN-γ production in mice, an important feature for the development of Th1 immune responses.

Prime/boost immunization with HIV-1 MPER-V3 fusion construct enhances humoral and cellular immune responses

Development of an effective vaccine against HIV-1 infection is a main concern in worldwide. A potent vaccine for HIV-1 requires the induction and maintenance of both humoral and cellular immunity. In this study, the levels of humoral and cellular immune responses were compared using MPER-V3 injection in three immunization strategies such as DNA/DNA, peptide/peptide, and DNA/peptide (prime-boost). MPG peptide and Montanide 720 were used as a DNA delivery system, and as a peptide adjuvant, respectively. Our results demonstrated that MPG forms stable non-covalent nanoparticles with plasmid DNA at N/P ratio of 10:1 (∼ 110-130 nm). The in vitro transfection efficiency of MPER-V3 DNA using MPG was comparable with lipofectamine and turbofect reagents as a common delivery system. In vivo prime-boost immunization using HIV-1 MPER-V3 could significantly enhance humoral and cellular immune responses as compared to control groups. The mixture of IgG1 and IgG2a was observed for each strategy, but IFN-γ production was significantly higher in prime-boost and peptide immunizations than that in DNA immunizations, inducing Th1 response. Moreover, our data showed that prime immunization with low dose of the nanoparticles (MPER-V3 DNA: MPG at ratio of 1:10) followed by MPER-V3 peptide drives T cell responses towards a Th1-type similar to high dose of the naked DNA prime/peptide boost immunization. Generally, the prime-boost strategy could improve both immune responses against MPER and especially V3 peptides suggesting its application as a promising HIV vaccine candidate in future.

MPG-based nanoparticle: An efficient delivery system for enhancing the potency of DNA vaccine expressing HPV16E7

DNA vaccines against human papillomavirus (HPV) type 16 have not been successful in clinical trials, due to the lack of an appropriate delivery system. In this study, a peptide-based gene delivery system, MPG, which forms stable non-covalent nanoparticles with nucleic acids, was used for in vitro and in vivo delivery of HPV16 E7 DNA as a model antigen. The results demonstrated that at Nitrogen/Phosphate (N/P) ratio over 10:1, this peptide can effectively condense plasmid DNA into stable nanoparticles with an average size of 180-210nm and a positive surface charge. The transfection efficiency of MPG-based nanoparticles was shown to be comparable with Polyethyleneimine (PEI). The efficient protein expression detected by western blotting and flow cytometry supports the potential of MPG-based nanoparticles as a potent delivery system in DNA vaccine formulations. Immunization with MPG/E7DNA nanoparticles at an N/P ratio of 10:1 induced a stronger Th1 cellular immune response with a predominant interferon-γ (IFN-γ) profile than those induced by E7DNA alone in a murine tumor model. These findings suggest that MPG peptide as a novel gene delivery system could have promising applications in improving HPV therapeutic vaccines.

Evaluation of Cell Penetrating Peptide Delivery System on HPV16E7 Expression in Three Types of Cell Line

BACKGROUND

The poor permeability of the plasma and nuclear membranes to DNA plasmids are two major barriers for the development of these therapeutic molecules. Therefore, success in gene therapy approaches depends on the development of efficient and safe non-viral delivery systems.

OBJECTIVES

The aim of this study was to investigate the in vitro delivery of plasmid DNA encoding HPV16 E7 gene using cell penetrating peptide delivery system to achieve the best conditions for cell transfection and protein expression. For this purpose, we have used a cationic peptide delivery system, MPG which forms stable non-covalent complexes with nucleic acids for delivery of pEGFP-E7 as a model antigen in vitro.

MATERIALS AND METHODS

DNA construct encoding HPV16 E7 (pEGFP-E7) was prepared in large scale with high purity. MPG peptide/ DNA complexes were prepared at different N/P (nitrogen/phosphate) ratios and physicochemical characterization and stability of nanoparticles were investigated. In vitro peptide-mediated E7-GFP DNA transfection, and its expression was evaluated in three cell types. To quantify the transfection efficiency of this delivery system, transfected cells were harvested and assessed for GFP-positive cells by flow cytometry. Furthermore, E7-GFP expression was confirmed by western blot analysis.

RESULTS

The cellular uptake of MPG based nanoparticles was shown to be comparable with standard reagent PEI. The COS-7 cells transfected by MPG-based nanoparticles at an N/P ratio of 15:1 showed the highest transfection efficiency and gene expression.

CONCLUSIONS

The results indicated that the efficient gene expression depends on both cell type and N/P ratio applied, in vitro. The efficient protein expression detected by western blotting and flow cytometry supports the potential of MPGbased nanoparticles as a potent gene delivery system.

Enhancement of HCV polytope DNA vaccine efficacy by fusion to an N-terminal fragment of heat shock protein gp96

Induction of a strong hepatitis C virus (HCV)-specific immune response plays a key role in control and clearance of the virus. A polytope (PT) DNA vaccine containing B- and T-cell epitopes could be a promising vaccination strategy against HCV, but its efficacy needs to be improved. The N-terminal domain of heat shock protein gp96 (NT(gp96)) has been shown to be a potent adjuvant for enhancing immunity. We constructed a PT DNA vaccine encoding four HCV immunodominant cytotoxic T lymphocyte epitopes (two HLA-A2- and two H2-D(d)-specific motifs) from the Core, E2, NS3 and NS5B antigens in addition to a T-helper CD4+ epitope from NS3 and a B-cell epitope from E2. The NT(gp96) was fused to the C- or N-terminal end of the PT DNA (PT-NT(gp96) or NT(gp96)-PT), and their potency was compared. Cellular and humoral immune responses against the expressed peptides were evaluated in CB6F1 mice. Our results showed that immunization of mice with PT DNA vaccine fused to NT(gp96) induced significantly stronger T-cell and antibody responses than PT DNA alone. Furthermore, the adjuvant activity of NT(gp96) was more efficient in the induction of immune responses when fused to the C-terminal end of the HCV DNA polytope. In conclusion, the NT(gp96) improved the efficacy of the DNA vaccine, and this immunomodulatory effect was dependent on the position of the fusion.

Recombinant Nonstructural 3 Protein, rNS3, of Hepatitis C Virus Along With Recombinant GP96 Induce IL-12, TNFα and α5integrin Expression in Antigen Presenting Cells

BACKGROUND

Hepatitis C virus (HCV) infection is the main cause of chronic liver disease and to date there has been no vaccine development to prevent this infection. Among non-structural HCV proteins, NS3 protein is an excellent goal for a therapeutic vaccine, due to its large size and less variation in conserved regions. The immunogenic properties of heat shock proteins (HSPs) for instance GP96 have prompted investigations into their function as strong adjuvant to improve innate and adaptive immunity.

OBJECTIVES

The aim of this study was to examine additive effects of recombinant GP96 (rGP96) fragments accompanied by rNS3 on expression levels of α5integrin and pro-inflammatory cytokines, IL-12 and TNFα, in Antigen Presenting Cells (APCs).

MATERIALS AND METHODS

Recombinant viral proteins (rNS3 and rRGD-NS3), N-terminal and C-terminal fragments of GP96 were produced and purified from E. coli in order to treat the cells; mouse spleen Dendritic Cells (DCs) and THP-1 macrophages.

RESULTS

Our results showed that rNT-GP96 alone significantly increases the expression level of IL-12, TNFα and α5integrin in THP-1 macrophages and DCs, while IL-12 and TNFα expression levels were unaffected by either rNS3 or rRGD-NS3. Interestingly, the co-addition of these recombinant proteins with rNT-GP96 increased IL-12, TNFα and α5integrin expression. Pearson Correlation showed a direct association between α5integrin with IL-12 and TNF-α expression.

CONCLUSIONS

we have highlighted the role of rNS3 plus rNT-GP96 mediated by α5integrin in producing IL-12 and TNFα. It can be suggested that rNT-GP96 could enhance immunity characteristic of rNS3 protein via production of pro-inflammatory cytokines.

Heat shock protein 70 kDa (HSP70) increase in sea bass (Dicentrarchus labrax, L 1758) thymus after vaccination against Listonella anguillarum

Heat shock proteins 70 kDa (HSP70) and apoptosis were investigated in thymus of sea bass juveniles (Dicentrarchus labrax) subsequently to a vaccination against Listonella (syn. Vibrio) anguillarum. HSP70 expression was measured by immunohistochemistry and immunoenzymatic methods, resulting in increase in HSP70 after bath immunization and persistent in fish exposed to an intraperitoneal (i.p.) booster. The HSP70 increase in thymus was suggested as induction in lymphocytic cells, to be related to immune system stimulation after vaccination. However, a thymic recruitment of lymphocyte subpopulations, characterized by higher expression of HSP70, was also hypothesized after vaccination. No apparent relationships were found between HSP70 and apoptosis. In fact, the vaccination did not modulate the apoptosis response, as measured by TUNEL assay and by immunohistochemistry for active caspase-3 expression. The lack of apoptosis effects could be ascribed to the use of inactivated bacteria that appeared not able to interfere with programmed cell death mechanisms. This manuscript aims to contribute to the knowledge of some biochemical features underlying the immunization, with a particular emphasis on the modulation of HSP70. However, further parameters involved in innate/adaptative immunity and apoptosis pathways have to be taken into account to well establish the functional role of HSP70 in fish vaccination.

Expression, purification and characterization of a recombinant fusion protein based on the human papillomavirus-16 E7 antigen

A fusion protein comprising a cell penetrating and immunostimulatory peptide corresponding to residues 32 to 51 of the Limulus polyphemus protein linked to human papillomavirus (HPV)-16 E7 antigen (LALF_32-51-E7) was expressed in E. coli BL21 (DE3) cells. The recombinant protein in E. coli accounted for approximately 18% of the total cellular protein and purified with a single affinity chromatographic step. Yields of approximately 38 mg purified LALF_32-51-E7 per liter of induced culture was obtained with an overall 52% recovery and constitutes a promising setting for the future production and scaling-up. Purified protein was characterized as soluble aggregates with molecular weight larger than 670 kDa, which is considered an important property to increase the immunogenicity of an antigen preparation. The recombinant fusion protein LALF_32-51-E7 will be a promising vaccine candidate for the treatment of HPV-16 related malignancies.

Mini-chaperones: potential immuno-stimulators in vaccine design

The immunogenic properties of heat shock proteins (HSPs) have prompted investigations into their application as immuno-modulatory agents. HSPs have been used as potent adjuvants in immunotherapy of cancer and infectious diseases. Some studies showed that immune activities reside within N- or C-terminal fragments of HSPs. These small fragments are sufficient to link peptides, to bind and be taken up by the receptors CD91 and scavenger receptor type A on antigen presenting cells (APCs). Thus, these mini-chaperones can be used in immunotherapy of tumors and vaccine development. The data clearly demonstrated the potential of using HSP fragments as a possible adjuvant to augment CTL response against infectious diseases. Some HSP domains have been shown to inhibit endothelial cell growth, angiogenesis or tumor growth. In this review, we describe the immuno-stimulatory activities of various mini-chaperones in development of different vaccine strategies (DNA-based vaccine and protein/peptide-based vaccines).

TAT-mediated gp96 transduction to APCs enhances gp96-induced antiviral and antitumor T cell responses

The heat shock protein gp96 is an adjuvant that can elicit T cell responses against cancer and infectious diseases, via antigen presentation, in both rodent models and clinical trials. Its uptake and internalization into antigen presenting cells (APCs) is a critical step in gp96-mediated immune responses. This study examined strategies to improve the cell internalization and T cell activation of gp96. It was found that recombinant fusion with the cell-penetrating peptide TAT (trans-activator of transcription) slightly decreased the aggregation level of gp96 and significantly increased its internalization into macrophages. Furthermore, immunization with the TAT-gp96 fusion dramatically enhanced gp96-mediated hepatitis B virus (HBV)-specific T cell responses and its antiviral efficiency in HBV transgenic mice compared to rgp96. In addition, the inclusion of TAT significantly improved the antitumor T cell immune response to a gp96 vaccine in the B16 melanoma model. These results provide evidence that the efficient transduction of gp96 into APCs can significantly enhance the outcome of gp96-based immunotherapy, and therefore provide a basis for more efficient approaches to improving the immunoregulatory and adjuvant functions of this unique T cell adjuvant.

Recombinant Leishmania tarentolae encoding the HPV type 16 E7 gene in tumor mice model

Background: Cervical cancer, the third most prevalent cause of cancer in women worldwide, is associated with HPVs. The critical role of E7 protein in HPV-related malignancies has designated it as a strong contender for generating vaccines against HPV. Materials & methods: In this study, we developed a novel live vaccine using recombinant Leishmania tarentolae expressing E7-green fluorescent protein (GFP) fusion protein for the protection of mice against HPV-associated tumors. In order to transfect L. tarentolae with E7-GFP fusion construct, pLEXSY-neo2 system was applied. Followed by PCR, fluorescence imaging and fluorescence-activated cell sorting analysis, integration of E7-GFP gene into parasites genome was confirmed. A comparative study of six groups of C57BL/6 mice was performed to analyze antigen-specific humoral and cellular immune responses against E7 encoding live and DNA vaccines. Furthermore, the anti-tumor protective effect of L. tarentolae-E7-GFP was compared to other vaccination strategies, namely pcDNA-E7 as the DNA vaccine and pcDNA-E7/L. tarentolae-E7-GFP as the prime-boost regimen. Results: We found that E7-GFP expressing recombinant L. tarentolae induces significant levels of IgG2a and IFN-γ, while there is no significant IL-5 production compared with that of other strategies and control groups before and after challenge with TC-1 tumor cells. It is noteworthy that the designed live vaccine showed the best protection and minimum tumor size among all groups against TC-1-induced tumors. Conclusion: Overall, the results obtained revealed that the E7-GFP recombinant L. tarentolae could be a potential live vaccine for induction of immune responses in vivo.

Different domains of glycoprotein 96 influence HPV16 E7 DNA vaccine potency via electroporation mediated delivery in tumor mice model

DNA vaccines have emerged as a promising approach for generating antigen-specific immunotherapy. However, due to their low immunogenicity, there is a need to enhance DNA-based vaccine potency. Two main strategies to increase DNA-based vaccine potency are the employment of immuno-adjuvants such as heat shock proteins (HSPs) and a method of improving the delivery of naked plasmid DNA by electroporation. In the current study, we evaluated the effects of linkage of human papillomavirus (HPV) type 16 E7 as a model antigen to N-terminal and C-terminal of glycoprotein 96 (NT-/CT-gp96) on the potency of E7-specific immunity generated by DNA vaccines. We found that subcutaneous DNA injection with E7-CT (gp96) followed by electroporation generates the significant E7-specific IFN-γ immune responses as well as the best protective effects in vaccinated mice as compared to E7 or E7-NT (gp96) DNA vaccines. Therefore, our data indicate that subcutaneous administration of E7 DNA linked to CT (gp96) fragment followed by electroporation can significantly enhance the potency of DNA vaccines. Indeed, the structural domains of immuno-chaperones show the potential of generating effective immune responses against different clinical disorders such as cancer. Altogether, our results show that comparable regions of gp96 (N-/C-terminal fragments of gp96) may have qualitatively different immunological effects in vaccine design.

Gp96 enhances the immunogenicity of subunit vaccine of porcine reproductive and respiratory syndrome virus

Porcine reproductive and respiratory syndrome virus (PRRSV) causes significant economic losses in the pig industry worldwide. Currently available commercial vaccines provide limited protection due to delayed and weak cell-mediated immunity and neutralizing antibody production, thus the immunomodulators should be considered in order to improve the efficacy of PRRSV vaccines. Heat shock protein gp96 may be used as a modulator to enhance both innate and adaptive immune responses. In the present study, two multi-epitope subunit vaccines, named as Cp1 and Cp2, were designed based on the conserved B cell epitopes of viral proteins with the N-terminal 22-370 amino acids (aa) of porcine gp96 (Gp96N) chosen as the adjuvant. Immune responses elicited by the different combinations of Cp1/Cp2 and Gp96N were examined in mice and piglets. The results indicated that the group of Cp1/Cp2-Gp96N (CG) combination induced 3-4-fold higher titers of Cp1/Cp2-ELISA antibodies and neutralizing antibodies (NAs) in mice than the groups which received Cp1/Cp2 immunization alone or with Freund's adjuvant. Additionally, Gp96N significantly enhanced the levels of lymphocyte proliferative responses of splenocytes or peripheral blood mononuclear cells from vaccinated mice or piglets. The production of IFN-γ in mice splenocytes, TNF-α, IFN-γ, and IL-12 in sera of piglets were also remarkably increased with the treatment of Gp96N, while IL-4 was reduced by half and IL-10 was decreased to an undetectable level. These results suggest that the porcine Gp96N could effectively enhance the innate and adaptive immune responses of Cp1/Cp2 with a Th1-type bias. Therefore, the multi-epitope subunit vaccine Cp1/Cp2 co-administered with porcine Gp96N might potentially be a promising candidate vaccine for the prevention and control of PRRSV in pigs.

The contribution of NT-gp96 as an adjuvant for increasing HPV16 E7-specific immunity in C57BL /6 mouse model

To control cervical cancer, efficient vaccination against human papillomavirus (HPV) is highly required. Despite the advantages and safety of the protein vaccines, additional strategies to enhance their immunogenicity are needed. E7 is a transforming protein which represents a perfect target antigen for vaccines or immunotherapies. Heat shock proteins (HSPs) facilitate cellular immune responses to antigenic peptides or proteins bound to them. Regarding to previous studies, vaccination with purified HSP/antigen complexes efficiently elicit antigen-specific immune responses in mice model. The N-terminal of glycoprotein 96 (NT-gp96) has adjuvant effect and can induce effective cumulative immune response against clinical disorders, especially cancers. In this study, the recombinant HPV16 E7 and E7 linked to NT-gp96 (E7-NT-gp96) proteins were generated in prokaryotic expression system. Mice were vaccinated twice with this recombinant proteins and the immunogenicity of the fusion protein was determined. The preventive efficacy of E7-NT-gp96 fusion protein was also evaluated and compared to E7 protein after challenging with cancerous TC-1 cell line. In vitro re-stimulated splenocytes of mice vaccinated with rE7-NT-gp96 protein induced higher IFN-γ response in comparison with E7 protein immunization. Moreover, immunization with E7-NT-gp96 protein displayed low but stable humoral responses at post-challenge time. The data showed that vaccination with fused E7-NT-gp96 protein delayed the tumour occurrence and growth as compared to protein E7 alone. These results suggest that fused adjuvant-free E7-NT-gp96 protein vaccination could direct the immune responses towards Th1 immunity. Furthermore, the linkage of NT-gp96 to E7 could enhance protective anti-tumour immunity.

Heat shock protein gp96 enhances humoral and T cell responses, decreases Treg frequency and potentiates the anti-HBV activity in BALB/c and transgenic mice

More than 350 million people worldwide are chronically infected with hepatitis B virus (HBV). Broad repertoire and strong magnitude of HBV-specific T cell responses are thought to play key roles for virus control and clearance. Previous studies together with ours showed that heat shock protein gp96 as adjuvant induces antigen specific T cell responses, yet little is known for its anti-viral properties. Here, we investigated the role of gp96 mediated cellular and humoral immunity in antiviral effects in HBV transgenic mice. Immunization with HBV surface (HBsAg) and core (HBcAg) antigens combined formulation along with gp96 induced robust antiviral T-cell and antibody immunity against HBsAg and HBcAg. Compared with non-immunized control, immunization with gp96 adjuvant vaccine led to decrease of serum HBs level and HBc expression in hepatocyte by 45% and 90% at maximum, respectively, and decreased serum HBV-DNA level to below or close to the detection limit 4 weeks after the last immunization, suggesting the therapeutic effect. A significant enhancement in cellular responses towards HBcAg and increased infiltration of CD8+ T cells in liver of transgenic were observed under treatment with gp96 compared with no treatment (P<0.05 or 0.01). Treatment with gp96 was capable of reducing Tregs by overall 30-40%. The superior immune responses induced with the aid of gp96 correlated with improved antiviral effect by vaccination with HBsAg and HBcAg. We conclude that gp96 may contribute to enhanced antiviral immunity in transgenic mice at least partly by Treg down-regulation. HBcAg may act as potent adjuvant for Th1 response. Our study reveals the novel property of gp96 in immune modulation and its potential use for breaking immunotolerance in immunotherapy of chronic HBV infection.

Modulatory effects of tumor-derived heat shock protein in DNA vaccination against nasopharyngeal carcinoma

Use of anti-idiotype antibody vaccines is a promising strategy against tumor, however, their immunogenicity still need to be improved. Heat shock proteins (HSPs) have been shown to act as adjuvants when coadministered with peptides or given as fusion proteins and enhance the vaccination efficiency. To evaluate the enhancement of the potency of anti-idiotype antibody immunogenicity by heat shock protein gp96, C57BL/6 mice were immunized with three intramuscular inoculations of the G22 DNA and/or gp96 DNA vaccine. Control was inoculated with empty plasmid pcDNA3.1. The levels of G22-specific antibody and lymphocyte phenotype were measured by ELISA, fluorescence activated cell sorter (FACS) analysis, respectively. In the tumor protection experiment, the immunized mice were then challenged with CMT-93-G22 cells. The tumor size and the survival time of the animals were compared among these groups. The results showed that the efficacy of G22 DNA vaccine could be enhanced by coadministrating with gp96 DNA which might be relevant with activating CD8(+)T cells. Furthermore, co-injection of G22 DNA with gp96 DNA could prolong the survival time and lessen the tumor size of the CMT-93-G22-bearing mice. Our study demonstrates for the first time that G22+gp96 DNA vaccine can induce comparable G22-specific CD8(+)T cell response and is a promising candidate DNA vaccine for nasopharyngeal carcinoma.

Evaluation of DNA/DNA and prime-boost vaccination using LPG3 against Leishmania major infection in susceptible BALB/c mice and its antigenic properties in human leishmaniasis

One of the main issues in vaccine development is implementation of new adjuvants to improve the antigen presentation and eliciting the protective immune response. Heat shock protein (HSP) molecules are known as natural adjuvants. They can stimulate the innate and adaptive immune response against infectious diseases and cancer. Lipophosphoglycan 3 (LPG3), the Leishmania homologous with GRP94 (glucose regulated protein 94), a member of HSP90 family, is involved in assembly of LPG as the most abundant macromolecule on the surface of Leishmania promastigotes. In the present study as a primary step, we tested LPG3 as a vaccine candidate in two regimens, DNA/DNA and prime-boost (DNA/Protein), against Leishmania major infection in BALB/c mice model. Our results showed that LPG3 and its fragment (rNT-LPG3) are highly immunogenic in BALB/c mice and can stimulate the production of both IgG1 and IgG2a. In prime-boost immunization strategy, the level of antibody response was higher compared with DNA/DNA immunization. The levels of IFN-γ in the supernatant of splenocytes from mice immunized with DNA/DNA and prime-boost regimens were significantly higher when compared to control groups. In fact, immunization with prime-boost vaccination has higher ratio of IFN-γ/IL-5, suggesting a shift towards a Th1 response. In addition, sera reactivity against LPG3 in visceral leishmaniasis (VL) patients was significantly higher in comparison with cutaneous leishmaniasis (CL) patients. Therefore, we recommend further investigations on the usage of LPG3 co-delivery with candidate antigens for vaccine development against leishmaniasis.

Hansenula polymorpha expressed heat shock protein gp96 exerts potent T cell activation activity as an adjuvant

Previous studies together with ours showed that heat shock protein gp96 as an adjuvant induces antigen specific T cell responses against cancer and infectious diseases. However, at present there is no efficient method to obtain high amount of full-length gp96 by in vitro expression. Here, we used the yeast Hansenula polymorpha as an efficient host for gp96 recombinant protein production. The transformant clones with highly expressed recombinant proteins were screened and selected by measuring the halo size which indicates enzymatic hydrolysis of starch in the medium. High-level production of gp96 (around 150mg/mL) was achieved by using high-cell density fed-batch cultivations. We showed that peptide binding of the recombinant protein has similar specificity and intrinsic binding parameters as that of the native gp96. We next examined the self-assembly properties and high-order structures of the recombinant protein. Moreover, the H. polymorpha expressed recombinant gp96 can effectively induce HBV-specific CTL response in immunized mice while Escherichia coli-expressed gp96 cannot. Our results therefore may provide bases for structure and functional studies of gp96 and thereby potentially expedite the development of gp96-based vaccines for immunotherapy of cancer or infectious diseases.