Recombinantly Expressed Chimeric Fibers Demonstrate Discrete Type-Specific Neutralizing Epitopes in the Fowl Aviadenovirus E (FAdV-E) Fiber, Promoting the Optimization of FAdV Fiber Subunit Vaccines towards Cross-Protection in vivo.

Vaccines against inclusion body hepatitis in chickens are complicated by the involvement of antigenically diverse fowl adenovirus types. Though immunization with fiber protein confers robust protection, type specificity of fiber antibodies is an obstacle for the desired broad coverage. In this study, we utilized information on multiple linear epitopes predicted in the Fowl Aviadenovirus E (FAdV-E) fiber head (knob) to develop chimeric fibers with an exchange between two serotypes' sequences, each containing proposed epitopes. Two consecutive segments pertaining to amino acid positions 1 to 441 and 442 to 525/523 in the fibers of FAdV-8a and -8b, types of Fowl Aviadenovirus E that cause inclusion body hepatitis, were swapped reciprocally to result in novel chimeras, crecFib-8a/8b and crecFib-8b/8a. crecFib was indistinguishable from monospecific recombinant fibers in its eactivity with different FAdV antisera in Western blotting. However, contrary to the results for monospecific fibers, crecFib induced cross-neutralizing antibodies against both serotypes in chickens. This demonstrates three nonidentical epitopes in the FAdV-E fiber, the conserved epitope detected in Western blotting and at least two epitopes participating in neutralization, being type specific and located opposite residue position 441-442. Furthermore, we supply conformational evidence for a site in the fiber knob with accessibility critical for neutralization. With such an extended neutralization spectrum compared to those of individual fibers, crecFib was anticipated to fulfill and even extend the mechanistic basis of fiber-mediated protection toward bivalent coverage. Accordingly, crecFib, administered as a single-antigen component, protected chickens simultaneously against challenge with FAdV-8a or -8b, demonstrated by up-to-complete resistance to clinical disease, prevention of target organ-related changes, and significant reduction of viral load. IMPORTANCE The control of inclusion body hepatitis, a disease of economic importance for chicken production worldwide, is complicated by an etiology involving multiple divergent fowl adenovirus types. The fiber protein is principally efficacious in inducing neutralizing and protective antibodies in vaccinated chickens; however, it faces limitations due to its intrinsic type specificity for neutralization. In this study, based on an in silico-guided prediction of multiple epitopes in the fowl adenovirus fiber head's loops, we designed chimeric proteins, swapping N- and C-distal fiber portions, each containing putative epitopes, between divergent types FAdV-8a and -8b. In in vitro and in vivo studies, the chimeric fiber displayed extended properties compared to those of individual monotype-specific fibers, allowing the number, distribution, functionality, and conformational bearings of epitopes of the fowl adenovirus fiber to be characterized in more detail. Importantly, the chimeric fiber induced cross-neutralizing antibodies and protective responses in chickens against infections by both serotypes, promoting the advancement of broadly protective subunit vaccination strategies against FAdV.

Immunological responses and anti-tumor effects of HPV16/18 L1-L2-E7 multiepitope fusion construct along with curcumin and nanocurcumin in C57BL/6 mouse model.

AIMS: Human papillomavirus (HPV) L1, L2 and E7 proteins were used as target antigens for development of preventive and therapeutic vaccines. Moreover, linkage of antigens to heat shock proteins (HSPs) could enhance the potency of vaccines. Curcumin and nanocurcumin compounds were suggested as the chemopreventive and chemotherapeutic agents against cancer. In this study, two multiepitope DNA and peptide-based vaccine constructs (L1-L2-E7 and HSP70-L1-L2-E7) were used along with curcumin and nanocurcumin to evaluate immune responses, and protective/therapeutic effects in tumor mouse model. MAIN METHODS: At first, the multiepitope L1-L2-E7 and HSP70-L1-L2-E7 fusion genes were subcloned in eukaryotic and prokaryotic expression vectors. The recombinant multiepitope peptides were generated in E. coli strain. Then, the cytotoxic effects of curcumin and nanocurcumin were evaluated on HEK-293 T non-cancerous and C3 cancerous cells. Finally, mice vaccination was performed using different regimens. Curcumin and nanocurcumin compounds were administered alone or along with different vaccine constructs. KEY FINDINGS: Our data indicated that the use of nanocurcumin along with the multiepitope HSP70-L1-L2-E7 vaccine construct could completely protect mice against HPV-related C3 tumor cells, and eradicate tumors in a therapeutic test. Furthermore, nanocurcumin showed higher protection than curcumin alone. Generally, curcumin and nanocurcumin compounds could reduce tumor growth synergistically with the multiepitope vaccine constructs, but they did not influence the immune responses in different regimens. SIGNIFICANCE: These data demonstrated that the designed multiepitope vaccine constructs along with curcumin and nanocurcumin can be used as a promising method for HPV vaccine development.

Identification of the mimotopes within the major capsid protein L1 of human papillomavirus types 18 and 45, using neutralizing monoclonal antibodies.

Persistent infection with high-risk mucosal human papillomavirus (HPV) types has much association with the development of cervical cancer. The major capsid protein L1 has been confirmed to be a major candidate antigen for the development of vaccines. Here, the HPV18 L1 protein was successfully expressed and purified, then nine anti-HPV18 L1 monoclonal antibodies were prepared. Four neutralizing monoclonal antibodies (NmAbs) were identified by using hemagglutination inhibition assay and pseudovirus based neutralization assay. The results of Dot-ELISA, Western blot and indirect immunofluorescence assay showed that the neutralizing antibodies could cross-react with HPV16/18/45/31/33/58/35/39 L1. The mimotopes on HPV18/45 L1 proteins were identified and analyzed by using both phage display and Bioinformatics tool. The B cell epitopes 43-54 aa and 116-126 aa of HPV18 L1 protein, the B cell epitope 381-389 aa of HPV45 L1 protein, and the mimotopes epitope of HPV45 L1 protein were identified by peptide-ELISA and competitive ELISA. The results of PyMOL and Pepitope server analysis indicated that epitopes recognized by NmAbs 7F4, 5A6, 3G11, and 2F5 are located on the surface of L1 VLPs. The results of this study enriched the library of HPV neutralizing antibodies, revealed the mechanism of antibody neutralization, might open new perspectives on the antibody-antigen reaction and have important implications for the development of novel HPV vaccines.

Rational design of a multi-valent human papillomavirus vaccine by capsomere-hybrid co-assembly of virus-like particles.

The capsid of human papillomavirus (HPV) spontaneously arranges into a T = 7 icosahedral particle with 72 L1 pentameric capsomeres associating via disulfide bonds between Cys175 and Cys428. Here, we design a capsomere-hybrid virus-like particle (chVLP) to accommodate multiple types of L1 pentamers by the reciprocal assembly of single C175A and C428A L1 mutants, either of which alone encumbers L1 pentamer particle self-assembly. We show that co-assembly between any pair of C175A and C428A mutants across at least nine HPV genotypes occurs at a preferred equal molar stoichiometry, irrespective of the type or number of L1 sequences. A nine-valent chVLP vaccine-formed through the structural clustering of HPV epitopes-confers neutralization titers that are comparable with that of Gardasil 9 and elicits minor cross-neutralizing antibodies against some heterologous HPV types. These findings may pave the way for a new vaccine design that targets multiple pathogenic variants or cancer cells bearing diverse neoantigens.

Rotavirus VP6 Adjuvant Effect on Norovirus GII.4 Virus-Like Particle Uptake and Presentation by Bone Marrow-Derived Dendritic Cells In Vitro and In Vivo.

We have previously shown that rotavirus (RV) inner capsid protein VP6 has an adjuvant effect on norovirus (NoV) virus-like particle- (VLP-) induced immune responses and studied the adjuvant mechanism in immortalized cell lines used as antigen-presenting cells (APCs). Here, we investigated the uptake and presentation of RV VP6 and NoV GII.4 VLPs by primary bone marrow-derived dendritic cells (BMDCs). The adjuvant effect of VP6 on GII.4 VLP presentation and NoV-specific immune response induction by BMDC in vivo was also studied. Intracellular staining demonstrated that BMDCs internalized both antigens, but VP6 more efficiently than NoV VLPs. Both antigens were processed and presented to antigen-primed T cells, which responded by robust interferon γ secretion. When GII.4 VLPs and VP6 were mixed in the same pulsing reaction, a subpopulation of the cells had uptaken both antigens. Furthermore, VP6 copulsing increased GII.4 VLP uptake by 37% and activated BMDCs to secrete 2-5-fold increased levels of interleukin 6 and tumor necrosis factor α compared to VLP pulsing alone. When in vitro-pulsed BMDCs were transferred to syngeneic BALB/c mice, VP6 improved NoV-specific antibody responses. The results of this study support the earlier findings of VP6 adjuvant effect in vitro and in vivo.

Evaluation on the efficacy and immunogenicity of recombinant DNA plasmids expressing S gene from porcine epidemic diarrhea virus and VP7 gene from porcine rotavirus.

Porcine rotavirus (PoRV) and porcine epidemic diarrhea virus (PEDV) usually co-infect pigs in modern large-scale piggery, which both can cause severe diarrhea in newborn piglets and lead to significant economic losses to the pig industry. The VP7 protein is the main coat protein of PoRV, and the S protein is the main structural protein of PEDV, which are capable of inducing neutralizing antibodies in vivo. In this study, a DNA vaccine pPI-2.EGFP.VP7.S co-expressing VP7 protein of PoRV and S protein of PEDV was constructed. Six 8-week-old mice were immunized with the recombinant plasmid pPI-2.EGFP.VP7.S. The high humoral immune responses (virus specific antibody) and cellular immune responses (IFN-γ, IL-4, and spleen lymphocyte proliferation) were evaluated. The immune effect through intramuscular injection increased with plasmid dose when compared with subcutaneous injection. The immune-enhancing effect of IFN-α adjuvant was excellent compared with pig spleen transfer factor and IL-12 adjuvant. These results demonstrated that pPI-2.EGFP.VP7.S possess the immunological functions of the VP7 proteins of PoRV and S proteins of PEDV, indicating that pPI-2.EGFP.VP7.S is a candidate vaccine for porcine rotaviral infection (PoR) and porcine epidemic diarrhea (PED).

Penton-dodecahedron of fowl adenovirus serotype 4 as a vaccine candidate for the control of related diseases.

In some serotypes of adenovirus (Ad), the penton base and attached trimeric fiber assemble into dodecameric virus-like particles called penton-dodecahedron (Pt-Dd), which can be internalized and used to deliver the vaccine antigens and drugs. Fowl adenovirus serotype 4 (FAdV-4) is an important pathogen, causing seriously economic loss to poultry industry in China and other counties. Pt-Dd particles from FAdV-4 infected cells, as well as in those infected with recombinant human Ad expressing fiber-1, fiber-2, and penton base of FAdV-4, were visualized by transmission electron microscopy. For the first time, we proved that FAdV-4 produced Pt-Dd in infected cells. Pt-Dd can also be assembled by the overexpressed recombinant proteins fiber-1, fiber-2, and penton base. Pt-Dd, as well as the recombinant proteins fiber-1, fiber-2, and penton base, were then used to immunize chickens. The humoral immune response, expression of selected immune molecules and challenge results were used to evaluate the immune efficacy of the vaccine candidates. Pt-Dd induced the highest level of enzyme-linked immunosorbent assay antibodies and significant high levels (p < 0.05) of interferonγ, interleukin-4, and major histocompatibility complex II expression in peripheral blood mononuclear cells at 48 h post-infection. The challenge results showed that Pt-Dd, inactivated FAdV-4 vaccine, and fiber-1 induced the best protection (100%), followed by fiber-2 (80%) and penton base (67%). The present study showed that FAdV-4 -Pt-Dd and recombinant fiber-1 are promising FAdV-4 vaccine candidates and could be used to replace the tissue-sourced inactivated FAdV-4 vaccine.

Safety and Immunogenicity of a Nonadjuvant Human Papillomavirus Type 6 Virus-like Particle Vaccine in Recurrent Respiratory Papillomatosis.

OBJECTIVES: To assess the safety and immunogenicity of a nonadjuvant human papillomavirus (HPV) type 6 L1 virus-like particle (VLP) vaccine in recurrent respiratory papillomatosis (RRP) in local Chinese patients. METHODS: Patients with RRP who had undergone surgical treatment before intramuscular administration of an escalating dose of HPV type 6 L1 VLPs (1, 5, and 25 µg at 4 weekly intervals) as part of their treatment were followed up for more than 10 years. Efficacy was assessed by detecting the vaccine-induced type-specific antibody titer, calculating the intersurgical interval, and observing recurrence or remission of papillomas after receiving the vaccine. RESULTS: Nonadjuvant HPV vaccine was generally well tolerated, with no serious vaccine-related adverse episodes. It induced seroconversion for each vaccine-related HPV type. At week 12 (4 weeks after injecting 25 µg), the vaccine-induced type-specific antibody titer was significantly high. Analysis of all patients found a significant increase in the intersurgical interval and decrease in the scores. One patient (16.7%; female) experienced complete remission. Five patients (83.3%) (two males and three females) experienced partial remission. In total, complete or partial remission was achieved in six (100%) patients. CONCLUSIONS: Administration of nonadjuvant HPV type 6 L1 VLPs vaccine to RRP was generally well tolerated and highly immunogenic.

N-terminal truncations on L1 proteins of human papillomaviruses promote their soluble expression in Escherichia coli and self-assembly in vitro.

Human papillomavirus (HPV) is the causative agent in genital warts and nearly all cervical, anogenital, and oropharyngeal cancers. Nine HPV types (6, 11, 16, 18, 31, 33, 45, 52, and 58) are associated with about 90% of cervical cancers and 90% of genital warts. HPV neutralization by vaccine-elicited neutralizing antibodies can block viral infection and prevent HPV-associated diseases. However, there is only one commercially available HPV vaccine, Gardasil 9, produced from Saccharomyces cerevisiae that covers all nine types, raising the need for microbial production of broad-spectrum HPV vaccines. Here, we investigated whether N-terminal truncations of the major HPV capsid proteins L1, improve their soluble expression in Escherichia coli. We found that N-terminal truncations promoted the soluble expression of HPV 33 (truncated by 10 amino acids [aa]), 52 (15 aa), and 58 (10 aa). The resultant HPV L1 proteins were purified in pentamer form and extensively characterized with biochemical, biophysical, and immunochemical methods. The pentamers self-assembled into virus-like particles (VLPs) in vitro, and 3D cryo-EM reconstructions revealed that all formed T = 7 icosahedral particles having 50-60-nm diameters. Moreover, we formulated a nine-valent HPV vaccine candidate with aluminum adjuvant and L1 VLPs from four genotypes used in this study and five from previous work. Immunogenicity assays in mice and non-human primates indicated that this HPV nine-valent vaccine candidate elicits neutralizing antibody titers comparable to those induced by Gardasil 9. Our study provides a method for producing a nine-valent HPV vaccine in E. coli and may inform strategies for the soluble expression of other vaccine candidates.

Extensive Transduction and Enhanced Spread of a Modified AAV2 Capsid in the Non-human Primate CNS.

The present study was designed to characterize transduction of non-human primate brain and spinal cord with a modified adeno-associated virus serotype 2, incapable of binding to the heparan sulfate proteoglycan receptor, referred to as AAV2-HBKO. AAV2-HBKO was infused into the thalamus, intracerebroventricularly or via a combination of both intracerebroventricular and thalamic delivery. Thalamic injection of this modified vector encoding GFP resulted in widespread CNS transduction that included neurons in deep cortical layers, deep cerebellar nuclei, several subcortical regions, and motor neuron transduction in the spinal cord indicative of robust bidirectional axonal transport. Intracerebroventricular delivery similarly resulted in widespread cortical transduction, with one striking distinction that oligodendrocytes within superficial layers of the cortex were the primary cell type transduced. Robust motor neuron transduction was also observed in all levels of the spinal cord. The combination of thalamic and intracerebroventricular delivery resulted in transduction of oligodendrocytes in superficial cortical layers and neurons in deeper cortical layers. Several subcortical regions were also transduced. Our data demonstrate that AAV2-HBKO is a powerful vector for the potential treatment of a wide number of neurological disorders, and highlight that delivery route can significantly impact cellular tropism and pattern of CNS transduction.

Assessment of structurally modified plant virus as a novel adjuvant in toxicity studies.

Spherical particles (SPs) generated by thermally denatured tobacco mosaic virus (TMV) coat protein can act as an adjuvant, as they are able to enhance the magnitude and longevity of immune responses to different antigens. Here, the toxicity of TMV SPs was assessed prior to it being offered as a universal safe adjuvant for the development of vaccine candidates. The evaluation included nonclinical studies of a local tolerance following the single administration of TMV SPs, and of the local and systemic effects following repeated administrations of TMV SPs. These were conducted in mice, rats and rabbits. General health status, haematology and blood chemistry parameters were monitored on a regular basis. Also, reproductive and development toxicity were studied. No significant signs of toxicity were detected following single or repeated administrations of the adjuvant (TMV SPs). The absence of toxicological effects following the injection of TMV SPs is promising for the further development of recombinant vaccine candidates with TMV SPs as an adjuvant.

Leukocytes and drug-resistant cancer cells are targets for intracellular delivery by adenoviral dodecahedron.

One of the major factors limiting the effectiveness of cancer chemotherapy is inefficient drug delivery. Systems enabling efficient delivery and enhanced intracellular uptake appear particularly promising in this respect. Virus-like particle, adenoviral dodecahedron (Dd), employs receptor-mediated endocytosis for cell penetration and is able to deliver intracellularly dozens of cargo molecules attached to one particle. We focused on studying Dd properties in the context of cancer treatment, showing that intratumoral injection of Dd, assessed in mouse xenograft model, results in vector accumulation in tumor without spreading in off-target organs. Moreover, we demonstrated that Dd is a promising vector targeting leukocytes and drug-resistant cancer cells. Dd uptake by human blood cells analyzed in vitro indicated the preference for leukocytes in comparison to red blood cells and platelets. Furthermore, internalization of Dd-doxorubicin conjugate by drug-resistant cells leads to increased nuclear accumulation of doxorubicin and significant enhancement of cytotoxicity against target cancer cells.

Potency of a Scalable Nanoparticulate Subunit Vaccine.

Nanoparticulate vaccines can potentiate immune responses by site-specific drainage to lymph nodes (LNs). This approach may benefit from a nanoparticle engineering method with fine control over size and codelivery of antigen and adjuvant. Here, we applied the flash nanocomplexation (FNC) method to prepare nanovaccines via polyelectrolyte complexation of chitosan and heparin to coencapsulate the VP1 protein antigen from enterovirus 71, which causes hand-foot-mouth disease (HFMD), with tumor necrosis factor α (TNF) or CpG as adjuvants. FNC allows for reduction of the nanovaccine size to range from 90 to 130 nm with relatively narrower size distribution and a high payload capacity. These nanovaccines reached both proximal and distal LNs via subcutaneous injection and subsequently exhibited prolonged retention in the LNs. The codelivery induced strong immune activation toward a Th1 response in addition to a potent Th2 response, and conferred effective protection against lethal virus challenge comparable to that of an approved inactivated viral vaccine in mouse models of both passive and active immunization setting. In addition, these nanovaccines also elicited strong IgA titers, which may offer unique advantages for mucosal protection. This study addresses the issues of size control, antigen bioactivity retention, and biomanufacturing to demonstrate the translational potential of a subunit nanovaccine design.

Oral immunization with recombinant protein antigen expressed in tobacco against fish nervous necrosis virus.

Nervous necrosis virus (NNV), also known as betanodavirus, has been recently implicated in mass mortalities of cultured marine fish. An effective vaccine is urgently needed to protect fish against this virus. However, parenteral immunization methods are very stressful. Individual immunization for thousands of fish is very labor intensive and expensive. Therefore, we expressed NNV coat protein in tobacco chloroplasts and used it as an oral vaccine to induce immunities in fish followed by challenges with NNV. Our results revealed that mice (IgG and IgA) and fish (IgM) immunized with the oral vaccine developed significantly higher antibody titers against the NNV coat protein. Fish were partially protected against viral challenge. Taken together, our results demonstrated that a plant-based vaccine could effectively induce immune response and protect groupers against NNV. The present method could be used to develop oral fish vaccine in the future.

Immune protection efficacy of FAdV-4 surface proteins fiber-1, fiber-2, hexon and penton base.

The spread of hydropericardium syndrome has recently become serious in China since 2015. There is, therefore, an urgent need for new, safe and effective vaccines that prevent the disease. Here, the immune protection induced by Escherichia coli-expressed capsid proteins of fowl adenovirus serotype 4, including fiber-1, fiber-2, penton base and hexon (loop-1 region) were compared in chickens at different inoculation amounts. According to challenge mortalities and tissue gross/micro lesion results, fiber-2 induced the best protection, followed by fiber-1 and hexon. Fiber-1 and fiber-2 provided complete protection against 105.5 TCID50 viral load challenge with 100 or 50µg doses per chicken, respectively. Penton could induce effective protection only at the high dosage of 200µg per chicken. The immunoprotective characteristics of these FAdV-4 capsid proteins may prove useful for developing subunit vaccines to control hydropericardium syndrome.

Canine Parvovirus ns1 gene and Chicken Anemia vp3 gene induce partial oncolysis of Canine Transmissible Venereal Tumor.

The oncolytic effect of Canine Parvovirus ns1 gene and Chicken Anemia vp3 gene in naturally occurring cases of Canine Transmissible Venereal Tumor (CTVT) is being reported. Dogs suffering from CTVT (N = 18) were systematically randomized into three groups viz. A, B, and C (n = 6). Animals of the groups A, B, and C received 100 µg of the ns1 gene, vp3 gene, and ns1 + vp3 gene combination, respectively, for three weeks intratumorally at weekly intervals; results were normalized against base values before commencement of therapy and after complete remission that were taken as negative and positive controls, respectively. Initiation of oncolytic gene therapy arrested the further progression of the tumor but most of the animals in the study underwent incomplete remission, indicating incomplete activity of ns1 and vp3 genes. The oncolytic effect of the treatments was in the order ns1 > vp3 > ns1 + vp3. Oncolysis was accompanied by decreased mitotic index and AgNOR count, and increased TUNEL positive cells and CD4+ lymphocyte counts. Our findings show that Canine Parvovirus ns1 may eventually find an important role as an oncolytic agent.

Immunogenicity of adenovirus vaccines expressing the PCV2 capsid protein in pigs.

Porcine circovirus type 2 (PCV2) is the main pathogen of porcine circovirus associated disease (PCVAD), causing great economic losses in pig industry. In previous study, we constructed adenovirus vector vaccines expressing PCV2 Cap either modified with Intron A and WPRE, or CD40L and GMCSF, and evaluated all of these vaccines in mice and in pigs. Although Ad-A-C-W and Ad-CD40L-Cap-GMCSF could induce stronger immune responses than Ad-Cap, neither of them was better than commercial inactivated vaccine PCV2 SH-strain. In this study, secretory recombinant adenoviruses (Ad-A-spCap-W and Ad-A-spCD40L-spCap-spGMCSF-W) and non-secretory recombinant adenovirus Ad-A-CD40L-Cap-GMCSF-W were constructed, and identified by western blot and confocal laser microscope observation. The results of ELISA and VN showed that humoral immune responses induced by Ad-A-spCap-W and Ad-A-CD40L-Cap-GMCSF-W were not significantly different from SH-strain, but Ad-A-spCD40L-spCap-spGMCSF-W could induce significantly higher humoral immune response than SH-strain. Lymphocytes proliferative and cytokines releasing levels of Ad-A-spCap-W and Ad-A-CD40L-Cap-GMCSF-W were not significantly different from SH-strain, but Ad-A-spCD40L-spCap-spGMCSF-W was significantly higher than SH-strain. PCV2-challenge experiment showed that virus loads were significantly reduced in Ad-A-spCD40L-spCap-spGMCSF-W vaccinated group, and no obviously clinical and microscopic lesions were observed in Ad-A-spCD40L-spCap-spGMCSF-W vaccinated group. Altogether, these results demonstrate that recombinant adenovirus vaccine Ad-A-spCD40L-spCap-spGMCSF-W induces stronger immune responses and provides better protection than commercial inactivated vaccine PCV2 SH-strain, and suggest that Ad-A-spCD40L-spCap-spGMCSF-W could be a potential vaccine candidate against PCVAD.

Phase I clinical trial of idiotypic DNA vaccine administered as a complex with polyethylenimine to patients with B-cell lymphoma.

We report on the design of a phase I, non-randomized, open-label study of idiotypic DNA vaccination in patients with B-cell non-Hodgkin's lymphoma (ISRCTN31090206). The study uses DNA fusion gene vaccination encoding patient-specific single chain variable fragment, or idiotype, linked to an immunostimulatory sequence. Two types of immunostimulatory sequence are being explored: potato virus X coat protein and human chemokine MIP3α. Linear polyethylenimine with low molecular weight (8 kDa) is used as a synthetic vehicle for vaccine delivery. Humoral and T-cellular immune responses to vaccination will be measured by ELISA and ELISPOT, respectively. The primary study endpoints are safety, tolerability and immunogenicity of DNA-PEI vaccination.

Gene delivery of apoptin-derived peptide using an adeno-associated virus vector inhibits glioma and prolongs animal survival.

Glioblastoma (GBM) is the most common malignant brain tumor in adults. We designed an adeno-associated virus (AAV) vector for intracranial delivery of the secreted HSP70-targeted peptide APOPTIN derived from Apoptin to GBM tumors. We applied this therapy to GBM models using human U87MG glioma cells and GBM xenograft models in mice. In U87MG and U251MG cells, conditioned medium from AAV2-apoptin-derived peptide (ADP)-expressing cells induced 83% and 78% cell death. In mice bearing intracranial U87MG tumors treated with AAV2-ADP, treatment resulted in a significant decrease in tumor growth and longer survival in mice bearing orthotopic invasive GBM brain tumors. These data indicate that ssAAV2-ADP injection in the left hemisphere effectively prevented ipsilateral tumor growth but was insufficient to prevent distal tumor growth in the contralateral hemisphere. However, the systemic route is the most effective approach for treating widely dispersed tumors. In summary, systemic delivery of AAV2-ADP is an attractive approach for invasive GBM treatment.

Exacerbated Leishmaniasis Caused by a Viral Endosymbiont can be Prevented by Immunization with Its Viral Capsid.

Recent studies have shown that a cytoplasmic virus called Leishmaniavirus (LRV) is present in some Leishmania species and acts as a potent innate immunogen, aggravating lesional inflammation and development in mice. In humans, the presence of LRV in Leishmania guyanensis and in L. braziliensis was significantly correlated with poor treatment response and symptomatic relapse. So far, no clinical effort has used LRV for prophylactic purposes. In this context, we designed an original vaccine strategy that targeted LRV nested in Leishmania parasites to prevent virus-related complications. To this end, C57BL/6 mice were immunized with a recombinant LRV1 Leishmania guyanensis viral capsid polypeptide formulated with a T helper 1-polarizing adjuvant. LRV1-vaccinated mice had significant reduction in lesion size and parasite load when subsequently challenged with LRV1+ Leishmania guyanensis parasites. The protection conferred by this immunization could be reproduced in naïve mice via T-cell transfer from vaccinated mice but not by serum transfer. The induction of LRV1 specific T cells secreting IFN-γ was confirmed in vaccinated mice and provided strong evidence that LRV1-specific protection arose via a cell mediated immune response against the LRV1 capsid. Our studies suggest that immunization with LRV1 capsid could be of a preventive benefit in mitigating the elevated pathology associated with LRV1 bearing Leishmania infections and possibly avoiding symptomatic relapses after an initial treatment. This novel anti-endosymbiotic vaccine strategy could be exploited to control other infectious diseases, as similar viral infections are largely prevalent across pathogenic pathogens and could consequently open new vaccine opportunities.