Search Results (4,966)

Background/Objectives: The lack of effective antiviral therapies for many viral infections highlights the need for the development of new antiviral agents. The broad antiviral effects of glycopeptide antibiotics (GPAs) and their derivatives have been previously described. In our studies, we investigated the in vitro viral inhibitory activity of newly synthesized GPA derivatives against Zika virus (ZIKV), chikungunya virus (CHIKV), o’nyong-nyong virus (ONNV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Methods: Antiviral activity (EC50) and cytotoxicity (CC50) of the active compounds were determined using cell-based assays. The mechanism of action of the lead compound was investigated using binding and entry assays, cell-free virion pre-incubation, a virion destabilization assay, a liposome-based capsid protection assay, and molecular docking analysis. Results: Seven of the compounds were able to inhibit ZIKV and two compounds inhibited all four tested viruses. Among them, a teicoplanin pseudoaglycone derivative, compound 7, showed the strongest antiviral activity, inhibiting all four viruses at low micromolar concentrations. Mechanistic studies demonstrated that compound 7 acts during an early stage of ZIKV infection and inhibits low-pH-triggered virus–liposome fusion. Molecular docking analysis suggested potential interactions between compound 7 and the viral envelope protein that could interfere with the conformational rearrangements required for membrane fusion. Conclusions: The present findings demonstrate that hydrophobic GPA derivatives, particularly compound 7, exhibit promising broad-spectrum antiviral activity in vitro. Whether similar mechanisms contribute to the antiviral activity against other viruses remains unknown. The studied GPA derivatives are promising candidates for further pre-clinical and clinical development as broad-spectrum antivirals. Full article

Background: Persistent cardiovascular and multisystem manifestations remain an important concern following hospitalization for coronavirus disease 2019 (COVID-19). However, the spectrum of newly identified conditions during follow-up and their relationship with acute disease severity remain incompletely characterized. This study aimed to describe cardiovascular and multisystem diagnoses, identified during short-term and long-term follow-up and to evaluate the association between acute-phase clinical characteristics, biomarkers, and subsequent outcomes. Methods: We conducted a retrospective observational cohort study including 762 adults hospitalized with laboratory-confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection between January 2021 and December 2022. Follow-up data were obtained from patients who re-presented to the same hospital during short-term follow-up (mean 4.33 months; n = 130) or long-term follow-up (mean 2.06 years; n = 186). Newly documented cardiovascular and non-cardiovascular diagnoses recorded during routine clinical care were analyzed separately for each follow-up cohort. Multivariable logistic regression was used to identify predictors of in-hospital mortality and cardiovascular outcomes. Results: At least one newly documented diagnosis was identified in 120/130 patients (92.3%) during short-term follow-up and in 175/186 patients (94.1%) during long-term follow-up. Cardiovascular diagnoses were identified in 32.3% and 45.2% of patients attending short-term and long-term follow-up, respectively. Hypertension and atherosclerosis were the most frequent cardiovascular diagnoses during short-term follow-up, whereas heart failure and ischemic heart disease predominated among patients attending long-term follow-up. Pulmonary fibrosis was the most common non-cardiovascular diagnosis at both follow-up periods. Elevated D-dimer and fibrinogen levels during acute COVID-19 were independently associated with in-hospital mortality, whereas acute-phase NT-proBNP was not independently associated with cardiovascular diagnoses identified during follow-up. Conclusions: Patients who re-presented for clinical evaluation after hospitalization for COVID-19 exhibited a substantial burden of newly documented cardiovascular and multisystem diagnoses. Given the retrospective design, independent follow-up cohorts, and absence of a non-COVID control group, these findings should be interpreted as observational post-hospitalization data rather than evidence of causal or progressive post-COVID-19 disease. Prospective controlled longitudinal studies are needed to better define the long-term health consequences of SARS-CoV-2 infection. Full article

Long COVID affects an estimated 10–20% of SARS-CoV-2 survivors with heterogeneous, multi-system symptoms persisting for months to years, contributing to significant workforce disruption and reduced functional capacity. This exploratory study identified symptom clusters following SARS-CoV-2 infection, examined associated personal and clinical characteristics, and assessed work status across clusters. Among 273 individuals from a single clinical site, we used baseline surveys to capture long COVID symptoms and 2-week follow-up surveys to assess work status, and applied K-means clustering to identify symptom groupings. Three preliminary clusters emerged: Cluster 1 (“brain fog”), characterized by fatigue (96%), difficulty remembering (97%), and difficulty concentrating (94%); Cluster 2 (“undifferentiated”), with low prevalence across all symptoms; and Cluster 3 (“persistent acute”), marked by cough (92%), congestion (80%), headaches (78%), and body aches (78%). Notably, among Cluster 1 (“brain fog”) respondents, 44% reported not working, and approximately half attributed their work absence to COVID-related symptoms. These hypothesis-generating findings suggest that neurocognitive symptom clusters may be associated with greater work absence in some individuals, though the small number of respondents limits firm conclusions. The findings suggest that targeted occupational rehabilitation strategies may warrant further investigation as potential strategies for individuals experiencing post-infectious cognitive impairment following SARS-CoV-2 infection. Full article

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative pathogen of coronavirus disease 2019 (COVID-19). Toll-like receptor 8 (TLR8), which is located on the X chromosome, plays as a key mediator of the innate immune response. Genetic variation in the form of single-nucleotide polymorphisms (SNPs) within TLR8 has been linked to changes in the transcriptional activity of this gene. Thus, we aimed to identify TLR8 SNPs in the proximal promoter region and investigate whether these SNPs are associated with COVID-19 case status in a Korean population. We performed amplicon sequencing to investigate the genotypes and allele frequencies of regulatory SNPs in COVID-19 patients (n = 191) and the control group (n = 173). Four polymorphic sites, rs5741883, rs186566524, rs3764879, and rs3764880, were identified within the TLR8 proximal promoter. Given the X-linked nature of this locus, allele and genotype frequencies were computed independently by sex. Notably, the minor C allele at rs3764879 occurred at a markedly reduced rate among male patients (10%) relative to male controls (24%), corresponding to an OR of 0.35 (95% CI 0.15–0.8; p = 0.018; q = 0.036). A parallel pattern emerged for rs3764880, where the minor A allele was likewise underrepresented in male patients (9%) versus male controls (24%), yielding an OR of 0.3 (95% CI 0.12–0.7; p = 0.01; q = 0.036). By contrast, neither genotype nor allele distributions differed significantly between female patients and female controls for any of the four variants. These results indicate that the TLR8 polymorphisms rs3764879 and rs3764880 may be associated with COVID-19 case status among Korean males, although further validation in larger, independent cohorts is required. Full article

Rhino-orbital mucormycosis is a rare, life-threatening opportunistic fungal infection, typically affecting immunocompromised patients. During the COVID-19 pandemic, increased cases were mainly linked to SARS-CoV-2 infection, diabetes, and corticosteroid exposure. We report a severe case in a previously healthy 44-year-old immunocompetent man who developed acute left-sided exophthalmos, ophthalmoplegia, severe visual loss, and systemic deterioration 10 days after AZD1222 COVID-19 vaccination. Clinical and radiologic findings suggested invasive rhino-orbital fungal disease, prompting immediate liposomal amphotericin B, broad-spectrum antibiotics, urgent endoscopic sinus surgery, and repeated orbital–sinonasal debridements with amphotericin B irrigation. Histopathological examination demonstrated broad aseptate hyphae with tissue necrosis, consistent with mucormycosis, while fungal culture and ITS sequencing identified Rhizopus arrhizus as the causative species. Therapy was later adjusted to include isavuconazole and antibacterial coverage for persistent inflammation and secondary colonization. Orbital and systemic improvement occurred within the first week, with globe preservation and marked proptosis reduction at 6 months, despite persistent ophthalmoplegia and residual light perception. Isavuconazole was continued for 2 years, with no recurrence during 3 years of follow-up. Although causality with vaccination cannot be established, the temporal association and biological plausibility warrant further investigation. Early suspicion and prompt combined medical–surgical management are essential in rapidly progressive orbital cellulitis. Full article

Persistent infection with high-risk human papillomavirus (HPV), particularly HPV16, is a major driver of HPV-associated cancers; however, strategies for treating established HPV-induced tumors remain scarce. Here, we developed a DNA-based vaccine linking the SARS-CoV-2 spike (S) protein with an HPV16 E7 epitope (aa 49-57) to simultaneously induce antiviral humoral immunity and antitumor cellular responses. We generated 2 constructs, S-E7 and S-RE7, with the latter incorporating a furin cleavage site (R) to enhance antigen processing. In vitro, S-RE7 significantly enhanced E7-specific CD8⁺ T cell activation compared to S-E7, highlighting the importance of the furin sequence. In vivo, both S-linked vaccines elicited robust E7-specific CD8⁺ T cell responses and provided complete protection against TC-1 tumor challenge in a prophylactic murine model, with long-lasting immunity upon tumor rechallenge. In therapeutic settings, vaccination with S-E7 or S-RE7 significantly suppressed tumor growth, extended survival, and reduced circulating myeloid-derived suppressor cells (MDSCs), indicating alleviation of systemic immunosuppression. Notably, S-RE7 demonstrated faster antitumor effects overall in early tumor progression. In addition to cellular immunity, both constructs induced high levels of anti-spike antibodies, with S-RE7 eliciting approximately fourfold higher responses than S-E7. Furthermore, S-RE7 effectively boosted pre-existing anti-spike immunity in mice that were previously vaccinated. This “two-in-one” strategy represents a promising and versatile platform for the prevention and treatment of HPV-associated cancers while maintaining preparedness against potential SARS-CoV-2. Full article

Background/Objectives: Clostridioides difficile infection (CDI) is an increasingly recognised nosocomial complication in patients hospitalised with coronavirus disease 2019 (COVID-19), driven by broad-spectrum antibiotic exposure, corticosteroid use, and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-related intestinal dysbiosis. The contribution of underlying cardiovascular comorbidities, particularly heart failure, to CDI susceptibility in hospitalised COVID-19 patients remains insufficiently characterised. We aimed to evaluate the prevalence, risk factors, and clinical impact of CDI in hospitalised COVID-19 patients at a tertiary Romanian infectious diseases centre, with a specific focus on cardiovascular disease and modifiable antimicrobial-prescribing factors. Methods: This single-centre retrospective observational cohort study enrolled 395 consecutive adult patients hospitalised with SARS-CoV-2 infection confirmed by reverse transcription polymerase chain reaction (RT-PCR) at the “Victor Babeș” Clinical Hospital for Infectious Diseases and Pneumophthisiology, Timișoara, Romania, between 1 March 2020 and 31 December 2024. Patients were stratified into a CDI group (n = 24) and a non-CDI group (n = 371) on the basis of hospital-onset CDI. Demographic, clinical, laboratory, therapeutic, and outcome variables were extracted from electronic medical records. Continuous variables were compared using Student’s independent-samples t-test, categorical variables using Fisher’s exact test; odds ratios (ORs) with exact 95% confidence intervals (CIs) were computed for all binary comparisons, and a parsimonious multivariable logistic regression was used to adjust the antibiotic-exposure effect for age. Temporal relationships between CDI onset and sepsis documentation were also analysed. A two-sided p-value < 0.05 was considered statistically significant. Results: CDI was identified in 24 patients (prevalence 6.1%). The CDI and non-CDI groups were comparable in age (71.1 ± 10.2 vs. 71.7 ± 11.4 years; p = 0.817), sex distribution (50.0% vs. 45.8% female; p = 0.833), and vaccination status (p = 0.383). Heart failure prevalence did not differ between groups (29.2% vs. 26.7%; OR 1.13, 95% CI 0.46–2.81; p = 0.813). Any antibiotic therapy was strongly associated with CDI (95.8% vs. 70.6%; OR 9.57, 95% CI 1.28–71.74; p = 0.004), as was longer duration of antibiotic therapy (8.1 ± 2.2 vs. 5.2 ± 3.7 days; p < 0.001). In the multivariable model, each additional day of antibiotic therapy was independently associated with a 13.6% increase in the odds of CDI (adjusted OR 1.14 per day, 95% CI 1.03–1.26; p = 0.013) after adjustment for age. Piperacillin/tazobactam accounted for 65.2% (15/23) of the recorded pre-CDI broad-spectrum antibiotic regimens among antibiotic-exposed CDI patients. Documented sepsis was substantially more frequent in CDI patients (95.8% vs. 15.4%; p < 0.001) and length of hospitalisation was prolonged (15.6 ± 8.2 vs. 12.0 ± 8.1 days; p = 0.038). In-hospital mortality did not differ significantly (4.2% vs. 7.5%; p = 1.000). Conclusions: Hospital-onset CDI complicated 6.1% of hospitalised COVID-19 admissions and was independently associated with the cumulative duration of antibiotic therapy. Heart failure was not significantly associated with CDI in this cohort; however, given the limited number of CDI events, this should be interpreted as absence of evidence rather than evidence of absence. CDI was also associated with prolonged hospitalisation and high co-occurrence of documented sepsis, although causality cannot be inferred from the retrospective design. These findings support strengthened antibiotic stewardship and targeted CDI surveillance in COVID-19 inpatient wards. Full article

Background: The BNT162b2 vaccine is safe and effective for COVID-19 prevention. BNT162b2 safety and immunogenicity have been evaluated in immunocompromised individuals in real-world observational studies, particularly in pediatric populations, but not in clinical trials. Methods: This phase 2b single-arm trial descriptively evaluated a Dose 3 (age-appropriate) BNT162b2 primary series with a Dose 4 in immunocompromised individuals 2–<5, 5−<12, 12–<18, and ≥18 years of age without a previous clinical or microbiological COVID-19 diagnosis. Primary objectives were to describe immune responses, reactogenicity, and adverse events following vaccination. Results: Out of 124 participants enrolled, 119 received Dose 3 and 90 received Dose 4. Among participants without evidence of past SARS-CoV-2 infection, neutralizing geometric mean titers (GMTs) and geometric mean fold rises (GMFRs) against the SARS-CoV-2 ancestral strain ranged from 344.6 to 1584.4 and 7.9 to 36.4 at 1 month after Dose 3 and from 1474.0 to 4157.9 and 31.0 to 95.6 at 1 month after Dose 4, respectively, across age groups. Among participants with or without evidence of past infection, GMTs and GMFRs ranged from 787.1 to 2940.6 and 9.6 to 54.3 at 1 month after Dose 3 and from 1031.3 to 13,457.1 and 9.1 to 220.0 at 1 month after Dose 4. Percentages of participants with or without evidence of past SARS-CoV-2 infection achieving seroresponse ranged from 50.0 to 92.9% at 1 month after Dose 3, and from 75.0 to 100% and 33.3 to 100.0% at 1 and 6 months after Dose 4 across age groups, respectively. No new safety signals were identified. Conclusions: BNT162b2 was immunogenic, increasing GMTs in immunocompromised individuals ≥2 years old, particularly after Doses 3 and 4. GMT increases were generally similar across age groups and disease subsets. Three or four BNT162b2 doses had a favorable risk-benefit profile in this population. Full article

The outbreak of coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has emerged as one of the most significant global health crises in recent history. Coronaviruses are a diverse group of RNA viruses classified into alpha, beta, gamma, and delta genera, with SARS-CoV-2 belonging to the beta-coronavirus family. The virus exhibits high transmissibility and causes a wide spectrum of clinical manifestations ranging from mild respiratory symptoms to severe complications such as acute respiratory distress syndrome, multi-organ failure, and death, particularly among elderly and immunocompromised individuals. Structurally, SARS-CoV-2 possesses a large single-stranded RNA genome encoding major structural proteins, including spike (S), envelope (E), membrane (M), and nucleocapsid (N) proteins, which play critical roles in host-cell recognition and viral infection. Understanding the molecular mechanisms of virus–host interactions, especially protein–protein interactions (PPIs), is essential for uncovering viral pathogenesis and identifying potential therapeutic targets. Traditional experimental techniques for PPI detection, such as yeast two-hybrid and affinity purification methods, are often expensive, labor-intensive, and prone to inaccuracies. Consequently, computational approaches based on machine learning (ML) and deep learning (DL) have gained significant attention for efficient and scalable PPI prediction. These methods use diverse biological information, including protein sequences, structural features, genomic data, Gene Ontology annotations, and interaction networks, to model complex biological relationships. This survey reviews computational approaches to PPI prediction, highlighting ML- and DL-based techniques, methodological advances, performance evaluation practices, and limitations that affect benchmark comparability. It also discusses biological databases and data sources commonly used in PPI studies and explicitly considers how models trained in coronavirus-centered settings may generalize to other viral families with different mechanisms of host interaction. Full article

The concurrent circulation of influenza A virus (IAV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has unveiled complex host–pathogen interactions governed by temporal dynamics of innate immune activation. This narrative review synthesizes evidence from human air–liquid interface (ALI) epithelial models, animal studies (hamster, ferret), clinical cohorts, and randomized controlled trials (2015–2026) to delineate the molecular mechanisms underlying viral interference between these two major respiratory pathogens. Prior IAV infection induces a robust type I/III interferon (IFN) response and broad interferon-stimulated gene (ISG) upregulation that restricts subsequent SARS-CoV-2 replication within a critical 24–72 h temporal window. Conversely, SARS-CoV-2 employs a multi-layered immune evasion strategy that blunts IFN induction, providing minimal heterologous protection. Simultaneous co-infection tends to exacerbate disease severity. Host genetic determinants, including OAS1 and TLR7 variants, modulate interference capacity. Therapeutically, early pegylated IFN-λ shows clinical benefit, while experimental evidence from in vitro and animal models suggests oseltamivir may paradoxically reduce IAV-induced interference. These findings underscore the need for multi-pathogen diagnostics, temporally informed clinical decision-making, and IFN-based therapeutic strategies during co-circulation periods. Full article

Objectives: The ongoing evolution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the current treatment limitations—particularly the emergence of drug resistance and the reduced efficacy of some existing drugs against new variants—highlight the need for novel antiviral strategies with novel action mechanisms. Fusion inhibitors that disrupt six-helix bundle (6-HB) formation during viral entry represent a promising approach. Posaconazole, an antifungal agent, has been identified as a weak fusion inhibitor, but suffers from poor membrane permeability and modest activity. This study aimed to enhance its antiviral potency by conjugating it with cell-penetrating polyarginine peptides and to investigate the mechanism of action. Methods: A series of posaconazole-polyarginine conjugates were synthesized via click chemistry. Antiviral activity was evaluated using pseudotyped SARS-CoV-2 Omicron XDV in HEK293T cells. Mechanisms were investigated by circular dichroism, native PAGE, size-exclusion HPLC, molecular docking, and isothermal titration calorimetry. Metabolic stability was assessed using hepatic microsomes. Results: Posa-R8 exhibited potent antiviral activity comparable to the clinical candidate EK1, with minimal cytotoxicity. Mechanistic studies confirmed that Posa-R8 binds the HR2 region of the spike protein, disrupts 6-HB formation, and inhibits membrane fusion. It also showed strong lipid bilayer affinity and improved phase I metabolic stability over EK1. Conclusions: Polyarginine conjugation enhances the membrane-binding affinity and antiviral efficacy of posaconazole. Posa-R8 represents a promising lead for developing next-generation SARS-CoV-2 fusion inhibitors. Full article

Objectives: We aimed to systematically review and meta-analyze the impact of COVID-19 infection on cardiorespiratory fitness (CRF): (1) within-athlete (the same participants before and after infection), and (2) between-athlete (infected vs. healthy reference participants). Methods: In this systematic review (PROSPERO Registry: CRD42024540430) we included observational studies enrolling recreational or competitive athletes ≥18 years old with laboratory confirmation of SARS-CoV-2 infection. The primary outcome was change in relative maximal oxygen uptake (VO_2max). Secondary outcomes included changes in absolute VO_2max, maximal ventilation (VE_max), and maximal heart rate (HR_max). We searched Embase, PubMed, Medline, Scopus, and Web of Science up to August 9th, 2025. Risk of bias was assessed with the JBI critical appraisal tool. Meta-analyses were performed with a random-effects model. Results: Twelve studies enrolling a total of 1595 participants met the eligibility criteria. COVID-19 infection was associated with lower relative VO_2max (MD = −1.83 mL·kg⁻¹·min⁻¹; 95%CI [−3.16, −0.49]; p = 0.007; I² = 54%) and absolute VO_2max (MD = −0.15 L·min⁻¹; 95%CI [−0.29, −0.01]; p = 0.03; I² = 0%). COVID-19 infection was associated with lower VE_max (MD = −7.99 L·min⁻¹; 95%CI [−12.94, −3.04]; p = 0.002; I² = 0%) but not with HR_max (MD = −0.34 bpm; 95%CI [−1.54, 0.86]; p = 0.58; I² = 0%). High heterogeneity of included studies was addressed with subgroup analyses. The risk of bias in most studies was high. The certainty of evidence was very low for each outcome. Conclusions: COVID-19 infection in athletes was associated with reduced VO_2max and VE_max. The relationships were highly dependent on the quality of the studies. CRF and athlete profile should be considered when making shared decisions regarding safe return to sport after infection. Full article

Polyamines such as putrescine, spermidine, and spermine play essential roles in most living organisms. They regulate fundamental processes, like cell proliferation, differentiation, growth, gene expression (DNA/RNA stability, transcription, and translation), and signal transduction. As important regulators, polyamines influence development, stress responses, and the progression of health and disease, including cancer and aging. These positively charged molecules have been extensively studied for decades. In humans, polyamines are often researched as potential therapeutic targets for diseases such as malaria and, more recently, COVID-19. Obligate parasites, such as Plasmodium falciparum, and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), rely on host cellular machinery for survival, replication, and growth. Notably, both hosts and pathogens need polyamines to sustain these processes. This review summarizes current advances in understanding the roles of polyamines in humans, viruses, and obligate parasites. It also explores strategies to prevent pathogens from hijacking host polyamine metabolism as a way toward developing novel therapeutic interventions. Full article

The co-circulation of respiratory viruses, including SARS-CoV-2, influenza A/B, and respiratory syncytial virus (RSV), represents a significant global health challenge that requires rapid, accurate, and differential diagnosis to support infection control and appropriate clinical decision-making. This narrative review summarizes emerging multimodal point-of-care testing (POCT) strategies for the detection and management of these respiratory viruses. Relevant studies were identified through literature searches of major scientific databases, including PubMed, Scopus, and Web of Science, focusing on recent advances in molecular diagnostics, biosensors, microfluidics, and digital health technologies. To improve clinical interpretation and comparative assessment, current POCT platforms were organized into four operational tiers based on infrastructure dependence, degree of portability, and level of decentralization of testing. Tier 1 (Professional Clinical Systems) includes fully integrated automated molecular diagnostic platforms designed for use in hospital and emergency care settings. Tier 2 (Field-Deployable Systems) comprises portable molecular and isothermal amplification technologies designed for use in decentralized or resource-limited environments. Tier 3 (Hardware-Lite Assays) includes simplified diagnostic approaches that minimize instrument requirements and are suitable for near-patient or low-infrastructure settings. Tier 4 (Consumer-Digital Diagnostics) encompasses emerging smartphone- and IoT-integrated diagnostic platforms that support user-driven testing and digital health connectivity. This tier-based framework reflects a proposed stratification of POCT technologies along a decentralization continuum and aims to facilitate comparison and selection of diagnostic strategies across diverse healthcare settings. Full article

Background: While vaccines are designed to elicit targeted immune responses, in some cases, the immunogenic molecules employed can inherently interact with broader host cellular pathways as a secondary consequence. This phenomenon can be exemplified by COVID-19 vaccines. COVID-19 vaccines, including mRNA platforms, use the SARS-CoV-2 spike protein as an immunogen to induce the production of neutralizing antibodies. The spike protein binds the ACE2 (angiotensin-converting enzyme 2) receptor on human cells, mediating viral entry and infection. ACE2 is widely expressed across multiple tissues and is a key component of the renin–angiotensin–aldosterone system (RAAS) that acts as a homeostatic regulator of systemic and local blood flow, blood pressure, cardiac function, fluid balance and immunity. Some studies have proposed the interaction between the spike protein and ACE2 as a possible contributing factor to rare adverse effects observed following COVID-19 vaccination, including myocarditis, pericarditis, thrombosis, and reported alterations in blood pressure, though these mechanisms remain to be fully elucidated. Objectives: As a proof-of-concept approach in vaccine antigen development, we engineered SARS-CoV-2 spike mutants with impaired binding to the host receptor ACE2. Methods: By rational design, we produced and validated in vitro and in vivo spike point mutants that do not effectively bind ACE2. Results: The engineered spike mutants do not effectively bind the human entry receptor ACE2 while retaining the immunogenic properties equal to or better than the wild type spike and thus generate a protective response in animals when used as a vaccination agent. Conclusions: By establishing a straightforward molecular strategy for rational vaccine design, this work demonstrates the feasibility of limiting specific antigen–host receptor interactions while maintaining immunogenicity. This approach may be applicable to future vaccination strategies where antigen interaction with host cells could potentially interfere with physiological pathways. Full article