UB-612 pan-SARS-CoV-2 T cell immunity-promoting vaccine protects against COVID-19 moderate-severe disease.

UB-612 pan-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine targets the monomeric Spike S1-receptor binding domain (RBD) subunit protein along with five sequence-conserved T cell epitopes found on Spike S2 and non-Spike M and N proteins. UB-612 vaccination safely induces potent, broad, and long-lasting immunity against SARS-CoV-2. A phase-2 trial-extended observational study during the Omicron BA.2-/BA.5-dominated outbreak was conducted to investigate UB-612's protective effect against COVID-19 hospitalization and intensive care unit (ICU) admission (H-ICU). Additionally, memory viral-neutralizing titer and T cell immunity behind disease protection were explored. No cases of H-ICU were reported beyond 14 months post-second dose or beyond 10 months post-booster (third dose). The positive outcome correlates with strong cytotoxic CD8 T cell immunity, in line with the results of an ongoing phase-3 heterologous booster trial showing that UB-612 can enhance anti-BA.5 seroconversion rate and viral-neutralizing titer for mRNA, adeno-vectored, and virus-inactivated vaccine platforms. The UB-612 multitope vaccine may serve as an effective primer and booster for those at risk of SARS-CoV-2 infection.

Toward a pan-SARS-CoV-2 vaccine targeting conserved epitopes on spike and non-spike proteins for potent, broad and durable immune responses.

BACKGROUND: The SARS-CoV-2 non-Spike (S) structural protein targets on nucleocapsid (N), membrane (M) and envelope (E), critical in the host cell interferon response and memory T-cell immunity, are grossly overlooked in COVID vaccine development. The current Spike-only vaccines bear an intrinsic shortfall for promotion of a fuller T cell immunity. Vaccines designed to target conserved epitopes could elicit strong cellular immune responses that would synergize with B cell responses and lead to long-term vaccine success. We pursue a universal (pan-SARS-CoV-2) vaccine against Delta, Omicrons and ever-emergent new mutants. METHODS AND FINDINGS: We explored booster immunogenicity of UB-612, a multitope-vaccine that contains S1-RBD-sFc protein and sequence-conserved promiscuous Th and CTL epitope peptides on the Sarbecovirus N, M and S2 proteins. To a subpopulation (N = 1,478) of infection-free participants (aged 18-85 years) involved in a two-dose Phase-2 trial, a UB-612 booster (third dose) was administered 6-8 months after the second dose. The immunogenicity was evaluated at 14 days post-booster with overall safety monitored until the end of study. The booster induced high viral-neutralizing antibodies against live Wuhan WT (VNT50, 1,711) and Delta (VNT50, 1,282); and against pseudovirus WT (pVNT50, 11,167) vs. Omicron BA.1/BA.2/BA.5 variants (pVNT50, 2,314/1,890/854), respectively. The lower primary neutralizing antibodies in the elderly were uplifted upon boosting to approximately the same high level in young adults. UB-612 also induced potent, durable Th1-oriented (IFN-γ+-) responses (peak/pre-boost/post-boost SFU/106 PBMCs, 374/261/444) along with robust presence of cytotoxic CD8+ T cells (peak/pre-boost/post-boost CD107a+-Granzyme B+, 3.6%/1.8%/1.8%). This UB-612 booster vaccination is safe and well tolerated without SAEs. CONCLUSIONS: By targeting conserved epitopes on viral S2, M and N proteins, UB-612 could provide potent, broad and long-lasting B-cell and T-cell memory immunity and offers the potential as a universal vaccine to fend off Omicrons and new VoCs without resorting to Omicron-specific immunogens. TRIAL REGISTRATION: ClinicalTrials.gov ID: NCT04773067; ClinicalTrials.gov ID: NCT05293665; ClinicalTrials.gov ID: NCT05541861.

A novel RBD-protein/peptide vaccine elicits broadly neutralizing antibodies and protects mice and macaques against SARS-CoV-2.

The development of safe and effective vaccines to respond to COVID-19 pandemic/endemic remains a priority. We developed a novel subunit protein-peptide COVID-19 vaccine candidate (UB-612) composed of: (i) receptor binding domain of SARS-CoV-2 spike protein fused to a modified single-chain human IgG1 Fc; (ii) five synthetic peptides incorporating conserved helper and cytotoxic T lymphocyte (Th/CTL) epitopes derived from SARS-CoV-2 structural proteins (three from S2 subunit, one from membrane and one from nucleocapsid), and one universal Th peptide; (iii) aluminum phosphate as adjuvant. The immunogenicity and protective immunity induced by UB-612 vaccine were evaluated in four animal models: Sprague-Dawley rats, AAV-hACE2 transduced BALB/c mice, rhesus and cynomolgus macaques. UB-612 vaccine induced high levels of neutralizing antibody and T-cell responses, in all animals. The immune sera from vaccinated animals neutralized the SARS-CoV-2 original wild-type strains and multiple variants of concern, including Delta and Omicron. The vaccination significantly reduced viral loads, lung pathology scores, and disease progression after intranasal and intratracheal challenge with SARS-CoV-2 in mice, rhesus and cynomolgus macaques. UB-612 has been tested in primary regimens in Phase 1 and Phase 2 clinical studies and is currently being evaluated in a global pivotal Phase 3 clinical study as a single dose heterologous booster.

High Neutralizing Antibody Levels Against Severe Acute Respiratory Syndrome Coronavirus 2 Omicron BA.1 and BA.2 After UB-612 Vaccine Booster.

The highly transmissible severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant has caused high rates of breakthrough infections in those previously vaccinated with ancestral strain coronavirus disease 2019 (COVID-19) vaccines. Here, we demonstrate that a booster dose of UB-612 vaccine candidate delivered 7-9 months after primary vaccination increased neutralizing antibody levels by 131-, 61-, and 49-fold against ancestral SARS-CoV-2 and the Omicron BA.1 and BA.2 variants, respectively. Based on the receptor-binding domain protein binding antibody responses, the UB-612 third-dose booster may lead to an estimated approximately 95% efficacy against symptomatic COVID-19 caused by the ancestral strain. Our results support UB-612 as a potential potent booster against current and emerging SARS-CoV-2 variants.

A multitope SARS-CoV-2 vaccine provides long-lasting B cell and T cell immunity against Delta and Omicron variants.

BackgroundThe Delta and Omicron variants of SARS-CoV-2 are currently responsible for breakthrough infections due to waning immunity. We report phase I/II trial results of UB-612, a multitope subunit vaccine containing S1-RBD-sFc protein and rationally designed promiscuous peptides representing sarbecovirus conserved helper T cell and cytotoxic T lymphocyte epitopes on the nucleocapsid (N), membrane (M), and spike (S2) proteins.MethodWe conducted a phase I primary 2-dose (28 days apart) trial of 10, 30, or 100 µg UB-612 in 60 healthy young adults 20 to 55 years old, and 50 of them were boosted with 100 µg of UB-612 approximately 7 to 9 months after the second dose. A separate placebo-controlled and randomized phase II study was conducted with 2 doses of 100 µg of UB-612 (n = 3,875, 18-85 years old). We evaluated interim safety and immunogenicity of phase I until 14 days after the third (booster) dose and of phase II until 28 days after the second dose.ResultsNo vaccine-related serious adverse events were recorded. The most common solicited adverse events were injection site pain and fatigue, mostly mild and transient. In both trials, UB-612 elicited respective neutralizing antibody titers similar to a panel of human convalescent sera. The most striking findings were long-lasting virus-neutralizing antibodies and broad T cell immunity against SARS-CoV-2 variants of concern (VoCs), including Delta and Omicron, and a strong booster-recalled memory immunity with high cross-reactive neutralizing titers against the Delta and Omicron VoCs.ConclusionUB-612 has presented a favorable safety profile, potent booster effect against VoCs, and long-lasting B and broad T cell immunity that warrants further development for both primary immunization and heterologous boosting of other COVID-19 vaccines.Trial RegistrationClinicalTrials.gov: NCT04545749, NCT04773067, and NCT04967742.FundingUBI Asia, Vaxxinity Inc., and Taiwan Centers for Disease Control, Ministry of Health and Welfare.

UB-311, a novel UBITh® amyloid ß peptide vaccine for mild Alzheimer's disease.

INTRODUCTION: A novel amyloid ß (Aß) synthetic peptide vaccine (UB-311) has been evaluated in a first-in-human trial with patients of mild-to-moderate Alzheimer's disease. We describe translational research covering vaccine design, preclinical characterization, and phase-I clinical trial with supportive outcome that advances UB-311 into an ongoing phase-II trial. METHODS: UB-311 is constructed with two synthetic Aß1-14-targeting peptides (B-cell epitope), each linked to different helper T-cell peptide epitopes (UBITh®) and formulated in a Th2-biased delivery system. The hAPP751 transgenic mouse model was used to perform the proof-of-concept study. Baboons and macaques were used for preclinical safety, tolerability, and immunogenicity evaluation. Patients with mild-to-moderate Alzheimer's disease (AD) were immunized by intramuscular route with 3 doses of UB-311 at weeks 0, 4, and 12, and monitored until week 48. Safety and immunogenicity were assessed per protocol, and preliminary efficacy was analyzed by Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog), Mini-Mental State Examination (MMSE), and Alzheimer's Disease Cooperative Study-Clinician's Global Impression of Change (ADCS-CGIC). RESULTS: UB-311 covers a diverse genetic background and facilitates strong immune response with high responder rate. UB-311 reduced the levels of Aß1-42 oligomers, protofibrils, and plaque load in hAPP751 transgenic mice. Safe and well-tolerated UB-311 generated considerable site-specific (Aß1-10) antibodies across all animal species examined. In AD patients, UB-311 induced a 100% responder rate; injection site swelling and agitation were the most common adverse events (4/19 each). A slower rate of increase in ADAS-Cog from baseline to week 48 was observed in the subgroup of mild AD patients (MMSE ≥ 20) compared with the moderate AD subgroup, suggesting that UB-311 may have a potential of cognition improvement in patients with early stage of Alzheimer's dementia. DISCUSSION: The UBITh® platform can generate a high-precision molecular vaccine with high responder rate, strong on-target immunogenicity, and a potential of cognition improvement, which support UB-311 for active immunotherapy in early-to-mild AD patients currently enrolled in a phase-II trial (NCT02551809).

Target integration by a chimeric Sp1 zinc finger domain-Moloney murine leukemia virus integrase in vivo.

A specificity protein 1 (Sp1) zinc finger domain containing two tandem zinc fingers was fused to the C terminus of the integrase (IN) protein of the Moloney murine leukemia virus (MuLV). The integrity of the MuLV IN was completely preserved, since the fusion was conducted at the last amino acid residue of the protein. The vector pMIN-Sp1, which carried the fused MuLV IN-Sp1 zinc finger domain gene, was cotransfected with a wild-type MuLV vector pMLV-K to NIH/3T3 cells. A nonradioactive reverse transcriptase assay was performed on culture supernatants collected from the cotransfected cells to confirm the production of recombinant viruses. The expression of the fusion protein and the integration of the MuLV genome by the fusion protein were confirmed by a Northern and then a Southern hybridization analysis on the total RNA or genomic DNA extracted from cells infected by viruses collected from the supernatants of the cotransfected cells. Regions of the host chromosome that were selected by the fusion protein as the integration targets were sequenced using the TOPO(TM) cloning method on a series of PCR products generated with a nested set of primers. The percentage of positive clones screened that contained the DNA-binding sequence of the fused Sp1 zinc finger domain was around 13% (5 out of 39 clones). It was found that the Sp1 DNA-binding sequence was only present in regions that were proximal to one of the long terminal repeats of the integrated viral genome, suggesting that the fusion protein could select a target sequence for integration. The host flanking sequences determined for all the positive clones were also used as queries to perform a BLAST search on the GenBank mouse EST entries. Although matching scores for sequences of some of the clones computed were more significant than others, it was difficult to judge whether or not the integration in these clones had been targeted to some gene sequences. Most of the integration sites might exist in the introns, since we found that the probability of the gene sequences containing an Sp1 DNA-binding site was low.