Secretory heat-shock protein as a dendritic cell-targeting molecule: a new strategy to enhance the potency of genetic vaccines

Transcriptomic Profiling Reveals Altered Expression of Genes Involved in Metabolic and Immune Processes in NDV-Infected Chicken Embryos

OBJECTIVE

The poultry industry is significantly impacted by viral infections, particularly Newcastle Disease Virus (NDV), which leads to substantial economic losses. It is essential to comprehend how the sequence of development affects biological pathways and how early exposure to infections might affect immune responses.

METHODS

This study employed transcriptome analysis to investigate host-pathogen interactions by analyzing gene expression changes in NDV-infected chicken embryos' lungs.

RESULT

RNA-Seq reads were aligned with the chicken reference genome (Galgal7), revealing 594 differentially expressed genes: 264 upregulated and 330 downregulated. The most overexpressed genes, with logFC between 8.15 and 8.75, included C8A, FGG, PIT54, FETUB, APOC3, and FGA. Notably, downregulated genes included BPIFB3 (-4.46 logFC) and TRIM39.1 (-4.26 logFC). The analysis also identified 29 novel transcripts and 20 lncRNAs that were upregulated. Gene Ontology and KEGG pathways' analyses revealed significant alterations in gene expression related to immune function, metabolism, cell cycle, nucleic acid processes, and mitochondrial activity due to NDV infection. Key metabolic genes, such as ALDOB (3.27 logFC), PRPS2 (2.66 logFC), and XDH (2.15 logFC), exhibited altered expression patterns, while DCK2 (-1.99 logFC) and TK1 (-2.11 logFC) were also affected. Several immune-related genes showed significant upregulation in infected lung samples, including ALB (6.15 logFC), TLR4 (1.86 logFC), TLR2 (2.79 logFC), and interleukin receptors, such as IL1R2 (3.15 logFC) and IL22RA2 (1.37 logFC). Conversely, genes such as CXCR4 (-1.49 logFC), CXCL14 (-2.57 logFC), GATA3 (-1.51 logFC), and IL17REL (-2.93 logFC) were downregulated. The higher expression of HSP genes underscores their vital role in immune responses.

CONCLUSION

Comprehension of these genes' interactions is essential for regulating viral replication and immune responses during infections, potentially aiding in the identification of candidate genes for poultry breed improvement amidst NDV challenges.

Novel recombinant vaccinia virus-vectored vaccine affords complete protection against homologous Borrelia burgdorferi infection in mice

The rising prevalence of Lyme disease (LD) in North America and Europe has emerged as a pressing public health concern. Despite the availability of veterinary LD vaccines, no vaccine is currently available for human use. Outer surface protein C (OspC) found on the outer membrane of the causative agent, Borrelia burgdorferi, has been identified as a promising target for LD vaccine development due to its sustained expression during mammalian infection. However, the efficacy and immunological mechanisms of LD vaccines solely targeting OspC are not well characterized. In this study, we developed an attenuated Vaccinia virus (VV) vectored vaccine encoding type A OspC (VV-OspC-A). Two doses of the VV-OspC-A vaccine conferred complete protection against homologous B. burgdorferi challenge in mice. Furthermore, the candidate vaccine also prevented the development of carditis and lymph node hyperplasia associated with LD. When investigating the humoral immune response to vaccination, VV-OspC-A was found to induce a robust antibody response predominated by the IgG2a subtype, indicating a Th1-bias. Using a novel quantitative flow cytometry assay, we also determined that elicited antibodies were capable of inducing antibody-dependent cellular phagocytosis in vitro. Finally, we demonstrated that VV-OspC-A vaccination generated a strong antigen-specific CD4+ T-cell response characterized by the secretion of numerous cytokines upon stimulation of splenocytes with OspC peptides. This study suggests a promising avenue for LD vaccine development utilizing viral vectors targeting OspC and provides insights into the immunological mechanisms that confer protection against B. burgdorferi infection.

Protein Quality Control Systems and ER Stress as Key Players in SARS-CoV-2-Induced Neurodegeneration

The COVID-19 pandemic has brought to the forefront the intricate relationship between SARS-CoV-2 and its impact on neurological complications, including potential links to neurodegenerative processes, characterized by a dysfunction of the protein quality control systems and ER stress. This review article explores the role of protein quality control systems, such as the Unfolded Protein Response (UPR), the Endoplasmic Reticulum-Associated Degradation (ERAD), the Ubiquitin-Proteasome System (UPS), autophagy and the molecular chaperones, in SARS-CoV-2 infection. Our hypothesis suggests that SARS-CoV-2 produces ER stress and exploits the protein quality control systems, leading to a disruption in proteostasis that cannot be solved by the host cell. This disruption culminates in cell death and may represent a link between SARS-CoV-2 and neurodegeneration.

DNA lipid nanoparticle vaccine targeting outer surface protein C affords protection against homologous Borrelia burgdorferi needle challenge in mice

Introduction

The incidence of Lyme disease (LD) in Canada and the United States has risen over the last decade, nearing 480,000 cases each year. Borrelia burgdorferi sensu lato, the causative agent of LD, is transmitted to humans through the bite of an infected tick, resulting in flu-like symptoms and often a characteristic bull’s-eye rash. In more severe cases, disseminated bacterial infection can cause arthritis, carditis and neurological impairments. Currently, no vaccine is available for the prevention of LD in humans.

Methods

In this study, we developed a lipid nanoparticle (LNP)-encapsulated DNA vaccine encoding outer surface protein C type A (OspC-type A) of B. burgdorferi.

Results

Vaccination of C3H/HeN mice with two doses of the candidate vaccine induced significant OspC-type A-specific antibody titres and borreliacidal activity. Analysis of the bacterial burden following needle challenge with B. burgdorferi (OspC-type A) revealed that the candidate vaccine afforded effective protection against homologous infection across a range of susceptible tissues. Notably, vaccinated mice were protected against carditis and lymphadenopathy associated with Lyme borreliosis.

Discussion

Overall, the results of this study provide support for the use of a DNA-LNP platform for the development of LD vaccines.

Heat shock proteins and viral infection

Heat shock proteins (HSPs) are a kind of proteins which mostly found in bacterial, plant and animal cells, in which they are involved in the monitoring and regulation of cellular life activities. HSPs protect other proteins under environmental and cellular stress by regulating protein folding and supporting the correctly folded structure of proteins as chaperones. During viral infection, some HSPs can have an antiviral effect by inhibiting viral proliferation through interaction and activating immune pathways to protect the host cell. However, although the biological function of HSPs is to maintain the homeostasis of cells, some HSPs will also be hijacked by viruses to help their invasion, replication, and maturation, thereby increasing the chances of viral survival in unfavorable conditions inside the host cell. In this review, we summarize the roles of the heat shock protein family in various stages of viral infection and the potential uses of these proteins in antiviral therapy.

Cytoskeletal regulation of dendritic cells: An intricate balance between migration and presentation for tumor therapy

Dendritic cells (DCs) are the main players in many approaches for cancer therapy. The idea with DC tumor therapy is to promote activation of tumor infiltrating cytotoxic T cells that kill tumor cells. This requires that DCs take up tumor Ag and present peptides on MHC class I molecules in a process called cross-presentation. For this process to be efficient, DCs have to migrate to the tumor draining lymph node and there activate the machinery for cross-presentation. In this review, we will discuss recent progress in understanding the role of actin regulators for control of DC migration and Ag presentation. The potential to target actin regulators for better DC-based tumor therapy will also be discussed.

PD-1 of Sigmodon hispidus: Gene identification, characterization and preliminary evaluation of expression in inactivated RSV vaccine-induced enhanced respiratory disease

Sigmodon hispidus or cotton rat is an excellent animal model for studying human infections of respiratory viruses including respiratory syncytial virus (RSV), which is the leading cause of hospitalization in infants and causes high rates of infection in the elderly and immunocompromised patient populations. Despite several decades of research, no vaccine has been licensed whereas inactivated vaccines have been shown to induce severe adverse reaction in a clinical trial, with other forms of RSV vaccine also found to induce enhanced disease in preclinical animal studies. While arguably the cotton rat is the best small animal model for evaluation of RSV vaccines and antivirals, many important genes of the immune system remain to be isolated. Programmed cell death-1 (PD-1) plays an integral role in regulating many aspects of immunity by inducing suppressive signals. In this study, we report the isolation of mRNA encoding the cotton rat PD-1 (crPD-1) and characterization of the PD-1 protein. crPD-1 bound to its cognate ligand on dendritic cells and effectively suppressed cytokine secretion. Moreover, using the newly acquired gene sequence, we observed a decreased level of crPD-1 levels in cotton rats with enhanced respiratory disease induced by inactivated RSV vaccine, unraveling a new facet of vaccine-induced disease.

Identification and characterisation of the CD40-ligand of Sigmodon hispidus

Cotton rats are an important animal model to study infectious diseases. They have demonstrated higher susceptibility to a wider variety of human pathogens than other rodents and are also the animal model of choice for pre-clinical evaluations of some vaccine candidates. However, the genome of cotton rats remains to be fully sequenced, with much fewer genes cloned and characterised compared to other rodent species. Here we report the cloning and characterization of CD40 ligand, whose human and murine counterparts are known to be expressed on a range of cell types including activated T cells and B cells, dendritic cells, granulocytes, macrophages and platelets and exerts a broad array of immune responses. The cDNA for cotton rat CD40L we isolated is comprised of 1104 nucleotides with an open reading frame (ORF) of 783bp coding for a 260 amino acid protein. The recombinant cotton rat CD40L protein was recognized by an antibody against mouse CD40L. Moreover, it demonstrated functional activities on immature bone marrow dendritic cells by upregulating surface maturation markers (CD40, CD54, CD80, and CD86), and increasing IL-6 gene and protein expression. The availability of CD40L gene identity could greatly facilitate mechanistic research on pathogen-induced-immunopathogenesis and vaccine-elicited immune responses.

Recombinant heat shock protein 70 functional peptide and alpha-fetoprotein epitope peptide vaccine elicits specific anti-tumor immunity

Alpha-fetoprotein (AFP) is a marker of hepatocellular carcinoma (HCC) and serves as a target for immunotherapy. However, current treatments targeting AFP are not reproducible and do not provide complete protection against cancer. This issue may be solved by developing novel therapeutic vaccines with enhanced immunogenicity that could effectively target AFP-expressing tumors. In this study, we report construction of a therapeutic peptide vaccine by linking heat shock protein 70 (HSP70) functional peptide to the AFP epitope to obtain HSP70-P/AFP-P. This novel peptide was administered into BALB/c mice to observe the effects. Quantification of AFP-specific CD8 ⁺ T cells that secrete IFN-γ in these mice via ELISPOT revealed the synergistic effects of HSP70-P/AFP-P with increased numbers of AFP-specific CD8 ⁺ T cells. Similarly, ELISA analysis showed increased granzyme B and perforin released by natural killer cells. Moreover, in vitro cytotoxic T-lymphocyte assays and in vivo tumor preventive experiments clearly showed the higher antitumor effects of HSP70-P/AFP-P against AFP-expressing tumors. These results show that treatment of BALB/c mice with HSP70-P/AFP-P induced stronger T-cells responses and improved protective immunity. Our data suggest that HSP70-P/AFP-P may be used as a therapeutic approach in the treatment of AFP-expressing cancers.

Immunological considerations underlying heat shock protein-mediated cancer vaccine strategies

The success of active immunotherapies in the prevention of many infectious diseases over the course of over 200 years has lead scientists to wonder if the same principles could be applied to cancer. Antigen-specific active immunotherapies for the treatment of cancer have been researched for over two decades, however, the overwhelming majority of these studies have failed to stimulate robust clinical responses. It is clear that current active immunotherapy research should incorporate methods to increase the immunostimulatory capacity of these therapies. To directly address this need, we propose the addition of the immunostimulatory heat shock proteins (HSPs) to active immunotherapeutic strategies to augment their efficacy. Heat shock proteins are a family of highly conserved intracellular chaperone proteins, and are the most abundant family proteins inside cells. This ubiquity, and their robust immunostimulatory capacity, points to their importance in regulation of intracellular processes and, therefore, indicators of loss of cellular integrity if found extracellularly. Thus, we emphasize the importance of taking into consideration the location of vaccine-derived HSP/tumor-antigen complexes when designing active immunotheraputic strategies.

Targeting the HA2 subunit of influenza A virus hemagglutinin via CD40L provides universal protection against diverse subtypes

The influenza viral hemagglutinin (HA) is comprised of two subunits. Current influenza vaccine predominantly induces neutralizing antibodies (Abs) against the HA1 subunit, which is constantly evolving in unpredictable fashion. The other subunit, HA2, however, is highly conserved but largely shielded by the HA head domain. Thus, enhancing immune response against HA2 could potentially elicit broadly inhibitory Abs. We generated a recombinant adenovirus (rAd) encoding secreted fusion protein, consisting of codon-optimized HA2 subunit of influenza A/California/7/2009(H1N1) virus fused to a trimerized form of murine CD40L, and determined its ability of inducing protective immunity upon intranasal administration. We found that mice immunized with this recombinant viral vaccine were completely protected against lethal challenge with divergent influenza A virus subtypes including H1N1, H3N2, and H9N2. Codon-optimization of HA2 as well as the use of CD40L as a targeting ligand/molecular adjuvant were indispensable to enhance HA2-specific mucosal IgA and serum IgG levels. Moreover, induction of HA2-specific T-cell responses was dependent on CD40L, as rAd secreting HA2 subunit without CD40L failed to induce any significant levels of T-cell cytokines. Finally, sera obtained from immunized mice were capable of inhibiting 13 subtypes of influenza A viruses in vitro. These results provide proof of concept for a prototype HA2-based universal influenza vaccine.

CD40 ligand preferentially modulates immune response and enhances protection against influenza virus

CD40L, a key regulator of the immune system, was studied as both a targeting ligand and a molecular adjuvant in nucleoprotein (NP)-based host defense against influenza in mouse models with different genetic backgrounds. Adenoviral vectors secreting NP-CD40L fusion protein (denoted as rAd-SNP40L) afforded full protection of immunocompetent and immunocompromised mice (CD40L(-/-) and CD4(-/-)) against lethal influenza infection. Mechanistically, rAd-SNP40L preferentially induced early and persistent B cell germinal center formation, and accelerated Ig isotype-switching and Th1-skewed, NP-specific Ab response. Moreover, it drastically augmented primary and memory NP-specific CTL activity and polyfunctional CD8(+) T cells. The markedly enhanced nonneutralizing Abs and CTLs significantly reduced viral burdens in the lungs of mice upon lethal virus challenge. Data generated from CD40L(-/-) and CD4(-/-) mice revealed that the protection was indeed CD40L mediated but CD4(+) T cell independent, demonstrating the viability of the fusion Ags in protecting immunodeficient hosts. Notably, a single dose of rAd-SNP40L completely protected mice from lethal viral challenge 4 mo after immunization, representing the first report, to our knowledge, on NP in conjunction with a molecular adjuvant inducing a robust and long-lasting memory immune response against influenza. This platform is characterized by an increased in vivo load of CD40-targeted Ag upon the secretion of the fusion protein from adenovirus-infected cells and may represent a promising strategy to enhance the breadth, durability, and potency of Ag-specific immune responses.

Suppressor of cytokine signaling 1 inhibition strategy to enhance anti-HIV vaccination

Extensive efforts aimed at stimulating immune responses by modifying HIV antigens and using various delivery systems and adjuvants have so far failed to generate promising HIV vaccines, highlighting the urgent need to explore alternative immunization approaches. Antigen-presenting cells, such as dendritic cells, play a critical role in the initiation and maintenance of immune responses against HIV infection and dendritic cells are regulated by stimulatory, as well as inhibitory signaling. Recent studies demonstrate that the suppressor of cytokine signaling 1 (SOCS1) functions as an antigen-presentation attenuator by restricting the Janus-activated kinase-signal transducers and activators of transcription and Toll-like receptor-signaling pathways. SOCS1-silenced dendritic cells produce higher levels of both T-helper 1- and 2-polarizing cytokines, broadly enhance memory HIV-specific B-cell and T-cell responses and activate natural killer cells owing to unbridled cytokine feedback signaling loops. Therefore, the inhibition of antigen-presentation attenuators represents a generally applicable and alternative strategy for enhancing the potency of various forms of prophylactic and therapeutic HIV vaccines.

HSP70 and modified HPV 16 E7 fusion gene without the addition of a signal peptide gene sequence as a candidate therapeutic tumor vaccine

Millions of women are currently infected with high-risk human papillomavirus (HPV), which is considered to be a major risk factor for cervical cancer. Thus, it is urgent to develop therapeutic vaccines to eliminate the established infections or HPV-related diseases. In the present study, using the mycobacterium tuberculosis heat shock protein 70 (MtHSP70) gene linked to the modified HPV 16 E7 (mE7) gene, we generated two potential therapeutic HPV DNA vaccines, mE7/MtHSP70 and SigmE7/MtHSP70, the latter was linked to the signal peptide gene sequence of human CD33 at the upstream of the fusion gene. We found that vaccination with the mE7/MtHSP70 DNA vaccine induced a stronger E7-specific CD8+ T cell response and resulted in a more significant therapeutic effect against E7-expressing tumor cells in mice. Our results demonstrated that HSP70 can play a more important role in mE7 and MtHSP70 fusion DNA vaccine without the help of a signal peptide. This may facilitate the use of HSP70 and serve as a significant reference for future study.

The significance of heat shock proteins in breast cancer therapy

The evalutionary conserved heat shock proteins are involved basically life protecting mechanisms against harmful extracellular effects such as primarily heat shock response. Normally, the expression of these proteins is increased for cellular adaptation to high temperature. This increase is also important in the etiology of breast cancer. Overexpression of heat shock proteins is associated with reduced disease-free survival in breast cancer. However, increased expression of these proteins is related to acquired resistance of traditional chemotherapeutic drugs in use in breast cancer treatment. In this review, we discuss the multiple roles of heatshock proteins in resistance and where we are to overcome this in clinical practice.

Glycoprotein 96 and α-fetoprotein cross-linking complexes elicited specific antitumor immunity

Hepatocellular carcinoma (HCC) is one of the most common malignant gastroenterological cancers over the world. α-fetoprotein (AFP) is an oncofetal protein produced during HCC development that could generate weaker and less reproducible antitumor protection, and it may serve as a target for immunotherapy. Therefore, it is imperative to enhance its immunogenicity and develop therapeutic vaccines to eliminate AFP-expressing tumors. In this study, by way of glutaraldehyde cross-linking, we constructed a potential therapeutic protein vaccine, glycoprotein 96 (gp96)/AFP. Our results demonstrated that AFP and gp96 synergistically exhibited significant increase in AFP-specific CD8⁺ T-cell responses and impressive cytotoxic antitumor effect against AFP-expressing tumors. Priming mice with the reconstructed vaccine, we elicited robust strong protective immunity. Our study suggests that tumor vaccine by cross-linking tumor antigen and gp96 is a promising approach to cancer therapy.

HSP72 and gp96 in gastroenterological cancers

Heat shock protein 72 (HSP72) and glycoprotein 96 (gp96) are highly expressed in cancer tissues. Recent studies indicate the possible roles of HSP72 and gp96 in the development and progression of gastrointestinal carcinomas but detailed mechanisms are still ambiguous. Human esophageal cancer, gastric cancer, colon cancer and liver cancer are common gastrointestinal malignant carcinomas in the world. The studies indicated that there existed a significant correlation between the expression of HSP72, gp96 and the development and progression of digestive carcinomas. HSP72 and gp96 expression were significantly associated with the presence of tumor infiltration, lymph node and remote metastasis. Interestingly, studies have found that HSP72 chaperoned alpha-fetoprotein (AFP), HBx in hepatocellular carcinoma, and CD44 in colonic carcinomas. The further researches demonstrated that HSP72-AFP or gp96-AFP recombined vaccine could elicit specific anti-tumor immunity. The high-level expression of HSP72 and gp96 may be not only used as diagnostic or prognostic markers for gastrointestinal carcinomas but also as better immunotherapeutic vaccines in the cancers.

A novel self-assembled nanoparticle vaccine with HIV-1 Tat₄₉₋₅₇/HPV16 E7₄₉₋₅₇ fusion peptide and GM-CSF DNA elicits potent and prolonged CD8⁺ T cell-dependent anti-tumor immunity in mice

Peptide-based vaccines derived from the E7 protein of human papillomavirus (HPV) type 16 were developed to induce effective T cell responses against established cervical cancer, but have met with limited clinical success. It is necessary to develop novel peptide-based strategies to substantially improve the immune response against HPV16-related cancer. In this study, we aimed to design a novel peptide-based self-assembled nanoparticle HPV16 vaccine by combining the cell-penetrating peptide HIV-1 Tat(49-57) that was fused with the HPV16 E7(49-57) cytotoxic T lymphocyte (CTL) epitope and the granulocyte-macrophage colony stimulating factor (GM-CSF) gene, and to investigate how it improves the immune response and the therapeutic outcome ex vivo and in vivo. Nanoparticles were prepared and identified by transmission electron microscopy (TEM), gel retardation and DNase I protection assays. This type of vaccine formulation formed the 20-80 nm nanoparticles, and greatly improved epitope-specific immunity both ex vivo and in vivo. Importantly, this vaccine type was associated with decreased tumor growth and enhanced long-term survival in the prophylactic and therapeutic mouse models. The underlying mechanisms were determined to involve priming of enhanced frequency of CD8(+) memory T subtype cells. These results suggest that the nanoparticle Tat-E7/pGM-CSF represents a promising novel approach to enhance the potency of peptide-based cervical cancer vaccines, and this vaccine design strategy may act as a useful reference for research of virus-associated diseases and specific tumor immunotherapies.

New Approaches to Immunotherapy for HPV Associated Cancers

Cervical cancer is the second most common cancer of women worldwide and is the first cancer shown to be entirely induced by a virus, the human papillomavirus (HPV, major oncogenic genotypes HPV-16 and -18). Two recently developed prophylactic cervical cancer vaccines, using virus-like particles (VLP) technology, have the potential to prevent a large proportion of cervical cancer associated with HPV infection and to ensure long-term protection. However, prophylactic HPV vaccines do not have therapeutic effects against pre-existing HPV infections and do not prevent their progression to HPV-associated malignancy. In animal models, therapeutic vaccines for persisting HPV infection can eliminate transplantable tumors expressing HPV antigens, but are of limited efficacy in inducing rejection of skin grafts expressing the same antigens. In humans, clinical trials have reported successful immunotherapy of HPV lesions, providing hope and further interest. This review discusses possible new approaches to immunotherapy for HPV associated cancer, based on recent advances in our knowledge of the immunobiology of HPV infection, of epithelial immunology and of immunoregulation, with a brief overview on previous and current HPV vaccine clinical trials.

A novel, broad spectrum therapeutic HPV vaccine targeting the E7 proteins of HPV16, 18, 31, 45 and 52 that elicits potent E7-specific CD8T cell immunity and regression of large, established, E7-expressing TC-1 tumors

Persistent infection by high risk genotypes of human papillomavirus (HPV) is the cause of cervical cancer, which remains one of the most common cancers among women worldwide. In addition, there is a growing appreciation that high risk HPVs are associated with a number of other cancers including anogenital cancers as well as a subset of head and neck cancers. Recently, prophylactic HPV vaccines targeting the two most prevalent high risk HPVs (HPV16 and HPV18) have been deployed in large-scale vaccination campaigns. However, the extent to which these prophylactic vaccines confer protection against other high risk HPV genotypes is largely unknown and prophylactic vaccines have been shown to be ineffective against pre-existing infection. Thus there continues to be an urgent need for effective therapeutic vaccines against HPV. The E7 protein of HPV16 has been widely studied as a target for therapeutic vaccines in HPV-associated cancer settings because HPV16 is the most prevalent of the high risk HPV genotypes. However, HPV16 accounts for only about 50% of cervical cancers and there are at least 15 other high risk HPVs that are known to be oncogenic. We have developed a novel, broad-spectrum, therapeutic vaccine (Pentarix) directed at the E7 proteins from five of the most prevalent high-risk genotypes of HPV worldwide (HPV16, 18, 31, 45 and 52) that together account for more than 80% of all HPV-associated cancers. Pentarix is a recombinant protein-based vaccine that elicits strong, multi-genotype specific CD8 T cell immunity when administered to mice in combination with adjuvants comprised of agonists of the TLR3 or TLR9 family of innate immune receptors. Furthermore, large, established E7-expressing TC-1 tumors undergo rapid and complete regression after therapeutic vaccination of mice with Pentarix. Together, these data suggest that Pentarix may be of clinical value for patients with E7-positive, HPV-associated precancerous lesions or malignant disease.

Molecular and functional characterization of a mortalin-like protein from Schistosoma japonicum (SjMLP/hsp70) as a member of the HSP70 family

Schistosomes are the causative agent of schistosomiasis. The 70-kDa heat-shock proteins (HSP70) are considered the predominant HSP family and play a key regulatory role in parasite development and pathogenesis. Based on the published sequences in Genbank/EMBL, an open-reading frame (ORF) encoding 653 amino acids (XP_002581385.1) and belonging to the Schistosoma HSP70 protein family with a molecular weight of 71.49 kDa was identified by bioinformatic analysis. Since the sequence shared 77% identity with the published full-length Homo sapiens HSP70 protein, it was named Schistosoma mortalin-like protein (MLP/Hsp70). Here, we report the molecular and functional characterization of the Schistosoma japonicum SjMLP/hsp70 as a member of the HSP70 family. The complete SjMLP/hsp70 coding sequence was amplified from a S. japonicum adult worm cDNA library by polymerase chain reaction (PCR) and subcloned into the pET28a expression vector. The purified recombinant protein, rSjMLP/hsp70, was identified as a member of 70-kDa HSP family by mass spectrometry and could be recognized by the S. japonicum-infected mouse serum. Reverse transcriptase polymerase chain reaction (RT-PCR) and western blotting analysis revealed that SjMLP/hsp70 was widely expressed in the eggs, cercariae, schistosomula, and adult worms of S. japonicum. A thermotolerance assay showed that rSjMLP/hsp70 could protect Escherichia coli cells from heat damage. This chaperone-like activity was demonstrated by full-length SjMLP/hsp70. The detection of specific antibody levels by indirect enzyme-linked immunosorbent assay and IFN-gamma secretion of splenocytes by ELISpot assay suggested that mice immunized with SjMLP/hsp70 were able to elicit Th1-type bias immune response. The challenge-protective experiment showed that DNA vaccine of SjGST combined with SjMLP/hsp70 could induce a 31.31% reduction of worm burden and 58.59% reduction of egg burden in intestinal tissue of immunized mice. Our results imply that SjMLP/hsp70 has a potential adjuvant function and might be a vaccine candidate for schistosomiaisis, which is the first report of the expression and preliminary characterization analysis of this molecule.

Immunotherapy for cervical cancer: Research status and clinical potential

The high-risk types of human papillomavirus (HPV) have been found to be associated with most cervical cancers and play an essential role in the pathogenesis of the disease. Despite recent advances in preventive HPV vaccine development, such preventive vaccines are unlikely to reduce the prevalence of HPV infections within the next few years, due to their cost and limited availability in developing countries. Furthermore, preventive HPV vaccines may not be capable of treating established HPV infections and HPV-associated lesions, which account for high morbidity and mortality worldwide. Thus, it is important to develop therapeutic HPV vaccines for the control of existing HPV infection and associated malignancies. Therapeutic vaccines are quite different from preventive vaccines in that they require the generation of cell-mediated immunity, particularly T cell-mediated immunity, instead of the generation of neutralizing antibodies. The HPV-encoded early proteins, the E6 and E7 oncoproteins, form ideal targets for therapeutic HPV vaccines, since they are consistently expressed in HPV-associated cervical cancer and its precursor lesions and thus play crucial roles in the generation and maintenance of HPV-associated disease. Our review covers the various therapeutic HPV vaccines for cervical cancer, including live vector-based, peptide or protein-based, nucleic acid-based, and cell-based vaccines targeting the HPV E6 and/or E7 antigens. Furthermore, we review the studies using therapeutic HPV vaccines in combination with other therapeutic modalities and review the latest clinical trials on therapeutic HPV vaccines.

Therapeutic HPV DNA vaccines

Human papillomavirus (HPV) has been associated with several human cancers, including cervical cancer, vulvar cancer, vaginal and anal cancer, and a subset of head and neck cancers. The identification of HPV as an etiological factor for HPV-associated malignancies creates the opportunity for the control of these cancers through vaccination. Currently, the preventive HPV vaccine using HPV virus-like particles has been proven to be safe and highly effective. However, this preventive vaccine does not have therapeutic effects, and a significant number of people have established HPV infection and HPV-associated lesions. Therefore, it is necessary to develop therapeutic HPV vaccines to facilitate the control of HPV-associated malignancies and their precursor lesions. Among the various forms of therapeutic HPV vaccines, DNA vaccines have emerged as a potentially promising approach for vaccine development due to their safety profile, ease of preparation and stability. However, since DNA does not have the intrinsic ability to amplify or spread in transfected cells like viral vectors, DNA vaccines can have limited immunogenicity. Therefore, it is important to develop innovative strategies to improve DNA vaccine potency. Since dendritic cells (DCs) are key players in the generation of antigen-specific immune responses, it is important to develop innovative strategies to modify the properties of the DNA-transfected DCs. These strategies include increasing the number of antigen-expressing/antigen-loaded DCs, improving antigen processing and presentation in DCs, and enhancing the interaction between DCs and T cells. Many of the studies on DNA vaccines have been performed on preclinical models. Encouraging results from impressive preclinical studies have led to several clinical trials.

A Mage3/Heat Shock Protein70 DNA vaccine induces both innate and adaptive immune responses for the antitumor activity

Heat shock proteins (HSPs) are highly effective and versatile molecules in promoting antitumor immune responses. We tested whether a HSP-based DNA vaccine can induce effective immune response against Mage3, a cancer testis (CT) antigen frequently expressed in many human tumors, thereby controlling the Mage3-expressing tumor. The vaccine was constructed by linking human inducible HSP70 to the C-terminus of a modified Mage3 gene (sMage3) that was attached at its N-terminus with the signal leader sequence of the human RANTES for releasing the expressed fusion protein from the transduced cells. Intramuscular injection of sMage3Hsp DNA induced CD4(+)/CD8(+) T cell and antibody responses. Vaccination with sMage3Hsp DNA was more effective in inhibiting Mage3-expressing TC-1 tumors. When we dissected the antitumor activity of CD4(+) and CD8(+) T cells by immunizing CD4(+) and CD8(+) knockout mice with sMage3Hsp DNA, we found that both CD8(+) T and CD4(+) T cells played a role in control of inoculated tumor, but did not constitute the whole of immune protection in the prophylactic immunization. Instead, depletion of natural killer (NK) cells led to a major loss of antitumor activity in the immunized mice. These results indicate that the HSP-based Mage3 DNA vaccine can more effectively inhibit tumor growth by inducing both the innate immune responses and Mage3-specific adaptive immune responses via the Hsp-associated adjuvant function.

A genetically engineered adenovirus vector targeted to CD40 mediates transduction of canine dendritic cells and promotes antigen-specific immune responses in vivo

Targeting viral vectors encoding tumor-associated antigens to dendritic cells (DCs) in vivo is likely to enhance the effectiveness of immunotherapeutic cancer vaccines. We have previously shown that genetic modification of adenovirus (Ad) 5 to incorporate CD40 ligand (CD40L) rather than native fiber allows selective transduction and activation of DCs in vitro. Here, we examine the capacity of this targeted vector to induce immune responses to the tumor antigen CEA in a stringent in vivo canine model. CD40-targeted Ad5 transduced canine DCs via the CD40-CD40L pathway in vitro, and following vaccination of healthy dogs, CD40-targeted Ad5 induced strong anti-CEA cellular and humoral responses. These data validate the canine model for future translational studies and suggest targeting of Ad5 vectors to CD40 for in vivo delivery of tumor antigens to DCs is a feasible approach for successful cancer therapy.

Transcriptional IL-15-directed in vivo DC targeting DNA vaccine

Dendritic cells (DC) engineered in vitro by DNA encoding OVAhsp70 and IL-15 up-regulated their expressions of CD80, CD86, CCR7 and IL-15Ralpha and promoted their productions of IL-6, IL-12 and TNF-alpha. Transcriptional IL-15-directed in vivo DC targeting DNA vaccine encoding OVAhsp70 elicited long-lasting Th1 and CTL responses and anti-B16OVA activity. CD8T cell-mediated primary tumor protection was abrogated by DC or CD4T cell depletion during the induction phase of immune responses. However, CD4T cell depletion during immunization did not impair CD8T cell-dependent long-lasting tumor protection. Furthermore, in vivo DC-derived IL-15 exerted the enhancements of cellular and humoral immune responses and antitumor immunity elicited by OVAhsp70 DNA vaccine. Importantly, the potency of this novel DNA vaccine strategy was proven using a self/tumor Ag (TRP2) in a clinically relevant B16 melanoma model. These findings have implications for developing next generation DNA vaccines against cancers and infectious diseases in both healthy and CD4 deficient individuals.

Induction of tumor-specific immune response by gene transfer of Hsp70-cell-penetrating peptide fusion protein to tumors in mice

To induce a tumor-specific immune response by delivering tumor-associated antigens in tumor cells to antigen-presenting cells (APCs), we designed a fusion protein which consists of heat-shock protein 70 (Hsp70) and the C-terminal 34 amino acids of herpes simplex virus VP22 protein (VP22(268-301)), the former having a peptide binding domain and an ability to be recognized by APCs, and the latter able to achieve cell penetration. Hsp70-VP22(268-301), the fusion protein, was efficiently taken up by mouse dendritic cell (DC) line DC2.4. Major histocompatibility complex (MHC) class I-restricted presentation of an epitope peptide of ovalbumin (OVA) was examined in DC2.4, and Hsp70-VP22(268-301) significantly increased the presentation of the peptide compared with Hsp70. Electroporation-assisted injection of naked plasmid vector expressing Hsp70-VP22(268-301) (pHsp70-VP22(268-301)) into subcutaneous tumors of EG7-OVA, a mouse lymphoma-expressing OVA, significantly increased the survival of mice compared with the same treatment with pHSp70, a plasmid expressing Hsp70. Splenocytes from the pHsp70-VP22(268-301)-treated mice exhibited cytolytic activity against both EG7-OVA and the parent EL4, but not against mouse melanoma B16-F10, suggesting that not only OVA-derived antigens but those common to EG7-OVA and EL4 are delivered to APCs. These results provide a new therapeutic method to induce tumor-specific antitumor immunity without identifying nor isolating tumor-associated antigens.

DNA/amphiphilic block copolymer nanospheres promote low-dose DNA vaccination

Intramuscular (i.m.) DNA vaccination induces strong cellular immune responses in the mouse, but only at DNA doses that cannot be achieved in humans. Because antigen expression is weak after naked DNA injection, we screened five nonionic block copolymers of poly(ethyleneoxide)-poly(propyleneoxide) (PEO-PPO) for their ability to enhance DNA vaccination using a beta-galactosidase (betaGal) encoding plasmid, pCMV-betaGal, as immunogen. At a high DNA dose, formulation with the tetrafunctional block copolymers 304 (molecular weight [MW] 1,650) and 704 (MW 5,500) and the triblock copolymer Lutrol (MW 8,600) increased betaGal-specific interferon-gamma enzyme-linked immunosorbent spot (ELISPOT) responses 2-2.5-fold. More importantly, 704 allowed significant reductions in the dose of antigen-encoding plasmid. A single injection of 2 microg pCMV-betaGal with 704 gave humoral and ELISPOT responses equivalent to those obtained with 100 microg naked DNA and conferred protection in tumor vaccination models. However, 704 had no adjuvant properties for betaGal protein, and immune responses were only elicited by low doses of pCMV-betaGal formulated with 704 if noncoding carrier DNA was added to maintain total DNA dose at 20 microg. Overall, these results show that formulation with 704 and carrier DNA can reduce the dose of antigen-encoding plasmid by at least 50-fold.

Polyamine compound deoxyspergualin inhibits heat shock protein-induced activation of immature dendritic cells

Polyamine compound deoxyspergualin (DSG) is a potent immunosuppressive agent that has been applied clinically for protecting graft rejection and treatment of Wegener's granulomatosis. Though DSG can bind to heat-shock proteins (HSPs) in cells, its mechanism of immunosuppressive action remains unknown. It is widely accepted that extracellular HSPs are capable of stimulating dendritic cells (DC) through cell surface receptors, leading to DC activation and cytokine release. In this study, we examined if DSG analogs could inhibit HSP70-induced DC activation. Bone marrow derived immature mouse DCs and peripheral blood mononuclear cell-derived immature human DCs were generated and incubated with Alexa 488-labeled Hsp70 in the presence of methoxyDSG (Gus-1) that had comparable HSP70-binding affinity to DSG or DSG analog GUS-7, which had much more reduced binding affinity for HSP70. The binding of HSP70 to immature DCs was analyzed by laser microscopy and flow cytometry. HSP70-induced DC activation was assessed by TNF-alpha release by enzyme-linked immunosorbent assay. Binding of Hsp70 to the cell surface of immature DCs was inhibited under the presence of Gus-1, but not under the presence of Gus-7. Immature DCs were activated and released TNF-alpha by the stimulation with HSP70 for 12 hours; however, the HSP70-induced TNF-alpha release was suppressed under the presence of Gus-1, and partially suppressed under the presence of Gus-7. Similar results were observed when immature human DCs were stimulated under the same conditions. Immunosuppressive mechanism of DSG may be explained, at least in part, by the inhibition of extracellular HSP70-DC interaction and HSP70-induced activation of immature DCs.

Heat-shock proteins as powerful weapons in vaccine development

Heat-shock proteins (HSPs) have been known as multifunctional proteins. They facilitate the folding and unfolding of proteins, participate in vesicular transport processes, prevent protein aggregation in the densely packed cytosol and are involved in signaling processes. HSPs have been involved in different fields, including autoimmunity, immunity to infections and tumor immunology. Although there are many different kinds of HSPs, only some HSPs, including HSP70 and Gp96, have immunological properties. HSP molecules have been applied into DNA- or protein (peptide)-based vaccines as antigens, chaperones or adjuvants. HSP-based vaccines have been shown to immunize against cancer and infectious diseases in both prophylactic and therapeutic protocols. The immunogenicity of HSPs results from two different properties: a peptide-dependent capacity to chaperone and elicit adaptive cytotoxic T-lymphocyte responses against antigenic peptides and a peptide-independent immunomodulatory capacity. Furthermore, HSPs could be immunoregulatory agents with potent and widely applicable therapeutic uses. Accordingly, certain HSPs, such as HSP70 and Gp96, are highly effective carrier molecules for cross-presentation. Their ability in eliciting immune responses against different pathogens (parasite and virus) and their role in cancer immunity will be discussed in this review.

DNA vaccines for cervical cancer: from bench to bedside

More than 99% of cervical cancers have been associated with human papillomaviruses (HPVs), particularly HPV type 16. The clear association between HPV infection and cervical cancer indicates that HPV serves as an ideal target for development of preventive and therapeutic vaccines. Although the recently licensed preventive HPV vaccine, Gardasil, has been shown to be safe and capable of generating significant protection against specific HPV types, it does not have therapeutic effect against established HPV infections and HPV-associated lesions. Two HPV oncogenic proteins, E6 and E7, are consistently co-expressed in HPV-expressing cervical cancers and are important in the induction and maintenance of cellular transformation. Therefore, immunotherapy targeting E6 and/or E7 proteins may provide an opportunity to prevent and treat HPV-associated cervical malignancies. It has been established that T cell-mediated immunity is one of the most crucial components to defend against HPV infections and HPV-associated lesions. Therefore, effective therapeutic HPV vaccines should generate strong E6/E7-specific T cell-mediated immune responses. DNA vaccines have emerged as an attractive approach for antigen-specific T cell-mediated immunotherapy to combat cancers. Intradermal administration of DNA vaccines via a gene gun represents an efficient way to deliver DNA vaccines into professional antigen-presenting cells in vivo. Professional antigen-presenting cells, such as dendritic cells, are the most effective cells for priming antigen-specific T cells. Using the gene gun delivery system, we tested several DNA vaccines that employ intracellular targeting strategies for enhancing MHC class I and class II presentation of encoded model antigen HPV-16 E7. Furthermore, we have developed a strategy to prolong the life of DCs to enhance DNA vaccine potency. More recently, we have developed a strategy to generate antigen-specific CD4(+) T cell immune responses to further enhance DNA vaccine potency. The impressive pre- clinical data generated from our studies have led to several HPV DNA vaccine clinical trials.

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

Human papillomavirus, particularly type 16 (HPV16) is present in more than 99% of cervical cancers. E7 is the major oncogenic protein produced in cervical cancer-associated HPV16. An efficient vaccine against viral infection requires induction of strong humoral and cellular responses against viral proteins. Heat shock proteins (HSPs) like Gp96 have been described as potent tumor vaccines in animal models and are currently studied in human clinical trials. In this study, we investigated the utility of HPV16 E7 along with Gp96 as an adjuvant in C57BL/6 mice model. We compared the level of humoral and cellular immune responses by E7+Gp96 co-injection as DNA/DNA and prime-boost (DNA/protein) immunization strategies. In prime-boost immunization strategies, we first immunized C57BL/6 mice with the complete open-reading frame of E7 and Gp96 (pcDNA-E7 and pcDNA-Gp96) and then boosted with rE7, rNT-gp96 (N-terminal extension of Gp96) and rCT-gp96 (C-terminal extension of Gp96) mixed with Montanide 720 in different formulations. The humoral immune responses against rE7 and the different truncated forms of rGp96 suggested a mixed Th1/Th2 response with high intensity toward Th2. Assessment of lymphoproliferative and cytokine responses against rE7 and the different fragments of Gp96, showed that DNA vaccination including E7 and Gp96 induced Th1 response. We concluded that co-delivery of naked DNA E7+Gp96 plasmid was immunologically more effective than E7 alone. Our study demonstrated that co-delivery of E7+Gp96 as DNA/DNA and E7+CT-gp96 as DNA/protein could be an effective approach to induce E7-specific immune responses as a potential vaccine candidate for cervical cancer.

Cancer immunotherapy using irradiated tumor cells secreting heat shock protein 70

Ovarian cancer is responsible for the highest mortality rate among patients with gynecologic malignancies. Therefore, there is an emerging need for innovative therapies for the control of advanced ovarian cancer. Immunotherapy has emerged as a potentially plausible approach for the control of ovarian cancer. In the current study, we have generated heat shock protein 70 (Hsp70)-secreting murine ovarian cancer cells that express luciferase (MOSEC/luc). Hsp70 has been shown to target and concentrate antigenic peptides in dendritic cells and is also able to activate dendritic cells. We characterized the antigen-specific immune response and the antitumor effect of the MOSEC/luc cells expressing Hsp70 using noninvasive luminescence images to measure the amount of ovarian tumors in the peritoneal cavity of mice. We found that mice challenged with MOSEC/luc cells expressing Hsp70 generate significant antigen-specific CD8+ T-cell immune responses. Furthermore, we also found that mice vaccinated with irradiated MOSEC/luc cells expressing Hsp70 generate significant therapeutic effect against MOSEC/luc cells. In addition, we have shown that CD8+, natural killer, and CD4+ cells are important for protective antitumor effect generated by irradiated tumor cell-based vaccines expressing Hsp70. Moreover, we also found that CD40 receptor is most important, followed by Toll-like receptor 4 receptor, for inhibiting in vivo tumor growth of the viable MOSEC/luc expressing Hsp70. Thus, the use of Hsp70-secreting ovarian tumor cells represents a potentially effective therapy for the control of lethal ovarian cancer.

Targeting hepatitis B virus antigens to dendritic cells by heat shock protein to improve DNA vaccine potency

AIM: To investigate a novel DNA vaccination based upon expression of the HBV e antigen fused to a heat shock protein (HSP) as a strategy to enhance DNA vaccine potency.

METHODS: A pCMV-HBeAg-HSP DNA vaccine and a control DNA vaccine were generated. Mice were immunized with these different construct. Immune responses were measured 2 wk after a second immunization by a T cell response assay, CTL cytotoxicity assay, and an antibody assay in C57BL/6 and BALB/c mice. CT26-HBeAg tumor cell challenge test in vivo was performed in BALB/c mice to monitor anti-tumor immune responses.

RESULTS: In the mice immunized with pCMV-HBe-HSP DNA, superior CTL activity to target HBV-positive target cells was observed in comparison with mice immunized with pCMV-HBeAg (44% ± 5% vs 30% ± 6% in E: T > 50:1, P < 0.05). ELISPOT assays showed a stronger T-cell response from mice immunized with pCMV-HBe-HSP than that from pCMV-HBeAg immunized animals when stimulated either with MHC classIor class II epitopes derived from HBeAg (74% ± 9% vs 31% ± 6%, P < 0.01). ELISA assays revealed an enhanced HBeAg antibody response from mice immunized with pCMV-HBe-HSP than from those immunized with pCMV-HBeAg. The lowest tumor incidence and the slowest tumor growth were observed in mice immunized with pCMV-HBe-HSP when challenged with CT26-HBeAg.

CONCLUSION: The results of this study demonstrate a broad enhancement of antigen-specific CD4⁺ helper, CD8⁺ cytotoxic T-cell, and B-cell responses by a novel DNA vaccination strategy. They also proved a stronger antigen-specific immune memory, which may be superior to currently described HBV DNA vaccination strategies for the treatment of chronic HBV infection.

Vaccination with a DNA vaccine based on human PSCA and HSP70 adjuvant enhances the antigen-specific CD8+ T-cell response and inhibits the PSCA+ tumors growth in mice

BACKGROUND

DNA vaccines have been shown to be an effective approach to induce antigen-specific cellular and humoral immunity. However, the lower immune intensity in clinical trials limits the application of DNA vaccine. Here we intend to develop a new DNA vaccine based on prostate stem-cell antigen (PSCA), which has been suggested as a potential target for prostate cancer therapy, and enhance the DNA vaccine potency with heat shock proteins (HSPs) as adjuvant.

METHODS

A series of DNA plasmids encoding human PSCA, human HSP70 and their conjugates was constructed and injected into male mice intramuscularly (i.m.). To evaluate the immune responses and therapeutic efficacy of these plasmids, major histocompatibility complex (MHC)-restricted PSCA and HSP70-specific epitopes were predicted and a mouse model with a human PSCA-expressing tumor was constructed.

RESULTS

The result showed that mice vaccinated with PSCA-HSP plasmids generated the strongest PSCA-specific CD8+ T-cell immune response, but the CD4+ TH1 and TH2 cell immune responses were similar with those vaccinated with other HSP-adjuvant PSCA plasmids or only PSCA DNA. The immunity of HSP70 was also observed and the mice i.m. injected with PSCA+ HSP mixed plasmids generated the lowest anti-HSP antibodies. Furthermore, these vaccinations inhibited the growth of PSCA-expressing tumors and prolonged mouse survival.

CONCLUSIONS

These observations emphasize and extend the potential of the human HSP70 gene as adjuvant for DNA vaccines, and the vaccine based on PSCA and HSP70 is of potential value for treating prostate cancer.

Coimmunization with RANTES plasmid polarized Th1 immune response against hepatitis B virus envelope via recruitment of dendritic cells

Induction of T help cell type 1 (Th1) response seems to be a prerequisite of HBV clearance. DNA vaccines have shown its potential to elicit Th1-biased immune response. However, its immunogenicity needs to be improved. Regulated upon activation normal T cell expressed and secreted (RANTES) is an inflammatory chemokine that promotes the accumulation and activation of CD4+, CD8+ T cells, and dendritic cells (DCs), which would favor antiviral immunity. In this study, the efficacy of a DNA vaccine encoding hepatitis B virus (HBV) preS2 plus S protein was enhanced through co-injection of a plasmid encoding RANTES in a BALB/c model. Co-injection of RANTES gene resulted in a moderate increase in the HBV specific humoral and cellular immune responses and a significant increase following an HBsAg booster vaccination compared to DNA encoding HBsAg alone. This enhancement was due to an enrichment of DCs in the draining lymph node and an up-regulation of DCs maturation by RANTES. More importantly, RANTES polarized the specific immunity towards a dominant Th1 profile and even converted an established Th2 response to a Th1 phenotype. Our study suggested the feasibility of using a plasmid-encoded RANTES as a modulatory Th1 adjuvant in genetic vaccination.

Enhancing DNA vaccine potency by modifying the properties of antigen-presenting cells

DNA vaccines represent a potentially promising approach for antigen-specific immunotherapy. Advances in our knowledge of the adaptive immune system have indicated that professional antigen-presenting cells, especially dendritic cells (DCs), play a key role in the generation of antigen-specific immune responses. Thus, the modification of the properties of DCs represents an important strategy for enhancing the potency of DNA vaccines. This review discusses strategies to increase the number of antigen-expressing DCs, enhance antigen expression, processing and presentation in DCs, promote the activation and function of DCs, and improve DC and T-cell interaction, in order to optimize DNA vaccine-elicited immune responses. Continuing progress in our understanding of DC and T-cell biology serves as a foundation for further improvement of DNA vaccine potency, which may lead to future clinical applications of DNA vaccines for the control of infectious diseases and malignancies.

L’apport des nouvelles technologies en vaccinologie

Despite important success of preventive vaccination in eradication of smallpox and in reduction in incidence of poliomyelitis and measles, infectious diseases remain the principal cause of mortality in the world. Technologies used in the development of vaccines used so far, mostly based on empirical approaches, are limited and insufficient to fight diseases like malaria, acquired immunodeficiency syndrome (AIDS) or adult tuberculosis. Until recently, technologies for making vaccines were based on live attenuated microorganisms, whole killed microorganisms and subunit vaccines such as purified toxoids. Fortunately, the recent advances in the understanding of host-pathogen interaction as well as our increasing knowledge of how immune responses are triggered and regulated have opened almost unlimited possibilities of developing new immunization strategies based on recombinant microorganisms or recombinant polypeptides or bacterial or viral vectors, synthetic peptides, natural or synthetic polysaccharides or plasmid DNA. Thus, considering the expending number of technologies available for making vaccines, it becomes possible for the first time in the history of vaccinology to design vaccines based on a rational approach and leading to increased efficacy and safety.

DNA vaccine construct incorporating intercellular trafficking and intracellular targeting motifs effectively primes and induces memory B- and T-cell responses in outbred animals

We developed a vaccine construct in which a BVP22 domain and an invariant-chain major histocompatibility complex class II-targeting motif capable of enhancing dendritic cell antigen uptake and presentation were fused to a sequence encoding a B- and T-cell antigen from the Anaplasma marginale major surface protein 1a and tested whether this construct would prime and expand immune responses in outbred calves. A single inoculation with this construct effectively primed the immune responses, as demonstrated by a significant enhancement of CD4(+) T-cell proliferation compared to that in calves identically inoculated but inoculated with a DNA construct lacking the targeting domains and compared to that in calves inoculated with an empty vector. These proliferative responses were mirrored by priming and expansion of gamma interferon-positive CD4(+) T cells and immunoglobulin G responses against the linked B-cell epitope. Priming by the single immunization induced memory that underwent rapid recall following reexposure to the antigen. These results demonstrate that DNA vaccines targeting key intercellular and intracellular events significantly enhance priming and expansion and support the feasibility of single-dose DNA immunization in outbred populations.

Targeting dendritic cells with biomaterials: developing the next generation of vaccines

Current vaccine and immunotherapy technology faces ongoing challenges in both efficacy and practicality: many chronic diseases cannot yet be addressed by vaccination, and several vaccines that do function well require multiple injections, which is a substantial limitation in various parts of the world. A possible key to developing the next generation of vaccines is the ability to deliver antigen to dendritic cells (DCs) more specifically and induce the subsequent activation of T-cell immunity. However, antigen delivery to, and activation of, DCs is a complex problem, involving antigen transport to DC-rich areas, DC binding and antigen uptake, and antigen processing and presentation. Addressing these challenges requires novel and multidisciplinary approaches, for example, the application of biomaterials to immunotechnology. Here, we review the latest advances in biomaterial drug vehicles, such as polymer microparticles and nanoparticles, and liposomes, that are being used to target DCs in new strategies for vaccination.

Assessing the safety of cytotoxic T lymphocytes transduced with a dominant negative transforming growth factor-beta receptor

Transforming growth factor (TGF)-beta, a pleiotropic cytokine that regulates cell growth, is secreted by many human tumors and markedly inhibits tumor-specific cellular immunity. It has previously been shown by our group that transduction of cytotoxic T lymphocytes (CTLs) with a retroviral vector expressing the dominant-negative TGFbeta type II receptor (DNR) overcomes this tumor evasion in a model of Epstein-Barr virus (EBV)-positive Hodgkin disease. TGFbeta is an important physiologic regulator of T-cell growth and survival, however, abrogation of this regulatory signal in genetically modified cells is potentially problematic. To ensure that unresponsiveness to TGFbeta did not lead to the unregulated growth of genetically modified CTLs, the characteristics of DNR-transduced CTLs in vivo were studied. Donor C57BL6 mice were vaccinated with human papillomavirus-E7 plasmid DNA to induce production of E7-specific CTLs. The E7-specific CTLs were genetically modified to express enhanced green fluorescent protein (GFP) or DNR and administered to syngeneic mice. All mice received monthly boosts with E7 DNA for 9 months, and during this time, transduced CTLs were detected in the peripheral blood of most of the mice using a quantitative real-time polymerase chain reaction. By 12 months, 3 months after cessation of vaccination, no DNR-transduced CTLs or GFP-transduced CTLs were detected in the peripheral blood. There were 4 cases of lymphoma (2 DNR-transduced mice and 2 control mice): all tumors were CD3-/CD8- and were also negative for the DNR transgene. Hence, mature antigen-specific cytotoxic T cells can be genetically modified to resist the antiproliferative effects of TGFbeta without undergoing spontaneous lymphoproliferation in vivo. They may be of value for treating human cancers, which use TGFbeta as a powerful immune evasion mechanism.

Heat shock fusion protein induces both specific and nonspecific anti-tumor immunity

Mucin 1 (MUC1) is a tumor antigen, and the most important epitopes that can induce cytotoxic T lymphocytes (CTL) reside in the variable-number tandem repeats (VNTR). Heat shock protein (HSP) complexes isolated from tumors have been shown to induce specific anti-tumor immunity. HSP alone can also induce nonspecific immunity. To explore the possibility to utilize the specific anti-tumor immunity induced by MUC1 VNTR and the nonspecific immunity induced by HSP, we constructed a recombinant protein (HSP65-MUC1) by fusing Bacillus Calmette-Guérin-derived HSP65 with the MUC1 VNTR peptide and tested its ability to induce anti-tumor activities in a tumor challenge model. The growth of MUC1-expressing tumors was significantly inhibited in mice immunized with HSP65-MUC1, both before and after tumor challenge. A much larger percentage of immunized mice survived the tumor challenge than non-immunized mice. Correlating with the anti-tumor activity, HSP65-MUC1 was shown to induce MUC1-specific CTL as well as nonspecific anti-tumor immunity. In the human system, HSP65-MUC1-loaded human DC induced the generation of autologous MUC1-specific CTL in vitro. These results suggest that exogenously applied HSP65-MUC1 may be used to treat MUC1 tumors by inducing the epitope-specific CTL as well as nonspecific anti-tumor responses mediated by the HSP part of the fusion protein.