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Multivalent presentation of ligands often enhances receptor activation and downstream signalling. DNA origami offers a precise nanoscale spacing of ligands, a potentially useful feature for therapeutic nanoparticles. Here we use a square-block DNA origami platform to explore the importance of the spacing of CpG oligonucleotides. CpG engages Toll-like receptors and therefore acts to activate dendritic cells. Through in vitro cell culture studies and in vivo tumour treatment models, we demonstrate that square blocks induce Th1 immune polarization when CpG is spaced at 3.5 nm. We observe that this DNA origami vaccine enhances DC activation, antigen cross-presentation, CD8 T-cell activation, Th1-polarized CD4 activation and natural-killer-cell activation. The vaccine also effectively synergizes with anti-PD-L1 for improved cancer immunotherapy in melanoma and lymphoma models and induces long-term T-cell memory. Our results suggest that DNA origami may serve as a platform for controlling adjuvant spacing and co-delivering antigens in vaccines. The spacing of ligands presented to cells can have a huge impact on cellular responses. DNA origami is used to block structures to control the distribution of Toll-like receptor ligands and optimize presentation in the activation of dendritic cells in cancer immunotherapy.

There are no known specific therapies or vaccines to treat or prevent Zika virus infection. In this report, encouraging data are presented from a phase 1 study of a DNA vaccine against ZIKV infection.

The Zika virus epidemic and associated congenital infections have prompted rapid vaccine development. We assessed two new DNA vaccines expressing premembrane and envelope Zika virus structural proteins. We did two phase 1, randomised, open-label trials involving healthy adult volunteers. The VRC 319 trial, done in three centres, assessed plasmid VRC5288 (Zika virus and Japanese encephalitis virus chimera), and the VRC 320, done in one centre, assessed plasmid VRC5283 (wild-type Zika virus). Eligible participants were aged 18–35 years in VRC19 and 18–50 years in VRC 320. Participants were randomly assigned 1:1 by a computer-generated randomisation schedule prepared by the study statistician. All participants received intramuscular injection of 4 mg vaccine. In VRC 319 participants were assigned to receive vaccinations via needle and syringe at 0 and 8 weeks, 0 and 12 weeks, 0, 4, and 8 weeks, or 0, 4, and 20 weeks. In VRC 320 participants were assigned to receive vaccinations at 0, 4, and 8 weeks via single-dose needle and syringe injection in one deltoid or split-dose needle and syringe or needle-free injection with the Stratis device (Pharmajet, Golden, CO, USA) in each deltoid. Both trials followed up volunteers for 24 months for the primary endpoint of safety, assessed as local and systemic reactogenicity in the 7 days after each vaccination and all adverse events in the 28 days after each vaccination. The secondary endpoint in both trials was immunogenicity 4 weeks after last vaccination. These trials are registered with ClinicalTrials.gov, numbers NCT02840487 and NCT02996461. VRC 319 enrolled 80 participants (20 in each group), and VRC 320 enrolled 45 participants (15 in each group). One participant in VRC 319 and two in VRC 320 withdrew after one dose of vaccine, but were included in the safety analyses. Both vaccines were safe and well tolerated. All local and systemic symptoms were mild to moderate. In both studies, pain and tenderness at the injection site was the most frequent local symptoms (37 [46%] of 80 participants in VRC 319 and 36 [80%] of 45 in VRC 320) and malaise and headache were the most frequent systemic symptoms (22 [27%] and 18 [22%], respectively, in VRC 319 and 17 [38%] and 15 [33%], respectively, in VRC 320). For VRC5283, 14 of 14 (100%) participants who received split-dose vaccinations by needle-free injection had detectable positive antibody responses, and the geometric mean titre of 304 was the highest across all groups in both trials. VRC5283 was well tolerated and has advanced to phase 2 efficacy testing. Intramural Research Program of the Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health.

Hundreds of scientists had worked on mRNA vaccines for decades before the coronavirus pandemic brought a breakthrough. Hundreds of scientists had worked on mRNA vaccines for decades before the coronavirus pandemic brought a breakthrough.

Legumain-based DNA vaccines have potential to protect against breast cancer. However, the lack of a safe and efficient oral delivery system restricts its clinical application. Here, we constructed alginic acid-coated chitosan nanoparticles (A.C.NPs) as an oral delivery carrier for a legumain DNA vaccine. First, we tested its characteristic in acidic environments in vitro. DNA agarose electrophoresis data show that A.C.NPs protected DNA better from degradation in acidic solution (pH 1.5) than did chitosan nanoparticles (C.NPs). Furthermore, size distribution analysis showed that A.C.NPs tended to aggregate and form micrometer scale complexes in pH<2.7, while dispersing into nanoparticles with an increase in pH. Mice were intragastrically administrated A.C.NPs carrying EGFP plasmids and EGFP expression was detected in the intestinal Peyer's patches. Full-length legumain plasmids were loaded into different delivery carriers, including C.NPs, attenuated Salmonella typhimurium and A.C.NPs. A.C.NPs loaded with empty plasmids served as a control. Oral vaccination was performed in the murine orthotopic 4T1 breast cancer model. Our data indicate that tumor volume was significantly smaller in groups using A.C.NPs or attenuated Salmonella typhimurium as carriers. Furthermore, splenocytes co-cultured them with 4T1 cells pre-stimulated with CoCl2, which influenced the translocation of legumain from cytoplasm to plasma membrane, showed a 4.7 and 2.3 folds increase in active cytotoxic T lymphocytes (CD3(+)/CD8(+)/CD25(+)) when treated with A.C.NPs carriers compared with PBS C.NPs. Our study suggests that C.NPs coated with alginic acid may be a safe and efficient tool for oral delivery of a DNA vaccine. Moreover, a legumain DNA vaccine delivered orally with A.C.NPs can effectively improve autoimmune response and protect against breast cancer in mice.

The authors test several candidate vaccines for Zika virus in mouse models and show that single-shot DNA vaccines and inactivated virus vaccines provide complete protection against Zika virus isolates from Brazil and Puerto Rico. A vaccine effective against Zika virus Dan Barouch and colleagues explore candidate vaccines for Zika virus in mouse models and show that single-shot DNA vaccines and inactivated virus vaccine provide complete protection against Zika virus isolates from Brazil and Puerto Rico. Protection correlates with Env-specific antibody titres and can be passively transferred. Zika virus (ZIKV) is a flavivirus that is responsible for the current epidemic in Brazil and the Americas 1 , 2 . ZIKV has been causally associated with fetal microcephaly, intrauterine growth restriction, and other birth defects in both humans 3 , 4 , 5 , 6 , 7 , 8 and mice 9 , 10 , 11 . The rapid development of a safe and effective ZIKV vaccine is a global health priority 1 , 2 , but very little is currently known about ZIKV immunology and mechanisms of immune protection. Here we show that a single immunization with a plasmid DNA vaccine or a purified inactivated virus vaccine provides complete protection in susceptible mice against challenge with a strain of ZIKV involved in the outbreak in northeast Brazil. This ZIKV strain has recently been shown to cross the placenta and to induce fetal microcephaly and other congenital malformations in mice 11 . We produced DNA vaccines expressing ZIKV pre-membrane and envelope (prM-Env), as well as a series of deletion mutants. The prM-Env DNA vaccine, but not the deletion mutants, afforded complete protection against ZIKV, as measured by absence of detectable viraemia following challenge, and protective efficacy correlated with Env-specific antibody titers. Adoptive transfer of purified IgG from vaccinated mice conferred passive protection, and depletion of CD4 and CD8 T lymphocytes in vaccinated mice did not abrogate this protection. These data demonstrate that protection against ZIKV challenge can be achieved by single-shot subunit and inactivated virus vaccines in mice and that Env-specific antibody titers represent key immunologic correlates of protection. Our findings suggest that the development of a ZIKV vaccine for humans is likely to be achievable.

A major challenge in cancer vaccine therapy is the efficient delivery of antigens and adjuvants to stimulate a controlled yet robust tumour-specific T-cell response. Here, we describe a structurally well defined DNA nanodevice vaccine generated by precisely assembling two types of molecular adjuvants and an antigen peptide within the inner cavity of a tubular DNA nanostructure that can be activated in the subcellular environment to trigger T-cell activation and cancer cytotoxicity. The integration of low pH-responsive DNA ‘locking strands’ outside the nanostructures enables the opening of the vaccine in lysosomes in antigen-presenting cells, exposing adjuvants and antigens to activate a strong immune response. The DNA nanodevice vaccine elicited a potent antigen-specific T-cell response, with subsequent tumour regression in mouse cancer models. Nanodevice vaccination generated long-term T-cell responses that potently protected the mice against tumour rechallenge. A DNA nanodevice vaccine has been developed and utilized to stimulate a tumour-specific cytotoxic T lymphocyte response in vivo, leading to the inhibition of tumour growth as well as prevention of metastasis.

Despite many years of research, human DNA vaccines have yet to fulfill their early promise. Over the past 15 years, multiple generations of DNA vaccines have been developed and tested in preclinical models for prophylactic and therapeutic applications in the areas of infectious disease and cancer, but have failed in the clinic. Thus, while DNA vaccines have achieved successful licensure for veterinary applications, their poor immunogenicity in humans when compared with traditional protein-based vaccines has hindered their progress. Many strategies have been attempted to improve DNA vaccine potency including use of more efficient promoters and codon optimization, addition of traditional or genetic adjuvants, electroporation, intradermal delivery and various prime-boost strategies. This review summarizes these advances in DNA vaccine technologies and attempts to answer the question of when DNA vaccines might eventually be licensed for human use.

Persistent expression of high-risk human papillomavirus (HPV) E6 and E7 is an obligate driver for several human malignancies, including cervical cancer, wherein HPV16 and HPV18 are the most common types. PD-1 antibody immunotherapy helps a subset of cervical cancer patients, and its efficacy might be improved by combination with active vaccination against E6 and/or E7. Immunotherapy for cervical cancer should target high-risk human papillomavirus types 16 and 18, which cause 50% and 20% of cervical cancers, respectively. Here, we describe the construction and characterization of the pBI-11 DNA vaccine via the addition of codon-optimized human papillomavirus 18 (HPV18) E7 and HPV16 and 18 E6 genes to the HPV16 E7-targeted DNA vaccine pNGVL4a-SigE7(detox)HSP70 (DNA vaccine pBI-1). Codon optimization of the HPV16/18 E6/E7 genes in pBI-11 improved fusion protein expression compared to that in DNA vaccine pBI-10.1 that utilized the native viral sequences fused 3′ to a signal sequence and 5′ to the HSP70 gene of Mycobacterium tuberculosis . Intramuscular vaccination of mice with pBI-11 DNA better induced HPV antigen-specific CD8 + T cell immune responses than pBI-10.1 DNA. Furthermore, intramuscular vaccination with pBI-11 DNA generated stronger therapeutic responses for C57BL/6 mice bearing HPV16 E6/E7-expressing TC-1 tumors. The HPV16/18 antigen-specific T cell-mediated immune responses generated by pBI-11 DNA vaccination were further enhanced by boosting with tissue-antigen HPV vaccine (TA-HPV). Combination of the pBI-11 DNA and TA-HPV boost vaccination with PD-1 antibody blockade significantly improved the control of TC-1 tumors and extended the survival of the mice. Finally, repeat vaccination with clinical-grade pBI-11 with or without clinical-grade TA-HPV was well tolerated in vaccinated mice. These preclinical studies suggest that the pBI-11 DNA vaccine may be used with TA-HPV in a heterologous prime-boost strategy to enhance HPV 16/18 E6/E7-specific CD8 + T cell responses, either alone or in combination with immune checkpoint blockade, to control HPV16/18-associated tumors. Our data serve as an important foundation for future clinical translation. IMPORTANCE Persistent expression of high-risk human papillomavirus (HPV) E6 and E7 is an obligate driver for several human malignancies, including cervical cancer, wherein HPV16 and HPV18 are the most common types. PD-1 antibody immunotherapy helps a subset of cervical cancer patients, and its efficacy might be improved by combination with active vaccination against E6 and/or E7. For patients with HPV16 + cervical intraepithelial neoplasia grade 2/3 (CIN2/3), the precursor of cervical cancer, intramuscular vaccination with a DNA vaccine targeting HPV16 E7 and then a recombinant vaccinia virus expressing HPV16/18 E6-E7 fusion proteins (TA-HPV) was safe, and half of the patients cleared their lesions in a small study (NCT00788164). Here, we sought to improve upon this therapeutic approach by developing a new DNA vaccine that targets E6 and E7 of HPV16 and HPV18 for administration prior to a TA-HPV booster vaccination and for application against cervical cancer in combination with a PD-1-blocking antibody.

Cancer is characterized by an accumulation of somatic mutations that represent a source of neoantigens for targeting by antigen‐specific T cells. Head and neck squamous cell carcinoma (HNSCC) has a relatively high mutation burden across all cancer types, and cellular immunity to neoantigens likely plays a key role in HNSCC clinical outcomes. Immune checkpoint inhibitors (CPIs) have brought new treatment options and hopes to patients with recurrent and/or metastatic HNSCC. However, many patients do not benefit from CPI therapies, highlighting the need for novel immunotherapy or combinatorial strategies. One such approach is personalized cancer vaccination targeting tumor‐associated antigens and tumor‐specific antigens, either as single agents or in combination with other therapies. Recent advances in next‐generation genomic sequencing technologies and computational algorithms have enabled efficient identification of somatic mutation‐derived neoantigens and are anticipated to facilitate the development of cancer vaccine strategies. Here, we review cancer vaccine approaches against HNSCC, including fundamental mechanisms of a cancer vaccine, considerations for selecting appropriate antigens, and combination therapies. Many patients with head and neck squamous cell carcinoma (HNSCC) do not benefit from checkpoint inhibitor therapies, which highlights the need for novel immunotherapy or combinatorial strategies. One such approach is personalized cancer vaccination targeting tumor‐associated antigens and tumor‐specific antigens, either as single agents or in combination with other therapies. Here, we review cancer vaccine approaches against HNSCC, including fundamental mechanisms of cancer vaccine, considerations for selecting appropriate antigens, and combination therapies.