Tumor-Derived Retinoic Acid Regulates Intratumoral Monocyte Differentiation to Promote Immune Suppression.

The immunosuppressive tumor microenvironment (TME) is a major barrier to immunotherapy. Within solid tumors, why monocytes preferentially differentiate into immunosuppressive tumor-associated macrophages (TAMs) rather than immunostimulatory dendritic cells (DCs) remains unclear. Using multiple murine sarcoma models, we find that the TME induces tumor cells to produce retinoic acid (RA), which polarizes intratumoral monocyte differentiation toward TAMs and away from DCs via suppression of DC-promoting transcription factor Irf4. Genetic inhibition of RA production in tumor cells or pharmacologic inhibition of RA signaling within TME increases stimulatory monocyte-derived cells, enhances T cell-dependent anti-tumor immunity, and synergizes with immune checkpoint blockade. Furthermore, an RA-responsive gene signature in human monocytes correlates with an immunosuppressive TME in multiple human tumors. RA has been considered as an anti-cancer agent, whereas our work demonstrates its tumorigenic capability via myeloid-mediated immune suppression and provides proof of concept for targeting this pathway for tumor immunotherapy.

Element concentrations, histology and serum biochemistry of arctic char (Salvelinus alpinus) and shorthorn sculpins (Myoxocephalus scorpius) in northwest Greenland.

The increasing exploratory efforts in the Greenland mineral industry, and in particular, the proposed rare earth element (REE) mining projects, requires an urgent need to generate data on baseline REE concentrations and their potential environmental impacts. Herein, we have investigated REE concentrations in anadromous Arctic char (Salvelinus alpinus) and shorthorn sculpins (Myoxocephalus scorpius) from uncontaminated sites in Northwest Greenland, along with the relationships between the element concentrations in gills and liver, and gill histology and serum biochemical parameters. Concentrations of arsenic, silver, cadmium, cerium, chromium, copper, dysprosium, mercury, lanthanum, neodymium, lead, selenium, yttrium, and zinc in gills, liver and muscle are presented. No significant statistical correlations were observed between element concentrations in different organs and gill histology or serum biochemical parameters. However, we observed positive relationships between age and histopathology, emphasizing the importance of including age as a co-variable in histological studies of fish. Despite no element-induced effects were observed, this study is considered an important baseline study, which can be used as a reference for the assessment of impacts of potential future REE mine sites in Greenland.

Retrieving high-quality genomic DNA from formalin-fixed paraffin-embedded tissues for multiple molecular analyses.

Formalin-fixed paraffin-embedded (FFPE) tissues represent the biggest source of archival materials for molecular biology research and pathology investigations. Nevertheless, fixation by formalin may cause denaturation and modification of macromolecules constraining DNA quality and its downstream applications. In this study, we developed a fast, simple, and cost-effective phenol/chloroform-based protocol for the extraction of high-quality DNA from 101 FFPE colorectal cancer tissue blocks that can be used in multiple molecular studies. DNA samples extracted using this phenol/chloroform protocol and the QIAamp DNA FFPE Tissue kit were evaluated for the quantity, quality, and amplificability. Spectrophotometer analyses revealed significantly higher quality and quantity of DNA samples obtained with the phenol/chloroform protocol as compared to those of the QIAamp DNA FFPE Tissue kit. In addition, the amplificability of these samples as assessed by conventional and multiplex polymerase chain reaction (PCR), followed by sequencing and fragment analyses presented an absolute success rate. Additionally, it is able to amplify a DNA fragment of 725 base-pairs at an adequate amount for downstream applications. This fast, simple, and cost-effective method may facilitate the molecular analyses of a large number of FFPE specimens that best suits the needs of the overall study design in terms of the quality and quantity of the extracted DNA.

Histological mucous cell quantification and mucosal mapping reveal different aspects of mucous cell responses in gills and skin of shorthorn sculpins (Myoxocephalus scorpius).

In teleosts, the mucosal epithelial barriers represent the first line of defence against environmental challenges such as pathogens and environmental contaminants. Mucous cells (MCs) are specialised cells providing this protection through mucus production. Therefore, a better understanding of various MC quantification methods is critical to interpret MC responses. Here, we compare histological (also called traditional) quantification of MCs with a novel mucosal mapping method to understand the differences between the two methods' assessment of MC responses to parasitic infections and pollution exposure in shorthorn sculpins (Myoxocephalus scorpius). Overall, both methods distinguished between the fish from stations with different levels of pollutants and detected the links between MC responses and parasitic infection. Traditional quantification showed relationship between MC size and body size of the fish whereas mucosal mapping detected a link between MC responses and Pb level in liver. While traditional method gave numerical density, mucosal mapping gave volumetric density of the mucous cells in the mucosa. Both methods differentiated MC population in skin from those in the gills, but only mucosal mapping pointed out the consistent differences between filament and lamellar MC populations within the gills. Given the importance of mucosal barriers in fish, a better understanding of various MC quantification methods and the linkages between MC responses, somatic health and environmental stressors is highly valuable.

Trichodinid infections in internal organs of shorthorn sculpin (Myoxocephalus scorpius) collected around an industrial harbour in Nuuk, Greenland.

Trichodinids are parasites generally found on gills and skin of a broad number of aquatic animals. Only a small number of endozoic species has been reported from the urinary tract, intestine and urogenital system in some fish, amphibians and molluscs. This is the first report on the presence of endozoic trichodinids in the spleen, kidney and liver of shorthorn sculpin (Myoxocephalus scorpius). In the present study, trichodinids displayed some of the typical morphological characteristics of endozoic trichodinids with narrow blades and straight rays of adhesive disc denticles. The parasites were observed at a relatively high prevalence (23.9%). There was a positive correlation between intensity of endozoic trichodinids in the internal organs and ectozoic trichodinids on the gills (R = 0.5, n = 46, P < 0.001) whereas there was no correlation between intensity of endozoic trichodinids and the host's body length, body weight or liver weight. Infection levels of endozoic trichodinids were not dependent upon sculpin sex and there was no effect of sampling locations on prevalence and intensity of endozoic trichodinids.

Genetic and morphological characterization of Mawsonascaris vulvolacinata n. sp. (Nematoda: Anisakidae) and associated histopathology in a wild caught cowtail stingray, Pastinachus ater.

There are limited reports of infectious agents affecting Australian cowtail stingrays. In the present study, a new species of ascaridoid nematode belonging to the genus Mawsonascaris is described. The most distinct characteristic features were observed in females (the presence of a polar spine in the eggs and a flap-like projection in the vulval area). An identification key for Mawsonascaris spp. is provided. Additionally, internal transcribed spacers (ITS) sequences were obtained for the new species. Alignment of the ITS sequence of the specimens in the present study with those deposited in GenBank showed that there exists no other highly similar sequence. Phylogenetic analyses resulted in a distinct grouping of our specimens supporting morphological distinction from previously described Mawsonascaris spp. Histology was used to investigate the pathology caused by the infection. Necrosis, inflammation and fibrosis were evident at the border of the nodules formed by parasite. A large number of parasites were present in muscularis mucosae and submucosa but not in the muscularis of the stomach. The parasites were associated with an increased inflammatory response, which was also found in the muscularis mucosae and submucosa. Similar pathology has been described in elasmobranchs infected by cestodes, although with more severe lesions.

Frequencies and expression levels of programmed death ligand 1 (PD-L1) in circulating tumor RNA (ctRNA) in various cancer types.

BACKGROUND: Precision medicine and prediction of therapeutic response requires monitoring potential biomarkers before and after treatment. Liquid biopsies provide noninvasive prognostic markers such as circulating tumor DNA and RNA. Circulating tumor RNA (ctRNA) in blood is also used to identify mutations in genes of interest, but additionally, provides information about relative expression levels of important genes. In this study, we analyzed PD-L1 expression in ctRNA isolated from various cancer types. Tumors inhibit antitumor response by modulating the immune checkpoint proteins programmed death ligand 1 (PD-L1) and its cognate receptor PD1. The expression of these genes has been implicated in evasion of immune response and resistance to targeted therapies. METHODS: Blood samples were collected from gastric (GC), colorectal (CRC), lung (NSCLC), breast (BC), prostate cancer (PC) patients, and a healthy control group. ctRNA was purified from fractionated plasma, and following reverse transcription, levels of PD-L1 expression were analyzed using qPCR. RESULTS: PD-L1 expression was detected in the plasma ctRNA of all cancer types at varying frequencies but no PD-L1 mRNA was detected in cancer-free individuals. The frequencies of PD-L1 expression were significantly different among the various cancer types but the median relative PD-L1 expression values were not significantly different. In 12 cases where plasma and tumor tissue were available from the same patients, there was a high degree of concordance between expression of PD-L1 protein in tumor tissues and PD-L1 gene expression in plasma, and both methods were equally predictive of response to nivolumab. CONCLUSIONS: PD-L1 mRNA can be detected and quantitated in ctRNA of cancer patients. These results pave the way for further studies aimed at determining whether monitoring the levels of PD-L1 mRNA in blood can identify patients who are most likely to benefit from the conventional treatment.

Comparison of heavy metals, parasites and histopathology in sculpins (Myoxocephalus spp.) from two sites at a lead-zinc mine in North East Greenland.

The former lead-zinc mine at Mestersvig, Greenland, continues to contaminate the surrounding environment despite its operations ceasing over 50 years ago. Elevated concentrations of heavy metals are found in water, sediment and biota in the terrestrial, freshwater and marine environments. To shed light on the present contamination and its potential effects on local fish we investigated gill and liver histology of sculpins (Myoxocephalus spp.) around the former mining area. Two species of sculpins were caught; shorthorn sculpins (M. scorpius; n = 16) and fourhorn sculpins (M. quadricornis; n = 17) at a contaminated site, Nyhavn, and shorthorn sculpins (M. scorpius; n = 25) at the reference site. In a previous study we found histopathological changes in the tissues of the sculpins, and we suspected this to be related to elevated heavy metal tissue concentrations. Concentrations of Fe, Hg, Mn, Pb, Se and Zn were significantly higher in sculpins at Nyhavn compared to the reference site. Reference NOED and LOEC thresholds for biochemistry, tissue lesions, growth, survival and reproduction for hepatic Hg, As, Cd and Pb from the ERED database were exceeded in both sculpin species. Histopathological investigations of the sculpins gills revealed significant increases in the prevalence of hyperplastic epithelium, inflammation, intensity of neutral and total mucus cells and chloride cells along with an increased infection of colonial Peritricha. At the contaminated Nyhavn site, fourhorn sculpins had a significantly higher prevalence of chondroplastic tissue and intensity of neutral, mixed and total mucus cells in the gills compared to the shorthorn sculpins. The data indicate that both sculpin species could be useful indicator species for environmental monitoring of metal pollution in Arctic areas. However, confounding effects of gender and species should be investigated further. Effects on other biomarkers as well as baseline measurements should be included in future environmental monitoring efforts around mining activities in Greenland.

Metal residues, histopathology and presence of parasites in the liver and gills of fourhorn sculpin (Myoxocephalus quadricornis) and shorthorn sculpin (Myoxocephalus scorpius) near a former lead-zinc mine in East Greenland.

Fourhorn sculpins (Myoxocephalus quadricornis) and shorthorn sculpins (Myoxocephalus scorpius) have been considered suitable local bioindicators for environmental monitoring studies in the Arctic. Because these species share many characteristics, data from the two species have previously been pooled when assessing marine metal contamination. A chemical and histological study was conducted on fourhorn and shorthorn sculpins collected around a contaminated lead-zinc mine at East Greenland to investigate whether there were any differences in the residues of metals, histopathology and parasites in liver and gills between the two sculpin species. The results demonstrated that concentrations of copper (Cu), zinc (Zn), mercury (Hg) and lead (Pb) were significantly higher in the fourhorn sculpins (p<0.001) while there were no significant differences for arsenic (As) or cadmium (Cd). Furthermore, density of blood vessel fibrosis (p=0.028), prevalence and density of chondroplasia (p=0.002 and p=0.005, respectively), number of mucin-containing mucous cells (p<0.001) and chloride cells (p<0.001) and mean intensity of colonial Peritricha (p<0.001) were significantly higher in fourhorn sculpin. Based on these results we suggest that pooling the two species when conducting environmental assessments is not recommended as it can lead to incorrect conclusions. We propose that a larger study investigating the biological effects of zinc-lead mining in Greenland is needed.

Reorganization of an intersubunit bridge induced by disparate 16S ribosomal ambiguity mutations mimics an EF-Tu-bound state.

After four decades of research aimed at understanding tRNA selection on the ribosome, the mechanism by which ribosomal ambiguity (ram) mutations promote miscoding remains unclear. Here, we present two X-ray crystal structures of the Thermus thermophilus 70S ribosome containing 16S rRNA ram mutations, G347U and G299A. Each of these mutations causes miscoding in vivo and stimulates elongation factor thermo unstable (EF-Tu)-dependent GTP hydrolysis in vitro. Mutation G299A is located near the interface of ribosomal proteins S4 and S5 on the solvent side of the subunit, whereas G347U is located 77 Å distant, at intersubunit bridge B8, close to where EF-Tu engages the ribosome. Despite these disparate locations, both mutations induce almost identical structural rearrangements that disrupt the B8 bridge--namely, the interaction of h8/h14 with L14 and L19. This conformation most closely resembles that seen upon EF-Tu-GTP-aminoacyl-tRNA binding to the 70S ribosome. These data provide evidence that disruption and/or distortion of B8 is an important aspect of GTPase activation. We propose that, by destabilizing B8, G299A and G347U reduce the energetic cost of attaining the GTPase-activated state and thereby decrease the stringency of decoding. This previously unappreciated role for B8 in controlling the decoding process may hold relevance for many other ribosomal mutations known to influence translational fidelity.

Abnormal nuclear envelopes in the striatum and motor deficits in DYT11 myoclonus-dystonia mouse models.

DYT11 myoclonus-dystonia (M-D) is a movement disorder characterized by myoclonic jerks with dystonic symptoms and caused by mutations in paternally expressed SGCE, which codes for ε-sarcoglycan. Paternally inherited Sgce heterozygous knock-out (KO) mice exhibit motor deficits and spontaneous myoclonus. Abnormal nuclear envelopes have been reported in cellular and mouse models of early-onset DYT1 generalized torsion dystonia; however, the relationship between the abnormal nuclear envelopes and motor symptoms are not clear. Furthermore, it is not known whether abnormal nuclear envelope exists in non-DYT1 dystonia. In the present study, abnormal nuclear envelopes in the striatal medium spiny neurons (MSNs) were found in Sgce KO mice. To analyze whether the loss of ε-sarcoglycan in the striatum alone causes abnormal nuclear envelopes, motor deficits or myoclonus, we produced paternally inherited striatum-specific Sgce conditional KO (Sgce sKO) mice and analyzed their phenotypes. Sgce sKO mice exhibited motor deficits in both beam-walking and accelerated rotarod tests, while they did not exhibit abnormal nuclear envelopes, alteration in locomotion, or myoclonus. The results suggest that the loss of ε-sarcoglycan in the striatum contributes to motor deficits, while it alone does not produce abnormal nuclear envelopes or myoclonus. Development of therapies targeting the striatum to compensate for the loss of ε-sarcoglycan function may rescue the motor deficits in DYT11 M-D patients.

Identification of eRF1 residues that play critical and complementary roles in stop codon recognition.

The initiation and elongation stages of translation are directed by codon-anticodon interactions. In contrast, a release factor protein mediates stop codon recognition prior to polypeptide chain release. Previous studies have identified specific regions of eukaryotic release factor one (eRF1) that are important for decoding each stop codon. The cavity model for eukaryotic stop codon recognition suggests that three binding pockets/cavities located on the surface of eRF1's domain one are key elements in stop codon recognition. Thus, the model predicts that amino acid changes in or near these cavities should influence termination in a stop codon-dependent manner. Previous studies have suggested that the TASNIKS and YCF motifs within eRF1 domain one play important roles in stop codon recognition. These motifs are highly conserved in standard code organisms that use UAA, UAG, and UGA as stop codons, but are more divergent in variant code organisms that have reassigned a subset of stop codons to sense codons. In the current study, we separately introduced TASNIKS and YCF motifs from six variant code organisms into eRF1 of Saccharomyces cerevisiae to determine their effect on stop codon recognition in vivo. We also examined the consequences of additional changes at residues located between the TASNIKS and YCF motifs. Overall, our results indicate that changes near cavities two and three frequently mediated significant effects on stop codon selectivity. In particular, changes in the YCF motif, rather than the TASNIKS motif, correlated most consistently with variant code stop codon selectivity.

Safety, immunogenicity and efficacy of the self-amplifying mRNA ARCT-154 COVID-19 vaccine: pooled phase 1, 2, 3a and 3b randomized, controlled trials.

Combination of waning immunity and lower effectiveness against new SARS-CoV-2 variants of approved COVID-19 vaccines necessitates new vaccines. We evaluated two doses, 28 days apart, of ARCT-154, a self-amplifying mRNA COVID-19 vaccine, compared with saline placebo in an integrated phase 1/2/3a/3b controlled, observer-blind trial in Vietnamese adults (ClinicalTrial.gov identifier: NCT05012943). Primary safety and reactogenicity outcomes were unsolicited adverse events (AE) 28 days after each dose, solicited local and systemic AE 7 days after each dose, and serious AEs throughout the study. Primary immunogenicity outcome was the immune response as neutralizing antibodies 28 days after the second dose. Efficacy against COVID-19 was assessed as primary and secondary outcomes in phase 3b. ARCT-154 was well tolerated with generally mild-moderate transient AEs. Four weeks after the second dose 94.1% (95% CI: 92.1-95.8) of vaccinees seroconverted for neutralizing antibodies, with a geometric mean-fold rise from baseline of 14.5 (95% CI: 13.6-15.5). Of 640 cases of confirmed COVID-19 eligible for efficacy analysis most were due to the Delta (B.1.617.2) variant. Efficacy of ARCT-154 was 56.6% (95% CI: 48.7- 63.3) against any COVID-19, and 95.3% (80.5-98.9) against severe COVID-19. ARCT-154 vaccination is well tolerated, immunogenic and efficacious, particularly against severe COVID-19 disease.

Recovery of tetrodotoxin from pufferfish viscera extract by amine-functionalized magnetic nanocomposites.

Tetrodotoxin (TTX) has been widely used in pharmacology, food poisoning analysis, therapeutic use, and neurobiology. In the last decades, the isolation and purification of TTX from natural sources (e.g., pufferfish) were mostly based on column chromatography. Recently, functional magnetic nanomaterials have been recognized as promising solid phases for the isolation and purification of bioactive compounds from aqueous matrices due to their effective adsorptive properties. Thus far, no studies have been reported on the utilization of magnetic nanomaterials for the purification of TTX from biological matrices. In this work, an effort has been made to synthesize Fe3O4@SiO2 and Fe3O4@SiO2-NH2 nanocomposites for the adsorption and recovery of TTX derivatives from a crude pufferfish viscera extract. The experimental data showed that Fe3O4@SiO2-NH2 displayed a higher affinity toward TTX derivatives than Fe3O4@SiO2, achieving maximal adsorption yields for 4epi-TTX, TTX, and Anh-TTX of 97.9, 99.6, and 93.8%, respectively, under the optimal conditions of contact time of 50 min, pH of 2, adsorbent dosage of 4 g L-1, initial adsorbate concentration of 1.92 mg L-1 4epi-TTX, 3.36 mg L-1 TTX and 1.44 mg L-1 Anh-TTX and temperature of 40 °C. Interestingly, desorption of 4epi-TTX, TTX, and Anh-TTX from Fe3O4@SiO2-NH2-TTX investigated at 50 °C was recorded to achieve the highest recovery yields of 96.5, 98.2, and 92.7% using 1% AA/ACN for 30 min reaction, respectively. Remarkably, Fe3O4@SiO2-NH2 can be regenerated up to three cycles with adsorptive performance remaining at nearly 90%, demonstrating a promising adsorbent for purifying TTX derivatives from pufferfish viscera extract and a potential replacement for resins used in column chromatography-based techniques.

Health-related quality of life in breast cancer patients in low-and-middle-income countries in Asia: a systematic review.

Introduction: Breast cancer remains one of the major cancers worldwide. In Asia, breast cancer is leading both incidence and mortality rates. Health-related quality of life (HRQoL) studies play an important role in clinical treatment. This systematic review aimed to summarize the evidence of HRQoL and associated factors among patients with breast cancer in low-and-middle-income countries (LMICs) in Asia. Method: Performed according to PRISMA guidelines for systematic review, the studies were searched from three databases (PubMed, Cochrane, Scopus) up to November 2020. The studies which met the predefined eligibility criteria were selected, extracted, and assessed the quality according to the Newcastle-Ottawa Scale (NOS) tool. Results and Discussion: A total of 2,620 studies were searched on the three databases, of which 28 met the selection criteria, then, were included in the systematic review. The Global Health Status (GHS) score of breast cancer patients based on the EORTC QLQ-C30 questionnaire ranged from 56.32 ± 25.42 to 72.48 ± 15.68. The overall HRQoL scores using the FACT-G and FACT-B instruments ranged from 60.78 ± 13.27 to 82.23 ± 12.55 and from 70.29 ± 13.33 to 108.48 ± 19.82, respectively. Factors affecting HRQoL of patients with breast cancer included age, education level, income, marital status, lifestyle, tumor stage, method, and treatment duration. Patient's income showed a consistent effect on HRQoL while the remaining factors reported inconsistent findings across the studies. In conclusion, the HRQoL of breast cancer patients in LMICs in Asia was low and affected by several sociodemographic factors which should be studied more in future research.

Factors associated with mask-induced dermatosis and its impact on patients' quality of life.

The COVID-19 pandemic continues to have a significant impact on society, both physically and mentally. Mask use in public places has been made mandatory in many countries, as it is one of the most effective methods to prevent transmission of the virus. However, continuous mask usage has been associated with the emergence of various cutaneous diseases in the areas of contact with the mask. This study aimed to evaluate the effect of various cutaneous manifestations resulting from mask use on patients' quality of life through a questionnaire survey. This was a cross-sectional study conducted at a hospital from May to July 2022. Patients who had experienced skin symptoms related to mask use in the past or present were included in the study. Participants completed the questionnaire with informed consent. A total of 165 participants participated in the survey, with the most common complaint being itching (58.18%), followed by acne (52.73%). Itching was found to have the highest dermatology life quality index score. Patients with skin redness had a lower quality of life compared to those without it. Prolonged mask-wearing can result in skin diseases that can seriously impair patients' quality of life.

A novel flat-panel photobioreactor for simultaneous production of lutein and carbon sequestration by Chlorella sorokiniana TH01.

Carbon dioxide is the major cause of global warming. However, it is a carbon source for phototrophic production of chemicals from microalgae. In this work, a novel flat-panel photobioreactor (FPP) was used for maximization of biomass and lutein production and CO2 fixation by a lutein-rich C. sorokiniana TH01. CO2 concentration, light intensity and aeration rate were optimized as 5%, 150 µmol/m2/s and 1 L/min, respectively. The highest biomass productivity, lutein productivity and CO2 fixation efficiency were measured for indoor single and sequential FPPs were 284 - 469 mg/L/d, 2.57 - 4.57 mg/L/d, and 63 - 100%, respectively. In a climatic condition of 25.5 - 33 °C and 86 - 600 µmol/m2/s, C. sorokiniana TH01 achieved lutein productivity and CO2 fixation efficiency of 2.1 - 3.03 mg/L/d and 56 - 81%, respectively, while the comparable biomass productivity of 284 - 419 mg/L/d was maintained. This pioneered FPP system was efficiently demonstrated for production of algal lutein from CO2.

Safety and immunogenicity of an egg-based inactivated Newcastle disease virus vaccine expressing SARS-CoV-2 spike: Interim results of a randomized, placebo-controlled, phase 1/2 trial in Vietnam.

Production of affordable coronavirus disease 2019 (COVID-19) vaccines in low- and middle-income countries is needed. NDV-HXP-S is an inactivated egg-based Newcastle disease virus (NDV) vaccine expressing the spike protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Wuhan-Hu-1. The spike protein was stabilized and incorporated into NDV virions by removing the polybasic furin cleavage site, introducing the transmembrane domain and cytoplasmic tail of the fusion protein of NDV, and introducing six prolines for stabilization in the prefusion state. Vaccine production and clinical development was initiated in Vietnam, Thailand, and Brazil. Here the interim results from the first stage of the randomized, dose-escalation, observer-blind, placebo-controlled, phase 1/2 trial conducted at the Hanoi Medical University (Vietnam) are presented. Healthy adults aged 18-59 years, non-pregnant, and with self-reported negative history for SARS-CoV-2 infection were eligible. Participants were randomized to receive one of five treatments by intramuscular injection twice, 28 days apart: 1 µg +/- CpG1018 (a toll-like receptor 9 agonist), 3 µg alone, 10 µg alone, or placebo. Participants and personnel assessing outcomes were masked to treatment. The primary outcomes were solicited adverse events (AEs) during 7 days and subject-reported AEs during 28 days after each vaccination. Investigators further reviewed subject-reported AEs. Secondary outcomes were immunogenicity measures (anti-spike immunoglobulin G [IgG] and pseudotyped virus neutralization). This interim analysis assessed safety 56 days after first vaccination (day 57) in treatment-exposed individuals and immunogenicity through 14 days after second vaccination (day 43) per protocol. Between March 15 and April 23, 2021, 224 individuals were screened and 120 were enrolled (25 per group for active vaccination and 20 for placebo). All subjects received two doses. The most common solicited AEs among those receiving active vaccine or placebo were all predominantly mild and included injection site pain or tenderness (<58%), fatigue or malaise (<22%), headache (<21%), and myalgia (<14%). No higher proportion of the solicited AEs were observed for any group of active vaccine. The proportion reporting vaccine-related AEs during the 28 days after either vaccination ranged from 4% to 8% among vaccine groups and was 5% in controls. No vaccine-related serious adverse event occurred. The immune response in the 10 µg formulation group was highest, followed by 1 µg + CpG1018, 3 µg, and 1 µg formulations. Fourteen days after the second vaccination, the geometric mean concentrations (GMC) of 50% neutralizing antibody against the homologous Wuhan-Hu-1 pseudovirus ranged from 56.07 IU/mL (1 µg, 95% CI 37.01, 84.94) to 246.19 IU/mL (10 µg, 95% CI 151.97, 398.82), with 84% to 96% of vaccine groups attaining a ≥ 4-fold increase over baseline. This was compared to a panel of human convalescent sera (N = 29, 72.93 95% CI 33.00-161.14). Live virus neutralization to the B.1.617.2 (Delta) variant of concern was reduced but in line with observations for vaccines currently in use. Since the adjuvant has shown modest benefit, GMC ratio of 2.56 (95% CI, 1.4-4.6) for 1 µg +/- CpG1018, a decision was made not to continue studying it with this vaccine. NDV-HXP-S had an acceptable safety profile and potent immunogenicity. The 3 µg dose was advanced to phase 2 along with a 6 µg dose. The 10 µg dose was not selected for evaluation in phase 2 due to potential impact on manufacturing capacity. ClinicalTrials.gov NCT04830800.